Synthesisand Modification Of UV-curing Vinyl Ester Resin

UV curing composite material with a fast curing speed,good uniformity,low shrinkage,environmentally friendly,and many other advantages,are widely used in trenchless repair of drainage pipeline and other fields.But,UV-curing composite materials have been facing limited thickness of the cured products,backlight surface area poor curing quality and other issues currently.These problems have seriously restricted the development of trenchless pipe repair and other structural repair techniques which based on UV-cured composite materials.As the UV-curable materials most widely used epoxy vinyl ester resin,how to further improve the efficiency and activityof UV-curing activity and study its application in the composite matrix having a importanttheoreticalmeaning and practical value.At present,there is less research on the vinyl ester resin for UV-curing compositein China,and the optical activity is generally low,the thickness of one-time cure is generally not more than 3mm.In this paper,UV-curable vinyl ester oligomer VE51 and VE53 were synthesized by two kinds of formulas through the molecular structure design: the first is ordinary bisphenol A epoxy resin E-51 and crotonic acid as the main raw material,the second is the ordinary bisphenol A epoxy E-53(a lower molecular weight,higher epoxy value)and acrylic acid as the main raw material.Blending four different degrees of functionalityreactive diluents: monofunctional hydroxyethyl methacrylate(HEMA),bifunctional 1,6-hexanediol diacrylate(HDDA),triacetate glycol diacrylate(TEGDA)and trifunctional trimethylol propane triacrylate(TMPTA)with the synthetic vinyl ester oligomer to study about the dilution effect on the synthetic vinyl ester oligomer.There were four kinds of efficient photoinitiators: 2-hydroxy-methyl-1-phenyl acetone(HMPP,1173),1-hydroxy-cyclohexyl-phenyl ketone(HCPK,184),2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone(HHMP,2959),2,4,6-trimethylbenzoyl diphenylphosphine ethyl ester(TPO-L)for research the UV-curing activity of the vinyl ester resin.On this basis,we designed the contrastexperiment,analysised and revealed the maximum influence of type and amount of the reactive diluents and photoinitiators,irradiation time and distance and other factors on one-time UV-cured thickness of the synthetic vinyl ester resin.Finally,after synthesis and optimization of a vinyl ester resin formulations,the resin cast specimens was prepared through UV irradiation,then tested and evaluatedphysical and mechanical properties of the specimen.The results showed that the influence of the one-time-UV-cured thickness in the two kinds of resin systems(VER51 and VER53)were: the resin which containing HEMA has better photo activity and conducive to the depth of cured products,HDDA,TEGDA and TMPTA is slightly worse than the HEMA.For the photoinitiators,the activity of TPO-L was highest in the two vinyl ester systems,1173 and 184 were slightly worse than the TPO-L,while the 2959 was the worst due to the poor compatibility with the system.Andcompared with VER51,thephoto-activity of VER53 UV-curing system were higher.When HEMA content was 40 wt.%,the adding amount of photoinitiatior agent TPO-L was 3 phr,one-time UV-cured thickness within 3min of cured productscould up to 9mm.And the mechanical properties of VE51 was betterin the same formula,the Barcol hardness of cured backlight surface could up to 35 HBa,bending strength was 99.4MPa,flexural modulus was 3.2 GPa,tensile strength was 62.1 MPa.The bending and tensile strength of VER51 were 13.6% and 12.3% higher than VER53,and the bending and tensile properties of two kinds of resin cured by UV have reached 85% or more of its thermal-curing properties.In addition,we studied UV curing characteristics and mechanical properties of the composites which were prepared by these two resin matrix with glass fiber.The results show that the mechanical properties of VER51 matrix composites are better than VER53 that of the composites with the thickness of 4 mm,the flexural and tensile strength of UV-curing VER51 composite can reach 414 MPa and 318 MPa,these two kinds of properties were higher than VER53 composite by 5.9% and 6.4% respectively.Only the VER53 composites can be cured by UV effectively within 10 min with the thickness of the composite samples in 4~6mm.This paper also studied the corrosion resistance of glass fiber reinforced resin matrix composite VER53 which with higher activity at two different curing methods(UV curing and thermal curing)for preparing composite samples,found that UV curing surface has better corrosion resistance.