Research On Preparation And Properties Of The Silicone/Polyurethane Composites

The silicone has excellent resistance of high temperature performance and water-repellent, excellent electrical insulating properties and chemical stability, physiological inertion and other advantages, but it is poor in mechanical strength. The polyurethane has friction-resistant, tearresistant, anti-flex performance, but it is poor in high temperature and aging-resistant properties. The silicone/polyurethane composite has excellent performance including the advantage of silicone and polyurethane. It shows good surface enrichment, excellent low temperature flexibility and the dielectric properties and biocompatibility. The composite material not only overcome the poor of the mechanical properties of organic silicon, but also make up for the poor weather resistance of polyurethane and can become a promising new type of polymer materials.The PDMS (poly dimethyl siloxane) was synthesized with DMC (the dimethyl Cyclosiloxane) as raw materials by bulk ring-opening polymerization in KOH catalysis. The silicone elastomer was synthesized with PDMS and tetraethyl orthosilicate (TEOS) by cross-linking method under catalysis of dibutyltin dilaurate (DBTDL). Different reaction conditions on the viscosity average molecular weight and viscosity of PDMS were studied. Water resistance, acid, alkali, salt and oil resistance of the silicone elastomer were researched. The results showed that the influence factors of viscosity and viscosity average molecular weight were reaction temperature, reaction time, catalyst amount and the amount of capping agent. When the temperature below80℃, the reaction in the induction period and can not create polymer, but the polymer can be make when the temperature is above80℃. When the reaction time was80min, the DMC concentration reached a critical number and the polymer viscosity average molecular weight began to decline. The optimum process conditions of PDMS prepared by DMC anionic bulk polymerization were:reaction temperature was120℃, the reaction time was80min, the amount of catalyst was0.03% (w/w). The vulcanization properties of PDMS with different viscosity-average molecular weight were quite different, low molecular weight PDMS was short vulcanization time and the film obtained was more flexible with more smooth surface and higher uniformity. Silicone elastomer was good at water resistance, acid resistance, but the alkali, salt, oil resistance performance was poor.The polyurethane pre-polymer was synthesized with polyethylene glycol (PEG) and isophorone diisocyanate (IPDI) in dibutyltin dilaurate (DBTDL) catalysis. The polyurethane elastomer was synthesized with the polyurethane pre-polymer and trimethylolpropane (TMP) by cross-linking method under catalysis of dibutyltin dilaurate (DBTDL). Different reaction conditions on isocyanate (-NCO) content of the polyurethane pre-polymer were studied. Water resistance, acid, alkali, salt and oil resistance of the polyurethane elastomer were researched. The results showed that the influencing factors of isocyanate (-NCO) content in the polyurethane pre-polymer were reaction time, reaction temperature, amount of catalyst. The optimum conditions of polyurethane elastomer prepared were:reaction temperature was60℃, reaction time was60min, amount of catalyst was1.5ml. Polyurethane elastomer was inadequate in water, acid, alkali, salt water-resistant but was good at oil resistance.The PDMS (poly dimethyl siloxane) was synthesized with DMC (the dimethyl Cyclosiloxane) as raw materials by bulk ring-opening polymerization in KOH catalysis. The polyurethane pre-polymer was synthesized with polyethylene glycol (PEG) and isophorone diisocyanate (IPDI) in dibutyltin dilaurate (DBTDL) catalysis. The silicone/polyurethane composite elastomer was prepared with PDMS, polyurethane pre-polymer, tetraethyl orthosilicate (TEOS), and trimethylolpropane (TMP) by interpenetrating polymer network (IPN) in dibutyltin dilaurate (DBTDL) catalysis. The power sciences on synthetic of PDMS and polyurethane pre-polymer were studied. Water resistance, acid, alkali, salt and oil resistance of the the silicone/polyurethane composite elastomer were researched. The results showed that the reaction rate constant of synthesize PDMS was K=0.02736mol/L.min. The reaction rate constant of synthesize polyurethane pre-polymer was K=0.02051mol/L.min. Silicone had improved acid, alkali and salt-resistant of polyurethane elastomer, but polyurethane had improved the oil resistance of silicone elastomer.