Kenaf fibers reinforced unsaturated polyester composites: A review

Recently development of high-performance polymer composites made from natural resources in the various sectors is increasing tremendously due to the environmental issues and health hazard possessed by the synthetic fibers during disposal and manufacturing. Among the many different types of natural resources, kenaf fibers have been extensively investigated as an alternative reinforcement for polymer composites over the past few years due to their low cost, good mechanical properties, high specific strength, nonabrasive, eco-friendly, and biodegradability characteristics. Kenaf is regarded as an industrial crop in Malaysia and grown commercially in other parts of the world for different applications. It is certainly one of the important plants cultivated for natural fibers globally which has great potential to use as automotive and construction materials. In many research studies, kenaf fibers have been used as reinforcement in unsaturated polyester (UPE) which perfectly improved the features of the polyester resin. The tensile properties of kenaf fiber reinforced UPE are mainly influenced by the interfacial adhesion between the fibers and the polyester resin. Several chemical modifications are employed to improve the interfacial bonding between kenaf fibers and polyester, resulting in the enhancement of mechanical properties of the composites. Therefore, this paper explores and highlights of the previous studies around kenaf fiber reinforced UPE composites, in terms of processing methods, mechanical, water absorption, and morphological properties to provide a perfect source of literature for doing further research in this topic

Receivers for Diffusion-Based Molecular Communication: Exploiting Memory and Sampling Rate

In this paper, a diffusion-based molecular communication channel between two nano-machines is considered. The effect of the amount of memory on performance is characterized, and a simple memory-limited decoder is proposed and its performance is shown to be close to that of the best possible imaginable decoder (without any restriction on the computational complexity or its functional form), using Genie-aided upper bounds. This effect is specialized for the case of Molecular Concentration Shift Keying; it is shown that a four-bits memory achieved nearly the same performance as infinite memory. Then a general class of threshold decoders is considered and shown not to be optimal for Poisson channel with memory, unless SNR is higher than a value specified in the paper. Another contribution is to show that receiver sampling at a rate higher than the transmission rate, i.e., a multi-read system, can significantly improve the performance. The associated decision rule for this system is shown to be a weighted sum of the samples during each symbol interval. The performance of the system is analyzed using the saddle point approximation. The best performance gains are achieved for an oversampling factor of three.Comment: Submitted to JSA

Rice Husk Filled Polymer Composites

Natural fibers from agricultural wastes are finding their importance in the polymer industry due to the many advantages such as their light weight, low cost and being environmentally friendly. Rice husk (RH) is a natural sheath that forms around rice grains during their growth. As a type of natural fiber obtained from agroindustrial waste, RH can be used as filler in composites materials in various polymer matrices. This review paper is aimed at highlighting previous works of RH filled polymer composites to provide information for applications and further research in this area. Based on the information gathered, application of RH filled composites as alternative materials in building and construction is highly plausible with both light weight and low cost being their main driving forces. However, further investigations on physical and chemical treatment to further improve the interfacial adhesion with polymeric matrix are needed as fiber-polymer interaction is crucial in determining the final composite properties. Better understanding on how the used polymer blends as the matrix and secondary fillers may affect the properties would provide interesting areas to be explored.</jats:p

Influence of Rubber Content on Mechanical, Thermal, and Morphological Behavior of Natural Rubber Toughened Poly(Lactic Acid)-Multiwalled Carbon Nanotube Nanocomposites

The effects of natural rubber (NR) on the mechanical, thermal, and morphological properties of multiwalled carbon nanotube (CNT) reinforced poly(lactic acid) (PLA) nanocomposites prepared by melt blending were investigated. A PLA/NR blend and PLA/CNT nanocomposites were also produced for comparison. The tensile strength and Young's modulus of PLA/CNT nanocomposites improved significantly, whereas the impact strength decreased compared to neat PLA. The incorporation of NR into PLA/CNT significantly improved the impact strength and elongation at break of the nanocomposites, which showed approximately 200% and 850% increases at 20 wt % NR, respectively. However, the tensile strength and Young's modulus of PLA/NR/CNT nanocomposites decreased compared to PLA/CNT nanocomposites. The morphology analysis showed the homogeneous dispersion of NR particles in PLA/NR/CNT nanocomposites, while CNTs preferentially reside in the NR phase rather than the PLA matrix. In addition, the incorporation of NR into PLA/CNT lowered the thermal stability and glass-transition temperature of the nanocomposites

Effect of acid hydrolysis time on tensile and morphological properties of microcrystalline chitin filled polylactic acid biocomposites

The objective of this study is to investigate the effect of acid hydrolysis time on microcrystalline chitin (MCC) filled polylactic acid (PLA) biocomposites using solution casting method. MCC was produced from commercial chitin using controlled hydrolysis process at four different hydrolysis time; 15, 30, 45 and 60 min. The tensile and morphological properties of PLA/MCC biocomposites were investigated using tensile testing machine and atomic force microscopy (AFM), respectively. Tensile strength and Young’s modulus of PLA/MCC biocomposites increased gradually by increasing hydrolysis time. The biocomposites with longest hydrolysis time (60 min) showed the higher tensile strength, Young’s modulus and elongation at break values. AFM analysis showed homogeneous dispersion of MCC fillers with smaller particles size at longer hydrolysis time, resulted in smother surface morphology compared to biocomposites with shorter hydrolysis time

