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).
PVC stands for Polyvinyl Chloride. What is interesting is that the Chloride makes up more than half the finished weight of PVC which is what makes the final window resistant to fire.The modern starting materials for the manufacture of PVC are oil and salt. Both of these are products of nature.hat is interesting is that the Chloride makes up more than half the finished weight of PVC which is what makes the final window resistant to fire. The modern starting materials for the manufacture of PVC are oil and salt. Both of these are products of nature.