固化剂分子结构对高交联环氧聚合物循环蠕变的影响,Journal of Polymer Science

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固化剂分子结构对高交联环氧聚合物循环蠕变的影响
Journal of Polymer Science ( IF 3.9 ) Pub Date : 2020-05-26 , DOI: 10.1002/pol.20200130
Hyungbum Park ₁ , Ingyun Chung ₁ , Maenghyo Cho _{1,

2}

Affiliation

考虑到固化剂分子结构的影响，通过分子动力学模拟研究了高度交联的环氧聚合物的棘轮行为。使用原子模型对脂族和芳族固化剂三亚乙基四胺（TETA）和二乙基甲苯二胺（DETDA）固化的环氧树脂进行了两种不同频率的循环装卸模拟，分别。在周期性变形模拟过程中，根据固化剂的分子结构，观察到不同的棘轮应变演变，二面角应力积累和刚度变化。用DETDA固化的环氧树脂表现出棘轮应变的更快增加，并且朝着装载方向的刚度降低。通过观察单体的取向顺序参数，回转半径和自由体积演化来进行结构分析，以了解棘轮应变行为和原子尺度的刚度变化。结构分析表明，在固化剂DETDA的苯环附近不可逆的二面角过渡是造成周期性变形过程中低棘轮阻力和刚度下降的原因。鉴于，

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Effect of molecular structure of curing agents on cyclic creep in highly cross‐linked epoxy polymers

Ratcheting behavior of highly–cross‐linked epoxy polymers was investigated considering the effect of molecular structure of curing agents by molecular dynamics simulations. Cyclic loading–unloading simulations at two different frequencies were conducted using atomistic models for epoxies cured by aliphatic and aromatic curing agents, triethylenetetramine (TETA) and diethyltoluenediamine (DETDA), respectively. Different ratcheting strain evolutions, dihedral angle stress accumulations, and stiffness variations were observed during the cyclic deformation simulations depending on the molecular structure of curing agents. The epoxy cured by DETDA exhibited a more rapid increase of ratcheting strain and a decrease of the stiffness toward the loading direction. Structural analyses were carried out by observing the orientation order parameter of the monomers, radius of gyration, and free volume evolution to understand the ratcheting strain behaviors and stiffness variations at atomistic scale. The structural analyses revealed that irreversible dihedral angle transitions near the benzene ring of the curing agent DETDA were responsible for low ratcheting resistance and stiffness degradation during the cyclic deformations. Whereas, the aliphatic curing agent TETA, which does not exhibit any stress possession by the irreversible dihedral angle change, was revealed to be advantageous for the ratcheting resistance and stiffness variation of the epoxy polymers.

更新日期：2020-05-26

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