聚合物熔体与粒子筏中Baumgärtel-Schausberger-Winter松弛谱的微观起源

中文摘要 AI 辅助

缠结聚合物熔体表现出稳健的双分支Baumgärtel-Schausberger-Winter（BSW）松弛谱，而相关谱也出现在非聚合物的单分散无序系统中。尽管BSW谱已成功应用于许多不同材料，但这些谱的分子推导仍然缺乏。我们构建了一个分子理论，其中链段相对于被屏蔽的、动态响应的多链环境运动。高斯链预平均给出$M_{\rm seg}(\Delta m)\sim(\Delta m)^{-1/2}$，因此$\lambda_p\sim p^{3/2}$，经过应力投影后，$H(\tau)\sim\tau^{-2/3}$。独立地，纵向原始路径扩散给出轮廓长度涨落，其$H(\tau)\sim\tau^{1/4}$。一个受分子量约束的实现同时针对四种单分散聚丁二烯（PBD）熔体的实验$G'(\omega)$和$G''(\omega)$数据进行测试，无需拟合谱指数或单个模态权重。所得的BSW谱在有限链末端边缘之前表现出从快速协同级联到缓慢约束更新级联的连续转移。一种共同的两扇区笼动力学随后将聚合物与粒子筏联系起来，而无需假设相同的微观机制。

英文摘要

Entangled polymer melts exhibit the robust two-branch Baumgärtel-Schausberger-Winter (BSW) relaxation spectrum, while related spectra occur in nonpolymeric monodisperse disordered systems. In spite of the successful application of BSW to many different materials, a molecular derivation of these spectra is lacking. We construct a molecular theory in which a chain segment moves relative to a screened, dynamically responding multichain environment. Gaussian-chain preaveraging gives $M_{\rm seg}(Δm)\sim(Δm)^{-1/2}$, hence $λ_p\sim p^{3/2}$ and, after stress projection, $H(τ)\simτ^{-2/3}$. Independently, longitudinal primitive-path diffusion gives contour-length fluctuations with $H(τ)\simτ^{1/4}$. A molecular-weight-constrained implementation is tested simultaneously against experimental $G'(ω)$ and $G''(ω)$ data for four monodisperse polybutadiene (PBD) melts, without fitting spectral exponents or individual modal weights. The resulting BSW spectrum exhibits a continuous transfer from the fast cooperative to the slow constraint-renewal cascade before a finite-chain terminal edge. A common two-sector caged dynamics then connects polymers to particle rafts without assuming identical microscopic mechanisms.

发表机构

• Rheonic Lab（Rheonic实验室）
• University of Massachusetts Amherst（马萨诸塞大学阿默斯特分校）
• University of Milan（米兰大学）

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