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Polyethylene (PE), including high‐density polyethylene (HDPE) and low‐density polyethylene (LDPE), makes up a significant part of post‐consumer plastics in municipal solid waste, presenting challenges for traditional recycling methods due to a wide range of melt flow properties and poor interfacial adhesion between the different resin, which often leads to low quality products (downcycling). In this study, a method is proposed to modify the molecular structure of post‐consumer PE (rHDPE and rLDPE) and their blends by using a straightforward organic peroxide crosslinking technique with 1 phr of dicumyl peroxide (DCP). Different rHDPE/rLDPE blend weight ratios (0/100, 20/80, 40/60, 50/50, 60/40, 80/20, and 100/0) were prepared using a combination of co‐rotating twin‐screw extrusion and pulverization. The final parts were produced via rotomolding where both the forming and crosslinking processes occurred concurrently. Subsequently, the materials were characterized in terms of chemical, thermal, and mechanical properties. It was found that the tensile strength (228%), tensile modulus (345%), flexural strength (145%), and flexural modulus (251%) increased by crosslinking the 80% wt. rHDPE (x‐rHDPE). Conversely, the gel content increased by 17%, thermal resistance by 37.2%, and the impact strength by 93% with 80% wt. rLDPE (x‐rLDPE). It can be concluded that a balance between the properties occurs as the addition of DCP improved both the interfacial adhesion and melt properties of rHDPE/rLDPE blends. This innovative approach represents a simple and straightforward method to upcycle mixed plastics (PE) streams, especially for rotomolding applications. It also offers promising avenues for sustainable waste management and material reuse. [ABSTRACT FROM AUTHOR]

Ethylene‐propylene‐diene monomer rubber, grafted with maleic anhydride functions (EPDM‐g‐MA) was organically reinforced by reactive extrusion from the in situ synthesis of a polyimide (PI) phase. The blends were reactively processed at 200°C in a twin‐screw extruder, with the PI content varying from 5 to 40 wt%. Transmission Electron Microscopy (TEM) revealed a very fine nodular dispersion of the PI phase with diameters ranging from 130 to 240 nm depending on the PI concentration. The reinforcement of the elastomer was evidenced with a sharp increase of the Young's modulus and the tensile strength, and the stiffness of the material was further increased with the PI content. The linear viscoelastic regime, as measured by the variation in storage modulus as a function of strain, was unaffected by this organic reinforcement, thus opening up an original way of controlling the Payne effect. Additionally, the cross‐linking of the blend with 20 wt% of PI with dicumyl peroxide (DCP) showed that the PI phase did not impact the creation of the cross‐linked network. The decrease of the swelling ratio and the improvement of the elastic recovery suggested that EPDM‐g‐PI copolymers can create a second network in the material, resulting in a higher apparent cross‐linking density. The mechanical properties of the cured blend showed a doubling of the Young's modulus and maximal stress values compared to those obtained for the pure matrix as well as a constant strain at break. Highlights: Ethylene‐propylene‐diene monomer rubber, grafted with maleic anhydride functions (EPDM‐g‐MA) was organically reinforced by reactive extrusion.The reinforcement was obtained from the in situ synthesis of a polyimide (PI) phase.The Young's modulus of cross‐linked EPDM containing 20 wt% PI was doubled.The linear viscoelastic regime was unaffected by this organic reinforcement.This original way of reinforcement opens the control of the Payne effect. [ABSTRACT FROM AUTHOR]

Different blends of poly(lactic acid) (PLA) and polybutylene succinate (PBS), and their harakeke fiber‐reinforced composites were studied. Scanning electron microscopy showed that the PLA and PBS are incompatible and poorly miscible. Tensile strength and tensile modulus of the blends were found to reduce as the amount of PBS increased. Reinforcement alone was not able to significantly improve the mechanical performance of the blend, which is lower than that of neat PLA. Therefore, simultaneous reinforcement and reactive compatibilization were performed using harakeke fiber, and dicumyl peroxide as reinforcement and compatibilizer, respectively. This produced about 201% increase in the crystallinity of PLA. Compared with the PLA/PBS blend, the dual effect approach increased the tensile strength and tensile modulus by 31% and 148%, respectively. Likewise, dynamic mechanical analysis showed that the thermomechanical properties of the composite greatly improved. [ABSTRACT FROM AUTHOR]

In the present work we have investigated the oligomerization process of Fischer-Tropsch synthesis products - gasoline (C5-C10) and diesel (C11-C18) hydrocarbon fractions with a total olefin content (consisting mainly olefins with a branched isomeric chain) of 79.3 and 31.8 wt.%, respectively. Oligomerization was carried out by radical initiation method using azobisisobutyronitrile, benzoyl peroxide, dicumyl peroxide and methyl ethyl ketone peroxide (Butanox M-50) as initiators. It was established that the yield of the oligomerization process depending on the initiator used decreases in the following order: azobisisobutyronitrile > benzoyl peroxide > dicumyl peroxide > Butanox M-50. It was determined that when the oligomerization is carried out in polar solvents such as acetone and dichloromethane the yield of product increases by ~2.1 and ~1.7 times, respectively, while at the same time adding a non-polar solvent such as tetrachloromethane to the reaction mixture decreases the product yield by ~2.0 times. The optimal technological parameters for carrying out oligomerization process of synthetic gasoline and diesel fractions were determined: where azobisisobutyronitrile, content 0.5 wt.%., is used as an initiator, acetone as solvent, with reaction temperature of 200 °C, and duration of 12 hrs. under inert atmosphere. The product yield from the diesel fraction is 39.5 %, and from the synthetic gasoline fraction - 36.0 %. At the same time, in terms of characteristics, the oligomerization product of the diesel fraction showed properties similar to commercially available Base oil 3cSt (Group III), and the gasoline fraction showed properties on par with the commercially produced PAO-2 (Group IV). [ABSTRACT FROM AUTHOR]

It is highly desired yet challenging to develop advanced elastomers with excellent mechanical properties, including high strength and toughness. In this work, strong and tough rubber/rubber compound vulcanizates were facilely prepared by blending ethylene-propylene-methylene (EPM) and isoprene rubber (IR) together with dicumyl peroxide (DCP) and subsequent vulcanization, since both EPM and IR can be vulcanized synchronously by DCP and the well-crosslinked structure of EPM/IR vulcanizate presented a stable phase separation state. By tuning their composition, EPM/IR vulcanizates could present remarkably improved mechanical strength and toughness, as well as excellent energy dissipation and deformation recovery abilities. Furthermore, EPM/IR/SiO2 nanocomposites with better properties were prepared by introducing silica nanoparticles into EPM/IR vulcanizates. It was found that the high toughness and strength of EPM/IR vulcanizates and EPM/IR/SiO2 nanocomposites mainly resulted from the combination of stretchability of EPM and strain hardening of IR. Their excellent energy dissipation and deformation recovery abilities were related to the macromolecular characteristics of EPM and IR, compatibility between EPM and IR, and their crosslinking dynamics. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is the main candidate among the synthetic polymers for food packaging application. However, its poor processing and mechanical performance have limited its practical application. Here, we prepared a supertough thermoplastic vulcanizate (TPV) using PLA and ethylene vinyl acetate (EVA) copolymer with optimized EVA composition. The dynamic curing agent, dicumyl peroxide (DCP), was used as EVA-DCP masterbatch to improve its curing efficiency. Cellulose nanocrystals (CNCs) were further used as the biocompatible and renewable nanofiller, used in the form of PLA-CNC masterbatch, leading to improved mechanical strength and shape memory performance (SMP). Dynamically curing the thermoplastic elastomer (TPE) precursors diminished the temperature-dependency of elastic modulus ( E ′ ) prior to PLA's glass transition. Thus, improving the shape fixity (FR) of the TPVs compared to their TPEs as the TPVs showed F R > 98 % while the TPV60 (60% PLA) showed the highest FR of 100%. The TPVs showed higher recovery ratio (RR) with R R > 87.25 % with the TPV60 containing 1.5% CNC, which showed the highest RR of 94.1%. The mechanical performance analyses showed that the optimized TPV: CNC possesses a supertough nature, achieved by tuning the rheological behavior and morphology of the final TPVs. The results were quite promising for smart food packaging applications. [ABSTRACT FROM AUTHOR]

