Poonsub Threepopnatkul

Control of Mechanical Properties and Permeability of Electrospun Natural Rubber with Different Composite Systems

The electrospun natural rubber (NR) with two different components namely: acrylonitrile butadiene styrene (ABS) and carbon black (CB) have been extensively studied. The main objective was to investigate the mechanical properties and permeability dependency of NR/ABS and NR/CB as well as its contents. NR/CB was compounded by torque rheometer (Brabender) while ABS was dissolved with NR using tetrahydrofuran (THF) as its solvent. Sulfur was used as the vulcanizing agent in both systems. Mechanical properties were evaluated by universal testing machine and permeability was observed by water vapour permeability. The optimum conditions for electrospun NR/ABS and NR/CB non-woven mats were as follows: flow rate 30 ml/h, voltage 15 kV, collector distance 20 cm and collected on rotating circular plate at 1000 rpm. The results of mechanical properties showed that for electrospun NR/CB fiber membranes, the higher the CB loading it had, the lower its tensile strength and elongation it would be. Whilst electrospun NR/ABS fiber mats, the elongation behavior was affected by the ABS loading but not the tensile strength. For permeability, NR/CB was shown to possess relatively higher permeability than the NR/ABS non-woven mats.

Polycarbonate with Pineapple Leaf Fiber to Produce Functional Composites

This research is to study the properties of pineapple leaf fiber reinforced polycarbonate composites (PC/PALF). Surface of pineapple leaf fiber (PALF) was pre-treated with sodium hydroxide (PALF/NaOH) and modified with two different functionalities such as γ-aminopropyl trimethoxy silane (PALF/Z-6011) and γ-methacryloxy propyl trimethoxy silane (PALF/Z-6030). The effects of PALF content and chemical treatment were investigated by Fourier transform infrared spectroscopy, Scanning electron microscopy and mechanical testing. The modified pineapple leaf fibers composite also produces enhanced mechanical properties. Young’s modulus is highest in the case of the PALF/NaOH composites. The PALF/Z-6011 composites showed highest tensile strength and impact strength. In thermal property, the results from Thermogravimetric analysis showed that thermal stability of the composites is lower than that of neat polycarbonate resin and thermal stability decreased with increasing pineapple leaf fiber content.

Morphology of Electrospun Natural Rubber with Acrylonitrile-Butadiene-Styrene

This research was aimed to study the electrospinning of natural rubber (NR)-acrylonitrile butadiene styrene (ABS) blend. The NR used in this research was compounded in a torque rheometor, with stearic acid, wingstay-L, dibenzothiazoledisulfide (MBTS), tetramethylthiuram disulfide (TMTD) and sulfur, respectively. The compounded NR was blended with ABS by dissolving them in tetrahydrofuran (THF), concentration of solution included 5, 10, and 15 w/w%. The ratio of NR/ABS was varied by varying the content of ABS of 20, 30, 40 and 50 wt%. Then NR/ABS electrospun membrane was built up by electrospinning technique with high voltage 15 kV, flow rate 30 ml/h, collector distance 15, 20 and 25 cm and collected the electrospun fiber on rotating circular at 1000 rpm. The morphology of electrospun fibers were characterized by scanning electron microscope (SEM). SEM images showed that NR/ABS membranes had higher porosity with decreasing ABS contents. Decreasing ABS contents, decreasing solution concentration and increasing collector distance decreased fiber diameter of electrospun NR/ABS.

Phosphate Derivative Flame Retardants on Properties of Pineapple Leaf Fiber/Abs Composites

Pineapple leaf fibers (PALF) are abundant to the agricultural products which are native to the tropical climate region. It also exhibit excellent tensile strength and tensile modulus. Acrylonitrile butadiene styrene (ABS) copolymer possess several prominent properties such as strength, rigidity and toughness. Both ABS and PALF are at high risk to the fire hazard when used in daily life. The improvement of flame retardancy of composite materials has been the priority for the safety requirements of natural fiber composite products. This research is aimed to study the effect of two different phosphate compounded flame retardants i.e., bisphenol-A bis (diphenyl phosphate) (BDP) and 9, 10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) on the flammability, mechanical and thermal properties of the composites of modified natural pineapple leaf fiber reinforced acrylonitrile butadiene styrene. 10% by weight of such PALF was compounded with ABS using diisononyl phthalate 1% w/w as plasticizer at the different flame retardant concentration (10 and 20 wt.% of ABS). The effects of flame-retardants showed that the PALF/ABS composite containing DOPO showed enhanced performance in terms of flame retardancy and even act as self-extinguisher. Higher content of flame retardants led to increase limiting oxygen index value. Moreover, DOPO added composites produced superior mechanical properties such as youngs modulus and tensile strength. Furthermore, both thermal degradation temperature of PALF/ABS composites with DOPO and thermal degradation temperature of PALF/ABS composites with BDP showed relatively lower temperature than the ones of PALF/ABS composites.

Effect of Flame Retardants on Performance of PALF/ABS Composites

This research is to study the effect of two different flame retardants i.e., bisphenol-A bis (diphenyl phosphate) (BDP) and 9, 10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) on the flammability and mechanical properties of the composites of modified natural pineapple leaf fiber (PALF) reinforced acrylonitrile butadiene styrene (ABS). A 10% by weight of such PALF was compounded with ABS using diisononyl phthalate 1% w/w as plasticizer at the different flame retardant concentration (10 and 20 wt%) in a co-rotating twin screw extruder. An injection molding machine was used to prepare the specimens. The effects of flame-retardants showed that the PALF/ABS composite containg DOPO showed superior performance in terms of flammabitily. Higher content of flame retardants led to increase LOI value. Moreover, the composites added DOPO produce enhanced mechanical properties such as youngs modulus and tensile strength.

