Nadras Othman

The Effect of Carbon Black/Multiwall Carbon Nanotube Hybrid Fillers on the Properties of Natural Rubber Nanocomposites

The properties of hybrid multiwall carbon nanotube (MWCNT) and carbon black (CB) in natural rubber nanocomposites were studied. The results show that the scorch and cure time decreased as the MWCNT loading increased in CB/MWCNT hybrid loading ratio but for the maximum torque, the result shown otherwise. As the MWCNT loading increased in CB/MWCNT hybrid loading ratio, the tensile strength, elongation at break and fatigue life are decrease, however the tensile modulus and rubber filler-interaction (Qf/Qg) value increased. The SEM results show a dispersion of CB and MWCNT in natural rubber matrix. Furthermore, the thermal stability for the hybrid nanocomposites is enhanced.

Compatibilization Effects of PE-g-MA on Mechanical, Thermal and Swelling Properties of High Density Polyethylene/Natural Rubber/Thermoplastic Tapioca Starch Blends

Effect of polyethylene grafted maleic anhydride (PE-g-MA) on mechanical, thermal and swelling characteristic of high density polyethylene (HDPE)/natural rubber (NR)/thermoplastic tapioca starch (TPS) blends were studied. The measurements from differential scanning calorimetric (DSC), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), proved the effectiveness of PE-g-MA as compatibilizer in improving the miscibility between HDPE/NR – TPS blends. A decrement in crystallinity index was found after adding PE-g-MA. It is due to restriction in mobility of the HDPE chains. In the presence of PE-g-MA, the blends have better thermal stability. On top of that, the storage modulus which is reflected to the blend stiffness also increased as indicated the improvement in HDPE/NR – TPS interaction.

Characterization of Citric Acid-Modified Tapioca Starch and its Influence on Thermal Behavior and Water Absorption of High Density Polyethylene /Natural Rubber/Thermoplastic Tapioca Starch Blends

Characterization of thermoplastic tapioca starch modified with citric acid (TPSCA) and its influence on the thermal analysis of high density polyethylene (HDPE)/natural rubber (NR)/thermoplastic tapioca starch (TPS) blends was investigated. Morphology and relative molecular weight of TPS and TPSCA were analyzed using scanning electron microscope (SEM) micrographs and high performance liquid chromatography (HPLC). TPSCA shows better plasticization as can be seen from SEM micrographs. The HDPE/NR/TPSCA blends exhibit the glass transition of NR shifted to higher temperature as compared to the HDPE/NR/TPS blends. This indicates better interaction between TPS-HDPE/NR as TPS is modified with citric acid (CA). The thermal behavior and water absorption of HDPE/NR/TPS blends were evaluated as a function of TPS loadings with and without modification with CA. The HDPE/NR/TPSCA blends exhibit better water resistance, which is attributed to a compatibilization effect that occurred in the HDPE/NR/TPSCA system as TPS was modified with CA.

Curing Characteristics and Mechanical Properties of Rattan Filled Natural Rubber Compounds

Rattan for its potential as a new type of filler was investigated in natural rubber (NR) compounds. Natural rubber (NR) compounds were prepared by the incorporation of rattan at different loadings into a natural rubber matrix with a laboratory size two roll mill. The effect of rattan loading as filler on curing characteristics, tensile properties, morphological properties using scanning electron microscopy (SEM) and rubber–filler interaction of rattan filled natural rubber compound were studied in the filler loading range of 0 to 30 phr. The results indicate that the scorch time (ts2) and cure time (t90) shorten with increasing filler loading, whereas the maximum torque (MH) showed an increasing trend. As the filler loading increases, the tensile strength and elongation at break decreases whilst tensile modulus; stress at 100 % elongation and stress at 300 % elongation increased. The rubber filler interactions of the rubber compound decreased with increasing filler loading. SEM studies indicate that the increasing rattan loading weakens the rubber-rattan interactions.

Influence of Surface Modifications on Interfacial Interaction of Zeolite Filled Polymer Composites

Interfacial interaction in zeolite filled polymer composites was investigated in this study. Two types of polymer which are polypropylene (PP) and ethylene vinyl acetate (EVA) were used as matrix in the preparation of the composites. Moreover, different modifications of zeolite filled polymer composites such as zeolite surface treatment with vinyl silane and alkylammonium and also chemical crosslinking were done to improve the interfacial adhesion between zeolite and polymer matrix. The zeolite filled polymer composites were homogenized using Thermo Haake Polydrive internal mixer and then compression molded into sheets according to standard test specimen. Uniaxial tensile test was performed in order to evaluate the mechanical behavior of the composites. The obtained experimental data for ultimate stress was correlated with Pukanszky theoretical model. The experimental results for all systems of zeolite filled polymer composites showed a good fit to the Pukanszky model. Interfacial interaction for each system of zeolite filled polymer composites was theoretically evaluated by determining the parameter B through this model. The value of parameter B for all zeolite filled polymer composite systems differs significantly from one another thus suggesting the applicability of this Pukanszky model in characterizing the filler-matrix interfacial adhesion.