To solve the problems on resource utilization and environmental pollution of waste concrete and waste polypropylene (PP) plastics, the recycling of them into asphalt pavement is a feasible approach. Considering the high melting temperature of waste PP, this study adopted a thermal-and-mechanochemical method to convert waste PP into high-performance warm-mix asphalt modifiers (PPMs) through the hybrid use of dicumyl peroxide (DCP), maleic anhydride (MAH), and epoxidized soybean oil (ESO) for preparing an asphalt mixture (RCAAM) containing recycled concrete aggregate (RCA). For the prepared RCAAM containing PPMs, the mixing temperature was about 30 °C lower than that of the hot-mix RCAAM containing untreated PP. Further, the high-temperature property, low-temperature crack resistance, moisture-induced damage resistance, and fatigue resistance of the RCAAM were characterized. The results indicated that the maximum flexural strain of the RCAAM increased by 7.8~21.4% after using PPMs, while the sectional fractures of the asphalt binder were reduced after damaging at low temperature. The use of ESO in PPMs can promote the cohesion enhancement of the asphalt binder and also improve the high-temperature deformation resistance and fatigue performance of the RCAAM. Notably, the warm-mix epoxidized PPMA mixture worked better close to the hot-mix untreated PPMA mixture, even after the mixing temperature was reduced by 30 °C. [ABSTRACT FROM AUTHOR]

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a very promising biodegradable copolyester of high interest in food packaging. Its inherent brittleness and narrow processing window make it necessary to blend it with flexible biopolyesters, such as poly(butylene succinate-co-adipate) (PBSA). However, the resultant biopolyester blends are thermodynamically immiscible, which impairs their performance and limits their applications. This study is the first to explore the use of poly(butylene succinate-co-adipate) grafted with maleic anhydride (PBS-g-MAH) as a novel reactive additive to compatibilize PHBV/PBSA blends. The compatibilizer was prepared by a reactive melt-mixing process of PBSA and maleic anhydride (MAH) using dicumyl peroxide (DCP) as an organic radical initiator, achieving a grafting degree (Gd) of 5.4%. Biopolyester blend films were thereafter prepared via cast extrusion and their morphological, thermal, mechanical, and barrier properties were characterized. Compatibilization by PBSA-g-MAH was confirmed by observing an improved phase interaction and lower dispersed domain sizes in the blends with 15 wt% PBSA. These compatibilized PHBV/PBSA blends were thermally stable up to 285 °C, showed enhanced ductility and toughness, as well as providing an improved barrier against water and limonene vapors and oxygen. These findings suggest that the use of MAH-grafted biopolyesters can represent an effective strategy to improve the properties of biopolyester blends and open up new opportunities for the application of PHBV-based formulations for food packaging. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) exhibit valuable mechanical properties like high stiffness and tensile strength but are sensitive to processing parameters. The influence of these parameters was evaluated by measuring the variation of melt viscosity during processing. For all experiments, in the absence of chain extenders, the decrease in melt viscosity clearly showed the degradation of polymers during processing. This is more pronounced for PHBV than PLA. In order to compensate for the degradation and, if possible, improve the melt strength of these bio-based polymers, two chain extenders have been evaluated: dicumyl peroxide (DCP) and a polymeric epoxy acrylate chain extender (Joncryl® ADR 4400). DCP reacts quickly with PLA and PHBV, while the epoxy-acrylate chain extender shows slower kinetics. For the PLA, with both investigated chain extenders, an increase in the molecular weight as compared with the virgin polymer and eventually the apparition of an insoluble fraction due to branching and crosslinking are observed. In the case of PHBV, the degradation is compensated by using DCP, requiring short processing times. No significant increase in molecular weight was observed when using the polymeric epoxy acrylate chain extender, requiring longer residence times, although the apparition of a gel fraction suggests the presence of branching and crosslinking. [ABSTRACT FROM AUTHOR]

Rubber compounds based on acrylonitrile‐butadiene rubber were filled with biopolymer fillers, namely kraft lignin, and calcium lignosulfonate. For cross‐linking of rubber compounds, sulfur curing system, dicumyl peroxide, and combination of dicumyl peroxide with trimethylolpropane trimethacrylate were used. The main objective of the work was to investigate the influence of biopolymer fillers content and curing system composition on vulcanization process of rubber compounds, cross‐link density, morphology, and physical‐mechanical properties of vulcanizates. The results revealed that rubber compounds filled with calcium lignosulfonate can be efficiently cured with sulfur as well as peroxide curing systems. Modulus, hardness, and elongation at break were strongly dependent on cross‐link density. Vulcanizates filled with high content of lignosulfonate exhibited comparable values of tensile strength, regardless of the curing system applied. The application of kraft lignin into peroxide systems cured rubber compounds resulted in undesirable reactions between functional groups of the biopolymer and peroxide radicals. Depletion of peroxide radicals resulted in significant deceleration of curing process and decrease in cross‐link density of vulcanizates. This was reflected in typical change of physical‐mechanical characteristics, decrease in modulus and hardness, and increase in elongation at break. Very good adhesion and compatibility between the kraft lignin and the rubber matrix resulted in enhancement of tensile behavior of vulcanizates cured with sulfur system. [ABSTRACT FROM AUTHOR]

Cross‐linking of polymers is an efficient method to tailor the end‐use properties of polymer materials. Cross‐linking using a chemical agent, e.g., dicumyl peroxide (DCP), allows for a spatially uniform network formation in the melt state. In addition, it is also associated with side reactions which influence the final properties of the plastic part. This work investigates the influence of DCP concentration on the tribological properties of a cross‐linked low‐density polyethylene (LDPE) grade. In particular, high DCP concentrations up to 20 phr are chosen in order to explore the effect of a high degree of cross‐linking. The viscoelastic properties below and above the melting temperature are studied in detail to support the interpretation of the tribological results. Rheological investigations allow one to monitor the cross‐linking of the long‐chain branched LDPE. The data and the subsequent optical analysis show that wear already is significantly reduced at a low DCP concentration of 1 phr because of the covalent bonds caused by cross‐linking. A high DCP concentration of 20 phr yields an increase of coefficient of friction which can be explained by the low stiffness and the resulting high contact area in the case of highly cross‐linked LDPE. [ABSTRACT FROM AUTHOR]

