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There is a need to develop environmentally friendly materials, especially plastics, that minimize environmental pollution. In this sense, polypropylene (PP) composites were produced with 20 wt% of Macaiba almond powder (MA*) and compatibilized with SEBS-MA and EPDM-MA to carry out a biodegradation investigation of these composites. Mechanical properties (impact, tensile), heat deflection temperature (HDT), scanning electron microscopy (SEM), and Fourier transform spectroscopy (FTIR) experiments were performed. These analyses verified that the best plasticization was reached in the composites with 15% of SEBS-MA and EPDM-MA, indicating an interaction between phases. The impact strength and elongation at break of the PP/MA*/EPDM-MA and PP/MA*/SEBS-MA composites increased significantly, suggesting tough behavior. Biodegradation occurred in the soil for 120 days, and both PP/MA*/10EPDM-MA and PP/MA*/15EPDM-MA demonstrated a mass loss of about 4.68% and 4.0%, respectively. Although PP is not biodegradable, the results show that macaíba almond powder can biodegrade in the PP matrix. [ABSTRACT FROM AUTHOR]

In this work, an experimental design was applied in the injection molding process of polycaprolactone (PCL), aiming to evaluate the mechanical properties (impact strength, tensile strength and Shore D Hardness), thermal (differential scanning calorimetry (DSC)) and thermomechanical (heat deflection temperature (HDT)), in PCL injected specimens. A type 2n planning was applied, with n = 3 and central point, having the input factors: processing temperature profile, mold temperature and injection flow. The results showed that the DSC curves presented a complex mechanism during crystallization, suggesting that depending on the processing conditions a high degree of crystallinity can be obtained. When using a higher processing temperature and a higher injection flow, there is an increase in the mass of the PCL parts. The impact strength is more expressive when a higher injection flow and a lower processing temperature are applied, reaching values around 260 J/m. The mold temperature impairs the elongation at the break of the PCL, while the elastic modulus was governed by the degree of crystallinity. A deleterious effect on HDT was observed with increased injection flow, suggesting that this parameter negatively affects thermomechanical resistance. The use of experimental design in the processing of PCL is important, since it is possible to optimize properties with the ideal conditions of injection molding. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the photooxidative stability of polystyrene/vulcanized rubber waste blends, compatibilized with styrene–butadiene–styrene. High-impact polystyrene (HIPS) was used for comparison. All samples were exposed to ultraviolet (UV) radiation for 8 weeks and then analyzed for mechanical properties (tensile and impact), infrared spectroscopy, colorimetry, and optical microscopy. It was observed that the mechanical behavior of the photodegraded samples was a consequence of the superficial chemical modification, which was accompanied by defect formation. The most sensitive properties to aging were the impact strength and elongation at break, with HIPS being the least photostable material. The penetration depth of the UV radiation was lower for the core of the blends than for the HIPS. This finding indicated that the protective additives and mineral fillers (titanium dioxide and talc, respectively), which are present in the rubber residue, minimized the transmittance of radiation into the blends. Consequently, losses in the mechanical properties were minimized. [ABSTRACT FROM AUTHOR]

In this work, polyhydroxybutyrate (PHB) was maleic anhydride (MA)-grafted in the molten state, using dicumyl peroxide (DCP) as a reaction initiator. Tin(II) 2-ethylhexanoate (Sn(Oct)2) and styrene monomer (St.) were used to maximize the maleic anhydride grafting degree. When PHB was modified with MA/DCP and MA/DCP/Sn(Oct)2, viscosity was reduced, suggesting chain scission in relation to pure PHB. However, when the styrene monomer was added, the viscosity increased due to multiple grafts of MA and styrene into the PHB chain. In addition, the FTIR showed the formation of a new band at 1780 cm−1 and 704 cm−1, suggesting a multiphase copolymer PHB-g-(St-co-MA). The PHB (MA/DCP) system showed a grafting degree of 0.23%; however, the value increased to 0.39% with incorporating Sn(Oct)2. The highest grafting efficiency was for the PHB (MA/DCP/St.) system with a value of 0.91%, while the PHB (MA/DCP/St./Sn(Oct)2) hybrid mixture was reduced to 0.73%. The chemical modification process of PHB with maleic anhydride increased the thermal stability by about 20 °C compared with pure PHB. The incorporation of 0.5 phr of the Sn(Oct)2 catalyst increased the efficiency of the grafting degree in the PHB. However, the St./Sn(Oct)2 hybrid mixture caused a deleterious effect on the maleic anhydride grafting degree. [ABSTRACT FROM AUTHOR]

