Effects Of Electron Beam Irradiation On The Mechanical Properties Of Ethylene Octene Copolymer, Polypropylene and Trimethylolpropane Triacrylate Blends

The effect of electron beam irradiation on blends of ethylene-octene copolymer (EOC) and polypropylene (PP) with and without trimethylolpropane triacrylate (TMPTA) at various ratios was studied. Initial study showed that specimens with 90 wt% PP : 10 wt% EOC displayed optimum tensile strength of 29.12 MPa at 40 kGy. Samples of this ratio were then blended with 1, 2 and 3 wt% TMPTA. There was a significant increase in gel content as the TMPTA increased crosslink density in the samples, compared to samples without TMPTA. The plasticizing of TMPTA was obvious during the tensile tests. Furthermore, TMPTA caused the system to break into smaller networks as a result of increasing number of radicals. However, the sample with 3 wt% TMPTA exhibited the highest tensile strength (30.46 MPa) at 40 kGy dose of irradiation. This was also proven in the tensile modulus test. As expected the elongation at break test indicated a decline in values as higher crosslink density decreased the chain mobility, thus reducing elongation. Further tests on samples with 90 wt% PP : 10 wt% EOC : 3 wt% TMPTA were also carried out. The hardness of the samples was quite stable throughout all irradiation doses. However, the impact test displayed a gradual decrease from 73.13 J/m at 0 kGy with increasing irradiation dose. Finally, the flexural strength and flexural modulus displayed optimum properties at 10 kGy irradiation of 39.89 MPa.

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