Preparation And Properties Of Ultraviolet Transparent Additional Liquid Silicone Rubber

Highly UV-transparent polymers have been used in the fields of optics, electronic,military industry. The study introduces five UV-transparent polymers:fluorine-containing polyimide, amorphous fluorinated polymer, acrylic, epoxy resin,organosilicon, the article also introduces the relationship between structure andUV-transmittance, then the addition liquid silicone rubber was choosed as the basematerial.Influence of raw materials on curing process, mechanical properties and opticalproperty of silicone rubber were studied. The results show that vinyl MQ resin andbranched-vinyl silicone oil have an inhibitory effect on curing process, with theincreased addition amount, the curing peak moved towards high temperature, the initialcuring temperature and gelation time increased, meanwhile the tensile strength andshore A hardness increased, however, the ultraviolet transmittance of silicone rubberdecreased. The optimal mechanical and optical property can be obtained when theaddition amount of vinyl MQ resin is80wt%, leading to the formation of a ultraviolettransparent silicone rubber. When the addition amount of branched-vinyl silicone oil is2wt%, the optimal mechanical and optical property can be obtained.The A value and catalyst have an inhibitory effect on curing process, with theincreased addition amount, the curing peak moved towards low temperature, the initialcuring temperature and gelation time decreased. The optimal mechanical and opticalproperty can be obtained when the A value is1.8, leading to the formation of aultraviolet transparent silicone rubber. When the addition amount of catalyst is2wt%,the optimal mechanical and optical property can be obtained.The curing behavior of additional liquid silicone rubber with three differentamounts of catalyst was analyzed from thermal studies using differential scanningcalorimetry (DSC) and model-free kinetic (MFK) analysis. The activation energy of thecuring process was obtained by the isoconversional methods ofKissinger-Akahira-Sunone(KAS), Flynn–Wall–Ozawa(FWO) and Friedman(FR). Thetime required for achieving a certain conversion at110℃and curing degree at a heatingrate of10℃/min were calculated by the isoconversional methods. The results indicatethat KAS and FWO methods were suited to predict the curing time and curing degree ofsilicone rubber, however the FR method has a large deviation due to the introduction ofinstantaneous speed, but the three methods all reveal that the activation energy increaseswith the raised addition amount of catalyst, and this result indicates that the curingreaction is more likely to happen when the addition amount of catalyst increases.