Hazleen Anuar

Improvement of Mechanical Properties of Injection-Molded Polylactic Acid–Kenaf Fiber Biocomposite

The motive of this study is to lessen the dependence on non-degradable plastic packaging by developing alternative material; reinforced poly(lactic acid) (PLA) with kenaf fiber (KF) biocomposite using available plastic processing machineries. For that reason, this study focuses on fabrication of PLA–KF biocomposite using intermeshing co-rotating twin-screw extruder and then injection molded for mechanical characterization. The effect of KF loading from 0 to 20 wt% was studied. No coupling agent was added due to high affinity of PLA and KF and both components are hydrophilic in nature. The average of KF aspect ratio is 30. Tensile properties and flexural properties show similar trend where significant improvement was attained at 20 wt% KF content. Scanning electron micrograph of tensile fracture specimen has revealed the hypothesis of interaction between fiber and matrix which subsequently amplified the tensile properties. It is an interesting finding where the experimental value of tensile modulus was 15% higher than theoretical tensile modulus at 20 wt% KF. Additionally, PLA–KF bicomposite produced, has high specific strength and specific modulus. This could suggest that KF may be incorporated into PLA to reduce mass of the end product and substantially reduce the cost of raw materials. As expected, impact strength however decreases with KF content.

Reinforced thermoplastic natural rubber hybrid composites with Hibiscus cannabinus, L and short glass fiber - Part I: Processing parameters and tensile properties

Hybrid composite of thermoplastic natural rubber (TPNR) reinforced with Hibiscus cannabinus, L fiber (kenaf fiber: KF) and short glass fiber (GF) were prepared via melt blending method using internal mixer, at various temperatures, speed and time. TPNR matrix is a blend of polypropylene (PP), liquid natural rubber (LNR) and natural rubber (NR) at a ratio of 70 : 10 : 20. Processing parameters were determined from the tensile strength based on fiber content with 50: 50 ratios of GF and KF. Using the optimum processing parameters, tensile test was carried out for reinforced TPNR—KF—GF hybrid composites (0—20% by volume), with and without addition of silane coupling agent and maleic anhydride grafted polypropylene (MAPP). The result of tensile strength has shown that the increasing in kenaf fiber content substantially reduced the tensile strength and modulus. Scanning electron microscopy (SEM) has shown that the composite, with coupling agent or compatibilizer, promotes better fiber—matrix interaction.

The Mechanical and Physical Properties of Thermoplastic Natural Rubber Hybrid Composites Reinforced with Hibiscus cannabinus, L and Short Glass Fiber

Thermoplastic natural rubber hybrid composites reinforced with kenaf and short glass fibers were compounded by melt blending method using an internal mixer, Thermo Haake 600P. Thermoplastic natural rubbers (TPNR) were prepared from polypropylene (PP), natural rubber (NR) and liquid natural rubber (TPNR) with ratio 70:20:10, which were blended using internal mixer for 12 minutes at 180°C and rotor speed 40 r.p.m. Glass fiber was treated with silane coupling agent while TPNR reinforced kenaf fiber composite is using MAPP as a compatibilizer. TPNR hybrid composite with kenaf/glass fibers was prepared with fiber content (5, 10, 15, 20 volume % of fiber). Mechanical properties of the composites were investigated using tensile test[ 1 ], flexural, impact, and hardness test and scanning electron microscope (SEM)[ 1 ]. The incorporation of the treated or untreated fiber into TPNR has result in an increment of almost 100% of flexural modulus and impact strength as compared to TPNR matrix. However, the maximum strain decreased with increasing fiber content. The optimum composition for hybrid composite is at the fiber ratio of 30% kenaf fiber and 70% glass fiber. The SEM micrograph had shown, that the composite with coupling agent or compatibilizer promote better fiber-matrix interaction.

Mechanical and Fracture Toughness Behavior of TPNR Nanocomposites

Thermoplastic natural rubber (TPNR) nanocomposites containing organophilic layered silicates were prepared by melt blending method at 180°C using internal mixer (Haake 600P). The aim of this study is to determine the influence of the organoclay filler on the mechanical and fracture properties. In this study, two mixing methods were employed to incorporate filler into matrix, namely the direct (DM) and indirect (IDM) method. The mechanical properties of TPNR nanocomposites were studied using tensile, flexural, and impact tests. The tensile and flexural tests revealed that the optimum loading of organoclay was at 4 wt% using the indirect method of mixing. Plane stress fracture toughness of thermoplastic natural rubber (TPNR) nanocomposite was determined by the essential work of fracture (EWF) concept using tensile-loaded deeply double-edge notched (DDEN-T) specimens. The EWF measurements indicated that the specific essential work of fracture (we) decreased in the presence of nanoclay. Nevertheless, these TPNR nanocomposites met the basic requirement of the EWF concept of full ligament yielding, which was marked by a load drop in the force—displacement curves of the DDEN-T specimens.