Acrylonitrile‐EPDM‐styrene (AES) was applied as an impact modifier for poly(lactic acid) (PLA), and the combined effect of dicumyl peroxide (DCP) crosslinking and annealing heat treatment was investigated. Torque rheometry, melt flow index (MFI), mechanical properties (impact, tensile, and Shore D hardness), X‐ray diffraction (XRD), infrared spectroscopy (FTIR), heat deflection temperature (HDT), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were investigated. There was a considerable torque increment and fluidity drop in the PLA/AES/DCP blends caused by the crosslinking process and the formation of PLA‐g‐AES. Consequently, the impact strength and elongation at break properties improved. As an engineering terpolymer, AES was decisive in maintaining high elastic modulus, Shore D hardness, and HDT values. The PLA/AES/DCP (0.8 phr) composition leaned towards a synergism of mechanical properties, gaining 505.6% and 264.8% in impact strength and elongation at break, respectively, compared to neat PLA. FTIR and XRD analysis revealed high crystallinity, with samples presenting large crystals. The higher crystallinity had a deleterious effect on the mechanical properties of the PLA/AES/DCP blends. However, there was a marked improvement in HDT and higher toughness compared to PLA. The results before and after annealing the PLA/AES/DCP (0.8 phr) blend are promising for constructing new semi‐biodegradable materials for additive manufacturing. [ABSTRACT FROM AUTHOR]

Rubber blends based on styrene–butadiene rubber, ethylene–propylene–diene monomer rubber and a combination of both rubbers were cured with different sulfur and peroxide curing systems. In sulfur curing systems, two type of accelerators, namely tetramethylthiuram disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, and combinations of both accelerators were used. In peroxide curing systems, dicumyl peroxide, and a combination of dicumyl peroxide with zinc diacrylate or zinc dimethacrylate, respectively, were applied. The work was aimed at investigating the effect of curing systems composition as well as the type of rubber or rubber combinations on the curing process, cross-link density and physical–mechanical properties of vulcanizates. The dynamic mechanical properties of the selected vulcanizates were examined too. The results revealed a correlation between the cross-link density and physical–mechanical properties. Similarly, there was a certain correlation between the cross-linking degree and glass transition temperature. The tensile strength of vulcanizates based on rubber combinations was higher when compared to that based on pure rubbers, which points out the fact that in rubber combinations, not only are the features of both elastomers combined, but improvement in the tensile characteristics can also be achieved. When compared to vulcanizates cured with dicumyl peroxide, materials cured with a sulfur system exhibited higher tensile strength. With the application of co-agents in peroxide vulcanization, the tensile strength overcame the tensile behavior of sulfur-cured vulcanizates. [ABSTRACT FROM AUTHOR]

Towards the goal of developing renewable, biocompatible and intelligent polymer materials, natural Eucommia ulmoides gum (EUG) was modified via epoxidation and then the epoxidized EUG (EEUG) was compounded with another sustainable and biobased polymer, polylactic acid (PLA), to develop shape memory thermoplastic vulcanizates (TPVs) through reactive blending. The prepared PLA/EEUG TPVs displayed not only enhanced toughness but also greatly improved shape recovery ability, which was generated from the co‐continuous phase structure and excellent interfacial adhesion induced by in situ compatibilization during reactive blending. It is shown that dicumyl peroxide content exerted little influence on the toughness of the TPVs. However, heat‐triggered shape memory effects of the TPVs were significantly affected by the dicumyl peroxide content with a decrease in deformation ratio (Δε) from 163.51% to 128.36% and an increase in shape recovery ratio (Rr) from 73.32% to 91.93%. The findings of the present study offer an idea for the industrialization of biocompatible and smart materials for biomedical applications. © 2024 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

As a biodegradable material, poly (butylene adipate-co-terephthalate) (PBAT) has important environmental significance, but its linear molecular chain structure makes it difficult to foam, and the traditional crosslinking modification will reduce its degradation performance. In this work, N-vinyl-2-pyrrolidone (NVP) was grafted to PBAT using dicumyl peroxide (DCP) as initiator, then the PBAT-g-NVP foam was prepared by supercritical N2. The results showed that the grafting reaction improved the melt strength and foaming performance, but the degradation performance was maintained. The grafting mechanism, rheological properties, thermal properties and foaming behavior were also studied. The rheological properties showed that the melt strength of PBAT-g-NVP was significantly improved. The foaming window was widened and the cell structure became uniform. When there were 0.4 wt% DCP and 3 wt% NVP, the expansion ratio of PBAT-g-NVP foam was 10.5 and the maximum compressive stress was 253.2 kPa. In addition, the degradation degree of PBAT-g-NVP foam reached 98% in 35 d. The products prepared by this work have a wide application prospect in the field of disposable packaging or medical supplies. [ABSTRACT FROM AUTHOR]

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) is a biodegradable polymer with significant potential for use in food packaging. However, its limited melt strength poses a challenge when employing film‐blowing techniques to produce flexible packaging. To overcome this obstacle, we developed blends consisting of 70 wt% PHBV and 30 wt% poly(butylene‐co‐succinate‐co‐adipate) (PBSA). Organic peroxides such as dicumyl peroxide and 2,5‐dimethyl‐2,5‐di‐(tert‐butylperoxy)hexane, were utilized as reactive compatibilizers to enhance the interfacial adhesion between the polymers. Additionally, acetyl tributyl citrate (ATBC) was employed as a plasticizer to improve processability and ductility. The inclusion of organic peroxides resulted in the formation of long‐branched structures, as confirmed by the van‐Gurp‐Palmen plot. The melt flow index decreased from 30 to 9.8 g/10 min without ATBC and 15.5 g/10 min with ATBC. Successful production of blown PHBV/PBSA films was achieved on a pilot scale (bubble height 180 cm). These films exhibited heat‐sealing capability and increased impact strength (7.7 kJ/m2). Moreover, the films maintained a maximum elongation at break of 4% during a 3‐month storage experiment with frozen food. Food safety was assessed through overall migration experiments, and the non‐plasticized films received approval. In conclusion, the compatibilized PHBV/PBSA blends demonstrate great potential as materials for manufacturing film‐blown flexible packaging. [ABSTRACT FROM AUTHOR]

The FKM-g-SiR macromolecular compatibilizer was produced by using a high-temperature thermomechanical grafting process to graft long-chain vinyl silicone oils (SiR, terminal vinyl dimethicone) with varying vinyl contents (0.09%,0.21%, and 0.63%) onto fluoroelastomer (FKM). The impact of initiator dosage, silicone oil dosage and vinyl content on the mechanical characteristics of FKM/MVQ (Methyl vinyl silicone rubber) blends was probed using a three-level orthogonal design experiment with a three-factor range analysis. Optimal conditions for the preparation of the compatibilizer were obtained accordingly. The findings indicated that the vulcanization properties, mechanical properties, and resistance to oil of the FKM/MVQ blends that were rendered compatible were optimized when the quantity of initiator Dicumyl Peroxide (DCP) was 0.25 parts, the volume of silicone oil was 9 parts, and the vinyl content was 0.63%. The composites exhibited the following specifications: the maximum torque difference can reach up to 12.56 dN.m, while the tensile strength and elongation at break can reach up to 8.39 MPa and 348.04%, respectively. Additionally, the rate of change in oil volume and mass can be reduced by 25.2% and 14.37%, correspondingly. The blended rubber's structure and performance were characterized using several methods, including Fourier transform infrared spectroscopy (FT-IR), Rubber processing analyzer (RPA), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Dynamic mechanical thermal analysis (DMTA). The results indicated that the compatibilizer significantly improved the compatibility of the FKM/MVQ blend. [ABSTRACT FROM AUTHOR]

