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PVC电线电缆料经辐照交联后,残存着很多自由基,在常温,甚至在120℃,这些自由基仍然保持稳定,消失很慢。然而,在XLPVC长期高温使用过程中这些自由基会进一步产生交联作用,使材料的性能发生变化,抗张强度增加,伸长率下降。XLPVC经136℃ 168h老化后,凝胶含量增加很多,并随着交联剂用量的增加,增加的百分率也变大。残存自由基的这种作用相当于PVC的交联率的增加,而使R_g下降。老化前后,溶胶分数与剂量的关系均可用R(S+S~(1/2))=B+AR~β来表述。
PVC wire and cable materials by radiation crosslinking, the residual many free radicals, at room temperature, even at 120 ℃, these radicals remained stable, disappear very slowly. However, these long-term high-temperature XLPVC use of the process will further produce cross-linking of the role of the material properties change, increased tensile strength, elongation decreased. XLPVC after aging at 136 ℃ 168h, the gel content increased a lot, and with the increase of the amount of crosslinking agent, the percentage of increase also increased. This effect of residual free radicals is equivalent to an increase in the crosslinking rate of PVC, leaving R_g to decrease. Before and after aging, the relationship between sol fraction and dose can be expressed as R (S + S ~ (1/2)) = B + AR ~ β.