Compatibilized PP/EPDM-kenaf fibre composite using melt blending method

Thermoplastic Elastomer (TPE) composite reinforced with Hibiscus cannabinus, L fiber (kenaf fiber, KF) was prepared via melt blending method using internal mixer at temperature 180°C, screw rotational speed at 40rpm for 10 min. TPE matrix is a blend of polypropylene (PP) and ethylene-propylene-diene monomer (EPDM) at a ratio of 70:30. The optimum fiber loading were investigated from 0% to 20% by volume. The effect of coupling agent maleic anhydride polypropylene (MAPP) on the TPE composite has been investigated. The result shown that, with increasing the kenaf fiber content gradually increased the tensile strength and flexural strength for both treated and untreated PP/EPDM-KF composite. However, at 20% of kenaf fiber loading, it showed decreasing in impact strength due to brittleness of the samples. From the scanning electron micrograph (SEM) it has shown that the composite, with compatibilizer promotes better interaction between TPE and kenaf fiber.

Mechanical Properties and Environmental Stress Cracking Resistance of Rubber Toughened Polyester/Clay Composite

Crosslinked polyester clay nanocomposites were prepared by dispersing originically modified montmorillonite in prepromoted polyester resin and subsequently crosslinked using methyl ethyl ketone peroxide catalyst at different clay concentration. Cure process and the mechanical properties of rubber toughened polyester clay composite have been studied. Rubber toughened thermoset polyester composite were prepared by adding 3 per hundred rubber (phr) of liquid natural rubber (LNR) was used in the mixing of producing this composite. Modification of polyester matrix was done due to the brittle problem of polyester composite. Addition of LNR will increase the toughness of composite and produce ductile polyester. Two types of composites were produced which is clay-lnr polyester composite and clay polyester composite. Addition of liquid natural rubber significantly increased the impact strength and flexural properties. Result shows that addition of 6% of clay-lnr composite give good properties on impact, strength and flexural. From the ESCR test, both composites showed good resistance to environmental.

Micromechanical Property Investigations of Poly(lactic acid)–Kenaf Fiber Biocomposites

In this research, investigation on the interfacial shear strength of poly(lactic acid)–kenaf fiber biocomposite was investigated using microbond tests. Tensile properties and fracture behaviors of single kenaf fiber are tested via in situ monitoring with acoustic emission (AE). During tensile loading, acoustic signal recorded higher amplitude of above 20 dB up to the maximum force, which corresponds to breakage of single kenaf fiber. Based on microbond tests and AE evaluation, a correlation has been established on failure of kenaf fiber, which is due to debonding of filament and internal structure, cracking of fiber and breakage of fiber.

Preparation and Characterization of Physical Properties of Durian Skin Fibers Biocomposite

Durian skin fibres (DSF) are cellulose-based fibres extracted from the durian peel. This paper present the physical behaviour, chemical structure and crystallinity of the fibres, as observed by environmental scanning electron microscope (ESEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD). The characteristic of the natural fibers produces from durian skins are similar with other types of natural fiber. The average diameter and density are 0.299 mm and 1.243 g/cm3, respectively while the crystallinity index is slightly higher than the common fibers. The properties and charecteristic of durian skin fibers are within the propertise of lignocellulosic fiber which is suitable for development of biocomposite materials.

Effects of Dilute Acid Pretreatment on Chemical and Physical Properties of Kenaf Biomass

In the current research, kenaf represents an agricultural biomass that possesses enormous potential for industrial applications. Because of its complex structure, which is composed of cellulose, hemicellulose, and lignin, pretreatment process was conducted. Here, dilute acid pretreatment process was conducted, statistically using the response surface method, which included three parameters: mass of biomass (g), temperature (°C), and time (min). About 2 g of kenaf biomass was treated with 2% dilute sulphuric acid, and it was found to have higher glucose conversion (25.3%) when the process was conducted for 60 min at the temperature of 180°C. The main aim of the current research is to investigate the chemical and physical changes of kenaf biomass before and after the pretreatment. The changes could be clearly seen in the cellulose, hemicellulose, and lignin composition before and after the pretreatment, which were evaluated via TAPPI standard test methods. Morphological observation under scanning electron microscope confirmed the changes that took place on the kenaf biomass from complex to simple surface structure. Fourier transform infrared analysis confirmed the presence of cellulose, hemicellulose, and lignin contents of the kenaf biomass before and after pretreatment. Crystallinity of the treated kenaf biomass also increased from 46.6% to 70.0%, as evidenced from X-ray diffractometer analysis.

Fabrication and Compressive Properties of Low to Medium Porosity Closed-Cell Porous Aluminum Using PMMA Space Holder Technique

In recent years, closed-cell porous Aluminum (Al) has drawn increasing attention, particularly in the applications requiring reduced weight and energy absorption capability such as in the automotive and aerospace industries. In the present work, porous Al with closed-cell structure was successfully fabricated by powder metallurgy technique using PMMA as a space holder. The effects of the amount of PMMA powder on the porosity, density, microstructure and compressive behaviors of the porous specimens were systematically evaluated. The results showed that closed-cell porous Al having different porosities (12%–32%) and densities (1.6478 g/cm3, 1.5125 g/cm3 and 1.305 g/cm3) could be produced by varying the amount of PMMA (20–30 wt %). Meanwhile, the compressive behavior results demonstrated that the plateau stress decreased and the energy absorption capacity increased with increasing amount of PMMA. However, the maximum energy absorption capacity was achieved in the closed-cell porous Al with the addition of 25 wt % PMMA. Therefore, fabrication of closed-cell porous Al using 25 wt % PMMA is considered as the optimal condition in the present study since the resultant closed-cell porous Al possessed good combinations of porosity, density and plateau stress, as well as energy absorption capacity.