Some Properties of Composite Panels Made from Wood Flour and Recycled Polyethylene

This study investigated the effect of board type (unmodified vs. MAPE modified) on the surface quality and thickness swelling-water absorption properties of recycled high density polyethylene (HDPE) based wood plastic composites. Additionally, two commercially available coatings (cellulosic coating and polyurethane lacquer coating) were also applied to composite surfaces and their adhesion strength, abrasion and scratch resistance, and gloss values were determined. This study showed that modification of the composites with MAPE coupling agent increased the surface smoothness and reduced the water absorption and thickness swelling of the panels. Abrasion resistance of the composites was also improved through MAPE modification. Regardless of board type, higher scratch resistance and gloss values were observed for polyurethane lacquer coated samples compared to those of cellulosic varnish coated ones. Improvement of adhesion strength was also seen on SEM micrographs

Determination of Thermal Properties and Morphology of Eucalyptus Wood Residue Filled High Density Polyethylene Composites

Thermal behaviors of eucalyptus wood residue (EWR) filled recycled high density polyethylene (HDPE) composites have been measured applying the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Morphology of the materials was also studied using scanning electron microscope (SEM). Addition of the EWR into the recycled HDPE matrix reduced the starting of degradation temperature. EWR filled recycled HDPE had two main decomposition peaks, one for EWR around 350 °C and one for recycled HDPE around 460 °C. Addition of EWR did not affect the melting temperature of the recycled HDPE. Morphological study showed that addition of coupling agent improved the compatibility between wood residue and recycled HDPE

Evaluation of emm gene types, toxin gene profiles and clonal relatedness of group A streptococci

The aim of this study is to evaluate antibiotic susceptibilities, emm gene types, toxin gene profiles and clonal relatedness of group A streptococci (GAS) isolates obtained from patients and carriers. A total of 79 clinical isolates from patients and 60 isolates from carriers were included in the study. Emm typing, toxin gene detection for speA, speB, speC, speG and smeZ genes and pulsed-field gel electrophoresis (PFGE) was performed. Twenty-one distinct emm types were detected; the most common types were emm12, emm89, emm1, emm77, emm4 and emm3. The detection rates of both emm types and the toxingenes didn't differ significantly between patients and carriers. The presence of speA and smeZ was significantly higher in emm1 and speG was significantly lower in emm4 when compared to the other emm types. The rate of clustering obtained with PFGE wasn't significantly different in patients and carriers. As a result, twelve of the 21 emm types detected in this study were covered by the 26-valent vaccine, constituting 77.7% of the emm typeable isolates; however the emm4 type which is one of the most common types in the present study is not among this coverage

Polyethylene/Polyhydroxyalkanoates-based Biocomposites and Bionanocomposites

The development of advanced polymer composite materials having superior mechanical properties has opened up new horizons in the field of science and engineering. Polyethylene (PE) is considered one of the most widely used thermoplastics in the world due to its excellent properties which have excellent chemical inertness, low coefficient of friction, toughness, near-zero moisture absorption, ease of processing and electrical properties. Polyhydroxyalkanoates (PHAs) are garnering increasing attention in the biodegradable polymer market because of their promising properties such as high biodegradability in different environments. This chapter covers polyethylene/polyhydroxyalkanoates-based biocomposites and bionanocomposites. It summarizes many of the recent research accomplishments in the area of PE/PHAs-based biocomposites and bionanocomposites such as state-of-the-art regarding different methods of their preparation. Also discussed are different characterization techniques and use of PE/PHAs-based biocomposites and bionanocomposites in biomedical, packaging, structural, military, coating, fire retardant, aerospace and optical applications, along with recycling and lifetime studies

Thermal Degradation, Mechanical Properties and Morphology of Wheat Straw Flour Filled Recycled Thermoplastic Composites

Thermal behaviors of wheat straw flour (WF) filled thermoplastic compositeswere measured applying the thermogravimetric analysis and differential scanningcalorimetry. Morphology and mechanical properties were also studied using scanningelectron microscope and universal testing machine, respectively. Presence of WF inthermoplastic matrix reduced the degradation temperature of the composites. One for WFand one for thermoplastics, two main decomposition peaks were observed. Morphologicalstudy showed that addition of coupling agent improved the compatibility between WFs andthermoplastic. WFs were embedded into the thermoplastic matrix indicating improvedadhesion. However, the bonding was not perfect because some debonding can also be seenon the interface of WFs and thermoplastic matrix. In the case of mechanical properties ofWF filled recycled thermoplastic, HDPE and PP based composites provided similar tensileand flexural properties. The addition of coupling agents improved the properties ofthermoplastic composites. MAPE coupling agents performed better in HDPE while MAPPcoupling agents were superior in PP based composites. The composites produced with thecombination of 50-percent mixture of recycled HDPE and PP performed similar with theuse of both coupling agents. All produced composites provided flexural properties requiredby the ASTM standard for polyolefin-based plastic lumber decking boards

