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Wood plastic composites (WPCs) consisting of high density polyethylene (HDPE) reinforced with high-loading (55 wt%) of wood flour (WF) were fabricated with melt-blending technique. In this compounding method, processing parameters such as different mixing temperatures (of 165, 180 and 195°C), mixing times (of 5, 10 and 15 minutes) and coupling agent contents (of 2 and 4 wt%) were evaluated. Prepared specimens were analyzed with tensile, Izod, shore D, DMTA, short-term creep, DSC, TGA, water absorption and water contact angle characterizations. Results revealed that mixing temperature of 180°C, mixing time of 10 minutes and coupling agent concentration of 4 wt% were found as the best processing conditions. The mentioned conditions provided enhanced dispersion of WF particles within the HDPE matrix, due to optimum viscosity of the polymer melt and effective residence time of compound in the mixer, and beside them efficient interfacial adhesion between WF and polymer matrix.

In this study, phenol production process was simulated. Further, the performance of distillation column was optimized through maximizing the mole fraction of cumene in upstream flow. Response surface methodology was applied for design of experiment, modelling, and optimizing the cumene mole fraction in upstream flow of separation column. The analysis of variance was performed for finding the important operative parameters as well as their effects. In this experiment, the effects of three parameters on separation performance were investigated, including number of tray (A), column temperature (B), and reflux ratio (C). Further, radial basis function (RBF) was applied to model the separation column. To develop the neural network model, leave-one-out method was used. This robust model was used for optimizing the performance of separation column. The statistical and artificial intelligence system were capable of predicting mole fraction in upstream flow of distillation column in different conditions with R2 of 0.99 and 0.93, respectively. According to statistical and RBF models, the optimized values of cumene mole fraction are 0.45 and 0.44, respectively.

In order to enhance properties of polylactic acid (PLA), its blend with polycarbonate (PC) and silica nanofiller were prepared and their properties were compared with neat PLA and PLA/PC alloy. To ...

In this study, the ability to remove methylene blue cation pigment using wood-plastic composite containing high density polyethylene and wood powder as a recycled material was studied. The effect of some important parameters such as pH, adsorbent amount and contact time were investigated. Adsorption efficiencies for methylene blue was maximized at alkaline pH. Adsorption capacity increased with increasing adsorbent amount and contact time. The value of R2 in Langmuir model was equal to 1 and the separation factor for 0.5 and 1 g of adsorbent were 0.09 and 0.1, respectively. Given that the methylene blue adsorption data were more consistent with the Langmuir isotherm model, it can be stated that the wood-plastic composite probably has uniform adsorption surfaces and the adsorption process occurred in homogeneous system on the adsorbent surface. Based on the results of this study, it was observed that this composite is a suitable adsorbent for removing methylene blue from aqueous solutions and used as a purifying agent in the decolorization of effluents containing pigments. This adsorbent is recyclable and is cost-effective to remove dye from textile industry wastewater.

In this study, one of the higher Poly α-olefins, poly1-hexene (PHex), was rationalized for possible application in in-vitro drug delivery system. In this aspect, PHex was synthesized using ...

To make potential the biodegradable polyethylene glycol (PEGO) toward photocrosslinking, it was cooligomerized with fumaryl chloride by esterification reaction. The obtained viscous liquid injectable macromere, OPEGF, was characterized by FTIR and GPC. In another reaction, nanosilica was treated with acryloyl chloride to obtain silica-AC nanopowder and subsequently dispersed in the OPEGO matrix in 1 and 2 wt.% in the presence of either 1,4-butanediol dimethacrylate (BDM) or 1,12-dodecanediol dimethacrylate (DDM) as reactive diluent. The obtained slurries were photocured by blue light irradiation and the characteristics of prepared nanocomposites as well as crosslinked OPEGF were studied via XRD, TEM, tensile, equilibrium swelling and cell culture tests. XRD patterns revealed amorphous nature of all samples. TEM and Si mapping pictures demonstrated good dispersion of silica-AC at nano level (particle size of 20–30nm) in the fabricated samples. Tensile test disclosed a noticeable improvement in mechanical properties of the nanocomposites by increasing in nanofiller level. Equilibrium swelling study revealed that the presence of nanosilica and reactive diluent improved the crosslinking phenomenon. Finally, cell culture test evidenced higher biocompatibility of the samples containing silica-AC nanofiller and BDM reactive diluent. As the consequence of employed tests, designed nanocomposites can be considered as capable candidates for biomedical applications.

