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首页> 外文期刊>Polymers >Microstructure Changes in Polyester Polyurethane upon Thermal and Humid Aging
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Microstructure Changes in Polyester Polyurethane upon Thermal and Humid Aging

机译：热湿老化后聚酯聚氨酯的微观结构变化

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The microstructure of compression molded Estane 5703 films exposed to 11%, 45%, and 80% relative humidity and 70 °C for 1 and 2 months has been studied by small-angle neutron scattering (SANS), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). Scattering data indicated increase of the interdomain distance and domain size with a higher humidity and longer aging time. GPC data showed a progressive shortening of polyurethane chains with increasing humidity and aging time. The shortening of the polyurethane chains caused a drop of the glass transition temperature of soft segments, and promoted crystallization of the soft segments during long-time storage of the aged samples at room temperature. FTIR showed a substantial increase in the number of inter-urethane H-bonds in the aged samples. This correlates with the increase of the hard domain size and the degree of phase separation as measured by SANS. The data collected reveals that the reduced steric hindrance caused by hydrolysis of ester links in polybutylene adipate residues promotes the organization of hard segments into domains, leading to the increase of domain size and distance, as well as phase segregation in aged Estane. These findings provide insight into the effects of humidity and thermal aging on the microstructure of aged polyester urethane from molecular to nanoscale level.
机译：通过小角度中子散射（SANS），傅里叶变换红外光谱（FTIR）研究了在11％，45％和80％相对湿度和70°C下暴露1％和2个月的压塑Estane 5703薄膜的微观结构。 ，凝胶渗透色谱（GPC）和差示扫描量热法（DSC）。散射数据表明随着较高的湿度和较长的老化时间，畴间距离和畴尺寸增加。 GPC数据显示，随着湿度和老化时间的增加，聚氨酯链逐渐缩短。聚氨酯链的缩短导致软链段的玻璃化转变温度下降，并在室温下长时间保存老化样品的过程中促进了软链段的结晶。 FTIR显示老化样品中氨基甲酸乙酯之间的氢键数量大大增加。这与通过SANS测量的硬域大小的增加和相分离的程度相关。收集到的数据表明，聚己二酸丁二酯残基中酯键水解引起的空间位阻的降低促进了硬链段的组织成为畴，导致畴尺寸和距离的增加，以及老化的乙烷中的相分离。这些发现提供了从分子到纳米水平的湿度和热老化对老化聚酯聚氨酯的微观结构影响的见解。

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