The industrial residue of Jatobá wood flour (JWF) was reused during production of biocomposites based on polycaprolactone (PCL), 50% by weight of JWF was added to PCL matrix. Initially, maleic anhydride-grafted polycaprolactone compatibilizer (PCL-g-MA) was synthesized and characterized using X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and degree of grafting. Afterwards, PCL/JWF and PCL/JWF/PCL-g-MA biocomposites were processed in an internal mixer and injection molded. From the gathered results, increase in torque and reduction in the melt flow index of PCL/JWF biocomposites were verified related to neat PCL. Upon addition of PCL-g-MA to PCL/JWF there was a lubricating effect with reduced torque and increased fluidity. PCL/JWF displayed increased elastic modulus, Shore D hardness, and heat deflection temperature (HDT) around 158.5%, 16% and 24.5%, respectively, related to PCL. Nevertheless, there was decline in tensile strength and impact strength, which were improved in PCL/JWF/PCL-g-MA, suggesting higher interaction among phases, providing greater stress transfer. An interesting finding was the nucleating effect of JWF in PCL matrix, as the increased degree of crystallinity and accelerated crystallization. Morphology of PCL/JWF evidenced several voids, but upon compatibilization with PCL-g-MA, the interfacial adhesion and wetness increased, improving the mechanical properties. JWF reusing presents great potential to produce sustainable biocomposites, reducing the final product costs. [ABSTRACT FROM AUTHOR]

The functionalization of the ethylene–vinyl acetate copolymer (EVA) was carried out in an internal mixer, using maleic anhydride (MA), dicumyl peroxide (DCP) and styrene monomer (St) as additives. Torque rheometry, Fourier transform infrared spectroscopy (FTIR), titration, gel content, thermogravimetry (TG) and differential scanning calorimetry (DSC) were evaluated. The EVA/MA/DCP and EVA/MA/DCP/St torque curves showed a significant increase, indicating the cross-linking process. FTIR confirmed the appearance of a new band in the EVA chain, at 1780 cm−1, attributed to the carbonyl group of maleic anhydride. However, maleic anhydride grafting to the EVA/MA/DCP system only occurred for the 5% MA/0.3% DCP ratio. When the EVA/MA/DCP system is additivation with the styrene monomer (St), all compositions grafted maleic anhydride into the EVA chain, suggesting that styrene increases the effectiveness of the degree of grafting. In addition, FTIR indicated the emergence of a band at 702 cm−1, due to the vibration of the aromatic core of styrene and, therefore, forming a multiphase copolymer (EVA-g-(St-co-MA)). The thermal stability was practically not altered when functionalizing the EVA with maleic anhydride, as verified by TG. The crystalline melting temperature, the crystallization temperature, the enthalpy of crystalline melting and the degree of crystallinity decreased with the EVA functionalization process. In general, a high degree of grafting of maleic anhydride in the EVA chain is difficult, due to the competitive effect with the cross-linking process. [ABSTRACT FROM AUTHOR]

