Phase Morphology and Chemorheology during Curing of Polyethersulfone/Bismaleimide Multi-phase System

Abstract

Curing characteristic of bismaleimide (BMI)/polyethersulfone (PES) multi-phase systems was studied by differential scanning calorimetry (DSC) using the non-isothermal method under different heating rates. The phase morphological evolution of BMI/PES-20 resin with the curing temperature and time was investigated by SEM. The chemorheology of BMI/PES was researched by rotational rheometer. Eventually, the relationship between phase separation and rheological properties was discussed. The results indicate that with the increase of the heating rate, the curing rate increases, and the curing characteristic temperatures of BMI/PES-25 systems shift toward higher temperature values but the curing enthalpy values are almost constant. With the increases of temperature, the viscosity keeps constant at low temperature in the curing temperature range of 110-150 ℃, and then increases rapidly. The temperature range, in which resin system maintains low viscosity, is widened with the increase of PES content. The viscosity of BMI/PES-25 displays a remarkable decrease in the curing temperature range of 180-200 ℃, as attributed to the phenomenon that the co-continuous structures convert to the phase inversion structures. The viscosity of BMI/PES-20 has no obvious change in the curing temperature range of 190-200 ℃, and increases rapidly above 200 ℃. The viscosities of BMI/PES-15, BMI/PES-10 and BMI/PES-5 resin systems increase rapidly above 180 ℃. SEM shows that these BMI/PES resins exhibit the ripening of phase structure during the temperature range of 180-200 ℃.

Keywords

• polyethersulfone (PES)
• bismaleimide (BMI)
• curing behaviour
• phase structure
• chemorheological behavior