Zuraida Ahmad

Influence of Halloysite Nanotubes Hybridized with Kenaf Core Fibers on the Physical and Mechanical Properties of Low Density Polyethylene/Thermoplastic Sago Starch Blends

In this work, halloysite nanotubes (HNTs) were hybridized with kenaf core fibers (KCF) to reinforce low density polyethylene (LDPE)/thermoplastic sago starch (TPSS) blends. The effects of HNT loading (3–15 wt.%) on the mechanical and physical properties were examined. The results showed an enhancement in tensile strength and modulus with the inclusion of HNTs. Formation of FTIR bands that are assigned to Al-OH and Si-O vibrations indicated the presence of HNTs in the system. Moreover, the thermal stability of hybrid composites was improved with the addition of HNTs. Water uptake decreased as higher amount of HNTs imparted to the hybrid composites.

Synthesis and characterization of Ni–P coated hexagonal boron nitride by electroless nickel deposition

Electroless plating has been receiving a steady progress over the last decade on the modification of the surface properties of ceramic materials in order to produce composite coatings with unique characteristics for critical tribological systems. In this work, an electroless nickel deposition process was used to deposit nickel-phosphorous (Ni–P) coating on hexagonal boron nitride (h-BN) particles via hypophosphitereduced acid bath solution. The substrate particles were initially subjected to series of pre-treatment operation in order to ensure that the particles are cleaned and catalytically active prior to electroless plating. The characterization of the as-received and Ni-coated powder was studied through scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and field emission scanning electron microscopy (FESEM). The result reveals that the pretreatment of h-BN powder provides substrate particle surfaces with coarse and roughened structures which are normally considered suitable for Ni–P deposition. Moreover, the result of the EDX analysis confirms the existence of nucleating agents and Ni–P coating on the surface of the treated h-BN powder. The cross-sectional microstructure of the coated powder shows that the h-BN particles were embedded in a continuous matrix layer of Ni–P deposit. The EDX mapping profiles further indicate that the deposited Ni–P alloy mass was uniformly distributed on the surface of the Ni–P codeposited h-BN particles (Ni–P–h-BN). The successful development of Ni coated h-BN powder will raise the potential of h-BN as a high-performance coating material.

Studies of properties and characteristics of low-density polyethylene/thermoplastic sago starch-reinforced kenaf core fiber composites

The disposal problems associated with the conventional plastic have imposed a long-standing quest of developing the degradable material. Indeed, blending of conventional plastic with renewable resources as the base materials is an attempt of imparting some level of biodegradability on the resulting composites. Thus, for this study, the effect of plasticized sago starch (plasticized) incorporation on the properties of low-density polyethylene (LDPE)-reinforced with kenaf core fiber (KCF) was evaluated. The ratio of LDPE/KCF was fixed at 80/20 and blended with the thermoplastic sago starch (TPSS) content ranging from 10 to 40 wt%. The blended samples were characterized by means of mechanical performance, Fourier transform infrared analysis, thermogravimetric and differential scanning calorimetry behavior, water uptake, and morphological properties. The experimental result shows that there is a gradual decrease in tensile strength, modulus, and elongation at break with an increase in TPSS loading. The degree of dispersion and adhesion of TPSS in LDPE/KCF composites revealed by scanning electron micrograph supports the findings of tensile properties. The thermal stability of the composite was clearly improved with the addition of TPSS. However, water uptake and hydrophilic character of the composite system tended to augment as the TPSS imparted to the composites.

Incorporation of Kenaf Core Fibers into Low Density Polyethylene/Thermoplastic Sago Starch Blends Exposed to Natural Weathering

The landfill disposal of a high volume of plastics that take a long time to decompose has led to a tremendous environmental problem. Incorporation of natural polymers and fibers into synthetic polymers accelerates the degradation rate by exposure to atmospheric agents such as sunlight, temperature and rainfall. In this work, thermoplastic sago starch (TPSS) and kenaf core fibers (KCF) from agricultural feed stocks were blended with low density polyethylene (LDPE) for natural weathering studies. The melt-mixed and compressed composite sheets had fiber loadings ranging from 0 to 40 wt.%, and were exposed to natural weathering conditions for a period of 3 and 6 months. The deterioration in mechanical, thermal, morphological and weight properties were investigated.

Fabrication and characterization of strontium-doped hydroxyapatite bioceramics scaffolds for bone implant application: A preliminary study

In this study, strontium doped hydroxyapatite (SrHA) nanopowder was synthesized through a sol-gel method. Strontium concentration was varied from 0 to 15 mol%. The obtained gel was then dried and subsequently subjected to 900 °C calcination. SrHA porous bodies were fabricated by using polymeric sponge method with different chemical compositions (0, 2 and 10 mol% SrHA). To prepare the porous samples, the synthesized SrHA powders was mixed with distilled water and appropriate amount of dispersing agent followed by drying in the ambient air for 72 hours. The dried impregnated sponges were then sintered at 1300°C for 3 hours. The XRD patterns showed high crystallinity of HA phase only for all porous samples. Morphological evaluation by FESEM measurement revealed that the SrHA scaffolds were characterized by a uniform distribution of interconnected pores (200-800 µm). Compression test on the porous scaffolds revealed that doping 10 mol% of strontium in HA has increased the compressive strength compared to the undoped HA.

