Thermal and mechanical properties of wood flour–polystyrene blends from postconsumer plastic waste

Polystyrene (PS) from packing materials and plastic cups was reinforced with 30 and 50% wood flour through a blending process with and without a commercial compatibilizing agent. The processability of the pure recycled polystyrene (rPS) and wood–rPS composites was studied in terms of the torque of the mixing process; this was then compared with that of a commercial virgin multipurpose PS. The physical and mechanical properties were compared with those of the virgin PS reinforced with 30 and 50% wood flour. The results show that the mechanical properties of the pure and reinforced rPS did not decrease with respect to the virgin PS, and in terms of the impact strength, the rPS was superior to the virgin plastic. The mechanical properties were not affected by the commercial compatibilizing agent, but the torque of the blends was significantly lower with the compatibilizer. Differential scanning calorimetry (DSC) and dynamic mechanical analysis were used to study the glass‐transition temperature (T_g) of both the pure virgin PS and pure rPS and the wood flour–PS composites. The T_g values of the rPS and wood–rPS composites were higher than those of the virgin PS and wood–virgin PS composites. The use of rPS increased the stiffness and flexural modulus of the composites. Thermogravimetric analysis revealed that the thermal stability of rPS and its composites was slightly greater than that of the virgin PS and its composites. These results suggest that postconsumer PS can be used to obtain composite materials with good mechanical and thermal properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Characterization of highly filled wood flour–polyvinyl chloride composites: Dynamic mechanical and dielectric analysis

Viscoelastic and dielectric properties of composites with polyvinyl chloride as major matrix constituent, ethylene vinyl acetate (EVA) as polymeric plasticizer, and wood flour (WF) and fly ash (FA) as filler have been studied. The effect of variation of WF, FA, and EVA on storage modulus E′, loss modulus E″, and glass transition temperature, T_g has been evaluated using dynamic mechanical analysis (DMA). Effect on permittivity ε′ and conductivity is evaluated using dielectric analysis. The results show considerable influence of constituents of the composite on the properties evaluated. DMA shows that WF contributes to an increase in T_g, E′, and E″ and a decrease in loss tangent, tan δ. The FA content has insignificant effect on these properties. Increasing WF content increases ε′. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Characterization of highly filled wood flour–PVC composites: Morphological and thermal studies

Composites with polyvinyl chloride (PVC) as major matrix constituent, ethylene vinyl acetate (EVA) as polymeric plasticizer and wood flour (WF) and fly ash (FA) as filler were extruded. Morphology of the samples was studied using scanning electron microscopy (SEM). Morphological study indicated good dispersion of the constituents. Infrared spectroscopy (IR) indicates interaction between EVA and PVC and also between the polymeric matrix and WF. The effect of various constituents on glass transition temperature (T_g) was evaluated using differential scanning calorimetry. Addition of EVA decreased the T_g, whereas T_g was increased due to addition of WF and FA. Study indicated that reduction in T_g on addition of EVA was compensated by increase in T_g due to addition of WF. The contribution of FA to change in T_g was not significant. Resulting composites have T_g close to that of PVC. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical,thermal, and water uptake characteristics of woodflour‐filled polyvinyl chloride/acrylonitrile butadiene styrene blends

Woodflour‐filled composites based on polymeric blends of polyvinyl chloride (PVC) and super high‐impact grade ABS were developed. Mechanical, thermal, and water uptake characteristics of the PVC/ABS matrix and their wood composites were evaluated. In the case of PVC/ABS matrix, the blend at a mass ratio of 50/50 rendered the impact strength with a very high value of up to 65 kJ/m², noticeably higher than those of the parent resins, that is, 6 kJ/m² of PVC and 35 kJ/m² of ABS. Dynamic mechanical analysis thermograms showed two distinct glass transition temperatures (T_gs) that shifted toward each other indicating partial miscibility of the blends. Water absorption of the blends after 24 h immersion was low, that is, within the range of 0.04–0.2 wt % and exhibits a behavior closed to pseudo‐Fickian type. The obtained PVC/ABS wood composites exhibited an increase of flexural modulus as well as T_gs with an increase of woodflour content. Finally, impact strength of the PVC/ABS composites was significantly higher than those of PVC composites or polyethylene composites comparing at the same woodflour content. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Dynamic mechanical properties of poly(vinyl chloride)–xonotlite composite system

