H. Kamarudin

Influence of Solidification Process on Calcined Kaolin Geopolymeric Powder

This paper aims at investigating the influence of solidification condition on the processing of calcined kaolin geopolymeric powder. This is a new process developed using the geopolymerization process. Geopolymer slurry was prepared from calcined kaolin and activating solution (mixture of NaOH and Na2SiO3). This slurry was allowed to solidify in oven and then crushed and grounded to fixed particle size. Compressive testing and SEM analysis were performed in this study. The results showed that the solidification condition at 80 °C for 4 hours was the best to synthesize the geopolymeric powder where this solidification condition results in geopolymeric powder which can produce higher strength resulted geopolymer paste. The microstructure showed more intervening gel phase which indicates that the geopolymerization process continued to react after the addition of water to the calcined kaolin geopolymeric powder.

Effect of Mechanical Activation on Kaolin-Based Geopolymers

Raw materials kaolin was subjected to mechanical modification; the effect of the mechanical activation of kaolin on the compressive strength and morphological properties of the geopolymers has been studied. Mechanical activation of the kaolin results in particle size reduction and morphology changes with increase in reactivity. Mechanical activated kaolin has overall higher strength gain compared to raw kaolin. Wider particle size distribution and some spherical particles produced, promote a higher packaging density in the sample resulting in higher strength obtained. Mechanically activation of kaolin can be considered as an alternative method to achieve better geopolymerization reaction for kaolin-based geopolymer.

The Influence of Curing Periods on the Compressive Strength of Fly Ash-Based Geopolymer at Different Aging Times

Omar A. Abdulkareem1a, A.M. Mustafa Al Bakri1b, H. Kamarudin1c, and I. Khairul Nizar2d 1Center of Excellence Geopolymer System Research, School of Material Engineering, Universiti Malaysia Perlis (UniMAP), P.O. Box 77, D/A Pejabat Pos Besar, Kangar, Perlis, 01000, Malaysia. 2School of Environmental Engineering, Universiti Malaysia Perlis (UniMAP), Box 77, D/A Pejabat Pos Besar, Kangar, Perlis, 01000, Malaysia. aeng.omar83@yahoo.com,bmustafa_albakri@unimap.edu.my, cvc@unimap.edu.my, dnizar@unimap.edu.my. Keywords: curing periods, geopolymerization, alkaline activator, compressive strength, fly ash.

Characterization of Linear Low Density Polyethylene/Rambutan Peels Flour Blends: Effect of Loading Content

The effect of rambutan peels flour (RPF) content on the tensile properties of linear low density polyethylene filled with rambutan peel flour was studied. RPF was melt blended with linear low–density polyethylene (LLDPE). LLDPE/RPF blends were prepared by using twin screw extruder at 150°C with the flour content ranged from 0 to 25 wt%. The tensile properties were tested by using a universal testing machine (UTM) according to ASTM D638. The highest tensile strength was pure LLDPE meanwhile the tensile strength LLDPE/RPF decreased gradually with the addition of rambutan peels flour. Young’s modulus of rambutan peels flour filled LLDPE increased with increasing fiber loading. The crystallinity of the blends was significantly reduced with increasing RPF content. Instead, the water absorption increased with the addition of RPF content.

Properties of Natural Rubber/Styrene Butadiene Rubber/Recycled Nitrile Glove (NR/SBR/rNBRg) Blends: The Effects of Recycled Nitrile Glove (rNBRg) Particle Sizes

The effects of different particle sizes of recycled nitrile glove (rNBRg) on curing characteristics and physical properties of natural rubber/styrene butadiene rubber/recycled nitrile glove (NR/SBR/rNBRg) blends were investigated. The particle sizes of rNBRg were differentiated by the method of sizing. S1 was obtained by cutting the rNBRg into smaller sheets; S2 was obtained by passing rNBRg through 2 rolls mill for 10 times; and S3 was obtained by passing rNBRg through 2 rolls mill for 10 times and then mechanically grinded. NR/SBR/rNBRg blends were prepared at 50/30/20 composition using two roll mill at room temperature, with different particle sizes, rNBRg (S1), rNBRg (S2) and rNBRg (S3). Curing characteristics (scorch time, cure time, minimum torque and maximum torque), tensile properties and physical properties (crosslink density, resilience and hardness) of the blends were investigated. Results indicated that scorch time, cure time and minimum torque decreased as the rNBRg particle size decreased, while maximum torque and crosslink density increased. Tensile strength of the blends decreased as the rNBRg particle size reduced, which explained the formation of holes on the surfaces of tensile fracture, observed by scanning electron microscope. The rigidity of NR/SBR/rNBRg blends increased when smaller rNBRg particles were used, which explained the increased in hardness and decreased in resilience of the blends.

The Effects on the Cure Characteristics and Physical Properties of Bamboo Activated Carbon Filled Styrene Butadiene Rubber (SBR) Compounds

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.

Mechanical and Thermal Properties of Polylactic Acid Filled Rice Straw

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.