Nylon 6/acrylonitrile-butadiene-styrene nanocomposites were prepared by mixing in a molten state and injection molded for application in electromagnetic interference shielding and antistatic packaging. Multi-wall carbon nanotubes (MWCNT) and maleic anhydride-grafted ABS compatibilizer were incorporated to improve the electrical conductivity and mechanical performance. The nanocomposites were characterized by oscillatory rheology, Izod impact strength, tensile strength, thermogravimetry, current-voltage measurements, shielding against electromagnetic interference, and scanning electron microscopy. The rheological behavior evidenced a severe increase in complex viscosity and storage modulus, which suggests an electrical percolation phenomenon. Adding 1 to 5 phr MWCNT into the nanocomposites produced electrical conductivities between 1.22 × 10−6 S/cm and 6.61 × 10−5 S/cm. The results make them suitable for antistatic purposes. The nanocomposite with 5 phr MWCNT showed the highest electromagnetic shielding efficiency, with a peak of –10.5 dB at 9 GHz and a value around –8.2 dB between 11 and 12 GHz. This was possibly due to the higher electrical conductivity of the 5 phr MWCNT composition. In addition, the developed nanocomposites, regardless of MWCNT content, showed tenacious behavior at room temperature. The results reveal the possibility for tailoring the properties of insulating materials for application in electrical and electromagnetic shielding. Additionally, the good mechanical and thermal properties further widen the application range. [ABSTRACT FROM AUTHOR]

Herein, we prepared toughened and electrical nanocomposites of polyamide 6 (PA6)/acrylonitrile‐butadiene‐styrene (ABS) compatibilized with maleic anhydride‐grafted acrylonitrile‐butadiene‐styrene (ABS‐MA). Functionalized multi‐walled carbon nanotubes (MWCNTf) were used as conductive nanofillers. Nanocomposites were processed in an internal mixer and injection molded. Torque rheometry, impact strength, elastic modulus, heat deflection temperature (HDT), differential exploratory calorimetry (DSC), melting and crystallization kinetic curves, electrical conductivity, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were evaluated. Torque increased with the MWCNTf content in the PA6/ABS/ABS‐MA/MWCNTf nanocomposites, suggesting an increase in viscosity. The MWCNTf were well dispersed in the nanocomposites, generating an electrical percolation path. The impact strength of the PA6/ABS/ABS‐MA/MWCNTf nanocomposites was superior to that of pure PA6, indicating improved flexibility and toughness. The addition of 1 pcr of MWCNTf in the PA6/ABS/ABS‐MA system was sufficient for antistatic application, with a 221% higher impact strength, compared to pure PA6. The DSC studies showed that the crystallization temperature of the nanocomposites shifted to higher temperatures. This was due to the MWCNTf that accelerated crystallization. Additionally, the nanocomposites HDT increased by 20°C compared to the PA6 matrix, suggesting a superior thermomechanical strength. The developed nanocomposites show improved mechanical, electrical, and thermomechanical properties. Therefore, they exhibit great technological potential for application in antistatic packaging. [ABSTRACT FROM AUTHOR]

In this work, polyamide 6 (PA6) properties were tailored and improved using a maleic anhydride-grafted acrylonitrile-butadiene-styrene terpolymer (ABS-MA). The PA6/ABS-MA blends were prepared using a co-rotational twin-screw extruder. Subsequently, the extruded pellets were injection-molded. Blends were characterized by torque rheometry, the Molau test, Fourier transform infrared spectroscopy (FTIR), impact strength, tensile strength, Heat Deflection Temperature (HDT), Differential Scanning Calorimetry (DSC), Thermogravimetry (TG), Contact Angle, Scanning Electron Microscopy (SEM), and water absorption experiments. The most significant balance of properties, within the analyzed content range (5, 7.5, and 10 wt.%), was obtained for the PA6/ABS-MA (10%) blend, indicating that even low concentrations of ABS-MA can improve the properties of PA6. Significant increases in impact strength and elongation at break have been achieved compared with PA6. The elastic modulus, tensile strength, HDT, and thermal stability properties of the PA6/ABS-MA blends remained at high levels, indicating that maleic anhydride interacted with amine end-groups of PA6. Torque rheometry, the Molau test, and SEM analysis suggested interactions in the PA6/ABS-MA system, confirming the high properties obtained. Additionally, there was a decrease in water absorption and the diffusion coefficient of the PA6/ABS-MA blends, corroborating the contact angle analysis. [ABSTRACT FROM AUTHOR]

