Study on Time Resolved Molecular Orientation of Hydrogen-Bonding Polymers by Polarized ATR-FTIR Measurement under a Flow Field

我们对熔体中的氢(H)键聚合物体系进行了线性和非线性流变性测量以及剪切流动下的FTIR测量：乙酸乙烯酯和乙烯醇无规共聚物P(VAc-VOH)。该体系的应力增长函数对应力超调依次表现为剪切变稀行为。这一结果表明，在稳定的剪切流动下，氢键结构断裂。然而，对同一样品的Rheo-ATR-FTIR测量表明，施加流场不会改变氢键的数量。这一结果提出了两种可能性：氢键数目的微小变化和/或从分子间氢键到分子内氢键的结构变化将导致剪切稀化行为。

We conducted linear and non-liner rheological measurements and also FTIR measurement under a shear flow for hydrogen(H) bonding polymer systems in the melts : random copolymer of vinly acetate and vinyl alcohol, P(VAc-VOH). Stress growth function of this system showed the shear thinning behavior successively to the stress overshoot. This result suggests that H-bonding structure break up under steady shear flow. However, RHEO-ATR-FTIR measurements on the same sample revealed that the number of hydrogen bonds did not change by applying flow fields. This result suggested two possibilities : small change in the number of H-bonds and/ or the structural change from inter-to intra-molecular H-bonds will be responsible for the shear thinning behavior.