The filler effect of xonotlite (6CaO.6SiO₂.H₂O; needle-shaped) on dynamic mechanical properties, such as storage modulus (E′), loss modulus (E″), and tan δ was studied for the PVC—xonotlite composite system. And the properties of the system containing mechanically or chemically disaggregated particle of xonotlite were compared with those of the system-filled aggregates. The dynamic mechanical properties obviously depends on the dispersion condition of xonotlite particle. The aggregates of xonotlite produces a remarkably high modulus, an increase in T_g, and a decrease in mechanical damping near T_g in the system. On the other hand, the disaggregates, especially the chemical disaggregate one, bring softer or more rubbery properties in these systems. The interaction between matrix and filler was the strongest in the aggregates system and decreases in the order, mechanical disaggregates system, chemical disaggregates system.     

Dynamic mechanical properties of lightly sulfonated polystryrene ionomers

The effects of counterion type and addition of plasticizers on the dynamic mechanical properties of sulfonated atactic polystyrene (SaPS) containing 2.1 mole percent ionic groups have been investigated. For SaPS neutralized with alkali metal counterions at temperatures below 180°C, the matrix T_g and elastic modulus were not significantly affected by counterion type. However, above 180°C, the breadth of the rubbery plateau significantly decreased with increasing counterion size. Neutralization of SaPS with alkyl ammonium counterions decreased both the matrix T_g and the breadth of the rubbery plateau with increasing counterion size. By incorporating an ionic plasticizer in Na⁺ neutralized SaPS, dynamic mechanical properties were observed to be intermediate of systems neutralized with the alkali metal and alkyl ammonium counterions.     

Effects of wood flour and chitosan on mechanical,chemical, and thermal properties of polylactide

Composites of polylactide (PLA, 100–60 wt%) and wood flour (0–40 wt%) were prepared to assess the effects of wood filler content on the mechanical, chemical, thermal, and morphological properties of the composites. The polysaccharide chitosan (0–10 wt%) was added as a potential coupling agent for the PLA‐wood flour composites. Addition of wood flour significantly increased the flexural modulus and the storage modulus of PLA‐wood flour composite, but neither the wood flour nor chitosan had an effect on the glass transition temperature (T_g). Fourier transform infrared spectra did not show any evidence of covalent bonding, but chitosan at the interface between wood and PLA is thought to have formed hydrogen bonds to PLA‐carbonyl groups. SEM images of fracture surfaces showed that fiber breakage was far more common than fiber pullout in the composites. No evidence of discrete chitosan domains was seen in SEM micrographs. When added at up to 10 wt% (based on wood flour mass), chitosan showed no significant effect on the mechanical, chemical, or thermal properties of the composites, with property changes depending on wood flour content only. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers.     

Dynamic mechanical properties of extruded nylon–wood composites

Dynamic mechanical properties determine the potential end use of a newly developed extruded nylon–wood composite in under‐the‐hood automobile applications. In this article, the dynamic mechanical properties of extruded nylon–wood composites were characterized using a dynamic mechanical thermal analyzer (DMTA) to determine storage modulus, glass transition temperature (T_g), physical aging effects, long‐term performance prediction, and comparisons to similar products. The storage modulus of the nylon–wood composite was found to be more temperature stable than pure nylon 66. The T_g range of the nylon–wood composite was found to be between 23 and 56°C, based on the decrease in storage modulus. A master curve was constructed based on the creep curves at various temperatures from 30 to 80°C. The results show that the relationship between shift factors and temperature follows Arrhenius behavior. Nylon–wood composites have good temperature‐dependent properties. Wood fillers reduced the physical aging effects on nylon in the wood composites. The comparison of the nylon–wood composite with other similar products shows that nylon–wood composites are a promising low cost material for industrial applications. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Effect of the filler size and content on the thermomechanical properties of particulate aluminum nitride filled epoxy composites

