Determination of moisture gradients in polyamide 6 using StepScan DSC
Determination of moisture gradients in polyamide 6 using StepScan DSC
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DOI：
10.1016/j.tca.2018.12.011
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发表时间：
2019-02-01
影响因子：
3.5
通讯作者：
Stommel, M.
中科院分区：
文献类型：
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作者：
Sambale, A.;Kurkowski, M.;Stommel, M.
已知聚酰胺吸收和解吸水以与其环境建立平衡。水通过扩散吸收导致材料的强度和刚度急剧降低，这被称为水诱导塑化效应。这种效应导致玻璃化转变区域向较低温度移动，这可以通过差示扫描量热法（DSC）来确定。然而，玻璃化转变温度T-g的测定是不准确的样品与不均匀的水分分布之前，通过扩散达到平衡和T-g是由水的具体效果叠加。结果表明，即使在样品内水分分布不均匀的情况下，也可以通过StepScan DSC测量玻璃化转变。此外，开发并验证了一种方法，该方法使用低热导率和T-g的偏移来检测非均匀条件下的PA 6样品中的水饱和样品边界层。
Polyamides are known to absorb and desorb water to establish an equilibrium with their environment. Water uptake by diffusion leads to a drastic reduction in the strength and stiffness of the material, which is referred as the water-induced plasticizing effect. This effect leads to a shift of the glass transition region towards lower temperatures what can be determined by differential scanning calorimetry (DSC). However, a determination of the glass transition temperature T-g is not accurate in samples with inhomogeneous moisture distribution before an equilibrium is reached by diffusion and T-g is superimposed by water-specific effects. It is shown that the glass transition can be measured by StepScan DSC even with inhomogeneous moisture distribution within the sample. In addition, a method is developed and validated which uses the low thermal conductivity and the shift of T-g to detect a water-saturated sample boundary layer in inhomogeneously conditioned PA 6 samples.