Advanced Materials Research Vol. 812

Abstract: Non-isocyanate polyurethane (NIPU) was synthesized from epoxidized linoleic acid (ELA) from rubber seed oil. In this study, carboxylation method was used to synthesize a new monomer, carboxylated linoleic acid (CLA) to produce urethane inter-linkage polymer. ELA with tetrabutylammonium bromide (TBABr) as catalyst was purged with carbon dioxide as gas reactant. Pressure and temperature reactions were controlled at 10 psi and 150 °C. CLA was mixed with ethylenediamine (EDA) and the viscous mixture was cured in a covered mold in an oven at 100 °C and curing was performed after 12 hours. Tacky test was done to evaluate the curing. The initial epoxy value of ELA was 7.36 % and it was observed during synthesis to reduce via Oxygen Oxirane Content test, which illustrated the conversion of ELA to CLA. The formation of epoxy group in ELA to carboxylate functional group in CLA was characterized using Fourier Transform Infrared (FTIR) at absorption peak of 1803.69 cm^-1 that represent cyclic carbonate group. H-NMR was used to support the characterization of ELA and CLA.

Abstract: This paper report the synthesis of a crosslink network of Carbazole substituted Poly (dimethylsiloxane). Vinyl Carbazole and Vinyl Trimethoxysilane were introduced into polydimethylsiloxane chain backbone through hydrosilylation reaction. 4-hydroxybutyl acrylate was then grafted into vinyl trimethoxysilane by condensation followed by UV curing to afford an elastomeric crosslink network. FTIR and ¹H NMR spectroscopy were used to confirm the structure of the product as well as monitoring the progress of the reactions. The visual observation shows the changing appearance of the samples with increasing curing time and distance from UV exposure. The materials displayed refractive index between 1.407 1.452 which is within an acceptable range of application as electronic encapsulant. The crosslink network improved material hardness compared to that without. These properties were examined and thoroughly discussed within the scope of Lorentz-Lorenz model.

Abstract: The value of Luffa acutangula, a species of the melon family, Curcubitaceae as food diminished as the fruit matured. They are then disposed as industrial or domestic waste material. However, the fibers of the matured fruits, also known as lignocelluloses fibers have high mechanical strength and can be used as reinforcing fillers for polymers. In this present study, treated and untreated fibers of Luffa acutangula were loaded as fillers for polypropylene (PP) at 1%, 3% and 5% loading. PP fiber composites loaded with alkali-treated fibers showed lower tensile and impact strength compared to PP fiber composites with untreated fibers. Thermal analysis of the fibers showed that alkali-treated fibers were deprived of the lignin content present in untreated fiber. This led to the lower mechanical properties of the alkali-treated luffa-filled PP composites as compared to its untreated counterpart. Increasing the fiber loading of the composites, increased the tensile and impact strength of untreated luffa-filled PP but decreased the tensile and impact strength of alkali-treated luffa-filled PP. This is in accordance to the removal of the lignin component upon alkali treatment which acts as a strengthening as well as energy absorption component of the fiber.

Abstract: Effect of natural and synthetic antioxidants on curing characteristic and properties of different natural rubber (NR) origin compounds were performed in this study. The evaluations of natural antioxidant (NA) performance in different NR origins were conducted and the changes in curing characteristic, crosslink density, fatigue life and compression set were recorded. The results indicated that Standard Thailand Rubber (STR) compound has longer processing time in curing characteristic due to a longer chain which is high molecular weight. Because of that, crosslink density, fatigue life cycle (K_c) and compression set (%) of STR compound show better result compared to other origins. On the other hand, NR compounds with NA have show better fatigue and compression set compared with trimethylquinoline (TMQ) especially for STR 5L. Thus, NA can be used as an alternative to the commercial antioxidant in all rubber compounds.

Abstract: In this work, the effects of adding different filler loadings (520 wt%) of zeolite to the ultra-high molecular weight polyethylene (UHMWPE) matrix on the crystallinity behaviour and tribological properties were studied. The zeolite/UHMWPE composites were fabricated using hot compression moulding. The crystallization behaviour was investigated using differential scanning calorimetry (DSC). The tribological properties were monitored using a Ducom TR-20 pin-on-disc tester under different sliding speeds of 0.209 ms^-1 and 0.419 ms^-1 and with various applied loads of 5, 10, 15, 20, 25, 30 and 35 N. The worn surfaces of the zeolite/UHMWPE composites were observed under the scanning electron microscope (SEM). The results showed that the addition of zeolite into UHMWPE matrix can effectively enhance the percentage crystallinity of the UHMWPE. 15 wt% zeolite-reinforced UHMWPE composites show the increase of 47% in percentage crystallinity as compared to pure UHMWPE. The wear mass loss of the composites was found to be reduced by the incorporation of zeolite in UHMWPE. In addition, the average coefficient of friction (COF) was also found to decrease with the addition of zeolite. The lowest average COF was obtained by 20 wt% zeolite reinforcements into UHMWPE. Shallower grooves and smoother worn surfaces were observed for zeolite/UHMWPE as compared to pure UHMWPE.