Magnetic and flexible nanocomposites of polyamide 6 (PA6)/styrene‐(ethylene‐butylene)‐styrene grafted with maleic anhydride (SEBS‐MA) were prepared using Ni‐Zn ferrite synthesized by combustion reaction. Thermal treatment was applied to the Ni‐Zn ferrite to form a more crystalline phase. The nanocomposites were processed in an internal mixer and later injection molded. The materials were characterized by torque rheometry, X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Izod impact strength, tensile strength, magnetic measurements, differential scanning calorimetry (DSC), thermogravimetry (TG), heat deflection temperature (HDT), and scanning electron microscopy (SEM). Ferrite calcination led to a higher degree of crystallinity and nanocomposites with a higher number of crystalline peaks. This favored a higher saturation magnetization. The magnetic hysteresis curves of the nanocomposites indicated a ferrimagnetic behavior. The impact strength and elongation at break increased significantly compared to neat PA6, suggesting the formation of flexible and magnetic nanocomposites. This behavior was ascribed to a chemical reaction between the terminal amine groups of PA6 and the maleic anhydride of SEBS‐MA, confirmed by FTIR and torque rheometry. Neat PA6 and the nanocomposites showed similar thermogravimetric, HDT, melting temperature, and crystallization properties. SEM results showed that the dispersed ferrite tends to form agglomerates, especially if calcined. In general, the addition of the non‐calcined Ni‐Zn ferrite to the PA6 matrix improved the mechanical properties. Conversely, the calcination of ferrite tended to improve the magnetic behavior of the nanocomposites. [ABSTRACT FROM AUTHOR]

This research aimed to evaluate the influence of styrene–butadiene–styrene (SBS) compatibilizer in the polystyrene blends properties with a recycled styrene–butadiene rubber compound. The SBS content was 5, 7.5, and 10%. Commercial high-impact polystyrene (HIPS) was used for comparison. The results indicated that the viscosity of the blends was higher than that of HIPS. The blends compatibilized with 5 and 7.5% had the same level of impact strength as HIPS, while the one with 10% obtained a gain of 80% in relation to HIPS. The flexural strength, hardness, heat deflection temperature, and Vicat softening temperature properties were similar to those of HIPS, which was attributed to the presence of inorganic fillers, minimizing losses in these properties. By atomic force microscopy, two distinct phases were observed, and in the morphology analyzed through scanning electron microscopy, a typical characteristic of immiscible blends was observed. [ABSTRACT FROM AUTHOR]

Polypropylene/Syagrus Cearensis fiber composites compatibilized with polypropylene‐graft‐maleic anhydride (PP‐g‐MA) and styrene(ethylene‐butylene)‐styrene copolymer (SEBS‐g‐MA) were successfully produced using a co‐rotating twin‐screw extruder followed by injection molding. The composites were characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The mechanical properties were determined by Izod impact and tensile testing. Thermal properties were obtained by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). Heat deflection temperature (HDT) was determined to study the thermomechanical properties of the composites. XRD and DSC indicated the presence of two polypropylene polymorphs: α and β. The unmodified PP/Fiber composites showed an incompatible behavior, presenting low fiber/matrix interaction and poor interfacial adhesion. The poor compatibility led to low elongation at break and impact strength but high tensile strength. PP‐g‐MA coupling agent promoted some adhesion to the PP/fiber interfaces but not enough to improve the impact strength. The composites with PP‐g‐MA exhibited improved tensile modulus and strength. The enhanced PP/fiber interfacial interaction promoted by SEBS‐g‐MA generated a better interplay of mechanical properties, improving impact strength and elongation at break while preserving the elastic modulus and tensile strength. In general, the fibers enhanced the thermomechanical stability of PP, as evidenced by higher HDT values. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA)/natural rubber (NR) blends were compatibilized with elastomeric ethylene grafted with glycidyl methacrylate (EE-g-GMA), and poly(ethylene octene) grafted with glycidyl methacrylate(POE-g-GMA), aiming at the PLA toughening. The blends were processed using a twin-screw extruder and then injection molded. The mechanical, thermal, and thermomechanical properties and morphology were investigated. The addition of 10% NR to PLA resulted in a 77% increase in impact strength. Incorporating 10% of EE-g-GMA and POE-g-GMA in the blends promoted a significant increase in impact strength, with gains of 256% and 250%, respectively. Elastic modulus and tensile strength decreased and the elongation at break compared increased to pure PLA. Therefore, the developed blends exhibited ductile behavior. The heat deflection temperature showed no significant differences between the blends and pure PLA, indicating that the thermomechanical stability was maintained. The differential scanning calorimetry analysis confirmed an increase in the degree of crystallinity. Additionally, the incorporation of EE-g-GMA accelerated the blend's crystallization. The thermal stability of the compatibilized blends was higher than PLA, confirming the increased tendency of the degree of crystallinity. The morphology indicated a refinement, good dispersion, and adhesion of the NR phases in the PLA matrix, contributing to improving toughness. These results show that the blends have the potential to produce eco-friendly materials, contributing to a more environmentally friendly cycle. [ABSTRACT FROM AUTHOR]