Polymer matrix composites based on brominated epoxy as the matrix and aluminum nitride (AlN) particles as the filler were prepared. The influences of the size, content, and size distribution of AlN on the thermomechanical properties, including the glass‐transition temperature (T_g), coefficient of thermal expansion (CTE), dynamic storage modulus (E′), dynamic loss modulus (E″), and loss factor (tan δ), of the composites were investigated by thermomechanical analysis and dynamic mechanical analysis. There was a total change trend for T_g; that is, T_g of the composites containing nano‐aluminum nitride (nano‐AlN; 50 nm) was lower than that of the micro‐aluminum nitride (micro‐AlN; 2.3 μm) filled composites, especially at high nano‐AlN contents. The T_g depression of the composites containing nano‐AlN was related to the aggregation of nano‐AlN and voids in the composites. On the other hand, the crosslink density of the epoxy matrix decreased for nano‐AlN‐filled composites, which also resulted in a T_g depression. The results also show that E′ and E″ increased, whereas tan δ and CTE of the composites decreased, with increasing the AlN content or increasing nano‐AlN fraction at the same AlN content. These results indicate that increasing the interfacial areas between AlN and the epoxy matrix effectively enhanced the dynamic modulus and decreased CTE. In addition, at a fixed AlN content of 10 wt %, a low E′ of pre‐T_g (before T_g temperature) and high T_g were observed at the smaller weight ratio of nano‐AlN when combinations of nano‐AlN plus micro‐AlN were used as the filler. This may have been related to the best packing efficiency at that weight ratio when the bimodal filler was used. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermal degradation of epoxy/silica composites monitored via dynamic mechanical thermal analysis

A dynamic mechanical thermal analyzer (DMTA) was used to monitor changes of dynamic mechanical properties during thermal degradation of two types of epoxy/silica composites, both of which are used as electrical insulation in power apparatus. It was found that the peak value of the dynamic loss factor (tan δ), glass transition temperature (T_g), and dynamic storage modulus (E′) above T_g changed considerably with increasing thermal degradation, while E′ at the glassy state only underwent a moderate change with increased thermal degradation. It is concluded that the DMTA technique is very sensitive to the structural changes in the investigated epoxy composites due to the thermal degradation. It is also confirmed by DMTA tests that further cross-linking and loss of dangling chains are occurring slowly during the stage prior to the onset of the severe degradation. © 1992 John Wiley & Sons, Inc.     

Synthesis and Thermomechanical Behavior of (Qua)ternary Thiol-ene(/acrylate) Copolymers

The objective of this work is to characterize and understand the structure-to-thermomechanical property relationship in thiol-ene and thiol-ene/acrylate copolymers in order to complement the existing studies on the kinetics of this polymerization reaction. Forty-one distinct three- and four-part mixtures were created with systematically varied functionality, chemical structure, type and concentration of crosslinker. The resulting polymers were subjected to dynamic mechanical analysis and tensile testing at their respective glass transition temperature, T_g, to quantify and understand their thermomechanical properties. The copolymer systems exhibited a broad range of T_g, rubbery modulus – E_r and failure strain. The addition of a difunctional high-T_g acrylate to several three-part systems increased the resultant T_g and E_r. Higher crosslink densities generally resulted in higher stress and lower strain at failure. The tunability of the thermomechanical properties of these copolymer systems is discussed in terms of inherent advantages and limitations in light of pure acrylate systems.     

