In this study, the effects of γ-irradiation on the crosslinking of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE) containing crosslinking agents were investigated to find the degree of crosslinking in the polymer. The LDPE and LLDPE specimens were prepared by blending crosslinking agents with each polymer, and by hot-press-molding into a sheet at 130 ℃. The γ-irradiation was conducted at 50 to 150 kGy in nitrogen. The crosslinking percentage in these specimens was measured in relation to the irradiation dose and the type of crosslinking agents. The mechanical properties, thermal properties and crystallinity of specimens were examined as a function of irradiation dose as well. It was found that the degree of crosslinking of the irradiated specimens was increased with increasing irradiation dose and by the addition of crosslinking agents. The mechanical properties and thermal properties of specimens were improved in proportion to an increase in the degree of crosslinking. The crystallinity of original resin was decreased with increasing crosslinking density.

본 연구에서는 고분자 수지의 가교율 향상을 위하여 가교제를 첨가한 low density polyethylene(LDPE), linear low density polyethylene (LLDPE) 수지의 가교에 있어서 γ-선 조사의 효과를 조사하였다. LDPE와 LLDPE 시편들은 가교제와 혼합하여 130 ℃의 hot-press mold에서 sheet 형태로 준비하였다. γ-선은 질소분위기에서 50부터 150 kGy로 변화시키며 조사하였다. 이렇게 준비된 시편을 이용하여 방사선 조사선량, 가교제의 종류에 따른 가교율의 변화를 조사하였으며 가교에 따른 기계적 특성, 열안정성과 결정화도의 변화도 평가하였다. 그 결과 방사선 조사선량이 크고, 가교제가 첨가되면 가교율은 상승하였다. 그것과 비례하여 물리적 성질과 열적인 성질도 개선되었다. 그리고 방사선 조사에 의해서 순수한 수지의 겔화율이 증가하면 결정화도는 감소하였다.

Keywords: γ-ray irradiation; LDPE; LLDPE; crosslinking agent; gelation