摘要
在-70～100℃下测量了EPDM的介电性能。结果表明,其介电常数(ε′)随试验温度的增加而下降,随辐照剂量(D)的增加而略有增加;在介电损耗因子(ε″)温度谱上,于-30℃附近的介电损耗峰,是EPDM的玻璃化温度(T_g),它随着D值和测试频率的增加而向高温移动。在D值低时,EPDM的拉伸强度和扯断伸长率随D值的增加而增加,达到极大值后,二者则随D值的增加而降低。D=20～30kGy时,EPDM具有优良的介电性能和力学性能。
Dielectric and some mechanical properties of ethylene -propylene - cthylidenenorbornene copolymer (EPDM) have been investigated. Because of the presence of unsaturated bond in EPDM , it can easily crosslinked at irradiation . When the irradiated dose ( D value) reached 35 kGy , the gel content was about 50% . The dielectric constant (ε ')and dielectric loss factor (ε ')were about 2.23 and 4 × 10-4 respectively , at room temperature (20°C) for frequence 300 Hz .The ε 'and ε' for EPDM were changed with radiation to a certain extent .The dielectric properties of EPDM were measured from- 70 °C to 100°C . The results showed that a dielectric loss peak was observed for ε ' temperature spectrum at -30°C (300 Hz),which is attributed to glass transition temperature (Tg).Because the crosslinking tied molecular motion of moving unit , the dielectric loss peak shifted to higher temperature with increasing D value (crosslinked extent), at the macrocosm as shown in Figure . It was also observed that ε ' peak temperature for unirradiated and irradiated EPDM moved to higher temperature with increasing the frequency of measurement . That is the relaxation characteristic of high polymer .ε' decreased with increasing test temperature , and decreased a little with increasing D value .The results of some mechanical properties for radiation crosslinked EPDM indicated that the tensile strength(Ts) and elongation (E) increased with increasing D value , at lower dose range . E and Ts reached a maximum , when D was 15 -20 kGy . After passing through the maximum , Ts and E decreased rapidly with increasing D value ,up to 150 kGy decreased slowly .When Dwas at 20 - 30 kGy ,the radiation crosslinked EPDM kept a favorable dielectric and mechanical properties . It is expected that EPDM may be a promising material for making the wire ,cable and heat shrinkable material .
出处
《合成橡胶工业》
CAS
CSCD
北大核心
1992年第1期41-43,共3页
China Synthetic Rubber Industry
基金
国家自然科学基金
关键词
乙烯
丙烯
乙叉降冰片烯
共聚
EPDM
ethyl ene-propylene - ethylidencnorbomene copolymer
radiation crosslinking
dielectric property
irradiated dose
mechanical property
