Plastic PBI

Polybenzimidazole 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.It was first discovered by American polymer chemist Carl Shipp Marvel in the pursuit of new materials with superior stability, retention of stiffness, toughness at elevated temperature. Due to its high stability, polybenzimidazole is used to fabricate high-performance protective apparel such as firefighter's gear, astronaut space suits, high temperature protective gloves, welders` apparel and aircraft wall fabrics. Polybenzimidazole has been applied as a membrane in fuel cells.

General physical properties
PBI is typically a yellow to brown solid that does not melt at 400 °C or higher. [7] The solubility of PBIs is controversial because while most linear PBIs are partially or fully soluble in strong protic acids (for example, sulfuric or methanesulfonic acid), conflicting records have been reported in weaker acids such as formic acid Solubility observations, as well as in aprotic amide-based solvents and non-acidic media such as dimethyl sulfoxide. For example, Iwakura et al. discovered a PBI prepared from phosphoric acid. [8] was partially soluble in formic acid, but completely soluble in dimethylsulfoxide and dimethylacetamide, while Varma and Veena [9] reported that the same polymer type was completely soluble in formic acid, but only partially soluble in dimethylacetamide. sulfoxide or dimethylacetamide.

Thermal stability
Imidazole derivatives are known to be stable compounds. Many of them are resistant to the harshest treatments by acids and bases and are not easily oxidized. The high decomposition temperature and high stability above 400 °C suggest that polymers with benzimidazole as repeating units may also exhibit high thermal stability. Polybenzimidazole and its aromatic derivatives can withstand temperatures in excess of about 500 °C without softening and degradation. Polymers synthesized from isophthalic acid and 3,3'-diaminobenzidine do not melt at 770 °C and lose only 30% of their weight after a few hours at high temperatures up to 900 °C.

flame retardancy
One property of a material to consider before putting it into an application is flammability, which indicates that a material can easily ignite and burn under actual operating conditions. This may affect its application in different fields such as construction, factory design and interior decoration. There are many quantitative assessments of flammability, such as the limiting oxygen index (LOI), the lowest oxygen concentration at which a given sample can be induced to burn in a candle-like structure. These allow a "rank" comparison of estimated flammability. The data shows that PBI is a highly flame retardant material compared to common polymers.