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聚丙烯和三元乙丙橡胶(EPDM)的γ辐射效应及辐射后的聚丙烯熔体流动速率的测定表明,在限定空气中聚丙烯随着辐照剂量的增加,熔体流动速率急剧下降,而三元乙丙橡胶随辐射剂量的增加,凝胶含量逐渐增加。在20kGy的剂量辐照下,凝胶含量为22.7%,加入2%的三聚异氰酸三烯丙酯,在相同的剂量辐照下,凝胶含量达到68%。在低剂量下辐照对共混物的拉伸强度影响不大,对冲击强度有很大的影响。在20kGy的剂量辐照下,加入50%EPDM的聚丙烯的缺口冲击强度由1.95kJ/m^2提高到30kJ/m^2,维卡软化温度由85.9℃提高到97.0℃。 相似文献
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用电子顺磁共振技术(ESR)研究了r-辐射聚酰胺-1010中俘获自由基的结构、升温中的转化与行为,及它们与其结构和转变多得性的联系,讨论了聚酰胺-1010辐射解和后裂解的反应机理及反应区域等问题。 相似文献
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Polyamide 1010 is a γ-radiation crosslinkable polymer. After irradiation, it is possible to raise its service temperature up to 240℃. Network formation greatly changes the crystallization behaviour of the polymer. In the present work, DSC was used to examine its isothermal crystallization kinetics. It is found that in addition to the necessity of more undercooling and the lowering of crystallization rate, the primary crystallization stage of the irradiated polymer is shortened. This effect is more evident with increasing radiation dose and content of enhanced difunctionai erosslinking agent. However, the crystallization mechanism of the primary stage is not changed as evidenced by the constancy of Avrami exponent. The lamella end surface free energy σ_e calculated according to Hoffman's equation is very sensitive to γ-radiation. It increases abruptly in 2—3 fold even though the radiation dose is not high enough. The origin of this phenomenon may be accounted for in terms of network structure of the polymer. 相似文献
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An NLMS algorithm with optimized preparatory step-size parameters for
SQUID-based MCG data processing 下载免费PDF全文
We present a new least-mean-square algorithm of adaptive filtering to
improve the signal to noise ratio for magnetocardiography data collected
with high-temperature SQUID-based magnetometers. By frequently adjusting the
adaptive parameter $\alpha $ to systematic optimum values in the course of
the programmed procedure, the convergence is accelerated with a highest
speed and the minimum steady-state error is obtained simultaneously. This
algorithm may be applied to eliminate other non-steady relevant noises as
well. 相似文献
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