Abstract
Unsaturated polyester resin (UP) is a critical polymer material in applications of many fields, such as the chemical industry, military, and architecture. For improving the mechanical properties, some hardeners, such as methyl ethyl ketone peroxide (MEKPO) or tert-butyl peroxy-2-ethylhexanoate (TBPO), can trigger the curing reaction in UP polymerization, which causes that UP changes the structure from monomer to polymer. However, polymerization is a strong exothermic reaction, which can increase the risk of thermal runaway reaction in UP. Therefore, the mechanisms and characteristics in the thermal runaway reaction of UP mixed with hardeners should be studied for preventing and controlling UP explosion. The thermal hazards of UP mixed with hardeners were determined by thermogravimetric analyzer (TGA) and differential scanning calorimetry (DSC) analysis. According to the results, UP mixed with MEKPO exhibited a more violent mass loss and exothermic reaction than UP mixed with TBPO. Furthermore, the thermal runaway reactions of UP mixed with MEKPO or TBPO with different mixing proportions of 1:1, 3:1, and 5:1 were determined. Irrespective of MEKPO or TBPO, the mixing proportions of 3:1 exhibited a high onset temperature and low enthalpy of curing reaction (ΔHexo). This demonstrated that this proportion was safer during UP polymerization. The results of this study can provide useful information for preventing UP explosion and developing polymerization technology.
Highlights
Unsaturated polyester resin (UP), which is a critical polymer, is widely applied in many fields, such as the chemical industry, military, and architecture
This study revealed the mass loss and exothermic characteristics for the curing reactions of UP-tert-butyl peroxy-2ethylhexanoate (TBPO) and UP-methyl ethyl ketone peroxide (MEKPO), which can determine the explosion risk of UP during the polymerization
The critical findings are summarized as follows: The thermal stability of UP and UP mixed with hardeners before or after the curing reaction was confirmed by thermogravimetric analyzer (TGA) and differential scanning calorimetry (DSC) results
Summary
Unsaturated polyester resin (UP), which is a critical polymer, is widely applied in many fields, such as the chemical industry, military, and architecture. For the applications in many fields and better mechanical properties, hardeners are used to carry out the curing reaction for UP polymerization, thereby changing the properties of UP from liquid to solid. If heat generation is too fast or heat remove rate is slower than heat generation, a considerable heat can accumulate in the reaction system, thereby increasing the risk of the thermal runaway reaction, even fire and explosion [1,2,3,4,5,6]. The thermal hazard of UP mixed with hardeners should be closely studied
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