Polyolefin elastomers (POEs), a new family of synthetic commercialized polymers, can be used as an alternative for lots of common elastomers such as ethylene propylene rubbers (EPR or EPDM), poly (ethylene-co- vinyl acetate) (EVA) and poly (styrene-co-butadiene) (SBR). In this research, 1-hexene/1,5-hexadiene copolymer (COPOLY), as a newfound POE was cured with different weight fractions of dicumyl peroxide (DCP) as a curing agent. Curing behavior and ultimate properties of COPOLY were compared with EPDM as a nearby practical and commercial rubber. Mooney viscosity results showed that; by increasing weight fraction of curing agent, scorch times decreased, and the scorch time of COPOLY was lower than EPDM. Tensile measurements showed that COPOLY has comparable Young’s modulus with it in EPDM sample (16.11 and 16.51 MPa, respectively). DMTA analysis confirmed more toughness and elastomeric properties of COPOLY in comparison to EPDM rubber. Melt viscosity analysis of the samples exhibited that synthesized rubber has lower melt viscosity than EPDM at all frequency ranges, and also EPDM showed slightly higher elastic modulus in comparison to COPOLY (0.89 and 0.82 GPa, respectively). Fatigue test acknowledged excellent behavior of COPOLY with 45,600 cycles till to failure. The synthesized COPOLY showed significantly higher ozone resistance (142 toward 105 h) and lower abrasion weight loss (11.34 toward 14.28%) than commercial EPDM. Altogether, our obtained results suggest new highly efficient rubber that in all studied aspects has higher capability than EPDM and can be considered as a high performance rubber in industrial applications.

In this work, carbonyl iron (CI) containing polya- niline composites (PANI+CI) were prepared via in-situ polymerization of aniline in an aqueous solution containing different amounts of CI as the magnetic filler for the micro- wave absorbers. The incorporation of the magnetic powder to the PANI matrix was confirmed by X-ray diffraction (XRD), IR and SEM. Synthesized PANI+CI composite particles were subsequently added to an epoxy resin matrix to produce related R-PANI+CI composites. Study of thermal properties by thermogravimetric analysis revealed enhanced thermal stability of the composites. The electromagnetic-absorbing properties were studied by measuring the reflection loss in the frequency range of 8.0 to 12.0 GHz. The experimental results indicated that the electromagnetic wave absorbing properties of PANI+CI composites are dependent on the PANI/CI weight ratio. The good reflection loss of the composite at the optimum PANI/CI weight ratio of 1:6 suggests its potential applicability as a good radar absorber.

In this study, three middle range α-olefin monomers including 1-hexene, 1-octene, and 1-decene were oligomerized using conventional AlCl3/H2O catalytic system. Molecular weight and microstructure of the oligomers were analyzed by GPC and 1HNMR, respectively. By 1HNMR spectra, both internal (CHR=CHR′ and CHR=CR′R′′) and external (CH2=CR′R′′) olefins containing di and tri-substituted C=C bonds were detected. After successful oligomerization, synthesized polyα-olefins underwent hydrogenation process using Pd(0)-Hal catalyst to yield synthetic oils of PHex, POct, and PDec, respectively and then completion of the hydrogenation was confirmed by 1HNMR spectroscopy. The microstructure of the synthesized oligomers was rationalized using the ratio under the peak of CH + CH2/CH3 hydrogens (S1/S2) in 1HNMR spectra and the degree of oligomerization obtained from Mn. According to the results, the best match between theoretical and real S1/S2 is obtained when considering double bond isomerization in the synthesized PAOs. By knowing PAO molecular weight, a relationship between monomer type and S1/S2 in the PAO homopolymers was detected. Our suggested methodology can be generalized to the unknown PAO homopolymers to unravel their monomer type by simple 1HNMR and GPC analyses.

