Razaina Mat Taib

Effects of Alkali Treatment on the Properties of Kenaf Fiber-Unsaturated Polyester Composites Prepared by Resin Transfer Molding

Composites of untreated and 6% sodium hydroxide (NaOH) treated kenaf fiber mat and unsaturated polyester resin matrix were manufactured via a resin transfer molding (RTM) technique. The treated fibers were characterized with SEM and XRD. Contact angle measurements of the fibers were performed using a tensiometer. Alkali treated fiber-unsaturated polyester composites showed superior flexural properties than the composites with untreated fibers. The water absorption pattern of these composites was found to follow Fickian behavior. The tendency of the composites to absorb water decreased when alkali treated fiber mats were used.

The Influence of AlkaliTreatment and Compatibilizer Addition on the Tensile Properties and Water Absorption Behavior of Polypropylene/Kenaf Fiber Composites

Composites of polypropylene (PP) and kenaf fiber (KF) were immersed in water at room temperature. The fiber was treated with alkaline solution. A compatibilizer, maleic anhydride-grafted polypropylene (MAPP) was added in some composite formulations. Composite with alkali treated fibers (KFA) showed similar tensile strength but lower tensile modulus than the composite with untreated fiber, KF. Addition of MAPP was crucial to improve the tensile properties and water resistance of either PP/KF or PP/KFA composites. Alkali treatment adversely affected the water absorption behavior of PP/KF composite.

Processing, Tensile, and Thermal Studies of Poly(Vinyl Chloride)/Epoxidized Natural Rubber/Kenaf Core Powder Composites with Benzoyl Chloride Treatment

ABSTRACT The kenaf core powder (KCP) has been treated with benzoyl chloride (BC) in poly(vinyl chloride)(PVC)/epoxidized natural rubber (ENR)/KCP composites. The presence of BC grafted on KCP was evident by infrared analysis. PVC/ENR/KCP samples were prepared using Haake Polydrive with the temperature of 140°C and KCP loading of 5, 10, 15, and 20 phr. The processing, tensile and thermal properties of the composites were investigated. The enhancement of tensile properties showed that the treatment improved the interfacial adhesion between KCP with PVC/ENR matrix. Higher glass transition temperature and higher thermal stability after treatment with BC support the enhancement of the composites’ tensile properties. GRAPHICAL ABSTRACT

Sodium dodecyl sulfate (SDS) as a filler treatment: effects on mechanical, morphological and swelling properties of poly (vinyl chloride) (PVC)/epoxidized natural rubber (ENR)/kenaf core powder composites

The effects of SDS treatment on properties of PVC/ENR/kenaf core powder composites were studied. Four different loadings of kenaf core powder (5, 10, 15 and 20 phr) were used. Samples were prepared using a Haake Polydrive with the temperature of 140 °C and rotor speed of 50 rpm, with the processing time of 8 min. Processing torque and stabilization torque during the compounding process were recorded. Tensile properties indicated that the tensile strength and elongation at break of the composites exhibited an increase for samples with SDS treatment. Morphological analysis using SEM showed better interfacial adhesion of kenaf fibre with SDS treatment with less kenaf powder agglomeration. Furthermore, swelling index indicated that the composites with SDS treatment show lower absorption of solvent compared to composites without SDS treatment.

Surface Characterization of Alkali Treated Kenaf Fibers by XPS and AFM

Kenaf fibers were immersed in 6% solution of sodium hydroxide (NaOH) for 1, 2, 3, 4 and 5 hours. The treated fibers were characterized with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The XPS results showed that the alkali treatment increased the proportion of oxygen atoms on the fiber surface as indicated by the increase in oxygen-carbon ratio. An increase in C2 peak (C-OH bonds) was also observed suggesting the present of cellulose on the fiber surface. The decrease in C1 peak (C-C bonds) suggested that lignin was removed from the fiber surface following the alkali treatment. Scale-like structures were observed from the AFM topographic images to indicate the presence of cellulose microfibrils in the primary cell wall of the treated fiber. Alkali treated fiber surface showed lower mean surface roughness than the untreated fiber indicating smoother fiber surface. The fiber surface became relatively smooth after the alkali treatment due to the removal of non-cellulosic layer.

Effects of Sodium Dodecyl Sulfate Filler Treatment and Thermo-Oxidative Ageing on the Properties of Poly(Vinyl Chloride)/Epoxidized Natural Rubber/Kenaf Core Powder Composites

An experimental study was conducted to investigate the influence of thermo-oxidative ageing on the tensile properties of PVC/ENR/KCP composites. Sodium dodecyl sulfate filler treatment was also carried out to evaluate the effect of filler treatment. The composites were prepared by melt compounding using Haake Polydrive internal mixer at 140 °C and 50 rpm. Compression-moulded samples were subjected to fracture surface morphology analysis and thermo-oxidative ageing for 3, 5 and 7 days. Thermo-oxidative ageing test indicates that after 3 days of exposure to heat, tensile strength increases, which is due to the further cross-linking reaction. With further exposure for 5 days and 7 days, the tensile strength is reduced probably due to the reduction in flexibility of the cross-link, which affect the stress distribution in the composites.

Kinetics of Moisture Absorption for Alkali Extracted Steam‐Exploded Fiber Filled High‐Density Polyethylene Composites

Acacia mangium wood fiber derived from steam‐explosion and fiber fractionation treatment was used as fillers for high‐density polyethylene (HDPE). The alkali extracted steam‐exploded fibers (AEF) obtained were acetylated to produce acetylated fibers (AAEF) having three different weight percent gain (WPG). Composites of AEF or AAEF and HDPE were prepared via 2‐roll mill, compression molded and cut into dumbbell specimens. All samples were immersed in water at room temperature for 30 days. The process of absorption of water by all composites followed the kinetics and mechanisms described by the Fick’s theory. Diffusion coefficient (D) values increased with filler loading but decreased with increasing WPG of the AAEF fiber. Further decrease was observed when maleated polyethylene (MAPE) was added to the composite system. This was due to improved fiber‐matrix adhesion that restricts movement of water molecules from further penetrate inside the composite structures.