▎ 摘　　要

NOVELTY - Preparing modified graphene-reinforced polyformaldehyde composite plastic pipe comprises (i) mixing deionized water, graphene oxide and ethanolamine, stirring, centrifuging, washing and drying to obtain hydroxylated graphene, (ii) reacting hydroxylated graphene in an oil bath pot to obtain boric acid modified graphene (iii) preparing polypropylene glycol grafted grapheme, (iv) subjecting polypropylene glycol grafted graphene to substitution reaction to obtain epoxidized polypropylene glycol grafted graphene, (v) subjecting epoxidized polypropylene glycol grafted graphene to ring-opening reaction to obtain oleic acid modified polypropylene glycol grafted graphene, and (vi) adding polyformaldehyde, oleic acid modified polypropylene glycol grafted graphene, filler diatomite powder and plasticizer diisooctyl phthalate into a reactor, transferring reactor to a cold mixer, stirring and discharging, transferring reactor to double-screw extruder for extrusion molding. USE - The method is useful for preparing modified graphene-reinforced polyformaldehyde composite plastic pipe. ADVANTAGE - The plastic pipe: has high flexibility, excellent compatibility, mechanical property and stable physical barrier layer; achieves the plasticizing and lubricating effects; can absorb the large amount of deformation work caused by plastic deformation. DETAILED DESCRIPTION - Preparing modified graphene-reinforced polyformaldehyde composite plastic pipe comprises (i) uniformly mixing deionized water, graphene oxide and ethanolamine in a mass ratio of 4500-8000:100:300-480, stirring the reaction in an oil bath at a constant temperature of 40-60degrees Celsius for 6-18 hours, centrifuging, washing and drying after the reaction to obtain hydroxylated graphene, (ii) adding hydroxylated graphene into a xylene solvent, continuing to adding boric acid after uniform ultrasonic dispersion, transferring to an oil bath pot for reaction, cooling a product, filtering, repeatedly washing with absolute ethyl alcohol and drying to obtain boric acid modified graphene, (iii) adding boric acid modified graphene into a mixed solvent of deionized water and xylene in a volume ratio of 10:6-8, performing ultrasonic dispersion uniformly, adding polypropylene glycol, transferring to an oil bath pot for boric acid esterification reaction, cooling a product, performing reduced pressure distillation to remove the solvent, washing and drying to obtain polypropylene glycol grafted graphene, (iv) adding polypropylene glycol grafted graphene into an ethanol solvent, carrying out uniform ultrasonic dispersion, continuously adding epichlorohydrin, tetrabutylammonium bromide and sodium hydroxide, transferring the mixture into an oil bath pot for substitution reaction, filtering, washing and drying to obtain epoxidized polypropylene glycol grafted graphene, (v) adding epoxidized polypropylene glycol grafted graphene into a dichloroethane solvent, carrying out ultrasonic mixing uniformly, then continuously adding oleic acid and N, N-dimethylbenzylamine, transferring the mixture to an oil bath pot for carrying out ring-opening reaction, cooling a product, centrifuging, washing and drying to obtain oleic acid modified polypropylene glycol grafted graphene, and (vi) adding polyformaldehyde, oleic acid modified polypropylene glycol grafted graphene, 2-8 wt.% filler diatomite powder and 5-10 wt.% plasticizer diisooctyl phthalate into a reactor, transferring the reactor to a cold mixer, stirring and discharging, transferring the reactor to a double-screw extruder for extrusion molding.