Effect of wood sawdust content on rheological and structural changes,and thermo‐mechanical properties of PVC/sawdust composites

The use of untreated sawdust as a filler in poly(vinyl chloride) (PVC) was examined—the effects of sawdust content on structural and thermal changes, and rheological and mechanical properties being of main interest. The results revealed that the torque and die entrance pressure drop values during mixing were independent of sawdust particles up to 23.1 wt%. The extrudate swell monotonically decreased up to 33.3 wt% sawdust content. Smooth wood‐like texture with controllable size of the extrudate could be obtained at a sawdust content greater than 33.3 wt%. Tensile, impact, flexural and hardness properties of the PVC/sawdust composites considerably decreased with up to 16.7 wt% sawdust content before leveling off for higher sawdust loadings. The composites having sawdust higher than 16.7 wt% showed a benefit of cost savings. The decreases in the mechanical properties of PVC with sawdust are explained in association with the presence of moisture, interfacial defects between fibre and polymer, and fibre dispersions in the PVC matrix. Thermal degradations of PVC in PVC/sawdust composites were evidenced by a decrease in decomposition temperature and an increase in polyene sequences, which were caused by Cl cleavage due to strong hydrogen bonds of fibre–PVC molecules. The maximum of tanδ transition and the glass transition temperature were found to improve with sawdust content as a result of re‐formation of hydrogen bonds between the macromolecules of the fibre and the polymer. The overall results in this work suggest that the properties of PVC/sawdust composites were strongly influenced by sawdust content up to 16.7 wt%. Beyond this value the effect of sawdust content on the properties was comparatively small. Copyright © 2003 Society of Chemical Industry     

Effect of moisture content on mechanical properties,thermal and structural stability and extrudate texture of poly(vinyl chloride)/wood sawdust composites

Mechanical properties and thermal and structural changes of poly(vinyl chloride) (PVC)/wood sawdust composites were assessed with respect to the effect of moisture content, varying from 0.33 to 3.00 % by weight in the composite, for three different wood sawdust contents. The swell ratio and texture characteristics of the composite extrudates were also evaluated. Unique explanations were given to describe changes in the composite properties in terms of molecular interactions between PVC, cellulosic sawdust and moisture, such as dipole–dipole interactions, interfacial defects and bonding, fibre swelling, and moisture evaporation. The results suggest that at low moisture content the tensile modulus decreased and elongation at break of the composites increased with moisture content, the effect being reversed for high moisture content. Tensile strength decreased with increasing moisture content up to 1–2 %, and then unexpectedly increased at higher moisture contents. The effect of moisture content on flexural properties of the composite was similar to that on tensile properties. Impact strength of the composites was considerably improved with moisture content at low sawdust contents (16.7 wt%), and was independent of the moisture content at higher sawdust contents (28.6 and 37.5 wt%). A decrease in decomposition temperature with an increase in polyene content was evidenced with increasing moisture content, while the glass transition temperature did not change with varying moisture content. The extrudate swell ratio increased with the shear rate but remained unaffected by moisture content. The bubbling and peeling‐off in the composite extrudate occurred as a result of the evaporation of water molecules and the application of a high shear rate. Copyright © 2004 Society of Chemical Industry     

Effects of compatibilizer type and rubber‐wood sawdust content on the mechanical,morphological, and thermal properties of PVC/LDPE blend

This article aimed to investigate the mechanical, morphological and thermal properties of PVC/LDPE blend with and without the addition of compatibilizers. The effects of LDPE content, compatibilizer type and rubber‐wood sawdust loading on the properties of the blend were evaluated. The experimental results suggested that as the LDPE content was increased the mechanical properties of PVC‐LDPE blend progressively decreased due to poor interfacial adhesion. The continuity and compatibility between PVC and LDPE phases could be improved through three different types of compatibilizers which included chlorinated polyethylene (CPE) poly(methyl‐methacrylate‐co‐butyl acrylate) (PA20) and poly(ethylene‐co‐methacrylate) (Elvaloy). The PA20 was found to be the most suitable compatibilizer for the blend. A radical transfer reaction was proposed in this work to explain the structure and thermal changes of the PVC in PVC‐LDPE blend. The decomposition temperature of PVC in the blend decreased with the loading of the PA20 and the wood sawdust. As the sawdust content was increased the tensile and flexural moduli increased with considerable decreased in the tensile, flexural and impact strength, a slight improvement being achieved if the PA20 was incorporated in the composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 598–606, 2006     

Influence of various wood modifications on the properties of polyvinyl chloride/wood flour composites

