Glass-reinforced plastics, agricultural

Other polymers find limited agricultural uses. Among these are glass-reinforced plastics (GRP) tanks, silos and vats, polyethylene terephthalate (PET) filament based thermal screens and flat covering sheets. Polycarbonate (PC) and polymethylmethacrylate (PMMA) are used in limited amounts for double- or triplewall sheets for top of the line greenhouses. 

Maleic anhydride is used as a chemical intermediate in the synthesis of fumaric and tartaric acids, certain agricultural chemicals, resins in numerous products, dye intermediates and pharmaceuticals [2]. It is primarily used as a co-monomer for unsaturated polyester resins, which are used in the production of bonding agents for plywood manufacture and when mixed with glass fibres for reinforced plastics. Annual production of maleic anhydride is estimated to be over one million tormes [3]. 

Uses. About 60% of the MA produced is used to make unsaturated polyester and aikyd resins, which are formed by reaction of MA with glycols. Polyester resins are used in the fabrication of glass fiber reinforced parts. Applications include boat hulls, automobile body parts, patio furniture, shower stalls, and pipe. Aikyd resins are mostly used in coatings (paint, varnish, lacquers, and enamels). MA also is widely used as a chemical intermediate in the manufacture of plasticizers and dibasic acids (fumaric, maleic, and succinic). About 15% of MA production goes into the manufacture of viscosity index improvers and dispersants used as additives in lube oils. Several agricultural chemicals are based on maleic anhydride, the best known being Malathion. 

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