Detection of Surface-Immobilized Components and Their Role in Viscoelastic Reinforcement of Rubber-Silica Nanocomposites
Detection of Surface-Immobilized Components and Their Role in Viscoelastic Reinforcement of Rubber-Silica Nanocomposites
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DOI：
10.1021/mz500192r
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发表时间：
2014-05-01
影响因子：
7.015
通讯作者：
Saalwaechter, K.
中科院分区：
文献类型：
--
作者：
Mujtaba, A.;Keller, M.;Saalwaechter, K.
固定化的聚合物部分已被认为是至关重要的大的机械增强纳米颗粒填充的弹性体中观察到的，但在实际应用相关的材料仍然难以捉摸。我们在这里隔离的添加剂填料网络的储能模量的工业丁苯橡胶（SBR）纳米复合材料填充二氧化硅在不同的频率和温度下的贡献，并证明它是粘弹性的性质。我们进一步量化的固定化聚合物的量，使用固态NMR和建立与机械加固的相关性，确定一个直接的，强烈的非线性依赖于固定化聚合物分数。一个温度无关的填料渗滤阈值的观察表明，固定化的聚合物部分可能不一定形成连续层周围的填料颗粒，但只能驻留在紧密填充的填料颗粒之间的高度受限的区域，在那里他们占主导地位的聚集颗粒的弯曲模量。
Immobilized polymer fractions have been claimed to be of pivotal importance for the large mechanical reinforcement observed in nanoparticle-filled elastomers but remained elusive in actual application-relevant materials. We here isolate the additive filler network contribution to the storage modulus of industrial styrene butadiene rubber (SBR) nanocomposites filled with silica at different frequencies and temperatures and demonstrate that it is viscoelastic in nature. We further quantify the amount of immobilized polymer using solid-state NMR and establish a correlation with the mechanical reinforcement, identifying a direct, strongly nonlinear dependence on the immobilized polymer fraction. The observation of a temperature-independent filler percolation threshold suggests that immobilized polymer fractions may not necessarily form contiguous layers around the filler particles but could only reside in highly confined regions between closely packed filler particles, where they dominate the bending modulus of aggregated particles.