Preparation of impact-resistant functional polyurea coatings and effect of γ-ray irradiation on its microstructure and performance

Abstract

New polyurea coatings were synthesized using aromatic diphenylmethane diisocyanate, large molecular weight amino-terminated polyether, and appropriate additives. Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy were used to examine the effects of γ-ray irradiation with different dose rates and cumulative doses on the microstructure of the new polyurea coatings. The variations of mechanical properties of the polyurea coatings before and after irradiation were studied using an electronic universal testing machine and a split Hopkinson compression bar. FTIR spectroscopy showed that the raw materials for preparing polyurea coatings had reacted completely, and polyurea had been synthesized. An analysis of the mechanical properties showed that the mechanical behavior of the new polyurea changed gradually from rubbery under a quasi-static load to glassy under a dynamic load, showing excellent impact resistance. The characteristic absorption peaks of the FTIR spectrum of polyurea did not change significantly before and after irradiation. However, the color of the polyurea changed from light yellow to dark red with decreasing dose rate or increasing cumulative dose, which is related to the radiation oxidation time. Some white fragments appeared after the polyurea was irradiated with γ-rays. The number of white fragments increased with decreasing dose rate or increasing cumulative dose, which may be caused by the soft segment embrittlement of polyurea under radiation oxidation. A comparison of the mechanical properties under different γ-ray irradiation conditions found that the newly synthesized polyurea coatings had good resistance to γ-ray radiation. Moreover, their performance was improved to a certain extent after irradiation. The performance of irradiated polyurea was optimum when the irradiation dose rate was 2 KGy/h, and the cumulative dose was 220 KGy.