Aminosilane, melamine and acetic anhydride treated wood flour were added to polyvinyl chloride (PVC) in order to process improved PVC/wood flour composites. The influence of wood treatment on water absorption and mechanical properties were evaluated. Treatments with amino-alkyl functional oligomeric siloxane and melamine in suitable concentration as well as acetylated wood flour composites showed decreased equilibrium moisture content and reduced speed of water absorption. Tensile strength, elongation at break and unnotched impact strength were considerably improved by the aminosilane treatments. The increase in strength and elongation was mainly influenced by the chemical structure and concentration of the used aminosilanes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanical properties and water absorption of low‐density polyethylene/sawdust composites

The mechanical properties and water absorption of low‐density polyethylene/sawdust composites were investigated. The relationship between the filler content and the composite properties was also studied. Different degrees of esterification of the sawdust with maleic anhydride were obtained with different reaction times. The experimental results demonstrated that the treatment of sawdust by maleic anhydride enhanced the tensile and flexural strengths. The water absorption for maleic anhydride treated sawdust indicated that it was more hydrophobic than untreated sawdust. The effects of the addition of benzoyl peroxide during the preparation of composite samples on the water absorption and mechanical properties were also evaluated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Dynamic rheological behavior and mechanical properties of PVC/CPE/MAP–POSS nanocomposites

Poly(vinyl chloride)/chlorinated polyethylene (PVC/CPE)/methylacryloylpropyl‐containing polyhedral oligomeric silsesquioxane (MAP–POSS) nanocomposites are prepared. The plastic behavior and dynamic rheological behavior of PVC/CPE/MAP–POSS are investigated. The influences of composition on dynamic storage modulus G′, loss modulus G″, and complex viscosity η* of PVC/CPE/MAP–POSS melts are discussed. The dynamic mechanical properties, mechanical properties, and morphology are determined. The results show that both plastic time and balance torque of the nanocomposites decrease, but the G′, G″, and η* all increase with increasing MAP–POSS content. The maximum value of the dynamic mechanical loss tan δ decreases and elasticity increases when MAP–POSS is added. The impact strength of the nanocomposites increases with increasing MAP–POSS content and has the best value at 10% content of MAP–POSS, which is 5.38 kJ/m² higher than that of the blend without MAP–POSS. The MAP–POSS can be used as an efficient process aid and impact aid for the PVC/CPE blend. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of wood species on the mechanical and thermal properties of wood–plastic composites

The effect of wood species on the mechanical and thermal properties of wood–plastic composites (WPCs) was explored. Various wood species, including cherry, sweet gum, hickory, yellow poplar, Osage orange, walnut, eastern red cedar, pine, maple, and red oak, were compounded with virgin isotactic polypropylene in a 50 : 50 weight ratio and injection‐molded. The tensile strength of WPCs made with cedar and hickory was higher than that of WPCs made with maple, oak, and Osage orange. The tensile modulus of WPCs made with gum and walnut was higher than that of oak WPCs. The tan δ peak temperatures and peak values from dynamic mechanical analysis indicated that pine and hickory WPCs had higher amorphous or void contents than walnut and cherry WPCs. The induction time during isothermal crystallization suggested that red cedar, cherry, and gum WPCs had higher nucleation density than walnut, pine, and oak WPCs. Dynamic mechanical properties of the WPCs appeared to be related to the crystallization behavior of the wood flour, which depends on the surface roughness. Although there were statistically significant differences in mechanical properties among the species, the differences were small, implying that wood flours from many species can be used successfully as raw materials for WPCs. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of intercalated Mg‐Al layered double hydroxides and its application in PVC thermal stability

The Mg‐Al oxide precursor prepared by the calcination of Mg‐Al‐carbonated layered double hydroxide (LDH) at 500 K for 4 h is used as the host material, 2‐hydroxy‐4‐methoxybenzophenone‐5‐sulfonic acid (BP) is used as the guest material, BP‐intercalated LDH (LDH‐BP) is prepared by ion‐exchange method. The structure of LDH‐BP is characterized by X‐ray diffraction (XRD), Fourier transform infrared (FTIR), and thermogravimetry and differential thermal analysis (TG‐DTA). The thermal stability of PVC/BP, PVC/LDH, PVC/LDH‐BP composites, as well as pure PVC is investigated by conventional Congo Red test and dynamic thermal stability analysis in both the open and closed processing environments. According to XRD and FTIR, BP anions have been intercalated into interlayer galleries of LDH. TG‐DTA results show that the layer‐anionic interaction results in the improvement of the thermal stability of BP. Congo Red tests indicate that the addition of BP catalyzes the thermal degradation of PVC. A little amount of LDH (such as 1 phr) makes PVC more stable, but excessive addition accelerates the thermal degradation of PVC. The addition of LDH‐BP markedly improves the static thermal stability of PVC. The results of dynamic thermal stability tests in both the open and closed processing environments are consistent with that of Congo Red tests. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Processability,rheology, and thermal,mechanical, and morphological properties of postconsumer poly(vinyl chloride) bottles and cables

The processability, rheology, and thermal, mechanical, and morphological properties of three different commercial poly(vinyl chloride) (PVC) compounds blended with postconsumer PVC bottles and PVC cables were examined with respect to the recycled PVC content. The addition of PVC bottle recyclates [recycled bottles (RBs)] into virgin PVC bottle (VB) and virgin PVC pipe (VP) compounds caused a progressive reduction in the average torque. No thermal degradation or color change in the RB‐blended PVC compounds used was detected through carbonyl and polyene indices from IR analysis. The rheological properties for VP compounds were more sensitive to RB addition than those of VB compounds. The extrudate swell ratio did not change with the RB content. The decomposition temperature for the VB and VP compounds increased at 60–80% RB, whereas the glass‐transition temperature was unaffected by the RB loading. The 20 and 80 wt % RB loadings were recommended for the VB and VP compounds, respectively, for the optimum impact strength, the blends showing ductile fracture with a continuous phase. At the optimum impact and tensile properties, introducing RB recyclates into the VB compounds gave better results than the VP compounds. The hardness and density of the VB and VP compounds did not change with the RB content. The RB property change was comparatively faster than that of recycled PVC pipes. Adding the PVC cable recyclate [recycled cable (RC)] to virgin PVC cable (VC) had no obvious effect on the torque value of the RC/VC blends. The decomposition temperatures of the RC/VC blends stabilized at 20–60% RC and tended to decrease at 80% RC. The ultimate tensile stress was improved by the addition of the RC compounds, whereas the hardness and density of the VC compounds were unaffected by the RC content. It was concluded that the optimum concentrations of PVC recyclates to be added to virgin PVC compounds were different from one property to another and also depended on the type of virgin PVC grade used. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2738–2748, 2003     

Amine treatment of polyvinyl chloride/wood flour composites

Ethanolamine and L ‐arginine treated wood flour were added to polyvinyl chloride (PVC) in order to improve the interphase between PVC and wood. The influence of the treatment on pH‐value changes and nitrogen fixation of the wood and mechanical properties of the composite were evaluated. The treatments changed the pH of wood from acidic to basic. The highest nitrogen fixation was measured for monoethanolamine and L ‐arginine treated wood flour at high concentrations. Tensile strength, elongation at break, and unnotched impact strength were improved by ethanolamine and L ‐arginine treatments considerably. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Nanocomposites of PVC/TiO2 nanorods: Surface tension and mechanical properties before and after UV exposure

In this study, nanocomposites of poly(vinyl chloride) (PVC), using the synthesized titanium dioxide (TiO₂) nanorods and commercial nanopowder of titanium dioxide (Degussa P25) were produced by melt blending. The presence of TiO₂ nanorods in PVC matrix led to an improvement in mechanical properties of PVC nanocomposites in comparison with unfilled PVC. The photocatalytic degradation behavior of PVC nanocomposites were investigated by measuring their structural change evaluations, surface tension, and mechanical properties before and after UV exposure for 500 h. It was found that mechanical and physical properties of PVC nanocomposites are not reduced significantly after UV exposure in the presence of TiO₂ nanorods in comparison with the presence of TiO₂ nanoparticles, which can be due to the amorphous structure of the synthesized nanorods. Therefore, it can be concluded that TiO₂ nanorods led to an improvement in photostability and mechanical properties of PVC nanocomposites. The interfacial adhesion between TiO₂ nanorods and PVC matrix was also investigated. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of hydrotalcite on the thermal stability,mechanical properties,rheology and flame retardance of poly(vinyl chloride)

Compounds of poly(vinyl chloride) (PVC) and hydrotalcite were prepared via melt blending, and the thermal stability, mechanical properties, rheology and flame retardance were studied. Transmission electron microscopy showed that the hydrotalcite achieved an optimal dispersion in PVC compounds when surface‐treated with titanate coupling agent. The Congo Red test and thermogravimetric analysis demonstrated that the thermal stability of PVC was improved significantly only in the presence of a complex of the hydrotalcite and the organotin stabilizer. Such a significantly positive thermal stabilizing effect was attributable to the stabilizing mechanisms that the electrostatic interaction generated between the electron cloud of chlorine atoms in PVC chain and the positive lay charge of hydrotalcite, which resulted in a decrease in electronic cloud density of chlorine atoms. This weakened the activity of chloride atoms, and restricted the initiation of the dehydrochlorination. A surface treatment for the hydrotalcite with the titanate coupling agent could reduce deterioration of the mechanical and rheological properties of the PVC at low concentration of hydrotalcite. The hydrotalcite also enabled useful application of PVC as a flame retardant as well as a smoke retarder in the light of a LOI value of more than 28.7 and UL 94 V‐0 grade at a PVC/hydrotalcite weight ratio of 70/30. Copyright © 2004 Society of Chemical Industry     

Thermal and mechanical properties of polypropylene/wood‐flour composites

In this research, polypropylene/wood‐flour composites (WPCs) were blended with different contents of wood and/or maleated polypropylene (MAPP) and clay. We found that the addition of MAPP or clay in the formulation greatly improved the dispersion of the wood fibers in the composite; this suggested that MAPP or clay may have played the role of an adhesion promoter in the WPCs. The results obtained with clay indicate that it also acted as a flame retardant. The thermal tests carried out with the produced samples showed an increased crystallization temperature (T_c), crystallinity, and melting temperature (T_m) with wood loading. The increase of the two former parameters was explained by the incorporation of wood flour, which played the role of nucleating agent and induced the crystallization of the matrix polymer. On the other hand, the T_m increase was ascribed to the insulating properties of wood, which hindered the movement of heat conduction. The effects of UV irradiation on T_m and T_c were also examined. T_c increased with UV exposure time; this implied that UV degradation generated short chains with low molecular weight that could move easily in the bulk of the sample and, thus, catalyze early crystallization. The flexural strength and modulus increased with increasing wood‐flour content. In contrast, the impact strength and tensile strength and strain decreased with increasing wood‐flour content. All of these changes were related to the level of dispersion of the wood flour in the polymeric matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Modification of the mechanical and thermal properties of PVC by semi IPN formation with poly(butyl acrylate)

Semi1 and semi2 interpenetrating polymer networks of poly(vinyl chloride) PVC and in situ formed poly(butyl acrylate) (PBA) have been synthesized and characterized using diallyl phthalate (DAP) and ethylene glycol dimethacrylate (EGDM) as the crosslinkers of PVC and PBA, respectively. These two types of IPNs have been compared with respect to their mechanical and thermal properties. The semi1 IPNs displayed a decrease in their mechanical parameters and the physical properties as well, while in contrast, the semi2 IPNs exhibited a marginal increase in the corresponding values when compared to the crosslinked PVC in the case of semi1 IPN and linear PVC in case of semi2 IPN. The representative samples of semi1 and semi2 IPNs revealed a two‐stage‐degradation typical of PVC while confirming the increased stability of the samples with higher onset temperature of degradation. The softening characteristics as detected by thermomechanical analysis are in conformity with their mechanicals. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Conductive composites of PVC and wood's metal with interpenetrating network structure

This work presents composite materials with interpenetrating network structure based on thermoplastic polymer and low melting metal alloy. Composites with various alloy content were prepared by PVC powder sintering to obtain polymer matrix with open pores. Then, liquid Wood's metal was intruded into the matrix using a pressure autoclave. Obtained composites have been studied with respect to microstructure, mechanical, thermal, and electrical properties. SEM micrographs revealed good dispersion of metal in the matrix but at low loading levels it is incomplete. Addition of metal improved mechanical properties, especially flexural strength. Electrical resistivity of samples varies from 10^?4 to 10^?5 Ω m and these values are typical of conductors. The measurements of electromagnetic interference shielding effectiveness (EMI SE) shows that generally PVC/Wood's metal composites have a good ability to shield electromagnetic waves. Composites containing more than 15 vol % Wood's metal exhibited EMI SE above 40 dB in the major part of frequency range. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fracture behavior of PVC/Blendex/nano‐CaCO3 composites

PVC/Blendex/Nano‐CaCO₃ composites were prepared by melt‐blending method. The Blendex (BLENDEX® 338) (GE Specialty Chemicals Co., Ltd., Shanghai, China) was an acrylonitrile‐butadiene‐styrene copolymer with high butadiene content. The fracture behavior of PVC/Blendex/nano‐CaCO₃ composites was studied using a modified essential work of fracture model, U/A = u₀ + u_dl, where u₀ is the limiting specific fracture energy and u_d is the dissipative energy density. The u₀ of PVC/Blendex blend could be greatly increased by the addition of nano‐CaCO₃, while the u_d was decreased. Nano‐CaCO₃ with particle size of 38 nm increased the u₀ of PVC/Blendex blend more effectively than that with particle size of 64 nm, when nano‐CaCO₃ content was below 10 phr. Both the u₀ and u_d of PVC/Blendex/nano‐CaCO₃ composites were not much affected by increasing specimen thickness from 3 mm to 5 mm, while the two fracture parameters were increased with increasing loading rate from 2 mm/min to 10 mm/min, and u_d was found to be more sensitive to the loading rate than u₀. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 953–961, 2005     

Physical,mechanical, and thermal properties of PVC/PMMA blends in relation to their morphologies

The effect of blending poly (methyl methacrylate) (PMMA) in various proportions with suitably stabilized and plasticized poly (vinyl chloride) (PVC) was studied with reference to their physical, mechanical, and thermal properties. The resulting morphologies of the various blends were also studied to find a suitable explanation of these properties. The physical and mechanical properties of such polyblends revealed a substantial increase in toughness accompanied with unusual increase in modulus and ultimate tensile strength after an initial drop at the initial stages of PMMA incorporation compared to pure reference compound PVC. The toughening effect, however, undergoes a reduction with increasing proportion of PMMA but it never goes below that of pure PVC (reference compound) within the ranges of PMMA incorporation under study. The various polyblends exhibit the two‐stage degradation typical of PVC and all of them possess higher thermal stability as manifested in their characteristic thermograms. The softening characteristics imparted by PMMA were also reflected in their respective TMA curves. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2721–2730, 2004     

Tensile properties,morphology, and thermal behavior of PVC composites containing pine flour and bamboo flour

Composites of unplasticized poly(vinyl chloride) (PVC) blended with bamboo flour and pine flour, respectively, were prepared in a batch mixer followed by compression molding. The effects of wood flour fillers on the morphology, static mechanical properties, and thermal properties of the composites were investigated. Compared with neat PVC resin, the introduction of both bamboo flour and pine flour significantly improved the stiffness of the composites, while decreasing the tensile strength to some extent. Tensile tests showed that pine flour–filled composites exhibited better mechanical properties than those filled with bamboo flour with the same particle size at the same loading level. Scanning electron microscopic examination revealed good dispersion and alignment tendency of short pine fiber within the composites at a lower loading level. Moreover, experimental results indicated that both bamboo flour and pine flour additions showed no obviously adverse effect on the thermal stabilities of these composites. Based on the comprehensive properties, these composites meet the need of woodlike material for use as wood structures. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1804–1811, 2004     

Processing and mechanical properties of organic filler–polypropylene composites

The addition of organic fillers into thermoplastic polymers is an interesting issue, which has had growing consideration and experimentation during the last years. It can give rise to several advantages. First, the cost of these fillers is usually very low. Also, the organic fillers are biodegradable (thus contributing to an improved environmental impact), and finally, some mechanical and thermomechanical properties can be enhanced. In this study, the effect of the addition of different organic fillers on the mechanical properties and processability of an extrusion‐grade polypropylene were investigated. The organic fillers came from natural sources (wood, kenaf, and sago) and were compared to short glass fibers, a widely used inorganic filler. The organic fillers caused enhancements in the rigidity and thermomechanical resistance of the matrix in a way that was rather similar to the one observed for the inorganic filler. A reduction in impact strength was observed for both types of fillers. The use of an adhesion promoter could improve their behavior. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1906–1913, 2005     

The preparation of core‐shell CaCO3 particles and its effect on mechanical property of PVC composites

In this study, a novel mechanochemical route to prepare core‐shell structured particles was introduced. XPS, TEM, and dissolving experimental results indicate the formation of [(inorganic particle)/(elastomer)] core‐shell structured particles, and several kinds of calcium carbonate (nano‐CaCO₃) particles with various interfaces were obtained. The mechanical properties and morphological results indicate that the surface treatment of nano‐CaCO₃ particles and the existence of outer elastic layer will strengthen the interfacial interaction between nano‐CaCO₃ particles and PVC matrix, which results in improvement of mechanical properties of PVC/CaCO₃ composites. The theoretical calculations of the interfacial interaction and DMA results confirm these especially when the surface of nano‐CaCO₃ particles was treated by MMA and coated in succession by ACR through vibro‐milling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1084–1091, 2006