Conventional fibre size has large surface area for binding site while nanocellulose posses higher surface area thus making more available binding site for fibre-matrix interaction. Kenaf has poor surface properties before treated. Treatment was applied to overcome this problem with alkali followed by acidic treatment. The nanocellulose has been produced from kenaf core (hibiscus cannabinus) by chemi-mechanical method. The fibre was treated with alkali followed by acidic treatment (HCl). Treated fibres were mechanically process by using pulverisette & cryocrushing to reduce the fibre size. The nanocellulose fibres were observed under Scanning Electron Microscope (SEM). The result convinced that chemi-mechanical method is a new technique for producing high yield kenaf nanocellulose.
Degradation of polylactic acid (PLA) was studied to investigate the best method of degradation to assist in reducing environmental pollution. Two condition of testing were conducted, which are natural weathering and landfill burial test. The rate of degradation was determined by weight loss, which was calculated once a month for six months. Natural weathering was achieved by exposing the samples to the natural environment, and this method was adopted according to ASTM D1435. Landfill burial testing was conducted by adopting ASTM G160-12 with a few modifications. The result shows that degradation was faster in a landfill burial condition. This was determined by the calculated weight loss, which was 2-4% of the total weight loss of PLA and its composites after six months' exposure to a natural weathering environment. In contrast, the landfill burial condition showed 4-17% weight loss after six months. The addition of natural fiber, whether bast or core fiber, assisted in the degradation of the composites. As well, the addition of natural fiber led to a 0.3-1.3% higher weight loss among the composites compared to neat PLA following natural weathering, while an 11-13% weight loss was recorded for composites exposed to the landfill burial condition. Natural weathering and landfill burial testing provide a time frame for the degradation of composite products. This is a good information for commercial composting facilities, providing data on the time frame required for material biodegradation.
This study was conducted to produce green composite from kenaf with better thermal properties. Kenaf fibre was successfully prepared by chemi-mechanical method. Kenaf fibre was firstly treated with sodium hydroxide (NaOH) at 6% w/w followed by acidic treatment with different concentrations (0.5M, 1.0M and 1.5M). The PLA/kenaf nanofibre composites were referred as KC0.5, KC1.0 and KC1.5 according to acid concentration used. Differential scanning calorimetry (DSC) was done to investigate thermal properties of the composites. The glass transition, crystallization and melting temperature shows similar trend where 1.0M treated fibre composites gives better thermal properties than 0.5M and 1.5M treated fibre composites. Transmission electron microscopy (TEM) micrographs suggested the nanofibre dispersion in mixed-pattern; exfoliation and small agglomeration.
In this paper, bending strength and physical properties (specific gravity, dimensional stability and equilibrium moisture content) of a Malaysian bamboo locally known as Beting bamboo (Gigantochloa levis) are addressed. Characterizations of physical and bending strength of G. levis in terms of the variability of location along culm height (top, middle, bottom), culm section (nodes and internodes), fiber orientation (longitudinal, tangential and radial) and culm layer (outer and inner) were conducted. Comparison of these properties is also made to some bamboo and commercial timber species. It was found that G. levis has favorable physical and mechanical properties although the specific gravity of G. levis has tendency to be on the higher side. The characteristics studied were found to have some variability at different locations, sections, and directions. There was variability in terms of bending strength along with the culm height of bamboo. It is indicated from this study that the bending strength and physical properties of G. levis were found to be satisfactory.
This study was conducted to study the degradation of poly (lactic acid) and its composites under natural landfill burial. Composites reinforced with natural fibres were expected to degrade faster than polymer itself. PLA was compounded with kenaf bast fibre (KBC) and kenaf core fibre (KCC) with twin screw extrusion at temperature range 150-160• C and being compression moulded at 170• C for 8 minutes. Samples were then cut prior to testing by burying under composting area in UiTM Shah Alam, Selangor, Malaysia for 6 month period. Samples were measured and observed monthly for the degradation of composites by weight loss and microscopic observation. As expected weight loss for kenaf bast composite (KBC) and kenaf core composite (KCC) was found to be higher, 15.9% and 17.1% respectively, than that of pure PLA of only 4.14%. Microscopic observation confirms degradation has occurred on surface of composites by making cracks, holes, and black spots on all samples, however degradation was more obvious on composites. FTIR analysis shows that spectra of exposed composites were reduced compared to those of unexposed composites.
Extrusion is one of established methods of polymer processing with fibre and consequently disperses fibre inside polymer. Different speed shows different behaviour of fibre dispersion. This study was conducted to produce composites from polylactic acid and kenaf by extrusion method. Kenaf bast and core was undergone chemical treatment with sodium hydroxide (6% w/w) followed by hydrochloric acid. Then, kenaf bast and core was mechanically beaten to reduce the fibre size. PLA and kenaf fibre (bast and core) was mixed by extrusion process with 3 different rotation speeds (60, 70 and 80 rpm). Kenaf bast composite and kenaf core composite was referred as KBC and KCC respectively. Flexural and impact strength was done to investigate the effect of different screw rotation speed on KBC and KCC. KBC and KCC processed with 60 rpm rotation speed shows better performance on flexural strength. For impact strength, KBC with 70 rpm and KCC with 60 rpm rotation speed have higher impact values.
This study was conducted to investigate the effect of nanoclay on hardness, pull off and blistering effect of polyester based coating. Polyester coat, nanoclay and hardener (MEKP) were mixed and mechanically stirred for one hour at ambient temperature at a shear rate of 1000 rpm. Prepared coating was then applied on the surface of plywood for the characterization of the hardness and pull off strength and for the observation of blistering effect towards sea and distilled water. As a result, 6% nanoclay loading gives better hardness strength which is 65% increment from unmodified polyester. However, the pull off strength shows that 2% of nanoclay loading gives higher strength among others with 114% increment compared to unmodified polyester coating. Blister was mostly observed at samples without nanoclay loading for both sea water and distilled water. While the less blistering effect was present at 2% nanoclay loading for sea water and 4% nanoclay loading for distilled water. The presence of nanoclay within the coating improves its bonding ability and the decreasing the micro space within the polymer. Blistering effect for highest and lowest frequency was observed by electron scanning microscope (SEM).
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