A. Baharin

Comparison of the mechanical properties of rice husk powder filled polypropylene composites with talc filled polypropylene composites

Abstract Unmodified and ground talc and rice husk (RHP) fillers were compounded with polypropylene (PP) separately in a Brabender plasticorder internal mixer at 180 °C and 50 rpm in order to obtain composites, which contain 0–60% php (per 100 part of polymer) of filler at 15% intervals. The Brabender torque development and the mechanical properties of the composites with reference to filler type and filler loading were investigated. In terms of mechanical properties, Young’s modulus and flexural modulus increased, whereas yield strength and elongation at break decreased with the increase in filler loading for both types of composite. Of these PP composites, the RHP composites exhibited lower yield strength, Young’s modulus, flexural modulus, and higher elongation at break than talc composites. Scanning electron microscopy (SEM) was used to examine the structure of the fracture surface and to justify the variation of the measured mechanical properties.

Electron beam irradiation of epoxidized natural rubber

Abstract The effect of irradiation on ENR50 was studied with particular attention to irradiation-induced crosslinking. ENR50 was irradiated by using a 3.0 MeV electron beam machine with doses ranging from 20 to 200 kGy. The influence of several additives such as TMPTA, Irganox1010 and tribasic lead sulfate on irrradiation-induced crosslinking of ENR50 was investigated. The gel fraction, Ts, M100, Eb, hardness and Tg were used to follow the irradiation-induced crosslinking of the rubber. Results revealed that the increase in gel fraction upon irradiation of pure ENR50 could be associated with both irradiation-induced crosslinking as well as ring opening side chain reaction of oxirane group. The observation on the trend shown in the properties studied confirmed that TMPTA is efficient in enhancing the irradiation-induced crosslinking of ENR50. The addition of Irganox1010 and tribasic lead sulfate found to inhibit irradiation-induced crosslinking of ENR50 to considerable extent. This influence of stabilizing additives in particular, antioxidant, was observed to be more prominent at lower doses. The importance of TMPTA in preventing ring opening side chain reactions as well as the role of the stabilizing additives in introducing free chain ends are also discussed. However studies did not reveal the exact nature of irradiation-induced reactions involved in ENR.

The effect of electron beam irradiation on the tensile and dynamic mechanical properties of epoxidized natural rubber

The effect of irradiation on the tensile and dynamic mechanical properties of ENR50 (ENR: epoxidized natural rubber) was investigated. ENR50 was irradiated using a 3.0 MeV electron beam machine with doses ranging from 20 to 200 kGy. The influence of several additives such as trimethylolpropane triacrylate (TMPTA), Irganox1010 and tribasic lead sulfate (TBLS) on the irradiation-induced changes of ENR50 was investigated. The general improvement on the tensile, as well as dynamic mechanical properties with irradiation indicates the formation of irradiation-induced crosslinks. An appreciable increase in Tg is observed with irradiation while the enhancement in stress at break is found to be marginal. This observation agrees well with the relatively small increase in storage modulus occurred beyond the Tg of the irradiated ENR. This in return reveals that only a small degree of crosslinking is achieved through irradiation. Based on these factors it can be inferred that the gradual increase in Tg upon irradiation of ENR50 could be associated with the occurrence of irradiation-induced ring opening side chain reaction of the oxirane group and irradiation-induced oxidation at the cis double bond along with the irradiation-induced crosslinking. From the observation in the properties studied it confirms that TMPTA is efficient in enhancing the irradiation-induced crosslinking of ENR50. The addition of Irganox1010 and TBLS are found to impart considerable stability to ENR50, although the antioxidant did cause some inhibition of crosslinking. The acceleration of crosslinking by the TMPTA as well as the inhibition of crosslinking the added stabilizing additives were further confirmed by using gel fraction data. However, the studies did not reveal the exact nature of irradiation-induced reactions involved in ENR.

Electron beam irradiation of epoxidized natural rubber: FTIR studies

The effect of irradiation on the structure of epoxidized (50 %) natural rubber (ENR50) has been studied using Fourier transform infrared spectroscopy (FTIR). ENR50 was irradiated using a 3.0 MeV electron beam machine with doses ranging from 20 to 200 kGy. The influence of several additives such as trimethylolpropane triacrylate (TMPTA). Irganox®1010, and tribasic lead sulfate on the irradiation-induced changes of ENR50 is investigated. Upon irradiation, ring opening of epoxide groups, and oxidation and crosslinking of residual double bonds occurred, leading to decreases in the intensities of epoxide and cis double bond bands and an increases in ether, furan and hydroxyl bands. Gel fraction and hardness values have been used to correlate changes in the structure of the rubber upon irradiation. The results show that the increase in gel fraction upon irradiation of pure ENR50 can be associated with irradiation-induced crosslinking, ring opening side-chain reactions of oxirane groups and oxidation at the cis-double bonds. The addition of Irganox®1010 and tribasic lead sulfate inhibits irradiation-induced reactions in ENR50 to a considerable extent. The importance of TMPTA in preventing intramolecular ring opening side-chain reactions is also discussed. However, our studies do not reveal the exact nature of the irradiation-induced reactions involved in ENR. © 2000 Society of Chemical Industry

