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Polyvinyl alcohol (PVOH, PVA, or PVAl) is a water-soluble synthetic polymer. It has the idealized formula [CH 2 CH(OH)] n. It is used in papermaking, textile warp sizing, as a thickener and emulsion stabilizer in polyvinyl acetate (PVAc) adhesive formulations, in a variety of coatings, and 3D printing. It is colourless (white) and odorless.
Polyvinylidene fluoride or polyvinylidene difluoride (PVDF) is a highly non-reactive thermoplastic fluoropolymer produced by the polymerization of vinylidene difluoride. Its chemical formula is (C 2 H 2 F 2) n. PVDF is a specialty plastic used in applications requiring the highest purity, as well as resistance to solvents, acids and hydrocarbons.
The melting point of α-crystalline regions is given as 185 [15] [16] to 220 °C, [15] [17] the density as 0.936 to 0.946 g·cm −3. [ 18 ] [ 19 ] The β-modification is in comparison somewhat less ordered, as a result of which it forms faster [ 20 ] [ 21 ] and has a lower melting point of 170 to 200 °C.
Polyglycolide has a glass transition temperature between 35 and 40 °C and its melting point is reported to be in the range of 225 to 230 °C. PGA also exhibits an elevated degree of crystallinity, around 45–55%, thus resulting in insolubility in water. [2]
Polybenzimidazole (PBI, short for poly[2,2’-(m-phenylen)-5,5’-bisbenzimidazole]) fiber is a synthetic fiber with a very high decomposition temperature. It does not exhibit a melting point, it has exceptional thermal and chemical stability, and it does not readily ignite. [1]
FEP is very similar in composition to the fluoropolymers PTFE (polytetrafluoroethylene) and PFA (perfluoroalkoxy polymer resin). FEP and PFA both share PTFE's useful properties of low friction and non-reactivity, but are more easily formable. FEP is softer than PTFE and melts at 260 °C; it is highly transparent and resistant to sunlight. [3] [4]
Melting point: 315 °C: Maximum operating temperature 260 °C: Water absorption (ASTM) <0.03 % after 24 hours Dielectric constant (Dk) at 1M Hz: 2.1 Dissipation factor at 1M Hz: 0.0001 Arc resistance < 180 seconds Resistivity at 50% R. H. > 10 16 Ω m
Dipole bonding is not as strong as hydrogen bonding, so a polyester's melting point and strength are lower than Kevlar's , but polyesters have greater flexibility. Polymers with non-polar units such as polyethylene interact only through weak Van der Waals forces. As a result, they typically have lower melting temperatures than other polymers.