Abstract: The objective of this research was to investigate the effect of incubation temperature towards the growth of Acetobacter xylinum 0416 and the production of bacterial cellulose. Fermentation of A.xylinum 0416 were carried out for 5 days in static condition using Hestrin & Schramm (HS) medium with initial glucose concentration of 4.0% (w/v) and initial pH of 6.4. The incubation temperature were varied at 5°C, 20°C, 25°C, 27°C, 28°C, 30°C, 35°C and 40°C respectively. Results indicated that 28°C served as the best incubation temperature for the growth of A.xylinum 0416 and produced the highest amount of bacterial cellulose with total dried weight of 0.3722 g/l. Meanwhile at incubation temperature of 5°C and 40°C, no significant growth of A.xylinum 0416 and bacterial cellulose were obtained. As a conclusion, incubation temperature plays an important role for the growth of A.xylinum 0416. The best incubation temperature is at 28°C in which the sufficient energy will be provided for bacterial growth thus enhancing the cellulose biosynthetic pathway in order to convert glucose into bacterial cellulose.
Abstract: The effects of adding hexanedioic acid (HA) into low density polyethylene (LDPE)/jackfruit seeds (JSF) blends on the properties were investigated by using differential scanning calorimetry (DSC). The influence of the crystallinity and thermal properties of HA on LDPE at various compositions was investigated. JSF was blended with LDPE by using internal mixer (Brabender) at temperature 150°C. JSF content was varied from 0 to 20 wt%. Crystallinity of the blends was significantly reduced with increasing JSF content and further increased with the presence of HA. Therefore, the crystallinity of the blends was improved with the presence of HA.
Abstract: The properties of blends made from low density polyethylene (LDPE) with various concentration of jackfruit seeds flour (JSF) with the presence of citric acid (CA) were investigated. The JSF content was varied from 0 to 20 wt%. The JSF were blended with LDPE by using an internal mixer (Brabender) at a temperature of 150°C. The test was carried out by using differential scanning calorimetry (DSC), with heating temperature of 100C/min. The crystallinity had improved with the presence of CA. However, the crystallinity slightly reduced with the increasing JSF content and further increased with the presence of CA.
Abstract: Cure characteristics and physical properties of EPDM/rNBR filled bamboo fillers were studied. Results indicated that the addition of bamboo fillers has significant effects on EPDM/rNBR blends. The scorch time, t2 decreased up to 25 phr fillers loading but increased further to 50 phr fillers loading. Cure time, t90 increases as the increase in bamboo fillers in the blends. At a similar blend ratio fine sizes bamboo fillers in EPDM/rNBR (S1: ≤125μm) exhibited higher value of t2 ad t90 compared to EPDM/rNBR (S2: 125-250μm & S3: 250-500μm). The minimum torque, ML also increases with increasing bamboo fillers in the blend. Meanwhile, the maximum torque, MH of the EPDM/rNBR filled bamboo fillers were in contrast. The hardness and degree of crosslink density of the blends increased with the increase in bamboo fillers and reduce percentage of resilience at all blends. The fine sizes of bamboo fillers contributed to the better properties compared to the coarse sizes and medium sizes.
Abstract: The role of activated carbon (AC) in rubber compounds was investigated to better understand the reinforcing mechanism. The activated carbon filled styrene butadiene rubber vulcanizates (SBR-AC) using bamboo activated carbon as filler were prepared by using two-roll mill and cured at 160 °C. AC filler loading from 10 to 50 phr (part per hundred rubber) were used in this study. Study into the influences of filler loading on the cure characteristics, swelling behaviour and physical properties (hardness and resilience) of SBR-AC vulcanizates were carried out. It was observed that SBR-AC vulcanizates has better cure characteristics compared to the styrene butadiene rubber gum vulcanizate (SBR-GV) which is a non-filled vulcanizate. The results showed that the scorch time (ts2) decreased with increasing filler loading. The cure time (tc90) slightly decreased up to 20 phr before a rise as the filler loading increased. The minimum torque (ML) of SBR vulcanizate increased and the maximum torque (MH) decreased up to 20 phr but then increased with increasing filler loading. The cure rate index (CRI) of SBR-GV vulcanizate was higher than that of all SBR-AC vulcanizates. Up to 20 phr of filler loading, the CRI increased before a decline occurred as the filler loading increased. As expected, the hardness value of SBR-AC vulcanizates was higher compared to SBR-GV vulcanizate which has lower resilience. The hardness and crosslink density showed an increasing trend meanwhile the resilience was adversely affected by the increase in filler loading. Bamboo activated carbon showed some potential enhancement on the reinforcing and physical properties of the vulcanizates.