Thermal and mechanical properties of compression‐molded pMDI‐reinforced PCL/gluten composites

Many biopolymers and synthetic polymers composites were developed by different researchers for environmental protection and for cost reduction. One of these composites is polycaprolactone (PCL) and vital wheat gluten or wheat flour composites were prepared and compatibilized with polymeric diphenylmethane diisocyanate (pMDI) by blending and compression‐molding. PCL/pMDI blend exhibited glass transition (T_g) at ?67°C (0.20 J/g/°C) and vital gluten at 63°C (0.45 J/g/°C), whereas no T_g was recorded for wheat flour. Although T_g was unmistakable for either PCL or gluten, all composite exhibited one T_g, which is strong indication of interaction between PCL and the fillers. Several samples amongst the blended or compression‐molded composites exhibited no T_g signifying another confirmation of interaction. The ΔH of the endothermic (melting) and the exothermic (crystallization) for PCL was decreased as the percentage of gluten or flour increased, whereas the overall ΔH was higher for all composites compared to the theoretical value. The presence of pMDI appeared to strengthen the mechanical properties of the composites by mostly interacting with the filler (gluten or flour) and not as much with PCL. The FTIR analysis ruled out covalent interaction between PCL, pMDI, or the fillers but suggested the occurrence of physical interactions. Based on the data presented here and the data published earlier, the presence of pMDI did not change the nature of interaction between PCL and gluten, but it improved the mechanical properties of the composite. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study on PVC composites containing Eugenia jambolana wood flour

This article describes the properties of composites using unplasticized PVC matrix and wood flour (obtained by crushing the bark of Eugenia jambolana) as filler. Composites were prepared by mixing PVC with varying amounts of wood flour (ranging from 10–40 phr; having particle sizes of 100–150 μm and <50μm) using two‐roll mill followed by compression molding. The effect of wood flour content and its particle size on the properties, i.e., mechanical, dynamic mechanical, and thermal was evaluated. Tensile strength, impact strength, and % elongation at break decreased with increasing amounts of wood flour. Stiffness of the composites (as determined by storage modulus) increased with increasing amounts of the filler. Modulus increased significantly when wood flour having particle size <50 μm was used. Morphological characterization (SEM) showed a uniform distribution of wood flour in the composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Dynamic mechanical properties of three‐component composites (acrylic polymer/epoxy/SiO2) in the glass‐transition region

In previous studies, we reported the linear and nonlinear rheological properties of three‐component composites consisting of acrylic polymer (AP), epoxy resin (EP), and various SiO₂ contents (AP/EP/SiO₂) in the molten state. In this study, the dynamic mechanical properties of AP/EP/SiO₂ composites with different particle sizes (0.5 and 8 μm) were investigated in the glass‐transition region. The EP consisted of three kinds of EP components. The α relaxation due to the glass transition shifted to a higher temperature with an increase in the volume fraction (?) for the AP/EP/SiO₂ composites having a particle size of 0.5 μm, but the α relaxation scarcely shifted for the composite having a particle size of 8 μm as a general result. This result suggested that the SiO₂ nanoparticles that were 0.5 μm in size adsorbed a lot of the low‐glass‐transition‐temperature (T_g) component because of their large surface area. The AP/SiO₂ composites did not exhibit a shift in T_g; this indicated that the composite did not adsorb any component. The modulus in the glassy state (E′_g) exhibited a very weak &phis; dependence for the AP/EP/SiO₂ composites having particle sizes of 0.5 and 8 μm, although E′_g of the AP/SiO₂ composites increased with &phis;. The AP/EP/SiO₂ composites exhibited a peculiar dynamic mechanical behavior, although the AP/SiO₂ composites showed the behavior of general two‐component composites. Scanning electron microscopic observations indicated that some components in the EP were adsorbed on the surface of the SiO₂ particles. We concluded that the peculiar behavior of the AP/EP/SiO₂ composites was due to the selective adsorption of the EP component. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40409.     

