Study on Preparation of Glass Fiber (GF) Reinforced Unsaturated Polyester Resin (UPR) Rebar by Light Curing

Five kinds of photoinitiators were used to prepare glass fiber(GF) reinforced unsaturated polyester resin(UPR) rebar with the diameter up to 1.5 cm by LED UV curing technology. The thermogravimetric analysis and mechanical property tests were carried out for the resultant composites and the effects of photoinitiator species and concentration(0.1%~2.0%, mass friction), wavelength of ultraviolet light(365 nm and 395 nm), light intensity(30~750 mW/cm²) and exposure time on the curing and properties were investigated. The results revealed that the light source with wavelength of 365 nm had better curing effect; the apparent curing time was generally shortened with the increase of light intensity for a given initiator; the Barcol hardness increased with the increase of light intensity and became more stable. Under the same ultraviolet light intensity, the apparent curing time generally decreased with the increase of photoinitiator concentration except for PI1 photoinitiator, with which, the apparent curing time decreased first and then increased with the increase of photoinitiator concentration. The tensile strength and the elastic modulus of the composite with PI0 or PI5 photoinitiators after UV exposure of 40 s reached up to 1 000 MPa and 45 GPa, respectively, which were higher than those of the composite by heat curing. These results suggested that the LED UV curing could be an efficient method to prepare GF/UPR rebars with diameter up to centimeter level.