The Preparation, Structure And Property Of PU/DCPDE IPN Modified By Organosilicon

DCPDE is a kind of epoxy resin of alicyclic. Because of its small epoxide equivalent and high degree of crosslinking, except for high mechanical strength, well electrical property, well chemical resistance and some other outstanding performance, its heat resistance and the rigidity of its curing product is higher than average epoxy resin. Thererfore, it can be widely used in fields of diluent, adhesives, insulating material, glass fiber reinforced plastics and laminate which produced by dry-press process, etc. However, its high innerstress and poor toughness and some other weakness restrict its applications in some high technology fields.Based on the research status of toughening of DCPDE, this research focused on DCPDE was used as the matrix, the polyurethane and the Organosilicon was used as modifying resin, maleix anhudride (MAH) was used as curing agent, and glycerol was used as accelerator, the PU/DCPDE IPN material which had the excellent heat resistance and toughness was prepared by physically blending and chemical crosslinking.In this paper, we characterized the chemical structure, thermal properties and mechanical properties of IPN materials by Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), etc. We determined the curing technological conditions and formula of DCPDE, discussed the reaction mechanism and toughening mechanism of PU./DCPDE IPN materials which modified by organosilicon, and studied the dynamic mechanical properties, structure and morphology of this kind of materials. The results showed:(1) Molding technology. The curing technology of DCPDE can be controlled by programmed temperature; it was "80℃/2h＋120℃/4h+150℃r/2h". The optimum ratio of curing system was n(DCPDE):n(MAH):n(glycerol)=1:1:0.3.(2) The results of FT-IR showed that there existed curing reaction of epoxy resin, polymerization of PU prepolymer and chemical crosslinking of PU and epoxy resin in the preparation process of PU/DCPDE IPN materials. The organosilicon which was processed by KH-550could react with active group in1PN materials, which was correspong to reaction mechanism.(3) The IPN structure prepared by polyurethane improved the flexibility of composite materials, decreased the rigidity of epoxy resin. When the content of polyurethane was30%, the combination property of composite materials was excellent, its tensile strength was24.8MPa, breaking elongation was14.7%, and flexural strength was26.4MPa, impact strength was18.7lkJ/m2. The mixture utilization of organosilicon and PU can remarkly improved the combination mechanical property of IPN materials. The optimum content of organosilicon was10%, PU was30%, and the tensile strength was37.5MPa. flexural strength was37.4MPa, and impact strength was28.7kJ/m2. It showed that the IPNs had good mechanical properties, especially excellent impact toughness.(4) The results of SEM showed that the IPN structure was formed between PU and DCPDE through physically blending and chemical crosslinking which improved the flexibility. The organosilicon thrust in the IPN materials which improved the compatibility of the interface and produced microcrack which could absorb impact energy and improved the tougheness of materials.(5) The results of dynamic thermomechanical analysis showed that the molecular chain segment movement of the DCPDE held a leading post in the PU/DCPDE IPNs, that was confirmed the IPNs constructed with the PU and the DCPDE.The glass transition temperature(Tg) of the IPNs were lower than that of DCPDE, the Tg of the composite could bu improved significantly by adding the organosilicon.(6) The results of thermal performance analysis showed that the decomposition temperature and glass-transition temperature decreased with the increasing of the content of PU, when the content of PU was30%, the thermal degradation temperature was around360℃. In addition, organosilicon could improve the thermostability of IPN materials, when the content of organosilicon was10%and PU was30%. the thermal degradation temperature was around38O℃.