Of Tde-85 Modified End Isocyanate Group Polysiloxane Adhesives

In this research, the prepolymer of polydimethylsiloxane(PDMS) andpolypropylene(PU)——the isocyanate terminated PDMS was synthesizedby a reaction of the PDMS and toluene-2, 4-diisocyanate (TDI) in the help of organic tin. This kind of isocyanate terminated PDMS had the good compatibility with epoxy resin TDE-85. As the modified reagent, the epoxy resin TDE-85 was mixed with the isocyanate terminated PDMS. Extended reagent of 1,4 butanediol(l,4-BDO), cross linker reagent of three hydroxymethyl groups of propane (TMP), cured reagent of methyltetrahydrophthalic anhydride (MeTHPA) and filler of MG and nano SiO₂ were added to the epoxy resin for modification, the system of isocyanate terminated PDMS modified with epoxy resin TDE-85 was eventually prepared.In this experiment, the IR was applied to perform the characterization of structure of the isocyanate terminated PDMS and the system of isocyanate terminated PDMS modified with epoxy resin TDE-85, and the best synthesis process of isocyanate terminated PDMS and the reaction mechanisms of epoxy resin TDE-85 modifying isocyanate terminated PDMS were discussed. The electronic powerful testing machine and impacting testing machine were applied to examine the tensile strength, impact strength and adhesive strength of the modified material. The effect on the tensile strength, impact strength and adhesive strength of the different kinds of influence factors were discussed. The influence factors contained that epoxy resin type, PDMS type, filler type, contents of TDE-85, contents of fillers, water and oil. The thermal stability of the modified materials was determined by TG method, the influence of TDE-85 proportion and type of filler on the thermal stability of modified materials was discussed in detail. The SEM was applied to analyze the fracture structure. The modified effect and mechanisms of the TDE-85 and fillers were analyzed.The experimental results show that:①the best synthesis process of isocyanate terminated PDMS is that the best temperature of reaction is 50～55℃and the best time of reaction is 5h;②by comparing the adhesive strength of the modified material prove that PDMS with 8% hydroxyl groups is better than PDMS with 1.86% hydroxyl groups as matrix resin of modified material;③the modified effect of TDE-85 is better than E-51;④epoxy resin TDE-85 can effectively improve property of the modified material obviously, and with the content of TDE-85 added, the tensile strength, impact strength, adhesive strength and oil-resistance of modified material are improved, but the thermal stability and water-resistance are reduced;⑤MG and nano SiO₂ can both effectively improve property of the modified material obviously, and with the content of MG and nano SiO₂ added, the tensile strength, impact strength and adhesive strength of modified material are improved at first then reduced at last;⑥by comparing the adhesive strength, tensile strength and impact strength of the modified material prove that the modified effect of nano SiO₂ is better than MG as filler of modified material.