Nano-sized polyhedral oligomeric silsesquioxane (POSS) diol or ethylene glycol (EG) as diol monomer was incorporated into hydroxyl-terminated polybutadiene (HTPBD) chain in the presence of fumaryl or thionyl chloride as extenders. Using these polyesterification reactions, two fumarate-based polyesters and two polyester sulfites were synthesized. Each couple of polyesters and polyester sulfites includes a linear (diol:EG) and a nanohybrid macromer (diol:POSS). Full structural characterization was performed using Fourier transform infrared, 1H NMR and 13C NMR spectroscopies. Gel permeation chromatography was undertaken to study polyesterification mechanisms by deconvolution of the obtained traces. Finally, differential scanning calorimetry, thermogravimetric analysis and cell culture were performed to evaluate the structure–property relationship for the synthesized macromers in comparison with unreacted HTPBD. © 2016 Society of Chemical Industry

Carbon nanotubes (CNTs) exhibit high conductivity, as well as outstanding electromagnetic properties, which make them excellent candidates for polymer composites with multifunctional properties. They can serve as materials for fabricating electromagnetic shielding, electronic devices, actuators, and sensors. In this chapter, after revisiting the basic key concepts in electrical conductivity and electromagnetic shielding interference calculations, the main factors affecting electromagnetic and/or electrical properties of CNT-polymer composites (such as CNT geometry, loading amount, polymer type, dispersion conditions, and composite geometry) are discussed.

Since 1963, when Karl Ziegler and Giulio Natta were jointly awarded the Nobel Prize for their discoveries of the catalytic polymerization of olefins with Ti-chlorides and Al-alkyls, heterogeneous Ziegler-Natta (ZN) catalysts have become the main catalysts for the industrial production of polyolefins. Despite of the relevance of ZN catalysts for the large-scale production of polyolefins, a clear mechanistic understanding of these catalysts is still incomplete due to the elusive nature of the active site structures. Over the last two decades, researchers have used density functional theory (DFT) methods to clarify the polymerization mechanisms and to identify the nature of the active sites, unraveling the influence of supports, cocatalysts, and the effect of internal and external donors on the polymerization processes. Major efforts were dedicated to understanding the origin of stereoselectivity in α-olefin polymerization as well as the termination reactions mechanisms, and the role that impurities can play in heterogeneous ZN catalysis. Here, we review the DFT studies on heterogeneous ZN catalysts and suggest promising areas for future research.

A nitratecitrate gel was prepared from metallic nitrates and citric acid by solgel process and was further used to synthesize Ni0.5Zn0.5Fe2O4 nanocrystalline powder by auto-combustion. Then, two novel 15 and 35% (w/w) magnetic Ni0.5Zn0.5Fe2O4 containing polyaniline nanocomposites, named as PANI-Ni15 and PANI-Ni35, respectively, were prepared via in-situ polymerization of aniline in an aqueous solution containing proper amount of Ni0.5Zn0.5Fe2O4 magnetic powder. The incorporation of the nanopowders to PANI matrix was confirmed by X-ray diffraction (XRD), IR and SEM. Synthesized PANI-NiZn ferrite composite particles were subsequently added to an epoxy resin matrix to produce related nanocomposites. The morphological properties of these nanocomposite materials were investigated by SEM and TEM. The electromagnetic-absorbing properties were studied by measuring the reflection loss in the frequency range of 8.0 to 12.0 GHz. Results showed the reflection loss of the PANI-Ni35 composite is higher than pure polyaniline and PANI-Ni15. The good reflection loss of the nanocomposites suggests their potential applicability as radar absorber.