Abstract: In this study rubber toughened polyester composite filled with kenaf was exposed in different environmental condition such as in artificial sea water (SW), distilled water (DS), environment exposure (Ex) and soil exposure (SL). Rubber-toughened polyester-kenaf fibre composites were prepared by adding 25% of kenaf fibre in unsaturated polyester resin and cross linked with a mixture of methyl ethylketone peroxide and cobalt octanoate. Three percent (3%) of liquid natural rubber (LNR) were added as a toughening agent. The sample was prepared using compression molding technique. The mechanical properties of the composites were evaluated by hardness, flexural and fracture toughness testing. It was found that the samples that being immersed in seawater (SW) had lower mechanical properties as compared to other conditions. The value of hardness strength were decrease about 1.7% and for fracture toughness the decreasing is about 8.53% while flexural strength had been decrease by 30%. Bonding mechanisms were then assessed by scanning electron microscope and FTIR analysis

Abstract: This study focuses on surface modification of local made fibres for use as reinforcement in the area of polymer matrix composite. Modified oil palm and Rice husk fibres were prepared by using alkaline treatment and the samples were investigated by using Helium pycnometry, Fourier transform infrared spectroscopy (FT-IR), Energy dispersive X-ray fluorescence (ED-XRF) and Field emission scanning electron microscope (FESEM). The oil palm fruit bunch and rice husk fibres were treated with 6.0 w.t % Sodium Hydroxide (NaOH). In order for the treated fibre to be compared, fibres without alkaline treatment were prepared. All the prepared samples were crushed and a sieving machine was used to prepare 100μm particles sizes. The changes in composition of the both fibres due to leakage of original elements as well as the changes in density have been successfully determined by these techniques. Density for both oil palm (OP) and rice husk (RH) fibres decreased after treated. A series of FT-IR spectra confirmed the reduction of the Hemicelluloses and Lignin content after the treatment. The significant changes between untreated and treated fibres were also discussed, whereby the rough surface of fibres becomes smooth due to elimination of impurities. ED-XRF analysis confirmed the percentage of Silica (Si) content for both fibres and proved the reduction of elements present in the composition.

Abstract: Previously, it was found that the brittle properties of polymehyl methacrylate (PMMA) film has been improved when blended with epoxidised natural rubber 50 % (ENR 50) hence enhanced the ionic conductivity of PMMA electrolytes. However, the PMMA and ENR 50 blend was not homogeneous thus limits the overall performance of the blend. Therefore, in this study, silicon dioxide (SiO₂) filler was incorporated into the polymer blend film to improve the homogeneity and the ionic conductivity of the system. It was found that the addition of SiO₂ has succesfully improve the homogeneity of the blend by assisting the dispersion of ENR 50 in the blend and hence provide better conducting path for the lithium ion. This was confirmed from its differential scanning calorimetry (DSC), fourier transform infrared (FT-IR) and optical microscopic (OM) analyses.

Abstract: The effect of preparation technique on the crystallisation behavior and thermal properties of TPNR filled nanoclay nanocomposites was investigated. The nanocomposites were prepared via melt blending method using internal mixer (Haake 600P). Two types of nanocomposites preparation technique were employed which is method A and B. In method A, the nanoclay was pre-mixed with liquid natural rubber (LNR) before it was charged into the other materials. For method B, the nanoclay was directly charged into the molten TPNR matrix. The result shows, preparation methods were significantly affect the crystallinity and thermal properties of TPNR nanocomposites. DSC thermogram revealed that nanocomposites crystallinity was increased when prepared by method A but decreased with method B. An increment in polypropylene crystallinity was attributed by the nanoclay which is believed to be as a nucleating agent. DMA thermogram suggested that the preparation method has affected the storage modulus and tan δ but not the glass transition temperature (t_g).

Abstract: In this study the effect of trimethylopropane triacrylate (TMPTA) content as a crosslinking agent on curing properties of UV-cured pressure sensitive adhesives (PSAs) was investigated. The curing properties were studied using gel fraction determination, photo-differential scanning calorimetry (photo-DSC) and Fourier transform infraredattenuated total reflection (FTIR-ATR) spectroscopy. Gel fraction sharply increased after expose to UV irradiation and increased with increasing TMPTA content. Moreover, the addition of TMPTA as crosslinking agent induced an earlier onset of auto acceleration and relative concentration of the C=C was not zero because they were trapped in the PSAs network.