Synthesis Of UV-Curable Polyurethane Acrylate Based On Degraded PET Waste

PET polyester is a petroleum-based polymer material that is widely used in daily life due to its low cost and excellent performance.However,the post-consumer PET is difficult to degrade under natural conditions,and results in a large amount of PET waste accumulating on a global scale,causing serious environmental pollution and waste of resources.In this paper,the waste PET was chemically recovered.Then the recycled material was utilized to prepare green and environmentally friendly UV-curable polyurethane acrylate,which has excellent comprehensive performance and practical value.The OEDs with different degrees of degradation were prepared by glycolysis of PET with ethylene glycol.After optimization of the glycolysis process,a series of OEDs were obtained as white powder,and the characterization results showed that the OEDs are oligomers of BHET with an average molecular weight of 458 g/mol to 819 g/mol,which is equivalent to the average polymerization degree between 2 and 4.The UV-curable polyurethane acrylate(PUA)was synthesized from OED,diisocyanate,and hydroxyacrylate.The effects of the average molecular weights of OEDs,diisocyanates,hydroxyacrylates,types and contents of active diluent and curing time on the PUA oligomers and the UV-cured films were studied by the controlling variable experiments and the orthogonal experiments.The properties of the PUA oligomers and the UV-cured films were characterized by FT-IR,~1H NMR,XRD and TG.The results showed that when the average molecular weight of OED was 665 g/mol,the diisocyanate was isophorone diisocyanate,the end-capping agent was single functional end-capping agent,the reactive diluent was 1,6-hexanediol diacrylate with 20%mass fraction and curing time was 40s,the comprehensive properties of the UV-cured films reach the best.The hardness of the pencil was 2H,the adhesion of the lattice method was 0-1 grade,the flexibility was 1mm,and the impact resistance could reach 50 kg·cm,and the UV-cured films passed the tests of water resistance,solvent resistance and chemical resistance.XRD test showed that the characteristic diffraction peaks of OED decreased or disappeared after they participated in the synthesis of PUA.TG analysis showed that the UV-cured film had good thermal stability.The UV curing kinetics of PUA was studied by real-time ultraviolet method,and the results showed that the reaction orders were zero.The water-diluted UV-curable polyurethane acrylate was synthesized by introducing dimethylolpropionic acid(DMPA)and triethylamine(TEA)into PUA oligomer.The effects of the molecular weight of OEDs,neutralizers,the degrees of neutralization,DMPA contents,and hydroxy acrylates on the properties of the WPUA oligomers and the UV-cured films were investigated.The WPUA oligomers were characterized by IR,particle size,Zeta potential,and GPC.The UV-cured films were characterized by solid ultraviolet,TG,and DSC.The results showed that when the average molecular weight of OED was 665 g/mol,neutralizer was TEA,the degree of neutralization was 90%,DMPA content was 38%,and end-capping agent was pentaerythritol triacrylate(PETA)and hydroxypropyl acrylate(HPA)(n(PETA)/n(HPA)=3:2,the WPUA oligomers and the UV-cured films had excellent comprehensive properties and were suitable for wood coatings.Particle size and Zeta potential measurements showed that the average particle size of WPUA resin was 140.7 nm,and it had good dispersion stability in water.GPC measurements showed that the average molecular weight of WPUA resin was moderate.Solid ultraviolet,TG and DSC measurements showed that the UV-cured films had good optical transparency and thermal stability.