Study on crystallization behaviour of co-polyamide 66 containing triaryl phosphine oxide

In this paper, the isothermal crystallization and non-isothermal crystallization behaviour of flame retardant co-polyamide 66 (FR-PA66) containing triaryl phosphine oxide (TPO) were researched by employing differential scanning calorimetry (DSC), polarized optical microscopy (POM), respectively. The effects of TPO groups on nucleation mechanism, nucleation pattern and crystallization rate of FR-PA66 were discussed in detail. Experimental results show that TPO unit does not nucleate first during crystallization process of FR-PA66. The nucleation mechanism and nucleation pattern of FR-PA66 do not virtually change with incorporation of TPO groups when compared with polyamide 66 (PA66). The mainly crystallization process of FR-PA66 is still free nucleation and growing during the prime crystallization stage, and is unimensional nucleation and growing during the second crystallization stage. But at the second crystallization stage, we think there is a para-crystal forming with the main-crystal unimensional nucleation and growing. In addition, incorporation of TPO groups result in the decrement of both nucleation rate and crystallization rate of FR-PA66, and the increment of crystallization activation energy. Hence the TPO groups were unfavourable for FR-PA66 crystallization. In addition, incorporation of TPO groups also result in the decrement of crystallization region of FR-PA66, and increment of spherulite defect.