The dynamic mechanical analysis,impact, and morphological studies of EPDM–PVC and MMA‐g‐EPDM–PVC blends

The dynamic mechanical studies, impact resistance, and scanning electron microscopic studies of ethylene propylene diene terpolymer–poly(vinyl chloride) (EPDM–PVC) and methyl methacrylate grafted EPDM rubber (MMA‐g‐EPDM)–PVC (graft contents of 4, 13, 21, and 32%) blends were undertaken. All the regions of viscoelasticity were present in the E′ curve, while the E″ curve showed two glass transition temperatures for EPDM–PVC and MMA‐g‐EPDM–PVC blends, and the T_g increased with increasing graft content, indicating the incompatibility of these blends. The tan δ curve showed three dispersion regions for all blends arising from the α, β, and Γ transitions of the molecules. The sharp α transition peak shifted to higher temperatures with increasing concentration of the graft copolymer in the blends. EPDM showed less improvement while a sixfold increase in impact strength was noticed with the grafted EPDM. The scanning electron microscopy micrographs of EPDM–PVC showed less interaction between the phases in comparison to MMA‐g‐EPDM–PVC blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1959–1968, 1999     

Viscoelastic Properties of Montmorillonite Clay/Polyimide Composite Membranes and Thin Films

Montmorillonite clay, cloisite 30B (nanoclay), was successfully dispersed in a polyimide (PI) matrix by in situ condensation polymerization followed by solution casting and thermal imidization. Wide angle X-ray diffraction, WAXD, test was used to study the structure of cloisite 30B clay powder and nanoclay/polyimide composites. The WAXD spectra of nanoclay powder and the composites show one major diffraction peak at 4.76° and 6°, respectively, suggesting that the d-spacing of nanoclay was decreased by about 26% after composite film processing. The viscoelastic property of polyimide and nanoclay/polyimide composite was studied by using dynamic mechanical spectrometer. The storage modulus and glass–rubber transition temperature of nanoclay/polyimide composites increases with increasing volume fraction of clay. The storage modulus of the composites in the rubbery plateau region, (T > 400 °C) increased remarkably with increasing volume fraction of clay. A modulus enhancement, (E_C/E_M) of about three orders of magnitude, (E_C/E_M ~1,440) was obtained for nanoclay/polyimide composite containing 6.8 vol% of nanoclay. The tangent of the loss angle (tan δ) for the composites, decreased with increasing volume fraction of nanoclay. The observed decrease in tan δ with increasing volume fraction of clay is consistent with the established trend of increasing storage modulus and glass–rubber transition temperature with increasing volume fraction of nanoclay. The phenomenal increase in the rubbery plateau storage modulus and glass–rubber transition temperature with increasing volume fraction of clay is believed to be due to increased restriction of chain motion with increasing nanoclay volume fraction.     

Effects of glass bead content and surface treatment on viscoelasticity of filled polypropylene/elastomer hybrid composites

The dynamic mechanical properties of A‐glass bead filled polypropylene (PP)/ethylene–propylene–diene monomers polymer (EPDM) ternary composites have been measured over a temperature range from −80 °C to 100 °C and at a fixed frequency of 1 Hz, using a dynamic mechanical analyser (DMA), to identify the effects of the filler content and its surface treatment with a silane coupling agent on the dynamic viscoelastic behaviour. The results show that the storage modulus (E′_c) and loss modulus (E ″_c) of these composites with 10% volume fraction of EPDM at 25 °C increase non‐linearly with increasing volume fraction of glass beads (ϕ_g). At the same test conditions, the E′_c value of the PP/EPDM filled with pretreated glass beads is higher than that of the uncoated glass bead filled PP/EPDM system, especially at higher ϕ_g, while the difference in E ″_c between both systems is very small. The mechanical damping for the former decreases with increasing ϕ_g, but the opposite is true for the latter. The glass transition temperature of these composites varies irregularly with ϕ_g. The dynamic complex viscosity increases nonlinearly with an increase of ϕ_g. In addition, the interfacial structure between the matrix and inclusions has been observed by means of a scanning electron microscope. © 1999 Society of Chemical Industry     

Interaction between wood and polyurethane‐alkyd lacquer resulting in a decrease in the glass transition temperature

