Messiha Mario, Frank Andreas, Heimink Jan, Arbeiter Florian, Pinter Gerald
PCCL GmbH, 8700 Leoben, Austria.
Evonik Operations GmbH, 45772 Marl, Germany.
Materials (Basel). 2021 Oct 8;14(19):5899. doi: 10.3390/ma14195899.
Thermoplastic materials have established a reputation for long-term reliability in low-pressure gas and water distribution pipe systems. However, occasional (SCG) and (RCP) failures still occur. SCG may initiate only a small leak, but it has the potential to trigger RCP, which is much rarer but more catastrophic and destructive. RCP can create a long, straight or meandering axial crack path at speeds of up to hundreds of meters per second. It is driven by internal (residual) and external (pressure) loads and resisted by molecular and morphological characteristics of the polymer. The safe installation and operation of a pipe throughout its service lifetime therefore requires knowledge of its resistance to RCP, particularly when using new materials. In this context, the RCP resistance of five different polyamide (PA) 12 grades was investigated using the ISO 13477 (S4) test. Since these grades differed not only in molecular weight but also in their use of additives (impact modifiers and pigments), structure-property relationships could be deduced from S4 test results. A new method is proposed for correlating these results more efficiently to evaluate each grade using the crack arrest lengths from individual S4 test specimens.
热塑性材料在低压气体和水分配管道系统中具有长期可靠性的良好声誉。然而，偶尔仍会发生慢速裂纹增长（SCG）和快速裂纹扩展（RCP）故障。SCG可能只会引发小泄漏，但它有可能引发RCP，RCP虽然更为罕见，但更具灾难性和破坏性。RCP能够以高达每秒数百米的速度形成一条长的、笔直的或蜿蜒的轴向裂纹路径。它由内部（残余）和外部（压力）载荷驱动，并受到聚合物的分子和形态特征的抵抗。因此，要使管道在其整个使用寿命期间安全安装和运行，就需要了解其对RCP的抗性，特别是在使用新材料时。在此背景下，使用ISO 13477（S4）试验研究了五种不同聚酰胺（PA）12等级的抗RCP性能。由于这些等级不仅分子量不同，而且添加剂（抗冲改性剂和颜料）的使用也不同，因此可以从S4试验结果中推断出结构-性能关系。提出了一种新方法，通过单个S4试验样品的止裂长度更有效地关联这些结果，以评估每个等级。