Heat seal and mechanical properties of 1‐octene grafted low density polyethylene films containing various concentrations of Dicumyl peroxide as the initiator and 1‐octene grafting agent is investigated through using experimental measurements. The results of differential scanning calorimeter (DSC) measurements revealed that the melting temperature shifts to higher values and the peak of the DSC curve becomes wider with the increase of 1‐octene concentrations. Thermogravimetric analysis (TGA) revealed a higher thermal stability up to 20 °C for 1‐octene grafted PE compared with neat LDPE alloy. The results of stress–strain measurements revealed that the 1‐octene grafted PE alloys has higher tensile strength in comparison with neat PE alloy and samples containing only DCP initiator. The results of heat seal analysis indicated that both DCP initiator and 1‐octene tended to offer a moderate increase peel strength of PE alloy. DMTA measurements for various grafted PE alloys show a higher damping factor in comparison with neat LDPE alloy. Rheological measurements indicated a higher storage modulus up to 25% and higher complex viscosity for grafted PE samples containing 1‐octene comonomer. [ABSTRACT FROM AUTHOR]

The investigation of chain branching in polypropylene (PP) holds significant importance for comprehending the impact of structural modifications on the properties of PP. The utilization of ethylene‐octene copolymer (EOC) presents a valuable opportunity to examine the influence of branching density on the ability of electron beam irradiation or a chemical agent in a PP blend. The introducing long chain branches (LCB) into PP can enhance its mechanical properties, particularly impact strength. This characteristic is of particular significance in applications where the material is subjected to mechanical stress, such as automotive components or packaging materials. Blends of PP/EOC were produced using 20 and 30 wt% of EOC and 0.5 phr trimethylolpropane trimethacrylate (TMPTMA) monomer. To evaluate the efficiency of branching in both solid and molten states, irradiated samples and samples mixed with dicumyl peroxide (DCP) were selected. The rheological properties of the molten blends in shear and extensional modes were assessed, and their morphology was examined using scanning electron microscopy. The existence of LCB in all samples was confirmed through dynamic viscoelastic measurements. It was concluded that although the irradiation promoted chain scission within the backbone, which resulted in long chain branching, DCP created LCB on the backbone chains of PP through chemical reaction in the melt state. Additionally, the strain hardening constant (n) was calculated, and its value for the irradiated sample PP/EOC 80/20 was 0.19, whereas its value for this blend when employing DCP was 0.14. While the complex viscosity of irradiated blend (8764 Pa.s) was greater than that of melt state branched blend (8377 Pa.s) at 0.1 rad/s, in the higher frequencies it became smaller due to the more effective creation of long chain branches through peroxide grafting in the molten state. The results of the study verified the presence of LCB in the materials by observing longer relaxation time and strain hardening behavior. Highlights: The chain branching of PP/EOC blends was investigated in both the melt state and solid state through the presence of TMPTMA monomer.The effectiveness of TMPTMA monomer in grafting was mostly notable in the molten state.The steady state viscosity of LCB‐(PP/EOC) was higher in the presence of dicumyl peroxide compared to irradiated PP/EOC.The samples containing 80 wt% of PP exhibited longer side branches compared to the sample with 70 wt% of PP according to shear and extensional rheometry.The induced side chain branches resulting from irradiation and the use of dicumyl peroxide help increase the miscibility of the polymers to a similar extent. [ABSTRACT FROM AUTHOR]

To investigate the influence of the crosslinked polyethylene (XLPE) structure on electrical performance, various analytical methods were employed to study polyethylene structures with different degrees of crosslinking. Dynamic rheological analysis was conducted to determine material shear viscosity, dynamic viscosity, storage modulus (G′), loss modulus (G″), and other rheological parameters. Additionally, the electrical performance of the material was analyzed by studying the phenomenon of space charge accumulation under direct current voltage. The results indicate that with an increasing mass fraction of the crosslinking agent, the crosslink density of crosslinked polyethylene initially increases and then decreases. When the dicumyl peroxide (DCP) content exceeds 1.0 wt.%, there is an accumulation of like-polarity space charges. The best rheological processing performance of crosslinked polyethylene is observed when the DCP content is in the range of 1.0–1.5 wt.%. [ABSTRACT FROM AUTHOR]

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The article presents the results of a study of the influence of the type and concentration of nitrile butadiene rubber on the main physical and mechanical properties of polymer compositions based on compatibilized ethylene/1-hexene copolymer (EHC*). SKN-18, SKN-26, and SKN-40 were used as nitrile butadiene rubber. The compatibilizer – polyethylene-graft-methacrylic acid was used to improve the compatibility of the mixed components of the mixture. At the first stage, the task of the study was to investigate the effect of the concentration of the considered nitrile rubbers on such properties of the compositions as yield strength, tensile strength, elongation at break, flexural strength, melt flow rate and heat resistance. It was found that, regardless of the type of used nitrile butadiene rubber, with an increase in its content in the composition of the ethylene/1-hexene copolymer, a regular decrease in strength parameters, heat resistance, and melt fluidity is observed. It is shown that with the loading of 30 wt% SKN-18 or 40 wt% SKN-26 and SKN-40 into the composition of the ethylene/1-hexene copolymer phase inversion occurs in the composite materials, according to which the dispersed phase becomes a dispersed medium. The thermomechanical properties of the considered samples were studied. It was found that in those samples in which phase inversion occurred, a region of a highly elastic plateau is formed, which increases with an increase in the content of the rubber component. This area indicates the formation of elastomer with rubber properties. The regularities of crystallization of the compositions depending on the content of the amorphous component were studied by the method of stepwise dilatometry. The mechanism of crystal formation was studied depending on the content of the amorphous component. The influence of the crosslinking agent concentration – dicumyl peroxide on the main properties of dynamically vulcanized elastomers has been studied. [ABSTRACT FROM AUTHOR]

Bio composites of acrylonitrile butadiene rubber (NBR) reinforced with chitosan were prepared using dicumyl peroxide (DCP) as a curing agent. Composites with two types of chitosan with different degrees of deacetylation (DD) were studied i.e., Chitosan with 85% DD and 75% DD. The cure characteristics of composites were studied. The mechanical properties of NBR were found to be improved by the incorporation of chitosan. The composite containing 20 phr chitosan has the best balance of mechanical properties. The swelling behavior of the composites in non-polar solvents such as petrol, diesel, kerosene, toluene, and hexane were analyzed for the swelling coefficient values which supports the results of mechanical properties. Antimicrobial properties of the composites were studied by inoculating the composites with Aspergillus niger (A. niger) fungus on a potato dextrose agar media and incubated for 60 days at room temperature. It is found that presence of chitosan resist the microbial action on the composite samples compared to the gum sample. It is believed that the outcome obtained from the present study is to develop environment-friendly composites for various applications such as oil seals, hoses, automobile bushes, etc. [ABSTRACT FROM AUTHOR]

