Preparation Of Waterborne Alkyd Resin Modified With The Product Of PET Waste Glycolysis And Its Microcapsule

Polyethylene terephthalate(PET)has become an indispensable in the field of various packaging materials due to its excellent thermal stability,chemical resistance and its low energy consumption.Almost all mineral water and soft drinks bottles are made from PET.PET waste is not only harmful to humans,but also seriously pollutes the environment,due to its widespread usage,short life time and the fact that it is very difficult to completely decompose in nature.Therefore,in this study,the chemical degradation of PET waste was explored,and an ecofriendly waterborne alkyd resin was prepared by using the product of PET glycolysis.In order to improve the use convenience of alkyd resin,microcapsules were prepared by in-situ polymerization with the alkyd resin as the core material and used for epoxy coating.The specific contents are as follows:(1)PET waste was glycolyzed by different polyhydric alcohol.The optimal conditions for the glycolysis of PET with EG are as follows:0.25%Zn(OAc)2·2H2O,the EG to PET molar ratio of 8:1,at 195? for 3 h(84%).The optimal conditions for the glycolysis of PET with TMP are as follows:0.25%Zn(OAc)2·2H2O,the TMP to PET molar ratio of 12:1,at 220? for 5 hours(88%).Under optimal conditions for the glycolysis of PET with TMP,PET waste was glycolyzed by TME,and the yield was 89%,without further optimization.(2)Waterborne alkyd resin were synthesized from the products of PET glycolysis,Zanthoxylum bungeanum seed oil(ZSO),trimethylolpropane(TMP),phthalic anhydride(PA),and 2,2-bis(hydroxymethyl)propionic acid(DMPA)in three stages including alcoholysis,polyesterification and neutralization recation.Experimental results indicates that the alkyd resin modified by PET glycolysis 9.3%(EG),11.7%(TMP)and 12.0%(TME),wherein,the alkyd resin gives oil length 50%and excess of hydroxyl 11.5%and 10.0%DMPA as hydrophilic monomer show improved performance.It not only maintains the adhesion and drying speed of alkyd resin,but also increases its hardness,water resistance and thermal properties.(3)The self-healing microcapsules were prepared by in-situ polymerization with melamine urea formaldehyde resin(MUF)as shell material and alkyd resin as core material.The effects of emulsifier type,concentration,core-wall ratio and end-point pH value on the formation of microcapsules were investigated.Furthermore,the mechanical and self-healing properties of epoxy coating were investigated by dispersing alkyd microcapsules into epoxy matrix.The microcapsules were uniform sphere with an average particle size of 97.44 ? m,when the concentration was 2.0 g/L and the core/wall was 2:1 with the end point pH of 3.5.The microcapsules possessed good thermal stability.When the content of microcapsule was 5wt%,the bending strength,tensile strength,bonding strength and impact strength of the coating were improved,and the self-healing performance of the coating significantly enhanced.