Abstract: Palm Oil Fuel Ash (POFA) is one of the solid waste in Malaysia and had trouble with the ash removal. Therefore, the use of waste oil palm ash can overcome the problem of solid waste. POFA is a pozzolanic material and it can act as a replacement of cement (OPC) to produce concrete with higher strength and low cost. POFA quality will increase as the range made up to a medium level of fineness in the size of 50 microns. POFA used to replace OPC is 0%, 10%, 30% and 50% by weight percent of OPC. POFA concrete compressive strength will be tested after a curing process that concrete age of 7 days and 28 days. POFA concrete density is also tested and compared with OPC concrete. Results showed that compressive strength POFA lower than normal concrete. On the other hand, the replacement of cement by 10% POFA shows a record high in compressive strength compared with other POFA mixing at the age of 7 days and 28 days. Fineness pozzolanic POFA is the best material and can be used as a cement replacement alternative.
Abstract: Natural fiber reinforced polylactic acid based biocomposites are broadly considered by the researchers to compete with non-renewable petroleum based products. In this study, the biodegradable composites which are the polylactic acid, PLA and rice straw, RS were prepared by using heated two roll-mill at 180°C. Mechanical properties showed that the tensile strength and elongation at break, Eb decreased with the increasing of RS while the Young’s modulus had increased. The TGA results confirmed that thermal stability of PLA with RS composites decreased when the RS fiber loading increased.
Abstract: The effects of imperata cylindrica on curing characteristics and physical properties of epoxidized natural rubbers (ENR25) filled recycled nitrile glove (rNBR) were examined. The compounds were prepared by two roll mill at five different compositions of imperata cylindrica (5, 15, 25, 35 and 45 phr). The size range of imperata cylindrica particles i.e., 0μm-63μm and 500μm-700μm were used. The result of cure characterization show that scorch time (t2) and cure time (t90) of the ENR25/rNBR decreased with the increased of imperata cylindrica content due to an insufficient amount of accelerator or curing agent and migration of sulphur from filler to the natural rubber. ENR25/rNBR with fine size, S1 of imperata cylindrica particles exhibit lower minimum torque (ML) compared with the coarse size, S2 which resulted in more efficient processing. The maximum torque (MH) of all ENR25/rNBR compounds show the increasing trend with increased imperata cylindrica content due to the good interactions between imperata cylindrica and ENR25/rNBR compounds. For physical properties, ENR25/rNBR compounds with fine size, S1 of imperata cylindrica particles exhibited the higher crosslinking density at all compound ratios meanwhile coarse size, S2 show highest hardness compared to fine size, S1. The results overall indicated that the ENR25/rNBR with fine size, S1 of imperata cylindrica particles show better cure characteristics and physical properties (crosslink density and hardness test) compared to coarse size, S2 of imperata cylindrica particles.
Abstract: The potential of activated carbon as a filler in rubber compound has been reviewed .Cure characteristics and physical properties of Imperata Cylindrica activated carbon filled natural rubber of Standard Malaysian Rubber (SMR L) were studied. SMR L was used as the elastomer and the composition of filler loading were varied from 0-50 parts per hundred rubber (phr). A semi-efficient vulcanization system was used throughout the study. The cure characteristics of the rubber compound was determined by using rheometer. The samples of hardness and resilience were measured by durometer shore A and Wallace Dunlop Tripsometer. Cure characteristics showed that cure time, t90 and scorch time,t2 increased as increased filler loading which indicate poor interaction between rubber and filler which slow down the vulcanization time. Minimum torque,ML and maximum torque,MH increased as increased filler loading due to the low processability of the SMR L compounds. Crosslink density and hardness exhibit increment as increased filler loading due to increase rigidity of the SMR L compounds. The resilience will decrease correspondingly as increased in rigidity of the compounds.