Water swellable rubber (WSR) was prepared from epoxidized natural rubber (ENR) and sodium acrylate (NaAA) by in‐situ polymerization using sulfur and dicumyl peroxide (DCP) as a vulcanizing agent and an initiator, respectively. The ENR, NaAA, and other additives were mixed in an internal mixer and a two‐roll mill. The effect of the vulcanization system, epoxide, and DCP, and NaAA content on the vulcanization, physical, and mechanical properties of WSR were investigated in this research. As the results, the scorch and curing time of WSR compounded with ENR 25 and vulcanized with a mixture of sulfur‐peroxided or mixed vulcanization system were less than other systems. Furthermore, the scorch and curing time decreased with the increase in DCP content. The WSR with ENR 50 vulcanized with DCP (1.5 phr) in the mixing system provided the highest tensile strength. However, the volume change of WSR with the mixing system (WSR/M) was lower than the WSR cured with peroxide (WSR/P). For WSR/P, the tensile strength, hardness, and volume change in water increased with increasing DCP, and NaAA content, while the elongation at break decreased. These results suggest that WSR has the potential for diverse applications, including waterproofing and sealing solutions in civil construction projects. Highlights: Water swellable rubber (WSR) was prepared from epoxidized natural rubber (ENR) and sodium acrylate (NaAA) by in‐situ polymerization using sulfur and dicumyl peroxide (DCP) as a vulcanizing agent and an initiator.The scorch and curing time of WSR compounded with ENR 25 and vulcanized with a mixed vulcanization system were less than those of other systems.During the vulcanization process, ENR 50 can be generated by the ring‐opening of the adjacent epoxide groups more than ENR 25, and the self‐crosslink of ENR 50 was higher than ENR 25.Water swelling and volume change of WSR tended to decrease with increasing epoxide, and DCP content, whereas those properties increased with increasing NaAA content.Tensile strength, elongation at break, and hardness of WSR with the mixing system (WSR/M) were higher than those of WSR with the peroxide system (WSR/P).Swelling and volume change of WSR/P were higher than those of WSR/M. [ABSTRACT FROM AUTHOR]

To produce ethylene–vinyl acetate (EVA) foams with a higher foaming ratio and stable cell size, the efficiency of the crosslinking reaction is required to conduct simultaneously with the blowing reaction. Hence, the multifunctional monomer trimethylolpropane trimethacrylate (TMP) as a crosslinking promoter and a crosslinking agent dicumyl peroxide are used together as a crosslinking system to EVA foaming, when chemical blowing agent azodicarbonamide (ADC) is used. The TMP concentration of approximately 1.0 phr (per hundred resin) is most effective for balancing the expansion ratio and fine cell size. In the SEM diagram and expansion ratio results, it can be found that when the concentration of TMP ranges from 0 to 1.0 phr, the cell mean size is reduced from 360.3 to 140.5 μm and the expansion ratio is reduced from 13.6 to 9.1 at 170°C. The results of time‐sweep experiment of thermogravimetric analysis (TGA) show that the foaming time of ADC in the melt increases with the addition of TMP. Capillary rheometer and rotational rheometer tests show that the viscosity and the crosslinking efficiency of the melt are improved with the TMP addition. The curing time has been reduced from 2.93 to 2.22 min for 170°C. [ABSTRACT FROM AUTHOR]

In this study, high density polyethylene (HDPE) was combined with dicumyl peroxide (DCP) to produce crosslinked parts via rotational molding. The effect of DCP content (0.1–2.5 phr) on the crosslinking degree was investigated to determine its effect on the chemical, mechanical, physical, and thermal properties of HDPE. The gel content and crosslink density was found to increase with DCP content. These trends led to a reduction in the degree of crystallinity, melting, and crystallization temperature. Thermogravimetric analysis (TGA) showed that crosslinked HDPE (xHDPE) has higher thermal stability than the neat matrix in both air and nitrogen atmosphere. In addition, a direct relationship was observed between improved thermal resistance and higher impact strength. Finally, relationships between the tensile properties of xHDPE and the degree of crystallinity were observed, which were all controlled by the level of crosslinking. These results have the potential to advance the manufacturing of high performance materials suitable for a wide range of applications such as automotive parts, agricultural products, chemical storage tanks, large waste containers, and fuel tanks in general. [ABSTRACT FROM AUTHOR]

This study compares the effect of sulfur and dicumyl peroxide (DCP) vulcanizing systems on the physical and mechanical properties of rubber compounds based on acrylonitrile butadiene rubber (NBR). NBR compounds cured by different amounts of DCP and NBR vulcanizates filled with various concentrations of carbon black (CB) and a constant amount of sulfur or DCP were prepared. The vulcanizates were characterized by tensile testing, dynamic mechanical thermal analysis (DMTA), and cross-link density determination. The tensile strength and Young's modulus were found to increase with the rising amount of DCP and CB, while elongation at break decreased. The samples vulcanized by the sulfur system and filled with CB show a substantial increase in tensile strength from 13.1 to 21.2 MPa. Higher storage modulus and glass transition temperature were observed with the increase in the amount of peroxide and filler, and consequently, the increase in cross-link density, indicating rigidity increase and lower molecular mobility. The changes in the physical and mechanical properties of the NBR vulcanizates were in correlation with the changes in solvent uptake and cross-link density. [ABSTRACT FROM AUTHOR]

Immiscible and incompatibility between the hydrophilic fiber phase and hydrophobic matrix phase results in a poor stress transfer between the two phases and deterioration in mechanical, physical, and barrier properties. Thus, this study aims to enhance the compatibility between hydrophobic polybutylene adipate-co-terephthalate (PBAT) and hydrophilic nature corn starch (CS) by substituting native corn starch with acetylated corn starch (ACS). The acetylation treatment was used to improve the hydrophobicity of corn starch. The native corn starch was used as a reference to study the effect of acetylation. Challenges in incorporating fillers into hydrophobic PBAT were overcome by adding plasticizer; sorbitol (S) and compatibilizers; maleic anhydride (MAH) and dicumyl peroxide (DCP). The composite films were characterized by fourier transform infrared (FTIR), tensile properties, differential scanning calorimetry (DSC), water contact angle (WCA) measurement, and thermogravimetric analysis (TGA). The morphology of the composites was examined by scanning electron microscopy (SEM). The tensile properties of PBAT/ACS were improved by adding compatibilizers. Meanwhile, adding plasticizer improved the tensile properties of PBAT/CS. PBAT/ACS/MAH composite possessed a tensile strength of 15.47 MPa, modulus of 95.30 MPa, and strain at break of 170.81%, while PBAT/CS/30S composite possessed tensile strength of 8.59 MPa, modulus of 104.60 MPa and strain at break of 1037.91% which have potential use in packaging applications. [ABSTRACT FROM AUTHOR]

New composite materials were developed with poly(lactide) (PLA) and Posidonia oceanica fibers through reactive extrusion in the presence of dicumyl peroxide (DCP) and subsequent injection molding. The effect of different amounts of methyl trans–cinnamate (MTC) on the mechanical, thermal, thermomechanical, and wettability properties was studied. The results showed that the presence of Posidonia oceanica fibers generated disruptions in the PLA matrix, causing a decrease in the tensile mechanical properties and causing an impact on the strength due to the stress concentration phenomenon. Reactive extrusion with DCP improved the PO/PLA interaction, diminishing the gap between the fibers and the surrounding matrix, as corroborated by field emission scanning electron microscopy (FESEM). It was observed that 20 phr (parts by weight of the MTC, per one hundred parts by weight of the PO/PLA composite) led to a noticeable plasticizing effect, significantly increasing the elongation at break from 7.1% of neat PLA to 31.1%, which means an improvement of 338%. A considerable decrease in the glass transition temperature, from 61.1 °C of neat PLA to 41.6 °C, was also observed. Thermogravimetric analysis (TGA) showed a loss of thermal stability of the plasticized composites, mainly due to the volatility of the cinnamate ester, leading to a decrease in the onset degradation temperature above 10 phr MTC. [ABSTRACT FROM AUTHOR]