Foaming of rigid PVC/wood-flour composites through a continuous extrusion process

The effects of chemical foaming agent (CFA) types (endothermic versus exothermic) and concentrations as well as the influence of all-acrylic processing aid on the density and cell morphology of extrusion-foamed neat rigid PVC and rigid PVC/ wood-flour composites were studied. Regardless of the CFA type, the density reduction of foamed rigid PVC/wood-flour composites was not influenced by the CFA content. The cell size, however, was affected by the CFA type, independent of CFA content. Exothermic foaming agent produced foamed samples with smaller average cell sizes compared to those of endothermic counterparts. The experimental results indicate that the addition of an all-acrylic processing aid in the formulation of rigid PVC/wood-flour composite foams provides not only the ability to achieve density comparable to that achieved in the neat rigid PVC foams, but also the potential of producing rigid PVC/wood-flour composite foams without using any chemical foaming agents

MECHANICAL PROPERTIES OF INJECTION-MOLDED FOAMED WHEAT STRAW FILLED HDPE BIOCOMPOSITES: THE EFFECTS OF FILLER LOADING AND COUPLING AGENT CONTENTS

This study investigated the effect of filler loading and coupling agent contents on the densities and mechanical properties of injection-molded foamed biocomposites. Biocomposite pellets were manufactured using wheat straw flour, maleic anhydrite grafted polyethylene (MAPE), paraffin wax, and high-density polyethylene (HDPE) with an extrusion process. Pellets and the chemical foaming agent (azodicarbonamide) were dry-mixed and foamed in an injection-molding machine. Densities and mechanical properties of the foamed biocomposites samples were measured and analyzed using central composite design (CCD). The results showed that both filler loading and coupling agent contents affected the density and mechanical properties of foamed biocomposites. Densities in the range of 0.57 to 0.81 gr cm-3 were achieved. Best results were obtained when less than 20% wheat straw flour and 1% coupling agent content were used. The flexural modulus and tensile modulus of foamed biocomposites were improved with increasing filler loading. However, flexural strength, tensile strength, elongation at break, and impact strength values were diminished. The tensile strength of the biocomposites was positively affected by CA contents, but other mechanical properties were not affected by it. Overall, injection molded foamed biocomposites with moderate mechanical properties were produced

Mechanical properties of extrusion-foamed rigid PVC/wood-flour composites

This study was conducted to characterize the mechanical properties of extrusion-foamed neat rigid PVC and rigid PVC/wood-flour composites by using endothermic and exothermic chemical foaming agents (CFAs). The specific elongation at break (ductility) of the samples was improved by foaming, while the opposite trend was observed for the tensile strength and modulus of the samples, regardless of the chemical foaming agent type. In addition, experimental results indicated that foaming reduced the Izod impact resistance of both neat rigid PVC and rigid PVC/wood-flour composites but that this reduction was not statistically significant for the composites. A comparison between batch microcellular processing and extrusion foam processing was made, which demonstrated that foams with very fine cells (microcellular processed) exhibit better impact strength than foams with larger cells (extrusion processed with CFAs)

The Effects of Coupling Agents on the Mechanical and Thermal Properties of Eucalyptus Flour/HDPE Composite

The aim of this research was to study the effects of the coupling agents, FusabondTM E-528 (polyethylene-grafted maleic anhydride; PE-g-MA, MA) and Amino Silane (Si), on the thermal properties, and mechanical properties of Eucalyptus flour-HDPE composite. Variation of the Eucalyptus flour contents in the HDPE resulted in properties of the composite. With increasing in the contents of Eucalyptus flour in polymer matrix, the mechanical properties of the HDPE composite decreased in EU-MA series samples while they were gradually decreased in EU-Si series samples. SEM micrographs showed the fracture surface of the HDPE/Eucalyptus composite at different ratios of Eucalyptus flour. SEM micrograpgh exhibited the dispersion of EU flour in polymer matrix. The samples of both coupling agents showed an increase in interfacial adhesion, observed for the considerable decreased of gaps between the matrix and the dispersed phase. However, the EU-MA sample appeared to be more uniformly than the EU-Si sample