Study On The Structures And Properties Of Epoxy Resin/Glass Fiber Composites For The Safety Toecaps

Excellent properties of epoxy resin/glass fiber composites were prepared using epoxy resin as polymer matrix and glass fiber as reinforcement,which were successfully applied to the manufacture of safety toecaps.The Differential Scanning Calorimetry(DSC),Fourier Transform Infrared Spectrophotometer(FTIR),Scanning Electron Microscope(SEM)and universal test machine were employed to study the curing behavior of the epoxy resin system.The n-degree kinetic model and the model free kinetics(MFK)of the system were set up based on multiple linear temperature data.The adaptability of n-degree kinetic model and the MFK to the curing process of the resin were analyzed and compared.The glass transition effects on the MFK predicting the curing behavior and on the isothermal curing behavior were inspected.The relationship between structure and mechanical properties of epoxy resin/glass fiber composites was studied.Conclusions were shown as follows:1.Compared with n-degree kinetics model and the traditional fitting model method,MFK is more suitable to describe and predict the curing process(above the glass transition temperature)of the epoxy resin system and can provide great guiding value to the selection of the curing condition.2.The variation of the degree of curing(a)and the glass transition temperature(Tg)with time exists significantly different when at high temperatures(90,120?)and at low temperatures(50,60 0C).At low temperatures,the increasing trend of a and Tg with time turns to slow or even stopped from a certain degree of curing.The prediction curve values of MFK become higher than the experimental values from a certain curing degree at low temperatures,generally beginning to deviate at 5-7?below reaction temperature.3.From the point of chemical structure,the thermal enthalpy and Tg of the cured resin reached the highest value ande the composites got the best properties when the content of curing agent was stoichiometry.While the content of rubber was 15wt.%,the toughening effect was best owing to the perfect physical structure.In a sense of the texture structure,the mechanical properties were improved by mingling fibers or ameliorating the interface or altering the stacking sequence etc.4.The theoretical research of the composites was successfully applied to manufacture and development of safety toecaps.The trial production accord well with European Standard EN12568:2010.Further more,the technological process is provided with distinguishing features such as none volatile organic compounds used,continuous sizing,low consumption and high efficiency.