Thermal Conductivity and Mechanical Properties of Wood Sawdust/Polycarbonate Composites

Wood sawdust was increasingly being used as reinforcement in commercial thermoplastics due to low cost, reusable raw materials. One of the problems of using wood sawdust is its interfacial adhesion with polymeric matrix. In this research, two types of silane coupling agents (N-(3-Trimethoxysilylpropyl) diethyllenetriamine and γ-aminopropyl trimethoxy silane) and sodium hydroxide were used for the modification of interfacial adhesion in wood sawdust/polycarbonate composites. The effects of chemical treatment and wood sawdust content (10, 20 and 30 % by wt) were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), thermal conductivity analysis. Youngs modulus of composites was in general higher than the neat PC except for the one with γ-aminopropyl trimethoxy silane treatment. Tensile modulus of composites was increased as the filler loading increased. Nevertheless, the addition of wood sawdust resulted in the tensile strength reduction of the composites. The SEM micrographs reveal that the aggregation of wood particles and weak interfacial bond between the treated wood sawdust and the polymeric matrix with increasing filler loading. Furthermore, the thermal conductivity was reduced significantly with the increment of wood sawdust contents.

In Vitro Drug Release Activity from Core/Shell Electrospun MATS of sPLA-cPEG/GS and sPLA/CA-cPEG/GS

In this research, the core-shell structured fiber was fabricated by coaxial electrospinning technique. A set of biodegradable polymers namely polylactic acid (PLA) and cellulose acetate (CA) were used as the shell material. Gentamicin sulfate (GS) as antimicrobial drug with polyethylene glycol (PEG) was used as the core structure. PEG formed the core section of the coreshell fibers for GS encapsulation. In-vitro drug release activity of the core-shell fibers was determined by total immersion method in pH 7.4 phosphate buffer solutions (PBS). It was found that core-shell fibers sPLA-cPEG/GS exhibit higher initial release compared to that of core-shell fibers sPLA/CA-cPEG/GS.

Effect of Co-Monomer Content on Rheological Property of Sawdust/ABS Composites

Effect of co-monomer content in Acrylonitrile-Butadiene-Styrene copolymer (ABS) on the rheological property of sawdust reinforced ABS composites was investigated using capillary die rheometer. Three grades of commercial ABS resin were used. Sawdust from Para rubber tree treated with N-2(aminoethyl) 3-aminopropyl trimethoxy silane was blended with ABS by melt blending process using twin-screw extruder. From the results, shear thinning behavior was found for all of composites in the same shear rate ranges for testing that were investigated. At the low shear rate, the composites which contain higher acrylonitrile content, showed higher viscosity. At high shear rate, the viscosity of each co-monomer dependent composites tends to come close to each other on the curves. In this study, Carreau’s model was used for curve fitting and those parameters were also determined. Die swell ratio of the composites tended to increase at the initial ranges of shear rate of 10-500 s-1, and then the swelling ratio value decreased dramatically once the shear rate were further applied. The molecular weight has more effects than comonomer content on the die swell behavior i.e., at the same molecular weight, composites with higher butadiene content show higher swelling ratio.

Improvement Properties of Recycled Polypropylene by Reinforcement of Coir Fiber

This research was to study the related mechanical and thermal properties of recycled polypropylene from post consumer containers reinforced with coir fiber. Surface of coir fiber was treated with sodium hydroxide to remove lignin and hemicelluloses and likely to improve the interfacial adhesion in the composites. The composites of treated coir fiber and recycled polypropylene were prepared by varying the coir fiber contents at 5%, 10% and 20% by weight using a twin screw extruder. The thermal properties were investigated by thermal gravimetric analysis (TGA) and differential scanning calorimeter (DSC). The results from TGA showed that thermal stability of the composites was lower than that of recycled polypropylene resin and thermal stability decreased with increasing coir fiber content. From DSC results, it indicated that the crystallinity of treated coir fiber composites increased as a function of fiber content. The mechanical properties of injection-molded samples were studied by universal testing machine. The treated coir fiber composites produced enhanced mechanical properties. The tensile strength, tensile modulus and impact strength of modified coir fiber/recycled polypropylene composites increased as a function of coir fiber content.

Poly(Lactic Acid)-Polybutylene Succinate-Activated Carbon Composite Foams

Polymer blends of poly (lactic acid) (PLA) and polybutylene succinate (PBS) containing activated carbon (AC) were foamed by using Azodicarbonamide (ADC) through an extrusion process. The composite foams containing 5 phr of AC had lower density than those without AC loading for PLA:PBS ratios of 90:10, 80:20, 70:30, and 60:40. The incident of higher void fraction was the consequences of more foaming nucleation centers which were induced by adding AC in the composite foam. Maximum reduction of density by 50% with the void fraction of 50% was achieved when both ADC and AC were applied at 5 phr with the PLA:PBS ratio of 80:20. The addition of AC in composite foams enhanced the crystallization in PBS phase but had no effects on PLA crystallinity. The thermal stability of composite foams with and without AC dosages for each PLA:PBS proportion was slightly changed. For PLA-PBS blend foams, the more PLA loading there was the more tensile strength and modulus there would be. For PLA-PBS-AC composite foams, AC could improve the modulus and tensile strength of composite foams in PBS-rich samples whereas no effect on PLA-rich samples.