Wan Aizan Wan Abdul Rahman

Comparison of rice husk-filled polyethylene composite and natural wood under weathering effects

The weathering performance of rice husk-filled high-density polyethylene (RHPE) and natural wood was investigated in this study. The injection molded RHPE, in column end-cap (CECap) shapes, was exposed to both natural and accelerated weathering attacks. The durability of RHPE was compared to Kempas wood (Koompassia malaccensis) and neat polyethylene. Wood underwent the greatest losses in properties among the specimens. Four months of outdoor weathering turned the color of RHPE CECap into silvery grey. When the exposure time increased, the color of RHPE composite faded faster than neat polyethylene. The wood surface darkened and RHPE surface flaked off after being exposed to accelerated weathering conditions. Prolonged weathering exposure caused loss of impact strength of the RHPE composites. In general, RHPE is more resistible to weathering attacks as compared to Kempas wood.

In situ surface modification of natural fiber by conducting polyaniline

Newly modified biofibers made up of kenaf fibers (KF) and conducting polyaniline (PANI) were successfully prepared via in situ polymerization. Several characterization methods were done to elucidate the interaction between the KF surfaces and the in situ polymerized PANI. The PANI coated KF (KF/PANI) achieved new electronic properties, without sacrificing its mechanical properties and natural fiber characteristic. Initial mercerization on the KF yielded better PANI coated fibers compared to the untreated KF. Fiber bundle tensile test on the untreated KF/PANI revealed a drop in the unit break of about 48% compared to the untreated neat KF. Meanwhile, the mercerized KF/PANI showed reduction of about 17% compared to the uncoated mercerized KF. The mercerized KF/PANI exhibits polaronic transitions, existence of favorable IR peaks and Raman scattering, enhanced DC conductivity, and better morphological characteristic as a result of the in situ PANI coating. Such electronically modified natural fibers could be suitable as green conducting fillers in composites to replace other synthetic fibers.

Electrically conductive nanocomposites of epoxy/polyaniline nanowires doped with formic acid: Effect of loading on the conduction and mechanical properties

This paper reports the preparation and characterization of nanocomposites consisting of epoxy resin (EP) and conducting polyaniline nanowires doped with formic acid (PANI-FA). The percolation threshold of this nanocomposites was obtained at 8 wt.% of PANI-FA loading. On the other hand, 8 wt.% of PANI-FA resulted in reduction of tensile and flexural modulus up to 30% and 16%, respectively. The fracture morphological analysis revealed a distinct PANI-FA domain on the EP matrix after the percolation threshold has been reached. Using the scaling law of the percolation theory, it was found that the conductivity of the nanocomposites exhibited an exponential factor, (t) of 0.417.

Enhanced Interfacial Interaction and Electronic Properties of Novel Conducting Kenaf/Polyaniline Biofibers

Conducting kenaf/polyaniline (KF/PANI) biofibers were successfully prepared via in situ oxidative polymerization. It was demonstrated, for the first time, the possibility of imparting new electronic properties on KF by coating with acid-doped PANI. The morphological analysis revealed three different PANI morphologies on the KF, depending on the type of acid doping. Enhanced interaction was achieved between the fiber-PANI surfaces, mainly from the π − π interactions. The newly developed conducting biofibers achieved enhancement in DC conductivity up to fivefold compared to the unmodified KF. Mechanical test on the conducting biofibers revealed no significant loss in the tensile properties.

Mechanical and water absorption properties of poly(vinyl alcohol)/sago pith waste biocomposites

A series of blends of sago pith waste (SPW) and poly(vinyl alcohol) (PVA) were prepared. Mechanical and water absorption properties of the composites have been investigated. In this study, variable amounts of plasticized SPW (pSPW) and PVA (pPVA) were processed in the presence of glycerol as plasticizers. Composites were compression molded and evaluated. The addition of pSPW reduced the tensile properties of the composites, lowering the elongation and increasing Young’s modulus. The reduction in mechanical strength with the addition of pSPW was a general phenomenon due to the poor interfacial adhesion between the pPVA and Pspw, which can be proved by the scanning electron microscope observations. The percentage of water absorbed of the pPVA/pSPW biocomposites was higher than either the pPVA or pSPW alone while pSPW showed better water resistance compared to pPVA because of the restricted mobility exerted by the cellulose fibers. The incorporation of SPW into PVA decreased both the mechanical and water absorption properties.A series of blends of sago pith waste (SPW) and poly(vinyl alcohol) (PVA) were prepared. Mechanical and water absorption properties of the composites have been investigated. In this study, variable amounts of plasticized SPW (pSPW) and PVA (pPVA) were processed in the presence of glycerol as plasticizers. Composites were compression molded and evaluated. The addition of pSPW reduced the tensile properties of the composites, lowering the elongation and increasing Young’s modulus. The reduction in mechanical strength with the addition of pSPW was a general phenomenon due to the poor interfacial adhesion between the pPVA and Pspw, which can be proved by the scanning electron microscope observations. The percentage of water absorbed of the pPVA/pSPW biocomposites was higher than either the pPVA or pSPW alone while pSPW showed better water resistance compared to pPVA because of the restricted mobility exerted by the cellulose fibers. The incorporation of SPW into PVA decreased both the mechanical and water absorption properties.