Long‐chain branched polylactides (PLA‐LCB) with high melt strength were prepared through a melting reaction using Trigonox301 or dicumyl peroxide (DCP). During this reaction, random chain scissions, branching reactions, and cross‐linking reactions took place, as confirmed by the torque‐time rheograms and gel permeation chromatography profiles. It is evident that the random chain scissions are more prominent in PLA‐LCBD compared to PLA‐LCBT. The rheological characterization further elucidated the formation of LCB architecture. With an increase in the content of Trigonox301 or DCP, both branch‐on‐branch architecture and cross‐linked architecture were observed. The preference for branch‐on‐branch architectures was found to be higher in PLA‐LCBT as compared to PLA‐LCBD. Additionally, the presence of gel fraction was more easily detectable in PLA‐LCBD samples, indicating a higher likelihood of cross‐linking reactions in these samples. The emergence of new peaks at the positions of 1.82 and 1.47 ppm establishes a solid theoretical foundation for the potential reaction mechanism. One possible explanation proposed is that the reaction rate of free radicals originating from PLA‐LCBD samples is significantly higher than the diffusion rate of macromolecular free radicals. Consequently, the occurrence of a free radical chain transfer reaction is limited to a very small region, resulting in the formation of a cross‐linked structure. While the free radicals that are produced by the cyclic peroxide actively contribute to the graft reaction, thereby promoting the formation of the LCB structure with a micro‐crosslinking component. [ABSTRACT FROM AUTHOR]

Linear low‐density polyethylene (LLDPE) and different concentrations (5‐20 wt%) of magnesium hydroxide (MAH) as a filler either with or without the addition of graphene nanoplatelets (GNPs) were peroxide cross‐linked using dicumyl peroxide as a cross‐linking agent in a twin‐screw extruder. The mechanical, thermal stability, flame retardancy, morphological, and rheological properties of the prepared samples were investigated. The mechanical properties of the peroxide cross‐linked LLDPE samples with higher MAH and GNP in the matrix were significantly improvement compared to neat LLDPE. This indicates that the addition of MAH and GNP to the peroxide cross‐linked LLDPE matrix could be suitable reinforcing fillers to achieve better and enhanced mechanical properties, particularly tensile strength. Conversely, a significant decrease in the elongation at break values was found for peroxide cross‐linked LLDPE samples compared to neat LLDPE. Similarly, results of thermogravimetric analysis revealed remarkable thermal stability enhancement in the peroxide cross‐linked LLDPE samples with higher MAH and GNP compared to neat LLDPE. The results from UL94 test demonstrated that the peroxide cross‐linked LLDPE samples comprising higher MAH with GNP exhibited improved V = 0 rating compared to poor no rating (NR) for neat LLDPE. Furthermore, the scanning electron microscope and digital images shown improved flame retardancy properties for these samples because of the formation of protective char layer on the sample surface. The complex viscosity for the peroxide cross‐linked LLDPE samples, at lower frequency, increased with increasing MAH loading and further addition of GNP compared to neat LLDPE. Highlights: Cross‐linked polyethylene with flame retardant (FR) and nanofiller were prepared.Effects of cross‐linking and FR on the final properties of the polymer were studied.20wt% FR with 3 phr nanofiller promoted the final properties of the polymer.Higher filler loading in the polymer improved flame retardancy and thermal stability.Combined effect of cross‐linking and FR has shown major improvement. [ABSTRACT FROM AUTHOR]

Liquid hydridopolycarbosilanes (LHPCS) with vinyl or allyl groups have attracted significant research interest due to their low curing temperature and high ceramic yield. In this study, allyl-terminated hydridopolycarbosilane (AHPCS) and vinyl-terminated hydridopolycarbosilane (VHPCS) were prepared by the Grignard coupling reaction and characterized by NMR and Fourier infrared spectroscopy (FTIR). And the curing reactions of AHPCS and VHPCS with or without initiators (dicumyl peroxide [DCP], tert-Butyl peroxybenzoate [TBPB]) or Karstedt catalyst were investigated using differential scanning calorimetry and in-situ FTIR. The main curing reactions of VHPCS and AHPCS are the double bond free radical polymerization and hydrosilylation reaction, respectively. The addition of initiators and Karstedt catalyst could promote the corresponding curing reaction and increase the weight residual at 1000°C. The thermal properties of the cured resins were investigated by thermogravimetric analysis. The addition of initiators and catalyst could significantly increase the weight residual of VHPCS and AHPCS, respectively. The addition of the Karstedt catalyst increased the weight residual of AHPCS from 75.6% to 83.1%. In addition, the addition of TBPB and DCP increased the weight residual of VHPCS from 74.2% to 81.2% and 80.2%, respectively. [ABSTRACT FROM AUTHOR]

Ordinary polypropylene homopolymer (PP) has low melt strength and mechanical properties, which greatly restricts its application in foam molding. In this work, high melt strength polypropylene (HMSPP) is successfully fabricated by melting grafting technique using dicumyl peroxide as an initiator and trimethylolpropane triacrylate (TMPTA) as a grafting monomer. The effects of different reaction temperatures and formulas on modified PP are investigated. The results show that the introduction of TMPTA will reduce the melt flow rate, and improve the grafting ratio, torque, melt strength (MS), mechanical properties, thermal stability, and crystallization rate of polypropylene. It is found that HMSPP prepared at 170 °C 1.2 Phr TMPTA has the best comprehensive properties, with MS increased by 3.8 times, elongation at break increased by 120%, flexural modulus increased by 25%, impact strength increased by 33.3%, and thermal decomposition temperature increased by 52.6 °C. In addition, PP/HMSPP is extruded and foamed, and the results show that the foaming performance of HMSPP is better than that of PP. In general, the introduction of TMPTA improves the mechanical properties, melt strength, foaming property, and thermal stability of PP. [ABSTRACT FROM AUTHOR]

In view of implementing green technologies for bioplastic turning polices, novel durable feedstock for Bacillus mycoides ICRI89 used for efficient polyhydroxybutyrate (PHB) generation is proposed herein. First, two food waste (FW) pretreatment methods were compared, where the ultrasonication approach for 7 min was effective in easing the following enzymatic action. After treatment with a mixture of cellulase/amylases, an impressive 25.3 ± 0.22 g/L of glucose was liberated per 50 g of FW. Furthermore, a notable 2.11 ± 0.06 g/L PHB and 3.56 ± 0.11 g/L cell dry eight (CDW) over 120 h were generated, representing a productivity percentage of 59.3 wt% using 25% FW hydrolysate. The blend of polyhydroxybutyrate/poly (methyl methacrylate) (PHB/PMMA = 1:2) possessed the most satisfactory mechanical properties. For the first time, PHB was chemically crosslinked with PMMA using dicumyl peroxide (DCP), where a concentration of 0.3 wt% had a considerable effect on increasing the mechanical stability of the blend. FTIR analysis confirmed the molecular interaction between PHB and PMMA showing a modest expansion of the C=O stretching vibration at 1725 cm−1. The DCP-PHB/PMMA blend had significant thermal stability and biodegradation profiles comparable to those of the main constituent polymers. More importantly, a 3-Dimetional (3D) filament was successfully extruded with a diameter of 1.75 mm, where no blockages or air bubbles were noticed via SEM. A new PHB/PMMA "key of life" 3D model has been printed with a filling percentage of 60% and a short printing time of 19.2 min. To conclude, high-performance polymeric 3D models have been fabricated to meet the pressing demands for future applications of sustainable polymers. [ABSTRACT FROM AUTHOR]