Hybrid poly(ϵ-caprolactone) (PCL) containing nanocomposites and non-hybrid linear PCL diols were synthesized by anionic ring opening polymerization of ϵ-caprolactone on a POSS or ethylene glycol central blocks, respectively. Monolith scaffolds were then fabricated from the hybrid nanocomposites and non-hybrid linear PCL diols via non-solvent induced phase separation technique. The effects of inclusion of POSS nanocage in the polymer chain structure on specific surface area and pore size of the scaffolds was investigated by multipoint BET method. This perfect scrutiny will introduce an excellent nanoparticle pendent to the PCL chains to promote the in vitro properties of the implants potentially applicable in tissue engineering.

In this study we have investigated computationally the mechanism of polymerization of 2,5-dibromo 3-butylthiophene via the GRIM method, with the focus on the origin of the head to tail (HT) selectivity. To this end, first the Grignard reagent underwent oxidative addition to the monomer to afford the 2-bromo-5-chloromagnesio-3-butylthiophene (intermediate I1) or the 2-chloromagnesio 5-bromo-3-butylthiophene (intermediate I2) regioisomers. Then intermediates I1 and I2 were polymerized catalytically to a series of regiospecific poly-3-butylthiophenes using the commonly used Ni(dppp)Cl2 [dppp: 1,3-bis(diphenylphosphino) propane] and Pd(dppp)Cl2 catalysts. Due to the asymmetric nature of I1 and I2 that act as the active monomeric species, 6 coupling modes may occur. The whole energy profile of all modes has been studied by considering a three-stage mechanism, including coordination, transmetalation, and reductive elimination, to compare quantitatively the ability of so-called catalysts in selective coupling of desired isomers to produce regioregular poly-3-butylthiophene. Finally, to quantify the steric role of the dppp in regioselectivity, analysis of the buried volume in terms of steric maps was performed.

Anionic ring opening polymerization of ϵ-caprolactone was studied by using different amounts of two potassium activated initiators containing ethylene glycol (EG) and polyhedral oligomeric silsesquioxane (POSS) diol, in tetrahydrofuran and toluene as solvents. The synthesized hydroxyl terminated macromers and linear poly(ϵ-caprolactone) (PCL) were characterized by proton and carbon nuclear magnetic resonance and gel permeation chromatography (GPC) techniques. Results showed an increase in molecular weight as the monomer/initiator molar ratio increased from 100 to 151 and 202, while the molecular weight distribution (MWD) showed a minimum by monomer concentration increase. Moreover, POSS-diol-initiated PCLs showed a higher MWD than the polymers initiated with the EG initiator. This was attributed to the formation of a vesicular structure of POSS diols which was confirmed by optical microscopy. By deconvolution of GPC peaks, the best conditions to synthesize PCL with the narrowest MWD were selected. Finally, the effects of some other parameters were studied in more detail.

Poly1-hexene was prepared using a conventional heterogeneous Ziegler–Natta catalyst and its stereoregularity was characterized using 13C-NMR analysis. New kind of high impact polystyrene (HIPS) was prepared by radical polymerization of styrene in the presence of different amounts of synthesized poly1-hexene (PH) as impact modifier (HIPS/PH) and compared with conventional high impact polystyrene with polybutadiene (HIPS/PB) as rubber phase. Scanning electron microscopy (SEM) revealed that the dispersion of poly1-hexene in polystyrene matrix was more uniform compared with it in HIPS/PB. The impact strength of HIPS/PH was 29–79% and 80–289% higher than that in HIPS/PB and neat polystyrene, respectively. FTIR was used to confirm more durability of HIPS/PH samples toward ozonation. To study the effect of rubber type and amount on the Tgs of polystyrene, differential scanning calorimetry was employed. Results obtained from TGA demonstrated higher thermal stability of HIPS/PH sample in comparison with conventional HIPS/PB one. Our obtained results suggest new high impact polystyrene that in all studied aspects has better performance than the conventional HIPS. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43882.