Starch Based Biofilms for Green Packaging

The aim of this study is to develop degradable starch-based packaging film with enhanced mechanical properties. A series of low-density polyethylene (LDPE)/tapioca starch compounds with various tapioca starch contents were prepared by twin-screw extrusion with the addition of maleic anhydride-grafted polyethylene as compatibilizer. Palm cooking oil was used as processing aid to ease the blown film process; thus, degradable film can be processed via conventional blown film machine. Studies on their mechanical properties and biodegradation were carried out by tensile test and exposure to fungi environment, respectively. The presence of high starch contents had an adverse effect on the tensile properties of LDPE/tapioca starch blends. However, the addition of compatibilizer to the blends improved the interfacial adhesion between the two materials and hence improved the tensile properties of the films. High content of starch was also found to increase the rate of biodegradability of LDPE/tapioca starch films. It can be proved by exposure of the film to fungi environment. A growth of microbes colony can be seen on the surface of LDPE/tapioca starch film indicates that the granular starch present on the surface of the polymer film is attacked by microorganisms, until most of it is assimilated as a carbon source.

Polyaniline-coated kenaf core and its effect on the mechanical and electrical properties of epoxy resin

Novel conducting kenaf core/polyaniline (KC-PANI) biofibers were successfully prepared via in situ oxidative polymerization. The newly developed conducting KC achieved enhancement in DC conductivity up to seven fold compared to the raw KC. Enhanced interaction was obtained between the acetylated KC-PANI surfaces compared to untreated KC-PANI, without significant loss in the cellulose crystallinity. The morphological analysis revealed uniform layers of PANI deposited on the surface of acetylated KC. Epoxy resin (EP) containing KC-PANI (EP/KC-PANI composites) showed that the electrical percolation of KC-PANI occurred at 20 wt.%. The tensile strength of the EP/KC-PANI composites was slightly reduced compared to that of EP/KC composites at the same loading fraction. However, the flexural test revealed that the presence of KC-PANI increased the flexural strength of the EP composites by up to 15 wt.% loading. Electron micrograph of the EP/KC-PANI composite indicated favourable adhesion between components.

Hybrid composites of short acetylated kenaf bast fiber and conducting polyaniline nanowires in epoxy resin

This article reports the preparation and characterization of newly developed hybrid composites consisting of epoxy resin (EP) matrix, acetylated kenaf bast fiber (AKF) and conducting polyaniline (PANI) nanowires. Initially, the EP/AKF composites were prepared by varying the AKF loading (5–30 wt%). The EP/AKF displayed an optimum tensile strength at 20 wt% AKF loading which was higher than that of untreated kenaf fiber EP composites (EP/UKF). The hybrid composites of EP/AKF/PANI were then prepared by using 20 wt% AKF loading with PANI inclusions from 2 to 14 wt%. The addition of PANI into EP/AKF induced positive electrical properties without considerably sacrificing its mechanical integrity. It was found that the electrical percolation threshold of these hybrid composites was at 11 wt% of PANI loading. PANI inclusions at above the percolation loading resulted in reduction of tensile and flexural strength. Meanwhile, no significant mechanical loss was observed below the threshold. The fracture morphological analysis revealed the occurrences of PANI nanowires pull out from the matrix. The Fourier transform infrared spectroscopy showed that the PANI component still maintained its doped condition inside the EP/20AKF. Water absorption and thermal analysis indicate that the PANI incorporation induced lower water uptakes and greater thermal stability to the EP/20AKF, respectively.

Para-Hydroxybenzene Sulfonic Acid as a Suitable Dopant for the Preparation of Conductive Epoxy/Polyaniline Nanowires Nanocomposites Blend: Electrical vs Mechanical Properties

This article reports improved mechanical properties of epoxy/polyaniline nanowires nanocomposite (EP/PANI) by using para-hydroxybenzene sulfonic acid as the dopant. The PANI nanowires show no chain dedoping in the EP. Mechanical properties of the nanocomposites were maintained while achieving its conductive state and revealed pull-out of bundles rather than individual nanowire.

Tapioca starch biocomposite for disposable packaging ware

Tapioca Starch Biocomposite for Disposable Packaging Ware Roshafima R. Ali*, Wan A. W. A. Rahman, Rafiziana M. Kasmani, Norazana Ibrahim, Siti N. H. Mustapha, Hasrinah Hasbullah Department of Polymer Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia. Gas Engineering Department, FPREE, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia. roshafima@cheme.utm.my