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).
From Wikipedia, the free encyclopedia. Polyvinyl fluoride (PVF) or â(CH 2 CHF) n â is a polymer material mainly used in the flammability-lowering coatings of airplane interiors and photovoltaic module backsheets. It is also used in raincoats and metal sheeting.Polyvinyl fluoride is a thermoplastic fluoropolymer with the repeating vinyl fluoride unit: It is structurally very similar to polyvinyl chloride. PVF has low permeability for vapors, burns very slowly, and has excellent resistance to weathering and staining.It is also resistant to most chemicals, except ketones and esters. It is available as a film in a variety of colors, and formulations for various end uses, and as a resin for specialty coatings.VF has low permeability for vapors, burns very slowly, and has excellent resistance to weathering and staining. It is also resistant to most chemicals, except ketones and esters. It is available as a film in a variety of colors, and formulations for various end uses, and as a resin for specialty coatings.