Tian Qiang, Krakovský Ivan, Yan Guanyun, Bai Liangfei, Liu Jiahui, Sun Guangai, Rosta László, Chen Bo, Almásy László
Key Laboratory of Neutron Physics and Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, China.
Department of Macromolecular Physics, Faculty of Mathematics & Physics, Charles University, Prague 180 00, Czech Republic.
Polymers (Basel). 2016 May 20;8(5):197. doi: 10.3390/polym8050197.
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.
通过小角中子散射（SANS）、傅里叶变换红外光谱（FTIR）、凝胶渗透色谱（GPC）和差示扫描量热法（DSC），研究了在相对湿度11%、45%和80%以及70°C条件下暴露1个月和2个月的模压成型Estane 5703薄膜的微观结构。散射数据表明，随着湿度升高和老化时间延长，域间距和域尺寸增大。GPC数据显示，随着湿度和老化时间增加，聚氨酯链逐渐缩短。聚氨酯链的缩短导致软段玻璃化转变温度下降，并在老化样品于室温下长期储存期间促进软段结晶。FTIR显示老化样品中聚氨酯间氢键数量大幅增加。这与通过SANS测量的硬域尺寸增加和相分离程度相关。收集到的数据表明，聚丁二酸丁二醇酯残基中酯键水解导致的空间位阻减小，促进了硬段形成域，导致域尺寸和间距增加，以及老化的Estane中出现相分离。这些发现为湿度和热老化对老化聚酯型聚氨酯微观结构从分子到纳米尺度的影响提供了深入见解。