The effects of initiator content on sago (metroxylon rottb.) starch-G-PAN hydrogel

This paper explores the effects of ammonium persulphate (S-PANHs) content (1wt % - 5 wt %) to the properties of sago starch-graft-polyacrylonitrile hydrogels (S-PANH). S-PANHs were prepared via graft copolymerization of polyacrylonitrile (PAN) onto sago starch in the presence of ammonium persulphate (APS) as initiator and N, N-methylenebisacrylamide (MBA) as crosslinker. The percentage of water absorbency is observed to increase with increasing initiator content from 1wt% until reaching optimum point of 3 wt% APS. 48.78 % water absorbency was recorded at 3 wt% APS sample. The morphology of the hydrogels from the micrographs captured via scanning electron microscope (SEM) revealed the existence of pores and matching with the results of percentage water absorbency. Fourier transform infrared (FTIR) spectroscopy proved that the grafting process had occurred in S-PANH.

Physical properties of heat-treated rattan waste binderless particleboard

The objective of this study is to investigate the effects of heat treatment on the properties of binderless particleboard (BPB) fabricated via hot-pressing process with pressing temperature, pressing time and pressing pressure of 180°C, 5 minutes and 1 MPa, respectively. The fabricated BPB with density in the range of 0.8-0.95g cm-3 was heated in a temperature-controlled laboratory chamber at 80°C, 120°C and 160°C for period of 2 and 8 hours before underwent physical observation, mass loss measurement and thickness swelling test. The samples had remarkable color changes, mainly with samples of treatment temperature of 160˚C, where the color differences were 9.5 and 20.3. This changed the fabricated BPB samples from yellowish brown to dark brown color when treatment conditions increased. Darker color indicates greater mass loss due to severity of chemical component in the powder. Dimensional stability of fabricated BPB was improved with higher treatment temperature as more cellulose cross-linked and hemicellulose degraded that removed the hygroscopicity behavior of powder. These results revealed that heat treatment helped in improving the BPB physical properties, particularly in dimensional stability of boards.The objective of this study is to investigate the effects of heat treatment on the properties of binderless particleboard (BPB) fabricated via hot-pressing process with pressing temperature, pressing time and pressing pressure of 180°C, 5 minutes and 1 MPa, respectively. The fabricated BPB with density in the range of 0.8-0.95g cm-3 was heated in a temperature-controlled laboratory chamber at 80°C, 120°C and 160°C for period of 2 and 8 hours before underwent physical observation, mass loss measurement and thickness swelling test. The samples had remarkable color changes, mainly with samples of treatment temperature of 160˚C, where the color differences were 9.5 and 20.3. This changed the fabricated BPB samples from yellowish brown to dark brown color when treatment conditions increased. Darker color indicates greater mass loss due to severity of chemical component in the powder. Dimensional stability of fabricated BPB was improved with higher treatment temperature as more cellulose cross-linked and hemice...

Rheological behavior and stability of cassava starch for ceramic mould binder application

Silica free binder was developed from cassava starch to correspond common ceramic mould binder for reactive metal casting application. Ceramic slurry rheology behavior and stability depends on both binder and refractory materials properties. Starch processing started from granule expansion or swelling, gelatinization, depolymerization via prolong heating and by adding plasticizer, citric acid is to improve viscosity. Pseudoplastic or shear thinning behavior for both binder and slurry were observed starting at 0.13 Pa.s and 2.5 Pa.s respectively. Calcium carbonate (aragonite) slurry from starch binder however, exhibited viscoelastic behavior compare to colloidal silica sol. Ceramic slurry aged as both cationic starch and CaCO3 flocculate and not exfoliate as indicated by increased in the pH of the slurry.

Fabrication of porous ceramic scaffolds via polymeric sponge method using sol-gel derived strontium doped hydroxyapatite powder

Recently, development of porous calcium phosphates ceramics have raised considerable interest. A porous structure promotes cell attachment, proliferation and provides pathways for biofluids. Therefore, a high porosity with interconnected pore structure generally favors tissue regeneration. In this work, replication of 0, 2, 5, 10 and 15% SrHA (strontium-doped hydroxyapatite) porous scaffolds via polymeric sponge method has been employed using the sol-gel derived SrHA powders. To prepare the porous samples, the synthesized SrHA powders was mixed with distilled water and appropriate amount of dispersing agent followed by drying in the ambient air and specific sintering process. Morphological evaluation by FESEM measurement revealed that the SrHA scaffolds were characterized by macro-micro interconnected porosity, which replicates the morphology of the cancellous bone. Compression test on the porous scaffolds revealed that doping 10 mol% of strontium in HA has increased the compressive strength by a factor of two compared to the undoped HA with 1.81±0.26 MPa at 41% porosity.

EFFECT OF FIBER LENGTH VARIATIONS ON PROPERTIES OF COIR FIBER REINFORCED CEMENT-ALBUMEN COMPOSITE (CFRCC)

This paper evaluated the effect of fiber length on the mechanical and physical performance of coir fiber reinforced cement-albumen composites (CFRCC). Albumen protein was added as a binder and the coir fibers with the lengths of 0, 2.5, 5, 10 and 20 mm was used as partial replacement of the cement mixture. Flexural and compressive strength, bulk density, moisture content and water absorption were investigated. The experimental investigations reveal that increasing in length of fiber augment the flexural strength. Incorporation of long fiber into the cement paste however, decreased the workability and thus introduced voids which results in low density. In fact, the water absorption and moisture content were also increased.