Related Legal Terms & Definitions. 1  COMPETENT WITNESS One who is legally qualified to be heard to testify in a cause. 2  RESPECTABLE WITNESS One who is competent to testify in a court of justice. 3  CREDIBLE WITNESS A credible witness is one who is competent to give evidence, and is worthy ofâ¦.
In general, combustibility of polymers depends on their chemical structures. Polymers with more carbon atoms in their macromolecular structure (e.g., PE, PP, PS, PMMA) are more combustible than polymers containing halogen atoms (e.g., PVC, PVDC, PTFE).
1 PVC is likewise a safe material to carry drinking water. 2  Copper and PVC water pipes do not suffer easily from corrosion, while iron corrodes relatively easily. 3  Copper is relatively easy to work with because it is much softer than iron or lead.4  PVC water pipes are also much easier to shape. PVC is likewise a safe material to carry drinking water. 2  Copper and PVC water pipes do not suffer easily from corrosion, while iron corrodes relatively easily. 3  Copper is relatively easy to work with because it is much softer than iron or lead.