Electron beam irradiation of low-density polyethylene filled with metal hydroxides for wire and cable applications

The effects of electron beam irradiation for crosslinking of polymers used for wire and cable insulations are still being researched. In this research, the influence of electron beam irradiation on the different blends of low-density polyethylene (LDPE) filled with aluminum trihydrate and magnesium hydroxide (ATH, MH) were studied. It was revealed by melt flow index, tensile strength, and elongation at break tests that addition of MH to LDPE increases the adhesion forces inside polymer matrices more efficient than similar ATH/LDPE compounds. Field emission scanning electron microscopy test showed that MH is platy in structure and more homogenous mixed than ATH with LDPE. The results on thermogravimetric analysis and limiting oxygen index tests revealed that the thermal stability and incombustibility properties of MH blends are more efficient than similar ATH blends. Meanwhile, it was observed by smoke density test that MH blends produce the lowest smoke density compared with virgin LDPE and similar ATH blends. It was also observed that increasing irradiation by electron beam had impressive affections on the density, gel content, and mechanical properties for all the polymeric samples in this study

10 MeV electron beam cross-linking of plasticized PVC in presence of EHPTM and TAC additives

Irradiation of plasticized PVC (PPVC) compound containing a cross-linking monomer was carried out by a 10 MeV electron beam. This compound mainly is used as insulation in the wire and cable industry. The cross-linking monomers EHPTM and TAC at different ratio of 3, 6, and 9 phr were used. The dose range was varied from 50 to 150 kGy. The effects of monomers and radiation dose on radiation cross-linking were studied by hot-set testing and gel content measurements. In the absence of EHPTM and TAC, cross-linking did not take place by high energy electron beam at any dose and samples had very large elongation in a hot-set apparatus. But in the presence of these monomers, gel content augmented with an increase in radiation dose and EHPTM level. The highest value of approximately 76% gel content was obtained. In this case the lowest hot-set value was about 12%. Also, tensile strength, elongation at break, modulus, volume resistivity, dielectric strength, and limiting oxygen index of samples were examined. It was found that the mechanical properties of samples containing EHPTM and TAC improved significantly with increasing radiation dose. But for PPVC samples loaded with EHPTM, tensile strength values were higher than those of the loaded ones with TAC at all radiation doses. From the hot-set data it is concluded that the samples loaded with EHPTM had a low thermal expansion compared with samples loaded with TAC. The results indicated that EHPTM is a more effective cross-linking agent for PPVC compound compared with TAC