Hydrolytic Degradation of Estane 5703
Hydrolytic Degradation of Estane 5703
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发表时间：
1999-04
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影响因子：
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通讯作者：
D. A. Wrobleski;M. E. Smith;E. B. Orler
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作者：
D. A. Wrobleski;M. E. Smith;E. B. Orler
相对于未老化的Estane{reg_sign} 5703，加热降低了干燥和潮湿样品的模量和极限应力。试样在干燥空气中老化后，很快恢复到原来的力学性能。机械性能的可逆性是硬段重组为畴的结果。对于在潮湿空气中老化的Estane 5703样品，机械性能仅随时间部分恢复。分子量数据证实，在潮湿环境下老化的样品的恢复程度的差异可能是由于聚酯软链段的水解断裂。由于在干燥和潮湿环境中老化的样品的拉伸模量相似，因此认为硬畴的相行为决定了低延伸率下的机械性能。然而，在较高伸长率下，机械性能由软链段主导。在利用加速老化预测聚合物长期性能时，必须同时考虑多相聚合物中由加热引起的形态变化和化学变化的影响。加速老化实验后，必须使形态恢复到平衡条件，以评估降解和老化的程度。此外，不同的湿度对水解降解速率的影响。
Relative to the unaged Estane{reg_sign} 5703, heating decreases the modulus and ultimate stress for both the dry and humid samples. The sample aged in dry air, quickly recovered to its original mechanical properties. The reversibility of the mechanical properties is a result of the reorganization of the hard segments into domains. For the Estane 5703 samples aged in humid air, the mechanical properties only partially recovered with time. Molecular weight data confirm that differences in the extent of the recovery for the samples aged under humid environments are likely due to the hydrolytic scission of the polyester soft segments. Since the tensile moduli are similar for the samples aged in both the dry and humid environments, it is believed that the phase behavior of the hard domains dictate the mechanical properties at low extensions. However, at higher elongations, the mechanical properties are dominated by the soft segments. Both the influences of morphological changes and chemical changes induced by heating must be considered in multiphase polymers when accelerated aging is utilized to predict long term polymer properties. After accelerated aging experiments, the morphology must be allowed to recover to equilibrium conditions in order to assess the extent of degradation and aging. Also, the effect of different humidities on the rate of hydrolytic degradation are presented.