Effect of different types of vulcanization systems on the mechanical properties of natural rubber vulcanizates in the presence of oil palm leaves-based antioxidant

Different types of vulcanization systems play an important role towards thermal degradation of natural rubber (NR) compound. In this study, NR compounds were cured with efficient vulcanization (EV), semi-efficient vulcanization (SEV) and conventional vulcanization (CV) system in the presence of natural antioxidant (NA) obtained from oil palm leaves to compare the effectiveness of NA on the properties of NR vulcanizate, the same compound was prepared in the presence of commercial antioxidant, trimethylquinoline (TMQ). The samples were then subjected to tensile and tear test before and after ageing process. Both SEV/NA and EV/NA NR vulcanizates showed comparable results on mechanical properties before and after ageing process as compared to TMQ. Meanwhile, for CV systems, the result showed reduction in mechanical properties after a longer time of ageing due to the breakage of polysulphidic cross-link.

Comparison of Mechanical Properties and Curing Characteristics of Natural Rubber Composites with Different Coupling Agents

Nanosilica (NS) was recently used as a filler to improve mechanical properties, morphology behaviors of natural rubber (NR) composites and also for light colored product. NS is hard to disperse in NR composite compare to carbon black due to large number of Silanol (Si-OH) group leads to strong filler-filler interaction. Silane coupling agent was extensively used to improve reinforce efficiency of NS and also for good filler-matrix interaction by reducing Si-OH group. In this study, Bis[3-(triethoxysilyl)propyl] tetrasulfide (Si-69) and (3-aminopropy)triethoxysilane (APTES) were used as a coupling agents with various loading 1.5, 3, 4.5 phr in conventional sulphur vulcanization system. Both Si69 and APTES gave a significance of the NR compound processing. However, hardness was gradually decreased up to 4.5 phr due to plasticizing effect. Si-69 can increase crosslink density because of 4 molecular of sulphur (S) and its structure retarded the curing where APTES accelerated the cured because APTES has lower molecular weight and viscosity than Si-69.

Effects of Natural Rubber Origin on Mechanical Properties of Rubber Compound in the Presence of Natural and Commercial Antioxidants

Different origin of rubber gives different effect towards the properties of end products. In this paper, effect of natural rubber (NR) origin on tensile properties and tear strength before and after aging for 4 and 7days were investigated in the presence of natural antioxidant (NA). Effectiveness of NA in different NR origin was compared with commercial antioxidants (TMQ). The NR from Malaysia (SMR CV60), Thailand (STR 5L), Vietnam (SVR 3L) and Cambodia (SCR L) were used in this study and cured using Semi-EV. For tensile and tear strength before aging process, STR 5L / NA shows the highest result followed by SVR 3L, SCR L and SMR CV60. This is due to higher molecular weight of STR 5L compound. But after aging for 4 and 7 days, SMRCV 60 has shown the highest percentage of retention for tensile and tear strength which indicated the lowest breakage of crosslink. From the results of tensile and tear properties, it is verified that different NR origin compound with NA vulcanizate gives reasonable result which are comparable to NR with TMQ vulcanizates.

The Effects of Rattan Filler Loadings on Mechanical Properties and Morphological Study of Rattan Powder Filled-Polypropylene Composites

Effects of filler loading were investigated in rattan powder-filled polypropylene composites. The composites were melt-blended using a Polydrive Thermo Haake internal mixer by incorporating rattan powder into polypropylene matrix. Rattan powders used were of average size 180µm with filler loadings ranging between 0 to 40 phr. The results indicate that tensile strength and elongation at break show a decrease with increasing filler loading. Tensile modulus increased with addition of rattan powder and eventually decreased with high filler loading. This is due to higher rattan powder content has more tendency to agglomerate causing weaker interfacial adhesion between rattan filler and polypropylene matrix. The deterioration in tensile properties was confirmed by morphological studies of fractured surfaces.

The Effect of Chitosan Loading on the Properties of Chitosan Filled Epoxidized Natural Rubber Compounds

The study of chitosan loading onto epoxidized natural rubber compounds were prepared by incorporation of chitosan into epoxidised natural rubber matrix using a two-roll mill. The effects of chitosan loading on the curing characteristics, tensile properties and morphology of the compounds were investigated. Results indicated that slight changes in curing time (t90), and scorch time (tS2) of the compounds with the incorporation of chitosan. An increment is observed in the maximum torque, tensile modulus and durometer hardness of the compounds while tensile strength and elongation at break declines with chitosan loading.