The present investigation aimed to produce ecological composites of biopolyethylene (BioPE) with macaíba shell (MS), using polyethylene‐graft‐maleic anhydride (PE‐g‐MA) and polyethylene‐graft‐acrylic acid (PE‐g‐AA) as compatibilizers, as well as macaíba almond oil as a plasticizing agent. The composites were processed in a co‐rotational twin‐screw extruder and injection molded. The addition of 30% by weight of MS in the BioPE matrix caused a reduction in impact strength and elongation at break, but improved stiffness and heat deflection temperature. The PE‐g‐MA and PE‐g‐AA compatibilizers improved the impact strength of the composites, suggesting increased interactions between the phases. There was an increase in the composites degree of crystallinity, indicating that the MS acted as a nucleating agent. The macaíba oil addition to the composites increased the impact strength, indicating a plasticizing effect. However, the elastic modulus, tensile strength, and degree of crystallinity tended to decrease. In general, the use of PE‐g‐MA compatibilizer was more effective to improve the composites mechanical properties. The reuse of MS is feasible for the production of sustainable composites. [ABSTRACT FROM AUTHOR]

Poly(ethylene-octene) grafted with glycidyl methacrylate (POE-g-GMA) and ethylene elastomeric grafted with glycidyl methacrylate (EE-g-GMA) were used as impact modifiers, aiming for tailoring poly(lactic acid) (PLA) properties. POE-g-GMA and EE-g-GMA was used in a proportion of 5; 7.5 and 10%, considering a good balance of properties for PLA. The PLA/POE-g-GMA and PLA/EE-g-GMA blends were processed in a twin-screw extruder and injection molded. The FTIR spectra indicated interactions between the PLA and the modifiers. The 10% addition of EE-g-GMA and POE-g-GMA promoted significant increases in impact strength, with gains of 108% and 140%, respectively. These acted as heterogeneous nucleating agents in the PLA matrix, generating a higher crystallinity degree for the blends. This impacted to keep the thermal deflection temperature (HDT) and Shore D hardness at the same level as PLA. By thermogravimetry (TG), the blends showed increased thermal stability, suggesting a stabilizing effect of the modifiers POE-g-GMA and EE-g-GMA on the PLA matrix. Scanning electron microscopy (SEM) showed dispersed POE-g-GMA and EE-g-GMA particles, as well as the presence of ligand reinforcing the systems interaction. The PLA properties can be tailored and improved by adding small concentrations of POE-g-GMA and EE-g-GMA. In light of this, new environmentally friendly and semi-biodegradable materials can be manufactured for application in the packaging industry. [ABSTRACT FROM AUTHOR]