We report the fixation of carbon dioxide (CO2) into novel rubber polymers based on polycarbonate domains. Our strategy consisted in the atom-efficient terpolymerisation of CO2 with a long-alkyl-chain epoxide and an unsaturated epoxide to obtain polycarbonates with a glass transition temperature (Tg) below room temperature and with pendant double bonds along the backbone to enable peroxide-promoted cross-linking, thus generating an elastic rubber. First, a wide range of epoxides with long alkyl chains (C6-C12) were coupled with CO2 to give polycarbonates with high yields, using a binary catalytic system consisting of an aluminium amino-tris(phenolate) complex and bis(triphenylphosphoranylidene) ammonium chloride (PPNCl). The synthesised polycarbonates were characterised using FTIR and NMR spectroscopy to determine yields and selectivity, using DSC to measure the Tg, and using GPC to obtain the molecular weight distribution. Next, the terpolymerisation was carried out by including allyl glycidyl ether (AGE) in the reaction mixture together with a long-alkyl-chain epoxide and CO2. Almost complete epoxide conversions (81-100%) and extremely high selectivity (>97%) towards the desired polycarbonates were achieved, with only traces of the cyclic carbonate side-products. The obtained polycarbonates displayed a Tg < 0 °C and thus behave as low-viscosity fluids at room temperature. The pendant unsaturated groups introduced with the AGE monomers allowed cross-linking of the terpolymers with dicumyl peroxide, leading to an elastic rubber-like behaviour as witnessed by their markedly decreased solubility in gel-content tests and by their storage modulus, loss modulus, and Tg, which were determined by dynamic mechanical analysis (DMA). In summary, we have successfully demonstrated that the terpolymerisation of long-chain epoxides, AGE and CO2 yields polycarbonates that can be cross-linked to obtain elastic rubber properties, thus opening the prospects for a new range of applications for CO2-based green polycarbonates. [ABSTRACT FROM AUTHOR]

The effect of the addition of 2-Hydroxypropyl-3-Piperazinyl-Quinoline carboxylic acid Methacrylate (HPQM) in Neusilin® into thermoplastic vulcanizates (TPV) Polypropylene/ethylene propylene diene monomer (PP/EPDM) type on the mechanical and antibacterial properties were studied. Ethylene propylene diene monomer compounds were mixed with Zinc dimethacrylate (ZDMA), Dicumyl peroxide (DCP), and paraffin oil by a two-roll mill machine. Polypropylene and HPQM in Neusilin® were extruded by varies HPQM content 0, 1250, 2500, 3750 and 5000 ppm. Polypropylene added antibacterial agent and EPDM compounds were mixed by twin-screw extruded weight ratios of 100:0, 75:25, 50:50, and 25:75 w/w with varied screw speeds of 60, 80, and 100 r/min. Polypropylene/Ethylene propylene diene monomer compounds were produced by compression moulding to form specimens. The mechanical properties were tested by tensile test and hardness test. It was found that screw speed did not affect the mechanical properties. Disk diffusion test and plate count agar (PCA) method were used for antibacterial properties. For both methods, the specimens contained an antibacterial agent against Escherichia coli (E. coli ATCC 25922) and Staphylococcus aureus (S. aureus ATCC 25923). The result of the disk diffusion test suggests that the more HPQM in Neusilin® content, the more the inhibition radius of only E. Coli bacteria. Plate count agar method proceeded by varying the contact time at 0, 1, 2, 3 and 4 h. Viable cell counts of E. coli decreased significantly at HPQM content 2500 ppm, while the viable cell count of S. aureus remained unchanged at 3750 ppm. Moreover, the rubber ingredients in EPDM, which are DCP and ZDMA, affect the release of antibacterial agents by hydrophobic characteristics and compatible conditions. [ABSTRACT FROM AUTHOR]

Biodegradable crosslinked blends of natural rubber latex (NRL) and dextrin (DXT) have been prepared in various ratios, with cumene hydrogen peroxide (CHP) as the curing agent. Characterization techniques employing infrared spectroscopy, thermogravimetric analysis and X-ray diffraction provide insights into the physico-chemical properties of the blends. The phase morphology and topographical analysis have been done through scanning electron microscopy (SEM) and atomic force microscopy (AFM) examinations respectively. Soil degradation studies, duly assisted with SEM examinations, were performed to confirm the biodegradability of the films. The stress-strain characteristics were analyzed using the Raman spectra. The mechanical properties of the cross-linked blends have been compared with relevant theoretical models. The experimental results for the mechanical properties were subjected to a one-way analysis of variance (ANOVA) using MINITAB software. The optimized crosslinked polymer blend showed biocompatibility with L929 (mouse fibroblast) cells and has been proposed for controlled drug delivery, with tuneable release characteristics. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs) have been blended into polylactic acid (PLA) to improve the polymer's properties. The dispersion of CNC in the matrix has a strong influence on the properties of the nanocomposites. In this study, PLA and CNC were compounded by a reactive extrusion process using dicarbonyl peroxide (DCP) as the free radical initiator. Isothermal and non-isothermal crystallization kinetics of the resulting nanocomposites were investigated to understand the effect of PLA-D-CNC on the crystallization of the materials. Nuclear magnetic resonance and Fourier transform infrared spectroscopy analyses confirmed the grafting of PLA onto CNC via reactive extrusion. The Avrami and Tobin model studies showed that the reactive extrusion product PLA-D-CNC exhibited much higher crystallization rates compared to neat PLA, PLA/CNC (without DCP), and PLA/DCP. The maximum crystallization rate temperature of PLA, PLA/CNC, and PLA/DCP was increased from ~100 to ~110°C for PLA-D-CNC. The results showed that CNC promoted PLA nucleation and crystallization at high temperatures under the action of DCP. Specifically, the maximum crystallization rate of PLA-D-CNC was 46 times higher than that of neat PLA. PLA-D-CNC showed a two-stage crystallization process, while the other three samples exhibited mostly single-stage processes. The much-enhanced crystallization of PLA-D-CNC was ascribed to the improved interaction between PLA and PLA-D-CNC and the homogeneous dispersion of CNC. [ABSTRACT FROM AUTHOR]

An efficient and versatile copper- or iron-catalyzed direct β-C(sp2)–H methylation of enamides by using dicumyl peroxide (DCP) as the methylating reagent has been developed. This methodology provides convenient access to a wide range of β-C(sp2)-methylated enamides with exclusive E-selective control in moderate to good yields. Mechanistic studies reveal that a methyl radical was involved in this transformation. Notably, this method features cheap copper or iron salts as the catalyst, a simple procedure, commercially available methylation reagents, a broad substrate scope, and excellent functional group tolerance. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) has been gaining prominence in academia and industry, mainly due to being a biopolymer and biodegradable material. Nevertheless, mainly due to its high fragility, work has been carried out in order to seek alternatives to improve this drawback. Hence, this work aims to evaluate the effect of the vinyl acetate content using two types of EVA (EVA1 with 28% and EVA2 with 19%) in dynamically vulcanized PLA/EVA blends, using several dicumyl peroxide (DCP) contents, that is, 0.3, 0.5, and 0.7 phr. Blends were produced using an internal mixer, and the tensile, impact and HDT specimens were injection molded. By FTIR and torque rheometry, it was verified that, upon DCP addition, there was evidences of reticulation, resulting in crosslinked PLA, crosslinked EVA, as well as PLA‐g‐EVA. Through tensile and impact strength tests, it was observed substantial increases in the elongation at break, and in impact strength, mainly for the compounds with higher content of vinyl acetate (EVA1). Impact specimens made with PLA/EVA120 0.7 DCP, PLA/EVA130 0.5 DCP, and 0.7 DCP, did not completely break, due to the probable development of the in situ PLA‐g‐EVA compatibilizer among the present phases. Therefore, it is believed that a more homogeneous microstructure was obtained, as observed by SEM images, highlighted upon the DCP content increase. It was verified that the highest vinyl acetate content is of paramount importance for obtaining PLA/EVA blends with better compatibility as well as EVA1 being more susceptible to crosslinking using DCP, resulting in blends with greater toughness. [ABSTRACT FROM AUTHOR]

