M. D. H. Beg

Polyester-Kenaf Composites: Effects of Alkali Fiber Treatment and Toughening of Matrix Using Liquid Natural Rubber

In this study, polyester-kenaf fiber composites were prepared by adding various percentages of kenaf fiber in unsaturated polyester resin and subsequently cross-linked using methyl ethyl ketone peroxide and the accelerator cobalt octanoate. Liquid natural rubber (LNR) (3%) was added as a toughening agent. Kenaf fibers were treated with sodium hydroxide solution to improve the interfacial bonding between the fiber and the matrix. The mechanical properties of the composites were evaluated by impact and flexural testing. Environmental stress cracking resistance (ESCR) of composites in acid and base medium was also studied. Bonding mechanisms were assessed by scanning electron microscope and Fourier transform infrared analysis. It was found that the addition of LNR increased the impact strength and fracture toughness. Alkali fiber treatment was found to provide better impact and flexural strengths to the composites. Measurement of ESCR shows that the composite with acid medium has the fastest diffusion rate, followed by that with base medium, and then without medium.

Fibre surface modifications through different treatments with the help of design expert software for natural fibre-based biocomposites

Composites of untreated and treated kenaf fibres with recycled polypropylene were fabricated by melt-cast technique with and without using maleic anhydride-grafted polypropylene. To improve interfacial bonding between kenaf fibres and recycled polypropylene, surface modifications of fibres were performed through ultrasound, enzyme and alkali pre-treatments. Klason lignin test, Fourier-transform infrared spectroscopy and scanning electron microscopy were used for the characterization of fibres. For characterization of composites, the samples were examined by density measurements, mechanical tests, field-emission scanning electron microscopy, X-ray diffraction study, differential scanning calorimetry and thermogravimetric analysis. Results revealed that ultrasound was able to remove the highest amount of lignin (32%). Tensile strength of the composites was increased by 57%, 58% and 40% due to the treatment with alkali, ultrasound and enzyme, respectively. Optimization of treatment parameters was carried out by means of the design expert software. The optimum treatment parameters, such as alkali concentration, soaking time in alkali, sonication power, temperature, enzyme concentration and soaking time in enzyme were found to be 4.6 wt%, 4.95 h, 99.96%, 94.46℃, 1.26 wt% and 3.89 h, respectively, which are reasonably close to the experimental ones. The preferential b-axis orientation in recycled polypropylene crystal was found to be more apparent due to treated kenaf fibres with maleic anhydride-grafted polypropylene than untreated kenaf fibres with maleic anhydride-grafted polypropylene. A correlation among crystallinity, surface morphology, and tensile and thermal properties of composites with the fibre-matrix interactions has been established.

Characterization of Oil Palm Empty Fruit Bunch and Glass Fibre Reinforced Recycled Polypropylene Hybrid Composites

The effects of hybridization of glass fibre on oil palm empty fruit bunch (EFB) and recycled polypropylene-based composites are described in this paper. The compounding process involved extrusion followed by injection moulding technique to prepare the samples for characterizations. Fibre loading were considered as 40 % of the total weight of the blends and EFB:glass fibre ratio was maintained as 30:70, 50:50, 70:30 and 90:10. Two types of coupling agents of maleic anhydride-grafted polypropylene such as polybond-3200 and fusabond P-613 of different molecular weight and maleic anhydride level were used to improve the interfacial adhesion between the fibres and the matrix. Composites were characterized by density, melt flow index, tensile, Izod impact and flexural testing. Morphological images of the fractured surfaces of the composites were examined by field-emission scanning electron microscopy. Samples were also characterized by thermal tests such as thermogravimetric analysis and differential scanning calorimetry to evaluate the thermal and crystalline properties, respectively. Optimization of hybridization of the fibres and effect of coupling agents were evaluated in terms of various properties of the samples. The composite prepared with EFB:glass fibre ratio of 70:30 showed better reinforcing properties than that of others.

Preparation, structure, and properties of the coir fiber/polypropylene composites

Coir fiber–reinforced polypropylene-based unidirectional composites were prepared by compression molding. Mechanical properties like tensile strength, tensile modulus and impact strength of the resulting composites were found to be increasing with increase in the loading of coir fibers, reached an optimum and thereafter decreased with further increase in fiber loading. Based on fiber loading, 30 wt% fiber-reinforced composites had the optimum set of mechanical properties. After alkali treatment of coir fiber, tetramethoxy orthosilicate treatment was conducted to promote adhesion between coir fiber and polypropylene matrix. Treatment of the coir fiber with tetramethoxy orthosilicate after the alkali pre-treatment enhanced the mechanical properties and water desorption of the resultant composites, resulting from the improved adhesion between the coir fiber and polypropylene matrix. These results were also confirmed by the scanning electron microscope observations of tensile fracture surfaces of coir fiber/polypropylene composites. The interfacial shear strength of the composites was also measured using a single-fiber fragmentation test and a microbond test.