Large waste amounts from wood industries as powder and sawdust are daily produced, and reusing these materials otherwise would be discharged to the environment has become an economically viable and environmentally friendly alternative to produce new materials. Based on these arguments, polypropylene (PP)/Jatobá wood powder composites upon addition of two types of PP were processed in a corotational twin screw extruder; specimens were injected and molded and their characterization was performed through differential scanning calorimetry, thermogravimetry, mechanical properties (impact, tensile, flexural, and hardness), heat deflection temperature (HDT), Vicat softening temperature, and scanning electron microscopy (SEM). Increased elastic modulus, shore D hardness, HDT, and Vicat related to neat PPs were reached. Nevertheless, losses in impact and tensile strength as well as in elongation at break were also verified. These lower data may be associated with the wood agglomeration, as shown in SEM images. Apparently, the investigated properties were not affected by PP viscosities, where both of them presented similar data. Summing up, presented results can be considered commercially feasible, focusing at economic and environmental benefits while producing higher performance products. [ABSTRACT FROM AUTHOR]

Environmental damage promoted trough post‐consumer waste from the wood industry has worried the society, while its inadequate disposal has raised concerns of the scientific community. Environmentally and economically effective alternative is reusing this residue to produce smart composites. Therefore, this work aimed to investigate the performance of polypropylene (PP)/Jatobá Wood Powder (WP) composites compatibilized with ethylene propylene diene monomer rubber‐maleic anhydride (EPDM‐MA). The effect of distinct melt flow index (MFI) (PP H103 and PP H503) was also investigated. The composites were characterized using differential scanning calorimetry, thermogravimetry, mechanical properties (tensile, flexural, impact, and Shore D hardness), heat deflection temperature, Vicat softening temperature, water absorption and scanning electron microscopy (SEM). Addition of EPDM‐MA, increased impact strength. The best performance was observed for the composition with 10% EPDM‐MA and PP with lower MFI (PP H503). EPDM‐MA also decreased the water absorption for both PP, most due to the chemical interactions among composite phases. SEM images suggest encapsulation of wood particles by EPDM‐MA, promoting better composites performance. Reported results are valuable for the recycling industry, as well as are economically and environmentally promising. [ABSTRACT FROM AUTHOR]

The aim of the present work is to evaluate the effect of NaOH solution as a stress cracking agent on the thermal and tensile properties of PET and PET/ZnO composites. The solutions were applied during tensile testing and the effects were monitored by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and testing the actual mechanical properties. The rate of crystallization was increased when the samples were exposed to NaOH, as observed by both cold and melt crystallization; this is possibly due to the reduction in molar mass of the PET molecules caused by NaOH. During melting, the DSC peaks became more complex, which is probably due to the distinct macromolecular mass, as well as crystallites with different sizes and levels of perfection. According to TGA analyses, no drastic changes were observed on the thermal stability of PET due to the action of NaOH. The tensile properties were shown to decrease drastically upon exposure to NaOH, which is the main symptom of stress cracking, leading to increased fragility, as also observed in the scanning electron microscopy (SEM) images. The presence of ZnO improved PET crystallization and provided some protection against the harmful effects of NaOH. [ABSTRACT FROM AUTHOR]

In this work, poly(lactic acid) (PLA)-based vegetal Babassu composites were compounded and their thermal properties ascertained. Babassu acted as a facilitator agent for the nonisothermal cold crystallization of PLA. Nonisothermal cold crystallization kinetics of PLA compounds was investigated by differential scanning calorimetry applying Ozawa and Mo models; the activation energy was evaluated by Friedman equation. Our results indicate that Mo's model describes the experimental data successfully; the maximum crystallization rates observed for PLA/Babassu composites are higher than that found for neat PLA. Ozawa model failed to provide an adequate description for the composites, mostly due to the neglected secondary crystallization and impingement of spherulites. Friedman analysis shows that 5 wt% Babassu filler reduced the activation energy of the crystallization process greatly, leading to a shorter crystallization time. [ABSTRACT FROM AUTHOR]