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 Toxicity. Testing has found that polyvinyl chloride (PVC) goods â a form of plastic used in many rubberized toys, tool handles, and many other goods â can contain several toxic plasticizers and stabilizers such as tributyltin and dibutylphthalates. PVC is made from converting chlorine gas to ethylene dichloride.