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Articles by Rokiah Hashim
Total Records ( 3 ) for Rokiah Hashim
  Mohammed Nasir , Othman Sulaiman , Rokiah Hashim , Noor Afeefah Nordin and Mohd Asim
  Cellulose and lignin are the two most abundant polymers found in plant cells. Cellulose microfibrils provide mechanical properties to woody cell whereas, hemicelluloses and lignin act as glue in between the crystalline cellulose. Cellulose crystallinity directly affects the physico-chemical behavior of the individual fiber such as modulus, hardness, stiffness, tensile and swelling-shrinkage properties and ultimately to its product. This study aims to improve the physico-chemical properties of rubber wood fiber by laccase hydrolysis in order to improve the crystalline structure. Two different times of reactions i.e., 60 and 120 min were applied at constant temperature 25°C, enzyme concentration 7 U g‾1 and pH 5. After the pulp treatment, fibers were sieved out and transferred in to autoclave at 121°C for 15 min to stop further enzyme reaction. Treated fiber was dried in electric oven drier at 80-90°C for 24 h to dry up the fiber until zero moisture content. Crystallinity index of the fiber was measured by X-ray diffraction method and it was observed maximum up to 14% higher compared to untreated fiber. The treated fiber was further analyzed for elemental composition, FE-SEM and TGA and compared with untreated fiber in order to evaluate its properties. Fiber treated with enzyme exhibited superiority in fiber surface structure and thermal degradation over untreated fibers. A fiber with improved mechanical strength and crystalline structure can be utilized for various purposes to produce high quality product.
  Razak Wahab , Hashim W. Samsi , Othman Sulaiman , Rafidah Salim and Rokiah Hashim
  The suitability of using an eco-friendly oil curing process was investigated on cultivated Bambusa vulgaris bamboo in order to prolong their service life span. B. vulgaris was chosen as it is a type of bamboo species that is easy to cultivate and has good physical as well as mechanical properties. Matured bamboo culms of 4 year-old from internodes 5, 6 and 7 in green and air-dried conditions were heat treated. The heat treatment process used palm oil as the heating medium at temperatures of 140, 180 and 220°C for durations of 30, 60 and 90 min. The air-dried culms exhibited overall higher physical, strength and durability properties than the green and untreated culms. The Modulus of Elasticity (MOE) values of heat treated bamboo in bending was reduced by 13 to 42% in green and by 3 to 29% in air-dried conditions. The compression strength were reduced by 18 to 33% in green and by 14 to 27% in air-dried ones. The heat treated bamboo lost from 5 to 34% of their initial weight after undergoing 12 months of ground-contact tests for both green and air-dried conditions.
  Siti-Noorbaini Sarmin , Wan-Mohd-Nazri Wan-Abd-Rahman , Jamaludin Kasim , Othman Sulaiman , Rokiah Hashim and Hazandy Abdul-Hamid
  The study was conducted to determine the dimensional stability properties of Laminated Veneer Lumber (LVL) from Oil Palm Trunk (OPT) bonded with three different cold set adhesives namely Emulsion Polymer Isocyanate (EPI) and polyvinyl acetate (PVAc). Three-ply experimental LVL from OPT veneers were bonded using two adhesive spread levels, 250 and 500 g m-2 for single glue line. Laminated veneer lumber from rubberwood was used as control. The dimensional stability properties investigated include dimensional changes associated with changes in relative humidity of 30 to 90%, hysteresis over a range of 30 to 90% and durability against biological attack through soil burial. Amongst the three adhesives, OPT LVL manufactured with EPI (VAc) had the highest Fibre Saturation Point (FSP) and the least was experienced by OPT LVL bonded with PVAc. Totally, the magnitude of hysteresis was below 1.00 which in the average 0.69 to 0.82 for OPT LVL panels while rubberwood LVL, 0.81 to 0.94, respectively. Overall, the dimensional stability properties of LVL from OPT bonded with cold setting adhesives namely EPI (SBR), EPI (VAc) and PVAc were found to be comparable with rubberwood.
 
 
 
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