Degradation And Stability Of Green Composites Fabricated From Oil Palm Empty Fruit Bunch Fiber And Polylactic Acid: Effect Of Fiber Length

In this work, polylactic acid and oil palm empty fruit bunch fiber-reinforced green composites have been fabricated by using random and fixed-length fibers through extrusion followed by injection molding. The prepared composites have been characterized by mechanical tests, thermal analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffractometry. Among all fabricated composites having various sizes and contents of fibers, 30-mm long and 40 wt% empty fruit bunch fiber-incorporated composites show the optimum tensile strength and modulus. As compared to raw empty fruit bunch fiber-loaded composites, simultaneous ultrasound and alkali-treated empty fruit bunch-reinforced composites have revealed improved mechanical performances, enhanced crystallinity, and thermal stability. In case of soil burial degradation studies, treated empty fruit bunch fiber-reinforced composite has been found to be more stable than untreated fiber-reinforced composite.

12 – The use of oil palm biomass (OPB) fibers as reinforcements in composites

Abstract: There are tremendous demands of lightweight materials for use in transportation and construction sectors. Natural fibers (NFs) in reinforced polymer composites are relatively lightweight. However, NFs have some limitations due to their moisture affinity, poor wettability and low thermal stability during processing with synthetic polymers. These drawbacks have been overcome by effective physical and chemical treatments of NFs. Among various NFs, oil palm biomasses (OPBs) are readily available in some tropical countries and have received intense attention in the composite industries. In this chapter, the performance of untreated and differently treated OPB fibers, reinforced thermoplastic and thermoset composites prepared through extrusion, compression and injection moldings have been discussed in detail.

Mechanical, thermal, and rheological properties of nano-calcium carbonate/polypropylene composites modified by methacrylic acid:

Polypropylene (PP)/nano-calcium carbonate (nCC) composites modified with methacrylic acid (MA) with and without dicumyl peroxide (DCP) were prepared by a twin-screw extruder. The effects of nCC and MA on the mechanical, thermal, and rheological properties of PP/nCC composites were investigated. The mechanical tests indicating that nCC could simultaneously reinforce and toughen PP. In addition, incorporation of MA further increased the mechanical properties of the composites. In the presence of DCP, a small amount of MA could increase markedly the mechanical properties of PP/nCC composites. Differential scanning calorimetry results indicate that the addition of nCC increased the crystallization temperature (T c) as a result of heterogeneous nucleation effect of nCC on PP and can induce β-phase PP. The addition of MA can further increase the T c of PP and the intensity of β-phase PP. The results of rheological property analysis indicated that the viscosity increased with increasing amount of the filler, especially at low shear rates. The addition of MA improved the dispersion of nCC resulting in the increasing of apparent viscosity.

Influence of Carbon Nano Tubes on the Thermo-Mechanical Properties of Unsaturated Polyester Nanocomposite

To date nano fillers are renowned reinforcing agent for polymer materials. In this work, unsaturated polyester (UPR) nanocomposites were fabricated by 0.1, 0.3 and 0.5 wt% multi walled carbon nanotubes (MWCNTs) through solution dispersion and casting method. The influence of MWCNT content was investigated by thermo-mechanical properties. Dispersion of nanotubes was observed by fracture morphology. The strength of nanocomposites rose with raising the CNT content. Moreover, DSC thermograms of nanocomposites represent noticeable improvement of glass transition temperature (Tg), melting temperature (Tm) and enthalpy (ΔHm). Micro-crystallinity of nanocomposites increased with increasing the CNT content. Moreover, the stiffness increased with increasing the CNT content.

Characterization of microwave-treated oil palm empty fruit bunch/glass fibre/polypropylene composites

Composites were prepared from recycled polypropylene (RPP), oil palm empty fruit bunch (EFB) and/or glass fibre (GF) using extrusion and injection moulding techniques. Two types of maleic anhydride-grafted polypropylene such as Polybond 3200 and Fusabond P 613 were used to improve the interfacial adhesion between fibres and matrix. The EFB: GF ratio was fixed as 70:30 and fibre loading was considered as 40 wt%. Microwave was used to treat the EFB fibre, which was soaked in a fixed mass concentration (12.5%) of alkali solution at different temperatures (70, 80 and 90°C) for a fixed period of time (60 min) and for different times (60, 90 and 120 min) at a fixed temperature (90°C). A magnetron controller was developed to control the time and temperature accurately for the treatment of fibre. Various characterization techniques such as density, melt flow index, tensile, Izod impact, flexural, field-emission scanning electron microscopy and water uptake testing were performed for the composites. Besides, thermogravimetric analysis and differential scanning calorimetry were also used to evaluate the thermal and crystalline properties of the composites, respectively. Result analyses revealed that microwave-treated fibre-based composites showed improved mechanical and thermal properties. EFB fibres treated at 90°C for 90 min were found to be suitable for better reinforcement into the composite in terms of mechanical, thermal and crystalline properties. Moreover, onset degradation temperature and water absorption properties were also found to be changed apparently due to treatment.