Kantima Chaochanchaikul

Mechanical Characterization of E-Chopped Strand Glass Fiber Reinforced Wood/PVC Composites

E-chopped strand glass fibers with different initial fiber lengths and contents are introduced into wood-polyvinyl chloride (PVC) composites having the wood content of 50 parts per hundred (phr). The initial fiber lengths and glass fiber contents varied from 3, 6, and 12 mm, and 10, 20, and 30 phr, respectively, and the mechanical and morphological properties of the wood/PVC composites are then monitored. The results suggest that the tensile and flexural moduli and strengths of the wood/PVC composites increase with increasing glass fiber contents. The tensile and flexural moduli and strengths of the WPVC composites at 10—20 phr glass fiber loadings are more dependent on carbonyl (C=O) content on the fiber surface, but those at 30 phr glass fiber loadings are influenced by the average final length of glass fibers. The impact strength of the wood/PVC composites progressively increase with increasing glass fiber content. The elongation at break is found to slightly decrease with increasing glass fiber content due to increases in fiber-end effects and stress concentrations in the wood/PVC composites. The effect of initial fiber length on the degree of composite shrinkage is very small, the values ranging from 0.3 to 1.3%.

Enhancing sound absorption properties of open-cell natural rubber foams with treated bagasse and oil palm fibers

The aim of this work was to study the effects of natural fiber type and loading content on the sound absorption efficiency of natural rubber (NR)/treated natural fiber composite foams. This was investigated by measuring the cell characteristics of composite foam, sound absorption coefficient (SAC), and viscoelastic behavior. Bagasse (BF) and Oil Palm (OPF) fibers were treated with sodium hydroxide (NaOH) solution and the optimal treatment conditions for BF and OPF were determined by varying treatment times and NaOH concentrations. Potassium oleate (K-oleate) was used as a blowing agent to create open-cell NR foam. The results indicated that the most suitable NaOH concentration for both BF and OPF was 10%wt. and optimal treatment times were 30 and 10 min, respectively. At low fiber loadings, the addition of treated BF and OPF resulted in a decrease in the average cell size and an increase in the number of foam cells. As loading increased above 5%wt., cell size and cell number exhibited the opposite trends. Both treated BF and OPF enhanced the sound absorption efficiency of NR foams, especially at medium and high frequencies. NaOH treatment improved the interfacial bonding between the matrix and natural fibers, and increased the roughness on the surface of BF and OPF, leading to an enhanced ability for BF and OPF to absorb sound waves. The results indicated that treated BF was more effective than treated OPF for increasing SAC values. Type and dispersion of fiber and viscoelastic behavior were important factors on SAC of composite foams more than cell characteristic.

Improvement of Structural and Thermal Stabilities of PVC and Wood/PVC Composite by Zn and Pb Stearates, and Zeolite

Three different chemical stabilizers were introduced into neat PVC and a wood/PVC composite (containing 50 phr wood flour) to improve their thermal and structural stabilities. The changes in CIE yellowness index, polyene index, %wt loss, and decomposition temperature (Td) were monitored. The effects of type and content of thermal stabilizers, thermal ageing time, and the presence of wood flour were our main interests. The experimental results suggested that the additions of Zn and Pb stearates into PVC and wood/PVC composite could improve the thermal stability of the PVC. At the test temperature of 177°C, the additions of Zn and Pb stearates could improve the thermal stabilities of PVC by retarding the upzipped reaction and by reducing the conjugated double bonds in PVC, Pb stearate being the most suitable for thermally stabilizing the PVC. Around the Td range (∼264°C), the addition of Zn stearate reduced the Td value of PVC whereas that of Pb stearate had no effect on the change in Td value. Zeolite loading could shift the Td value of the PVC from 264 to 280°C. The addition of wood particles increased the polyene content and decreased the decomposition temperature of the PVC. The effect of wood flour on the thermal and structural changes of PVC overruled that of thermal stabilizer loading.