Mechanical Properties and Morphological Characterization of PLA/Chitosan/Epoxidized Natural Rubber Composites

Poly (lactic acid) (PLA)/chitosan (CS) natural polymer/epoxidised natural rubber (ENR) composites were successfully prepared through a solution casting method. The morphological characteristics of fabricated composites were investigated by scanning electron microscopy (SEM) and optical microscopy. The microstructure of PLA/ENR was significantly altered with the addition of CS. SEM analysis of composites fractured surfaces revealed smooth and homogeneous texture and good dispersion of CS. However for 15 wt% CS composites, the phase segregation and poor adhesion between the polymers were observed. Fourier transform infrared spectroscopy revealed some levels of attractive interaction between CS, PLA, and ENR in the composites. The mechanical properties of composites in terms of tensile strength and tensile modulus were significantly improved with the addition of CS into the matrix while the percent elongation at break decreased. The tensile strength increased up to 5 wt% CS loading for both PLA/CS and PLA/ENR/CS and thereafter decreased while Young’s modulus increased up to 10 wt%. However, when the CS content was increased to 15 wt%, the tensile strength and tensile modulus were slightly decreased. These improvements were attributed to good dispersion of CS at the optimum filler levels and attractive interaction between the composites components.</jats:p

ISOLATION AND CHARACTERIZATION OF MICROCRYSTALLINE CELLULOSE FROM OIL PALM FRONDS USING CHEMO-MECHANICAL PROCESS

This study investigates the characteristic of the microcrystalline cellulose (MCC) isolated from oil palm (Elaies guineensis) fronds using acid hydrolysis method. The morphology and size of the MCC were characterized using both Sherrer equations for X-ray diffraction (XRD) result and transmission electron microscopy (TEM). The thermal stability of MCC was determined from thermogravimetry analysis (TGA) profiles whilst, Fourier transform infrared spectroscopy (FTIR) was used to analyse the chemical modifications that occurred under these conditions. The XRD results showed that the MCC isolated from oil palm fronds (OPF-MCC) fibres had an average diameter and crystallinity index of 12.15 nm and 60.1 % respectively. Both the FTIR and the XRD indicated that lignin and hemicellulose contents decreased while the cellulose-I polymorph remained constant. Thermogravimetric analysis (TGA) revealed that OPF-MCC had higher thermal stability compared to the OPF fibres. The study revealed the potential applications of the MCC isolated from the oil palm biomass as green reinforcement or/and fillers in the production of biodegradable biocomposite

Kenaf fibers reinforced unsaturated polyester composites:A review

Recently development of high-performance polymer composites made from natural resources in the various sectors is increasing tremendously due to the environmental issues and health hazard possessed by the synthetic fibers during disposal and manufacturing. Among the many different types of natural resources, kenaf fibers have been extensively investigated as an alternative reinforcement for polymer composites over the past few years due to their low cost, good mechanical properties, high specific strength, nonabrasive, eco-friendly, and biodegradability characteristics. Kenaf is regarded as an industrial crop in Malaysia and grown commercially in other parts of the world for different applications. It is certainly one of the important plants cultivated for natural fibers globally which has great potential to use as automotive and construction materials. In many research studies, kenaf fibers have been used as reinforcement in unsaturated polyester (UPE) which perfectly improved the features of the polyester resin. The tensile properties of kenaf fiber reinforced UPE are mainly influenced by the interfacial adhesion between the fibers and the polyester resin. Several chemical modifications are employed to improve the interfacial bonding between kenaf fibers and polyester, resulting in the enhancement of mechanical properties of the composites. Therefore, this paper explores and highlights of the previous studies around kenaf fiber reinforced UPE composites, in terms of processing methods, mechanical, water absorption, and morphological properties to provide a perfect source of literature for doing further research in this topic

Exploring the effects of fermented chitin nanowhiskers on tensile and thermal properties of poly(ethylene glycol) modified polylactic acid nanocomposites

The incorporation of fermented chitin nanowhiskers (FCHW) into poly(lactic acid) (PLA) increased the tensile modulus and strength of PLA at the expense of ductility. The brittleness of PLA can be overcome with the use of plasticizer such as polyethylene glycols (PEG). The objective of this study is to investigate the effect of FCHW on the tensile and thermal properties PLA incorporated with PEG as plasticizer (PLA/PEG). PLA/PEG and FCHW reinforced PLA/PEG nanocomposites were prepared using solution mixing technique. Thermogravimetric analysis (TGA) was used to determine the thermal properties while tensile properties were determined from the tensile test. The incorporation of PEG successfully increased the ductility and tensile strength of PLA at the expense of modulus. Based on the tensile properties, 5 phr PEG was chosen for further investigation on the effect of FCHW on PEG modified PLA. Incorporation of 1 phr FCHW PLA/PEG increased the tensile strength and Young's modulus. However, the tensile strength decreased with further addition of FCHW. The elongation at break of PLA/PEG decreased drastically with the incorporation of 1 phr FCHW and decreased gradually with further increase of FCHW. The thermal stability from TGA of FCHW reinforced PLA/PEG nanocomposites at 5 phr FCHW content was observed to be significantly higher compared to PLA/PEG, as indicated by T20 and Tmax