The long‐term properties of paint and glue are of great interest to both manufacturers and users of these materials. If a good bond is achieved, the surface between the wood and the paint or glue will be less susceptible to degradation. Thus, the wood and polymer must be compatible and develop some kind of bonding force between them. A high degree of interaction between wood and commercial polyurethane‐alkyd lacquer was shown as a decrease by 10°C of the glass transition temperature (T_g) for the lacquer on wood compared to the pure lacquer. The lacquer also demonstrated good adhesion to wood at a microscale. The interaction was investigated with dynamic mechanical thermal analysis and scanning electron microscopy fractography. The reason for the decrease in Tg is probably because of the lacquer having a higher free volume when applied to the wood, most likely due to it being subjected to tensile forces developed during the drying of the lacquer. Results from investigations of wood impregnated with two different acrylates, a polymethylmethacrylate and a more hydrophilic acrylate, support the suggestion that a decrease in T_g will occur if the polymer adheres to wood, but that poor interaction with little or no adhesion will result in no decrease in T_g. This article also presents results of the dynamic mechanical behavior of Scots Pine in the tangential direction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 595–605, 2002     

Preparation and characterization of poly(vinyl chloride)–continuous carbon fiber composites

In this article, we report on the preparation and characterization of novel poly(vinyl chloride) (PVC)–carbon fiber (CF) composites. We achieved the reinforcement of PVC matrices with different plasticizer contents using unidirectional continuous CFs by applying a warm press and a cylinder press for the preparation of the PVC–CF composites. We achieved considerable reinforcement of PVC even at a relatively low CF content; for example, the maximum stress (σ_max) of the PVC–CF composite at a 3% CF content was found to be 1.5–2 times higher than that of the PVC matrix. There were great differences among the Young's modulus values of the pure PVC and PVC–CF composites matrices. The absolute Young's modulus values were in the range 1100–1300 MPa at a 3% CF content; these values were almost independent of the plasticizer content. In addition, we found a linear relationship between σ_max and the CF content and also recognized a linear variation of the Young's modulus with the CF content. The adhesion of CF to the PVC matrix was strong in each case, as concluded from the strain–stress curves and the light microscopy and scanning electron microscopy investigations. The mechanical properties of the PVC–CF composites with randomly oriented short (10 mm) fibers were also investigated. At low deformations, the stiffness of the composites improved with increasing CF content. Dynamic mechanical analysis (DMA) was used to determine the glass‐transition temperature (T_g) of the PVC–CF composites. The high increase in the Young's modulus entailed only a mild T_g increase. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Characterization and thermal degradation of poly(d,l‐lactide‐co‐glycolide) composites with nanofillers

Chemical and thermal characterization of poly(d ,l ‐lactide‐co‐glycolide) (PLGA) composites filled with hydroxyapatite (HA) or carbon nanotubes (CNT) were evaluated by infrared spectroscopy, differential scanning calorimetry, thermogravimetry, and dynamic–mechanical–thermal analysis. The morphology and distribution of the nanoparticles were studied by transmission electron microscopy. The composites were prepared by solvent casting using 30% HA or 1, 3, and 5% of pristine and functionalized CNT as nanoparticles and PLGA 75:25 and PLGA 50:50 as copolymer matrix. The Coats–Redfern and E₂ function methodologies were used to calculate the reaction order and the activation energy (E_a) of the thermal degradation process. It was found that the addition of nanoparticles increased the glass transition temperature (T_g) of the composites. Also, higher degradation temperatures and E_a values were obtained for PLGA–HA composites and compared with the neat copolymer, and the opposite behavior was exhibited by PLGA–CNT composites. The thermal and mechanical properties were highly dependent on the morphology and dispersion of the filler. The functionalization process of CNT promoted, to some extent, a better distribution and dispersion of CNT into the matrix, and these composites exhibited a slight enhancement on storage modulus. On the other hand, PLGA–HA composites showed a good dispersion but no improvement on the storage modulus below T_g. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers