Effect of chemical treatment of wood flour on the properties of styrene butadiene rubber/polystyrene composites

Composites from SBR/PS blend and the chemically treated wood flour have been prepared. The materials used for such treatment are NaOH, MAN, MAN‐glycidyl methacrylate, and silane coupling agent, used to improve the dispersion of wood flour in the SBR/PS blend. The effects of chemical treatment on curing characteristics, and physicomechanical and electrical properties of SBR/PS composites were studied. The rheological as well as the mechanical parameters were improved by using the modified wood flour with MAN‐glycidyl methacrylate (SMG), followed by SM obtained at 15 phr, while the other treatments slightly affect these parameters. The permittivity ?′ and dielectric loss ?″ were measured in the frequency range from 100 Hz up to 100 kHz and at temperatures ranging from 30 up to 90°C. The dielectric investigations indicate that the samples containing wood flour treated with both SMG and SM increase the values of ?′ and decrease those of ?″, which allow such samples to be used in insulation purposes. The increase in the relaxation time and the crosslinking density ν for such composites indicate the increase in filler–polymer interaction rather than filler–filler interaction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5861–5870, 2006     

Use of construction and demolition wastes as mineral fillers in hybrid wood–polymer composites

The recycling of construction materials has been the subject of much research in past years. In this study, the use of construction and demolition wastes (CDWs) as mineral fillers in hybrid wood–polymer composites was studied. Two types of waste materials were used as fillers in the composites: (1) a mixture consisting of waste mineral wool (MW) and plasterboard (PB) and (2) mixed CDWs. The performance of the composites was evaluated from their mechanical properties and water‐absorption behavior. We found in the study that the addition of mineral fillers decreased the flexural strength and modulus values of the wood–polypropylene (PP) composites. On the other hand, the exchange of part of the wood with a mineral filler resulted in an increase in the impact strength of the composite. The composite manufactured with the combination of MW and PB had the lowest water absorption. The decrease in wood loading resulted in improved dimensional stability in the hybrid wood–mineral filler–PP composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43412.     

Natural fiber composites of high‐temperature thermoplastic polymers: Effects of coupling agents

Our earlier paper (Jana, S.C.; Prieto, A. J Appl Polym Sci 2002, 86, 2159) on the development of natural fiber composites of high‐performance thermoplastic polymers described a new methodology for the manufacturing of composite materials of a high‐temperature thermoplastic polymer, poly(phenylene ether) (PPE) and wood flour, a cellulosic natural filler. A thermosetting epoxy, used as a reactive solvent, reduced the processing temperature of PPE/epoxy blends to well below the decomposition temperature of natural fillers. In addition, the epoxy component, upon polymerization, formed coating layers around the filler particles to provide resistance against moisture diffusion and attacks by acids and alkali. This article describes the results of an investigation on two outstanding issues: (1) the influence of cellulosic wood particles and coupling agents on the speed of epoxy curing and reaction‐induced phase separation and (2) the effects of coupling agents on the morphology of crosslinked epoxy at the surfaces of natural fillers and mechanical properties of the composites. It was found that wood particles expedited epoxy curing in the composites; the extent of epoxy curing, however, was reduced in the presence of coupling agents. Also, the coupling agents promoted complete coverage of wood flour particles by polymerized epoxy, although the mechanical properties deteriorated over systems without coupling agents. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2168–2173, 2002     

Effects of filler–filler and polymer–filler interactions on rheological and mechanical properties of HDPE–wood composites

High‐density polyethylene (HDPE)–wood composite samples were prepared using a twin‐screw extruder. Improved filler–filler interaction was achieved by increasing the wood content, whereas improved polymer–filler interaction was obtained by adding the compatibilizer and increasing the melt index of HDPE, respectively. Then, effects of filler–filler and polymer–filler interactions on dynamic rheological and mechanical properties of the composites were investigated. The results demonstrated that enhanced filler–filler interaction induced the agglomeration of wood particles, which increased the storage modulus and complex viscosity of composites and decreased their tensile strength, elongation at break, and notched impact strength because of the stress concentration. Stronger polymer–filler interaction resulted in higher storage modulus and complex viscosity and increased the tensile and impact strengths due to good stress transfer. The main reasons for the results were analyzed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Anisotropy of a fiber structure and the frictional wear of composites on the basis of polyarylate

An influence of the anisotropy of surface structure of short fibers on an interfacial layer structure in polymer composites is studied. In its turn, mentioned changes of structure cause an essential variation of frictional wear for these materials. In this aspect, the existence of a hydrogen bonds polymer‐filler plays an important role. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2821–2823, 2006     

AC impedance analysis and EMI shielding effectiveness of conductive SBR composites

Flexible conductive polymer composites were prepared using styrene–butadiene rubber (SBR) as a matrix and conductive carbon black as filler. The filler loading was varied from 10 to 60 phr. The complex AC impedance and electromagnetic interference shielding effectiveness (EMI SE) of the composites were measured at the microwave frequencies of 7.8–12.4 GHz. The effect of variation in filler concentration and measurement frequency on the AC impedance and EMI SE of the composites were investigated. Equivalent circuits describing the conduction behavior of the composites were determined by means of Nyquist plots. The complex electric modulus of the composites was also determined. Increase in the filler loading increased the capacitive nature of the materials. The composites were better defined by a parallel resistor–capacitor circuit in series with a resistor. The EMI SE was found to pass through a maximum with increase in frequency. However, with the increase in filler loading and sample thickness of the material, the EMI SE was found to increase continuously. POLYM. ENG. SCI., 46:1342–1349, 2006. © 2006 Society of Plastics Engineers.     

Biofibers as reinforcing fillers in thermoplastic composites

Four biofiber materials were compared against wood flour for their ability to act as reinforcing fillers in melt-blended composites with polypropylene as the matrix polymer. The four materials were a waste wood composite (mixture of plywood, particleboard, and fiberboard), kenaf core, a waste jute–polyester composite panel, and waste newspaper. The composites were prepared either by extrusion or by blending in a high intensity thermokinetic mixer (K-mixer), and mechanical properties were determined on injection molded specimens. Although some property differences were observed compared to wood flour/polypropylene composites, it appeared that any of the four materials might substitute for wood flour if local supply and cost circumstances offered advantages. However, waste newspaper clearly provided the best balance of mechanical properties relative to the other three test materials or wood flour. Relative to wood flour, waste newspaper filler increased unnotched impact by over 30 percent and flexure and tensile strengths by about 25 percent.     

Effects of material parameters on the diffusion and sorption properties of wood‐flour/polypropylene composites

Composites of wood in a thermoplastic matrix (wood–plastic composites) are considered a low maintenance solution to using wood in outdoor applications. Knowledge of moisture uptake and transport properties would be useful in estimating moisture‐related effects such as fungal attack and loss of mechanical strength. Our objectives were to determine how material parameters and their interactions affect the moisture uptake and transport properties of injection‐molded composites of wood‐flour and polypropylene and to compare two different methods of measuring moisture uptake and transport. A two‐level, full‐factorial design was used to investigate the effects and interactions of wood‐flour content, wood‐flour particle size, coupling agent, and surface removal on moisture uptake and transport of the composites. Sorption and diffusion experiments were performed at 20°C and 65 or 85% relative humidity as well as in water, and diffusion coefficients were determined. The wood‐flour content had the largest influence of all parameters on moisture uptake and transport properties. Many significant interactions between the variables were also found. The interaction between wood‐flour content and surface treatment was often the largest. The diffusion coefficients derived from the diffusion experiments were different from those derived from the sorption experiments, suggesting that different mechanisms occur. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 752–763, 2007     

Micromechanical properties of injection‐molded starch–wood particle composites

The micromechanical properties of injection‐molded starch–wood particle composites were investigated as a function of particle content and humidity conditions. The composite materials were characterized by scanning electron microscopy and X‐ray diffraction methods. The microhardness of the composites was shown to increase notably with the concentration of the wood particles. In addition, creep behavior under the indenter and temperature dependence were evaluated in terms of the independent contribution of the starch matrix and the wood microparticles to the hardness value. The influence of drying time on the density and weight uptake of the injection‐molded composites was highlighted. The results revealed the role of the mechanism of water evaporation, showing that the dependence of water uptake and temperature was greater for the starch–wood composites than for the pure starch sample. Experiments performed during the drying process at 70°C indicated that the wood in the starch composites did not prevent water loss from the samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4893–4899, 2006     

Evaluation of dynamic elastic properties of wood‐filled polypropylene composites

Dynamic modulus of elasticity (MoE) and shear modulus of wood‐filled polypropylene composite at various filler contents ranging from 10% to 50% was determined from the vibration frequencies of disc‐shaped specimens. Wood filler was used in both fiber form (pulp) and powder form (wood flour). A novel compatibilizer, m‐isopropenyl‐α,α‐dimethylbenzyl‐isocyanate(m‐TMI) grafted polypropylene with isocyanate functional group was used to prepare the composites. A linear increase in dynamic MoE, shear modulus, and density of the composite was observed with the increasing filler content. Between the two fillers, wood fiber filled composites exhibited slightly better properties. At 50% filler loading, dynamic MoE of the wood fiber filled composite was 97% higher than that of unfilled polypropylene. Halpin‐Tsai model equation was used to describe the changes in the composite modulus with the increasing filler content. The continuous improvement in elastic properties of the composites with the increasing wood filler is attributed to the effective reinforcement of low‐modulus polypropylene matrix with the high‐modulus wood filler. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1706–1711, 2006     

Synthesis and characterization of brominated polyester composites

Two unsaturated polyesters containing a halogen (bromine) in the backbone of the polymer chain were synthesized and compared with a halogen‐free polyester. The bromine content was measured by elemental analysis. The chemical structures of the polyesters were characterized by means of IR and ¹H‐NMR spectroscopies. Feldspar was used as the filler to form the polyester composites. The effects of the halogen substituents, filler concentration, and crosslinking monomers and comonomers on the electrical and mechanical properties of the polyester composites were studied. The flammability was also investigated. The styrenated polyesters and their composites achieved fire resistance and good mechanical and electrical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1356–1365, 2006     

Surface tearing and wall slip phenomena in extrusion of highly filled HDPE/wood flour composites

The extrudate surface tearing of highly filled high‐density polyethylene (HDPE)/wood flour composites has been investigated in relation to the rheological properties and the wall slip phenomenon in capillary dies. Rotational and capillary rheometers were employed to measure the rheological properties. Mooney analysis was used for determination of wall slip velocity. The results showed considerable increase of storage modulus, dynamic and shear viscosity with increasing wood flour loading. It was also found that all wood filled composites did not obey the Cox–Merz rule. The wall slip velocity depends on wood filler content and shear rate. Generally, with increasing shear rate the slip velocity sharply increases leading to plug‐like flow. It was observed that the surface of the extrudates becomes smoother with increase in shear rate and wood flour content. POLYM. ENG. SCI., 46:1204–1214, 2006. © 2006 Society of Plastics Engineers     

A comparative investigation of bio waste filler (wood apple‐coconut) reinforced polymer composites

During the last century natural fibers are used as reinforcement in polymer composite has been continuously growing in the composite industry. This polymer matrix composite has wide range of application in hostile environment where it is exposed to external attacks such as solid particle erosion. The mechanical properties of different polymer composites are also most important characteristics. An attempt has been made to compare the mechanical and tribological properties of the both biowaste wood apple and coconut shell particulate polymer matrix composite. The results show that maximum flexural strength is obtained 78.19 MPa for wood apple shell and 68.25 MPa for coconut shell at 15 wt% filler content. The wood apple particulate composite shows best erosion and mechanical properties than coconut particulate composite. POLYM. COMPOS., 35:180–185, 2014. © 2013 Society of Plastics Engineers     

Effect of dehydroxylation of hydrothermal barium titanate on dielectric properties in polystyrene composite

In today's world, technology for capacitors has grown significantly with its requirements in the direction of better dielectric properties. Developing an ideal composite material (polymer and ceramic) for satisfying the processing parameters is of great interest for capacitor industry. In this study, chemically treated barium titanate (BT) nanocrystals were prepared and used to make ceramic–polystyrene (PS) composites. A unique methodology was used in processing these materials. Effects of the chemically treated BT, filler loading, and frequency on the dielectric properties of these composites were examined, and compared with untreated BT–PS composites. Composite dielectric constant was proportional to the volume ratio of the BT filler and remained stable at different frequencies. The experimental data show that the dielectric constant of composites made with treated BT powders can attain values 2.5 times higher than that of untreated BT–PS composites. In addition, the composite shows consistency in dielectric constant values measured at different frequencies. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Barrier properties of chlorobutyl nanoclay composites

Elastomeric materials are used as barriers to protect workers against exposure to chemicals. The effectiveness of a polymer as a chemical protective material depends on the rate of permeation of chemicals through it. The permeation rate is dependent on the type and amount of fillers added into the polymer matrix. In this study, Chlorobutyl nanoclay composites were prepared by addition of organically modified and unmodified nanoclays at different filler loadings. The nanocomposites were swollen in three solvents of varying cohesive energy density until equilibrium and desorption experiments were carried out. The data obtained from desorption experiments was used to determine the diffusion coefficients. The concentration‐dependent diffusion coeffecient (D) was calculated at high and low concentration regions and it was found that D is one‐order less in lower concentration region than in the higher concentration range. The aspect ratio of the nanoclay fillers in the composite was calculated by assuming square and disc shapes and it was found to vary with the type of solvent and the used and filler loading. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3630–3637, 2006     

Experimental and modeling study of effective thermal conductivity of polymer filled with date palm fibers

The scope of this article is to evaluate the possibility of using waste date palm wood in polymer matrices to obtain a low thermal conductivity biocomposite material in view to reduce heat losses in buildings. Experimental and numerical investigation of effective thermal conductivity properties of composites were carried out using guarded hot plate method and 3D finite element modeling. Water absorption of composites materials was also investigated. The results showed that the thermal conductivity of the polymer‐based materials decreases with increasing date palm fiber concentration and that the size of fillers has no significant effect. The water test revealed that the composites have a strong tendency to absorb water, particularly with increasing filler contents. POLYM. COMPOS., 38:1712–1719, 2017. © 2015 Society of Plastics Engineers     

Aluminosilicate‐filled composites of PVA–PVP—An improved biodegradable polymeric material

Poly(viny alcohol)–poly(vinyl pyrrolidone) biodegradable polymer blend was modified with aluminosilicate. Sample films containing 5, 10, 15, and 20 wt % filler were prepared by conventional solvent casting technique using glass plates as casting surfaces. The newly developed biodegradable composites are bright red, with magnetic properties due to the presence of iron compounds. Physical, chemical, and biodegradable properties of the films were studied with the conclusion that the presence of aluminosilicate affects the properties of the matrix and enhances biodegradability of the polymer composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4963–4970, 2006     

Effect of the processing techniques on the properties of ecocomposites based on vegetable oil‐derived Mater‐Bi® and wood flour

Polymer composites based on biodegradable polymers and natural‐organic fillers are becoming more and more important because of their interesting properties in terms of environmental impact, manufacturing cost, and esthetic features. In particular, the use of biodegradable polymer matrices allows obtaining a full biodegradability. One of the most interesting biodegradable polymer families is the Mater‐Bi® one. In this work, we investigated the processability, the influence of different processing techniques, and the influence of the filler particle size on the properties of Mater‐Bi/wood flour composites. Injection molding caused a partial degradation of the macromolecular chains, whereas single‐screw extrusion followed by calendering and twin‐screw extrusion provoked an increase of the elastic modulus and of the viscosity. The use of wood flour led to a significant increase of the rigidity, whereas a reduction of the ductility was observed. Because of the very similar aspect ratios of the two different filler size classes, no dramatic differences in the properties were found. These results are useful in order predicting and setting up the optimum preparation and processing strategy for the production of fully biodegradable polymer composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of the moisture and fiber content on the mechanical properties of biodegradable polymer–sisal fiber biocomposites

The matrix of the composites that were used in this work was a commercial blend based on starch and cellulose derivatives. The biodegradable polymer was reinforced by short‐sisal fibers with a range in fiber content of 5–15 wt %. The effects of humidity on the diffusion coefficients, equilibrium moisture content, and mechanical properties were studied. Equations obtained from microscopic mass balances for diffusion in solids were used to predict the absorbed humidity in both components (the sisal fibers and biodegradable polymer) and in the composites as a function of time. Different model predictions of the composite diffusion coefficients as a function of the filler concentration were also examined, and they were found to be in agreement with the experimental results. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4007–4016, 2004     

Long‐term water uptake behavior of lignocellulosic‐high density polyethylene composites

Composites of different lignocellulosic materials and high‐density polyethylene were prepared and their long‐term water absorption behaviors were studied. Wood flour, rice hulls, newsprint fibers, and kenaf fibers were mixed with the polymer at 25 and 50 wt % fiber contents and 1 and 2% compatibilizer, respectively. Water absorption tests were carried out on injection‐molded specimens at room temperature for five weeks. Results indicated a significant difference among different natural fibers with kenaf fibers and newsprint fibers exhibiting the highest and wood flour and rice hulls the lowest water absorption values, respectively. Very little difference was observed between kenaf fiber and newsprint composites and between rice hulls and wood flour composites regarding their water uptake behavior. The difference between 25 and 50% fiber contents for all composite formulations increased at longer immersion times, especially for the composites with higher water absorption. Kenaf fiber composites containing 50% kenaf fibers exhibited the highest water diffusion coefficient. A strong correlation was found between the water absorption and holocellulose content of the composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3907–3911, 2006