Effects of Thermal-Oxidative Aging on the Flammability, Thermal Degradation Kinetics and Mechanical Properties of DBDPE Flame Retardant Long Glass Fiber Reinforced Polypropylene Composites

Long glass fiber reinforced polypropylene composites containing 2,2',3,3',4,4',5,5' ,6,6'-decabromobibenzy flame retardants (LGF/DBDPE/PP) are prepared by melt blending method. The flame-retardant properties of the composites with various thermal-oxidative exposure time (0-50 days) at 140 degrees C were investigated by the limiting oxygen index (LOI) and UL-94 vertical burning test. The LOI values vary slightly with increasing the aging time, while the UL-94 level maintains a constant V-0 rating. The results demonstrate that the flammability of LGF/DBDPE/PP composites can remain at a relatively stable level in long time thermal-oxidative aging process, which can be attributed to the excellent efficiency of DBDPE fire retardant and the impacts of thermal-oxidative aging on the thermal stability of the composites turned out to be small. The thermal degradation kinetics of the unaged and aged LGF/DBDPE/PP composites are investigated by the Flynn-Wall-Ozawa and Kissinger methods. The obtained activation energy values can further provide objective evidence for revealing the regularities about the flammability of the LGF/DBDPE/PP composites during the thermal-oxidative aging process. However, the crystallinity and mechanical properties of LGF/DBDPE/PP composites show a slow downtrend after thermal-oxidative aging. (C) 2018 Society of Plastics Engineers