Hydroxyl functionalized nano-sized POSS or ethyleneglycol as diol monomers was incorporated to hydroxyl-terminated polybutadiene (HTPBD) chain in the presence of fumaryl chloride as extender. Blue light photocrosslinking system based on camphorquinone (photoinitiator) and dimethylaminoethyl methacrylate (accelerator) was applied to cure these two synthesized fumarate based macromers. Self-crosslinkability of unsaturated macromers and also crosslinking in presence of a reactive diluent were investigated in absence and presence of 1,4-butanediol dimethacrylate, respectively. Finally, photocured samples were characterized by XRD, SEM, equilibrium swelling study, TGA, DMTA, AFM and cell culture. The results showed that incorporation of POSS nanoparticle into the polymer matrix with a perfect distribution and dispersion can enhance thermal stability, mechanical and biocompatibility properties which can prove a good potential of this in-situ photocrosslinkable nanohybrid in medical applications.

Hydrogenolysis of a series of model Ziegler–Natta (Z–N) catalysts to form Ti–H bond was studied within DFT. We focused our efforts on Ti species attached to the (110) lateral cut of MgCl2 which exist as different centres including Ti–C2H5, Ti–CH2CH(CH3)2, and Ti–CH(CH3)CH2CH3 in ethylene and propylene polymerization. In the next step, reactivity of Ti–H bond towards ethylene and propylene (1,2- and 2,1-) insertion was investigated. Results showed that insertion of ethylene and propylene into Ti–H bond has less barrier, in comparison with their insertion in Ti–C bond, however, ethylene and propylene 2,1- insertion lead to Ti–C2H5 and Ti–CH(CH3)2 centres respectively, which were stable due to strong β-agostic interactions. Finally, by considering different possible reactions of active centre, activity depression in ethylene polymerization and activity increase in propylene polymerization were explained in detail.

O2 and CO2 gases plasma were applied to modify surface properties of bacterial source poly(3-hydroxybutyrate) (PHB) to improve its biocompatibility. Results indicated that the PHB films with an irregular and coralloid surface change to a regular surface morphology with nano indentation and nanoprotrusion, especially for O2 treated one, while no changes in bulk properties occurred. This led to an improved L-929 fibroblast cell growth of plasma-treated films compared with the untreated one. Further, we showed that among surface morphology, wettability and electrostatic interaction between cell and surface, the first two parameters have a more significant effect in obtaining biocompatibility feature.

Two types of biodegradable, in situ photocrosslinkable macromers were synthesized consisting a linear copolyester i.e., PCLF based on fumaric acid (FA) and poly(e-caprolactone diol) (PCL diol), and its nanohybrid counterpart (POSS-PCLF) composed of FA, PCL diol and polyhedral oligomeric silsesquioxane (POSS). Chemical structure of the macromers was characterized by 1HNMR and FTIR spectroscopy. The synthesized macromers were photocrosslinked by visible light irradiation in the presence of camphorquinone and N,N’-dimethylaminoethyl methacrylate as a photoinitiator and accelerator, respectively. Photocrosslinking characteristics of the compositions were investigated as a function of the initial PCL diol molecular weight, presence of POSS nanoparticles or N-vinylpyrrolidone (NVP, as a reactive diluent) by tracing degree of conversion by FTIR spectroscopy, equilibrium swelling studies. Thermal and dynamical properties of the macromers and the resulting networks were studied by TGA, DSC and DMA techniques pre- and post-photocrosslinking. In contrast to the self-crosslinkability of the macromers, the crosslinking reaction was promoted more efficiently in the presence of NVP as a reactive diluent. This scrutiny showed that there is an optimum point for POSS concentration to obtain the maximum improvement in the network properties.