Blending Techniques Affecting Mechanical and Morphological Properties of Fly Ash/LDPE and CaCO3/LDPE Composites

The effects of blending methods on mechanical and morphological properties of CaCO3/LDPE and fly ash/LDPE composites were investigated as a function of filler loadings. The CaCO3/LDPE and fly ash/LDPE composites considered in this work were prepared by dry blending (high-speed mixer) and melt blending (using single- and twin-screw extruders). It was found that as the CaCO3 or FA loading was increased, the modulus and hardness for all blending techniques were increased, due to rigidities of the fillers and increased crystallinity level of the composites. Increasing the CaCO3 and FA loadings decreased the ultimate mechanical properties (tensile strength, elongation at break and impact strength) due to poor dispersion and interfacial defects of the composites. Composites prepared by the twin-screw extruder had the best mechanical properties as compared to those prepared by the dry blending or single-screw extruder, except for the impact strength. The overall mechanical properties of LDPE composites with CaCO3 were similar to those with FA particles, but the changes in the composite properties with CaCO3 particles were more sensitive than those with FA particles, this being associated with the differences in particle characteristics and dispersion level of CaCO3 or FA fillers.

Effect of Blowing Agent on Cell Morphology and Acoustic Absorption of Natural Rubber Foam

The sound absorbing efficiency of natural rubber (NR) foam is affected by the cell morphology of foam. Potassium oleate (K-oleate) and sodium bicarbonate (NaHCO3) were used as blowing agents to create open-cell foam. Amounts of the blowing agent were varied from 0.5 to 8.0 part per hundred of rubber (phr) to evaluate cell size and number of foam cell as well as sound adsorption coefficient of NR foam. The NR foam specimens were prepared using mould and air-circulating oven for vulcanizing and foaming processes. The results indicated that K-oleate at 2.0 phr and NaHCO3 at 0.5 phr led to form NR foam with the smallest cell size and the largest number of foam cell. At low frequencies, the optimum sound adsorption coefficient of NR foam was caused by filling K-oleate 2 phr. However, that of NR foam at high frequencies was provided by 0.5 phr-NaHCO3 addition.

Effect of Banana Fibers on Mechanical and Physical Properties of Light Weight Concrete Blocks

This work was to investigate the mechanical and physical properties of light weight block with addition of banana fiber. The formulation series of concrete block were divided into two groups: banana fiber for replacing cement and sand, respectively. Banana fibers were varied from 0.0 to 7.5 %wt. and were evaluated by compressive testing, density and water absorption and changing length at water immersion of 28 days. Optimum formulation of concrete adding banana fiber is ratio of sand: cement: lime: gypsum: aluminum powder: banana fibers: 50: 27.5: 9: 9: 2: 2.5, respectively. The increase of water absorption and changing length were found with increase of fiber content whereas the density decreased. However, the mechanical and physical properties of banana fiber/concrete block were subject to standard according to Thai Industrial Standard 1505-2541. From this study, it indicates that banana fiber can be used as an alternative precursor material for producing the light weight and cost effectiveness block.

Influence of Natural Oil Polyol on Mechanical Properties of Polylactic Acid

The aim of this work was to improve the mechanical properties of polylactic acid (PLA) by natural oil polyol. Castor oil is natural oil polyol used for this work. It was directly extracted from castor seed and without chemical modification. The contents of castor oil were varied from 0 to 10 wt%. The effect of castor oil content on mechanical properties of PLA were evaluated by tensile and impact testings. Differential scanning calorimetry (DSC) and morphology analysis were used for explanation of the result. The result showed that the elongation at break and impact strength of PLA /10 wt% castor oil blend were increased about 108 and 30 % as comparing neat PLA whereas tensile strength tended to decrease about 24 %. The changes in glass transition temperature, crystallinity content and morphology of PLA corresponded well with the result of mechanical properties.

Influence of Multifunctional Monomers on Gamma Irradiated Polylactic Acid

The aim of this work was to compare and discuss the influence of multifunctional monomers as crosslinking agent (Triallyl Isocyanurate; TAIC) and chain extender (Joncryl ADR4368) on the gamma irradiated Polylactic acid (PLA). The modified PLA samples with varying amount of TAIC and Joncryl were characterized by observing the molecular characteristics and mechanical properties. The results showed that irradiated PLA had lower average molar mass and mechanical properties compared to non-irradiated PLA due to irradiation induced chain scission. Gel content was observed and increased with increasing irradiation dose for the TAIC modified sample, indicating that the further crosslink of irradiated PLA was occurring. Crosslinking and chain extension were responsible for the improved modulus and tensile strength of irradiated PLA, however the decrease in tensile strength at high irradiation dose was observed for crosslinked PLA.