Abstract

A method for producing superabsorbent polymers from polyacrylonitrile (PAN) virgin or recycled from acrylic fibre manufacturing waste and discarded fabrics subjecting the PAN to alkaline hydrolysis with pressurized water vapour of up to 5 kgf/cm2 and a PAN:OH− molar ratio of 1:0.5 to 0.95, to obtain a cross-linked poly(acrylic acid-co-acrylamide) salt without using mechanical agitation, graphitizing agents with starch or cross-linking agents, and without precipitating the superabsorbent polymer obtained from the reaction medium with solvents or through pH adjustment with acids, the polymer obtained with recycled PAN leaves the autoclave already having a moisture content of 20% to 35% and a swelling capacity of >150 g H2O/g.

IPC Classes  ?

• B01J 20/26 - Synthetic macromolecular compounds
• B01J 20/30 - Processes for preparing, regenerating or reactivating
• C08F 20/44 - Acrylonitrile
• C08F 8/12 - Hydrolysis
• C08K 3/22 - OxidesHydroxides of metals
• C08J 11/14 - Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with steam or water

Abstract

The present invention describes a method for producing superabsorbent polymers from polyacrylonitrile (PAN) that is virgin or recycled from acrylic fibre manufacturing waste and discarded fabrics. In order to produce the superabsorbent polymer, the PAN must be subjected to alkaline hydrolysis with pressurized water vapour in an autoclave. In conditions with a water vapour pressure of up to 5 kgf/cm2and a PAN:OH-22O/g, for use in agricultural applications as a water retainer or soil conditioner, and in other applications. The invention is therefore relevant in the field of the environment and sustainability as it helps to solve three technical problems: recycling polymers, reducing water consumption for irrigation, and producing food.

IPC Classes  ?

• C08F 20/44 - Acrylonitrile
• C08F 8/12 - Hydrolysis
• C08F 120/44 - Acrylonitrile
• C08J 3/03 - Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
• C08J 11/00 - Recovery or working-up of waste materials
• B29B 17/00 - Recovery of plastics or other constituents of waste material containing plastics
• D04H 1/43 - Acrylonitrile series
• C08K 3/22 - OxidesHydroxides of metals