Study On The Properties Of Polyurethane Adhesives Based On Waste PET Alcoholysis Diols

Polyethylene terephthalate(PET)is almost everywhere in daily life,which brings convenience to people’s lives,but also causes great pressure on the environment.Degradation of waste PET by alcoholysis is the most widely used technology at present.It can not only solve the impact of solid waste on the environment,but also use its alcoholysis products to prepare value-added materials.Polyurethane adhesive(PUa)has the advantages of good adhesion,low temperature resistance and shear resistance.It is widely used in packaging,construction.electronic components and other fields.In this paper,the waste PET alcoholysis product is used as one of the raw materials for the preparation of PUa-alcohol chain extender to prepare waste PET alcoholysis diol-based PUa,and it is added as a sizing agent to the preparation of waste paper-based pulp molded products,which provides another possibility for the high-value treatment of waste PET and waste paper.The specific work is as follows:(1)Waste PET was degraded by neopentyl glycol(NPG)and dipropylene glycol(DPG).The alcoholysis solution(GOPL)was collected and purified by absolute ethanol,chloroform/methanol mixed solution(volume ratio 7:3)and petroleum ether/ethyl acetate mixed solution(volume ratio 1:3).Four groups of GOPL were obtained.Microscopic morphology showed that the purification reduced the number and size of particles in GOPL,and the size was reduced by up to 89 nm.Structural analysis showed that the substance in the GOPL system was a benzene ring structure with hydroxyl and carbonyl groups,and the purification could remove some of the substances in the GOPL.(2)Waste PET-based PUa with almost no release of toxic substances was prepared using four GOPL as chain extenders.In ahe structure,four GOPLs all formed hard segments with p-phenylene diisocyanate(PPDI),and PUa was successfully prepared by chimera with soft segments.The thermal stability of PUa is affected by the type and content of GOPL.When the type of GOPL is different.the best thermal performance is PUa2 sample with 10%GOPL content.and the initial decomposition temperature range is 268.1-275.9℃.When PUa was bonded in air the best adhesive property was N-PUa2(unpurified GOPL,content of 10%).The adhesion properties of N-PUa2 to four substrates(glass,paper,PET and wood)reached more than 126 kPa.The purified GOPL could not improve the adhesion properties of PUa.When the samples were bonded in the water environment,the adhesion properties of most PUa decreased by about 50%.After 38 cycles of adhesion-deadhesion-adhesion,PUa still retained at least 39.2%adhesion.The PUa prepared by this method has good adhesion properties and is suitable for use in low temperature/room temperature environments.(3)The preparation of waste paper-based pulp molded products was proposed by using self-made PUa as sizing agent and montmorillonite(MMT)as composite filler.Finally,a sample with an average density of 0.124 g/cm~3 was obtained.The maximum deformation can reach 74%when subjected to external pressure.It has a certain cushioning performance and can be used as a lightweight cushioning packaging material.At the same time,the pulp molding mold explored also provides another possibility for the material type of the mold.In summary.this paper proposes to use waste PET alcoholysis solution to prepare PUa,which is used as a sizing agent for the preparation of waste paper-based pulp molding products.It provides a solution to solve the problem of environmental pollution and realizes the closed-loop treatment of waste PET and waste paper.