Solvent-free low-temperature curing BMI preparation revealed

China Coatings Online News News: Recently, Sichuan University School of Polymer Science and Engineering/National Key Laboratory of Polymer Materials Engineering developed a solvent-free low-temperature cured bi-Malayamide resin system (BMI). They added ole propylphenol active thinners to the vinyl pyride compound modified bi-Malayamide resin system, obtained a viscosity of less than 1000mPa.s, the processing application period is greater than 8h, in 150 to 155 degrees C to complete curing and post-curing, suitable for winding molding process resin system. After toughening, the glass transition temperature of the resin reached 261 degrees C, and the stretch strength and bending strength were 73MPa and 133MPa, respectively. Resin-based composite winding molding technology first appeared in the 1940s, that is, solid rocket engine shell and pressure vessel development system research. At present, winding molding has become one of the most important means in the composite manufacturing process, from the solid rocket engine housing for aerospace, to civil glass and steel pipes, storage tanks have winding molding products in widespread use. In terms of production costs, winding molding has been considered the preferred method for low-cost manufacturing of composite structural products.
is the bi-Malayamide resin system (BMI) prepared so winding with solvent-free low temperature curing? Double Malayamide resins used in the manufacture of advanced composite winding molding are rarely reported. In order to adapt to the development of the aerospace field, it is necessary to develop a double Malayamide resin suitable for winding molding, which has the following characteristics: the use of active thinners, excellent low temperature curing properties, curing and post-curing at 150 to 155 degrees C, winding molding temperature is low, about 40 degrees C, resin curing has better heat resistance and force properties. For this purpose, the following products were selected for the experimental raw materials: 4,4'-diamethane bimariumamide (BMI), industrial products; 4-dioene propyl-6-methylphenol (DMP); promoter, isopropylene peroxide (DCP), chemical pure reagent; and toughener, a liquid oxycodone compound (OXAZOLINE). The viscosity of the resin is determined by the NDJ-1 rotary viscosity meter of Shanghai Xunhong Instrument Co., Ltd., and the glass transition temperature (Tg) of the cured material is determined by dynamic dynamic performance analysis (DMA) method on the DMA Q800 V7.1 of TVB Instrument Corporation in the United States, and the differential scanning thermal analysis experiment (DSC) is carried out on DuPont's TA2910 DSC analyzer.
resin casting system preparation is first of all BMI and modifier VB by the amount ratio of the substance (1:1) mixed, between 90 to 120 degrees C prejudgent reaction 10 to 15min, added active thinner D After MP and toughener OXAZOLINE (the amount of active thinner is 30% of the quality of the resin main system), the reaction at this temperature of 5min, reduced to 40 oC to add the promoter DCP, stirring about 5min, that is, pre-polymer resin. While hot pre-polymer resin poured into the preheated mold, after 60 degrees C vacuum de-foaming after the transfer oven according to the design process curing: 80 degrees C / 4h , 100 degrees C / 4h , 120 degrees C / 4h , 150 degrees C / 10h, and then after 155 degrees C / 4h of the curing treatment. The resin casting sample is taken after the furnace has been cooled to room temperature release. Because VB compounds (electron giver) can form charge transfer complexes with BMI (electronic subject), this reaction mechanism is different from the traditional free-based reaction mechanism, so the system has low temperature curing properties. Moreover, due to structural differences, the performance of this VB compound modified BMI is different from that of traditional styrene modified BMI resins. In addition, the promoter DCP accelerates the low temperature curing of BMI and maintains good moisture and heat resistance and aesthetic properties. The use of low viscosity active diluent DMP to reduce the viscosity of the system, improve the molding process of composite materials.
of VB compounds and BMI is a liquid with poor fluidity at room temperature, and the system has good low temperature curing properties under the action of promoters. However, its high viscosity at room temperature, so a certain amount of active thinner needs to be added to reduce the viscosity of the system, so that it meets the requirements of solvent-free winding molding process. There are many options for active thinners in BMI resin systems, commonly used in acrylic compounds, low viscosity epoxy resins, silicone monomers, unsaturated polyesters, etc. The selection of active thinners is mainly based on the following requirements: active thinners and main resin have good compatible, active thinners have a high reaction activity, active thinners have a strong solubility of resin, especially at the resin processing temperature can significantly reduce the viscosity of the resin. For VB compound modified BMI resin system, in addition to the above requirements, it is also required that the addition of thinner does not affect the low temperature curing performance of the main resin. Acrylic compounds contain C-C double bonds, which are compounds containing rich electron groups and can also form a charge transfer compound with BMI. Therefore, low viscosity acrylic compounds are expected to become active thinners in the system of entangled BMI resins.