Electron-beam irradiation of poly(vinyl chloride)/epoxidized natural rubber blend in the presence of Irganox 1010

Abstract The effect of irradiation on a 50/50 poly(vinyl chloride)/epoxidized natural rubber blend was studied in the presence of 0–1.5 phr Irganox 1010. The blend was irradiated by using a 3.0 MeV electron beam machine at 0, 100 and 200 kGy irradiation doses. The results on the gel fraction and tensile strength revealed the inhibition of the irradiation-induced crosslinking by the Irganox 1010. The dynamic mechanical analysis and scanning electron microscopic studies further confirmed these observations. The consumption of the Irganox 1010 during irradiation and the stability offered by the antioxidant against irradiation-induced oxidative degradation was evident from FTIR analysis. The retention in the tensile strength upon ageing at 70°C/168 h suggests that the addition of 0.5 phr Irganox 1010 is essentially sufficient to provide stability to the blend with minimum loss in mechanical properties during irradiation.

Irradiation crosslinking of unplasticized polyvinyl chloride in the presence of additives

Abstract Electron beam initiated crosslinking of unplasticized polyvinyl chloride, UPVC, has been carried out over a range of irradiation doses (20–200 kGy). The effects of trimethylolpropane triacrylate (TMPTA) and Irganox 1010 on the rate of crosslinking were also studied. Changes in gel fraction, hardness, tensile strength and damping properties upon irradiation were investigated. Results revealed that under the irradiation conditions employed, the stabilized UPVC are crosslinked by the electron beam. Addition of 4 phr TMPTA was found to be effective in increasing the rate while Irganox 1010 inhibits crosslinking. A considerable increase in glass transition temperature upon irradiation of UPVC in the presence of TMPTA was noted. Further, within the dose range studied, the degradation caused by electron beam irradiation was found to be minimal.

Effect of Processing Time on the Tensile, Morphological, and Thermal Properties of Rice Husk Powder‐Filled Polypropylene Composites

Abstract Brabender plasticorder internal mixer was used to incorporate rice husk powder into polypropylene. Rice husk powder (RHP)‐filled polypropylene (PP) composite was prepared by varying mixing time under constant rotor speed (50 rpm) at two mixing temperatures. Brabender mixing torque, tensile properties, morphology, and thermal properties were investigated in detail. Results indicate that the tensile properties, such as Youngs modulus, yield strength, and elongation at break, do not exhibit a significant trend with the increasing of processing time. Scanning electron microscope (SEM) micrographs reveal the better filler dispersion at longer processing time. Differential scanning calorimetry (DSC) analysis indicates nucleating ability of RHP and reduction of degree of crystallinity of PP at higher temperature and longer processing time. In fact, RHP changes the melting point of PP in the composites.

EFFECT OF BLENDING PARAMETERS ON ELECTRON BEAM ENHANCEMENT OF PVC/ENR BLENDS

Poly(vinyl chloride)/epoxidised natural rubber (PVC/ENR) blends were prepared with a Brabender Plasticorder at various mixing time and temperatures. They were mixed at fixed rotor speed of 50 rpm. The blends were irradiated with doses ranging from 0 to 200 kGy. Changes in tensile strength, modulus at 100% elongation, gel fraction, and tan δ curves of the blends with the mixing parameters and irradiation doses were investigated. In general, it was observed that the mixing parameters such as temperature and time studied in this work are important in maximizing the positive effect of irradiation. Results revealed that a readily miscible blend enjoy maximum benefit from irradiation. However, irradiation can impart miscibility to a partially miscible PVC/ENR blends. The enhancement in blend properties can be attributed to the irradiation-induced crosslinking along with irradiation-induced interaction between the polymers. The irradiation-induced degradation was found to be prominent at higher doses for blend that has undergone excessive thermal degradation. However, evidence did not reveal the specific nature of irradiation-induced reaction responsible for the improved interactions of the blends.