A pseudo-thermodynamic description of dispersion for nanocomposites
A pseudo-thermodynamic description of dispersion for nanocomposites
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DOI：
10.1016/j.polymer.2017.09.040
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发表时间：
2017-10
期刊：
影响因子：
4.6
通讯作者：
Yan Jin;G. Beaucage;K. Vogtt;Hanqiu Jiang;V. Kuppa;Jay Kim;J. Ilavsky;M. Rackaitis;Andrew Mulderig;Kabir Rishi;Vishak Narayanan
中科院分区：
文献类型：
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作者：
Yan Jin;G. Beaucage;K. Vogtt;Hanqiu Jiang;V. Kuppa;Jay Kim;J. Ilavsky;M. Rackaitis;Andrew Mulderig;Kabir Rishi;Vishak Narayanan
聚合物纳米复合材料中的分散是由混合动力学和化学亲和性决定的。像增强填料/弹性体共混物这样的化合物与胶体溶液有一些相似之处，因为填料颗粒在加工过程中几乎是随机分散的。利用聚合物混合动力学和胶体热驱动分散动力学之间的这种类比，应用伪热力学方法是很有吸引力的。为了证明这种伪热力学方法，用三种炭黑和两种二氧化硅对两个聚丁二烯和一个聚异戊二烯进行了研磨。使用小角x射线散射作为填料浓度的函数来检测这些样品，以确定伪二阶维里系数A2，该系数用作填料与聚合物相容性的指标。研究发现，a2符合预期行为，初生颗粒越小，其值越低，表明颗粒越小，混合越困难。a2类似于非平衡纳米复合材料的排除体积和远程相互作用势。a2的测量值可以用来指定填料/弹性体体系的粗粒DPD模拟的排斥相互作用势。此外，还获得了新的方法来量化填料渗透阈值和填料网格尺寸作为填料浓度的函数。研究结果为理解和预测聚合物纳米复合材料中的分散提供了一种基于热力学类比的新方法。
Dispersion in polymer nanocomposites is determined by the kinetics of mixing and chemical affinity. Compounds like reinforcing filler/elastomer blends display some similarity to colloidal solutions in that the filler particles are close to randomly dispersed through processing. It is attractive to apply a pseudo-thermodynamic approach taking advantage of this analogy between the kinetics of mixing for polymer compounds and thermally driven dispersion for colloids. In order to demonstrate this pseudo-thermodynamic approach, two polybutadienes and one polyisoprene were milled with three carbon blacks and two silicas. These samples were examined using small-angle x-ray scattering as a function of filler concentration to determine a pseudo-second order virial coefficient,A2, which is used as an indicator for compatibility of the filler and polymer. It is found thatA2follows the expected behavior with lower values for smaller primary particles indicating that smaller particles are more difficult to mix.A2is analogous to the excluded volume and long-range interaction potential for non-equilibrated nanocomposites. The measured values ofA2can be used to specify repulsive interaction potentials for coarse grain DPD simulations of filler/elastomer systems. In addition, new methods to quantify the filler percolation threshold and filler mesh size as a function of filler concentration are obtained. The results represent a new approach to understanding and predicting dispersion in polymer nanocomposites based on a thermodynamic analogy.