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wglhun_23

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专业: 高分子合成化学

[交流] 【求助】高分子交联前后密度变化的问题

小弟在做实验的时候要计算交联密度估计大家也做过类似的计算吧
我不知道用交联剂交联同一种高分子材料后它们的密度变化怎么去计算呀，或者是否可以忽略不计呀，我用的交联剂含量从1%到10%
交联密度=（Ws-Wg）/Wg*P(高分子材料密度)/P（溶剂密度）
请知道的告知我了
谢谢

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chinajinlei

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Since NC hydrogels show extraordinarily large reversible deformation, and the polymer chains in the swollen state at ambient temperature could be regarded as flexible polymer chains just like those in the rubbery state of solid polymer above glass transition temperature [22], the effective cross-link chain density of NC hydrogels can be evaluated by the kinetic theory for rubber elasticity, which was developed on the basis of the entropy elasticity of flexible polymer chains. From the rubber elasticity theory, the equation of state of the swollen network for tensile strains is
σ = νeRT(λ –1/λ2)
= RTρ/Mc(1 – 2 Mc/ Mn)( λ –1/λ2) (2)
where σ is the tensile stress, νe is the effective crosslink chain density, R is gas constant, T is the absolute temperature, and λ = L/L0 is the draw ratio, ρ is the density of the hydrogel, Mc is the molecular weight of chain between cross-links, Mn is the average molecular weight of the primary molecular chains. The term (2Mc/Mn) is a traditional correction for chain ends not effectively tied into conventional cross-linked networks and becomes negligible when the number of chain ends is small relative to cross-linked chains.
Values of νe and Mc can be calculated at a given draw ratio by Eq. (2).

【来源】Yuanqing Xiang, Zhiqin Peng, Dajun Chen. A new polymer/clay nano-composite hydrogel with improved response rate and tensile mechanical properties. European Polymer Journal 42 (2006) 2125–2132.