This study used ethylene‐propylene diene monomers (EPDM), an elastomer, to develop foams incorporating clay as filler using simple compounding, chemical foaming, and peroxide‐mediated light crosslinking methods. The low‐temperature batch mixer was employed for compounding azodicarbonamide (ADC) as a foaming agent, dicumyl peroxide (DCP) as a crosslinker, followed by compression molding for sheet preparation and the high‐temperature foaming process. Fourier transform infrared spectroscopy (FTIR) equipped with a hot stage attenuated total reflection (ATR) was employed to elucidate the ADC decomposition and foaming. The DCP (0.25 phr) content was optimized based on the foaming expansion ratio (>4) and stability, which was further optimized in conjuncture with clay to generate high‐performance composite foams. The incorporation of 1% organoclay enhances the expansion ratio and specific tensile strength by >7 and ~ 270%, respectively, compared with EPDM foams without clay while displaying a density of 0.11 g/cm3. Overall, the developed foaming process can be extended to other elastomeric polymers for various applications such as protective gears (e.g., helmets and shin guards), thermal/sound insulation, packaging/containment, footwear soles, oil absorption, etc. [ABSTRACT FROM AUTHOR]

Two novel polymeric cationic asphalt emulsifiers modified respectively by polyoxyethylene ether [named as polyether-type cationic asphalt emulsifier (PEAE)] and polystyrene [named as polystyrene-type cationic asphalt emulsifier (PSAE)] via free radical polymerization were synthesized by using cumene hydrogen peroxide as the initiator and 3-mercaptopropionic acid as the chain transfer agent. The investigation was conducted on the effects of polyoxyethylene ether dosage, initiator dosage, monomer molar ratio, acid/amine ratio, emulsifier dosage, and pH value on the high- and low-temperature performance of emulsified asphalt and storage stability at room temperature. The molecular structures of emulsifiers were characterized using Fourier transform infrared spectroscopy (FT-IR), and their surface activity and emulsifying performance were evaluated. The results demonstrate that the indexes of PEAE and PSAE satisfied the Chinese national standard regulations, and displayed excellent emulsifying capacity, low-temperature performance, and storage stability at room temperature. Both emulsifiers belong to slow cracking cationic asphalt emulsifiers. PEAE and PSAE can reduce the side effect of traditional small molecular cationic asphalt emulsifier on the low-temperature ductility of emulsified asphalt and improve the low-temperature performance of emulsified asphalt. PSAE was found to serve as an asphalt modifier and could improve the high-temperature performance of emulsified asphalt. The emulsified asphalt prepared using PEAE and PSAE shows promising applications in slurry seal coat construction and microsurface treatment. It is conducive to solving the problem that the traditional small molecular cationic asphalt emulsifier has large negative effect on the low-temperature performance of emulsified asphalt, which can open the window of the subsequent synthesis of polymeric cationic asphalt emulsifiers. [ABSTRACT FROM AUTHOR]

The recycled high‐density polyethylene (rHDPE) feedstock containing calcium carbonate (CaCO3) mineral was obtained from post‐consumer single‐use grocery bags. This feedstock is transformed into new composite materials with improved mechanical properties using a high‐shear compounding process. The rHDPE/CaCO3 feedstock is injected into the high‐shear polymer mixer and blended with acrylonitrile‐butadiene copolymer or nitrile rubber (up to 10 wt%) and crosslinked with dicumyl peroxide. The resultant materials exhibit high mechanical performance, with a maximum tensile strength of 20.3 MPa, stiffness of 1262 MPa, and impact strength of 63 kJ/m2. These mechanical properties are profoundly higher than those of neat rHDPE feedstock. Notably, the post‐consumer plastic bags contain a high amount of CaCO3 mineral of approximately 30 wt% (13 vol%), impacting the materials' mechanical properties with additives such as nitrile rubber. In addition, the materials' melt‐rheology, viscoelastic, and phase morphology are analyzed. The melt‐rheological characteristics indicate that the materials' complex viscosity and storage modulus are frequency‐dependent, demonstrating the thermoplastic nature of the composite materials and the possibility of thermomechanical recyclability of the materials. However, treating rHDPE/nitrile rubber blends with peroxide creates resistance to the melt‐flow of the materials. [ABSTRACT FROM AUTHOR]

Polymers are part and parcel of our life and society due to the immense applications resulting from their unique properties. High performing products based on bio feed stocks have gained special attention compared to non‐renewable resources. In the present research work, carbon black (CCF) prepared from waste chicken feathers has been used as reinforcement in styrene butadiene rubber (SBR). Cure kinetics of SBR‐CCF composites and their mechanical properties have been evaluated with respect to loading of filler and concentration of dicumyl peroxide crosslinking agent. The cure reaction of all compounds obeys first order kinetics and the rate constants increase with filler loading as well as temperature. A decrease in energy of activation of cure has been noted with increase of loading of CCF filler, which assists for an increase in the rate of production of articles using the filled SBR compounds. The improvement in tensile properties with CCF has been supported by the fractography of the composites and by the crosslink density values obtained using equilibrium swelling method. The performance of the developed composites points to their applications in the area of car‐tire industry, tread rubber sector and structural applications such as drive and shaft couplings. [ABSTRACT FROM AUTHOR]

Organic peroxides combined with ionic liquids had a high application value in the desulfurization process. However, thermal stability between organic peroxides and ionic liquids displayed a significant difference. Moreover, it was of great significance to investigate the thermal hazard of organic peroxides due to the influence of ionic liquids. In this study, a common organic peroxide cumene hydroperoxide (CHP) and two imidazole ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([Bmim]BF4 and Bmim[NTf2]), with good desulfurization performance were selected for experiments. The thermal stability of [Bmim]BF4 and Bmim[NTf2], respectively, mixed with cumene hydroperoxide in air and nitrogen conditions was studied by thermogravimetry (TG) analysis. The kinetic data of CHP which was mixed with two ionic liquids were evaluated using two different isoconversional methods: Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS). Furthermore, their gas decomposition products were investigated by thermogravimetry coupled with Fourier-transform infrared spectroscopy (TG-FTIR) analysis. The experimental and calculated results demonstrated that the apparent activation energy was decreased after CHP was mixed with the two ionic liquids. The main decomposition stage ranged from 350.0 to 480.0 K with a mass loss of CHP under air and nitrogen conditions. The thermal decomposition behavior of the CHP under air conditions displayed higher apparent activation energy compared with that in nitrogen atmosphere. The experimental results provide an important reference for organic peroxides combined with ionic liquids applicated in the desulfurization process. [ABSTRACT FROM AUTHOR]

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