화학공학소재연구정보센터
Journal of Polymer Science Part B: Polymer Physics, Vol.36, No.12, 2225-2235, 1998
Thermal stability and nonisothermal crystallization of short fiber-reinforced poly(ether ether ketone) composites
The thermal stability of a short carbon-fiber-reinforced PEEK composite was assessed by thermogravimetry and by a Rheometrics dynamic analyzer. The results indicated that holding for 10 min at 380 degrees C was a suitable melting condition to avoid the thermooxidative degradation under air. After proving that the heating rate of 50 degrees C/min can be used to evaluate the crystallinity, a heating stage was used to prepare nonisothermally crystallized specimens using cooling rates from 1 to 100 degrees C/min after melting at 400 degrees C for 3 or 15 min. The degree of crystallinity and the melting behavior of these specimens were investigated by DSC at a heating rate of 50 degrees C/min. The presence of three or four regions indicated that the upper melting temperature, T-m, changed with the crystallization temperature. The first region with the highest T-m,T- which corresponded to the cooling rate of 1 degrees C/min, can be associated with the crystallization in regime II. There was a second region where T-m decreased as the amount of crystals formed in regime II decreased with increasing cooling rate from 5 to 20 degrees C/min. The third region, a plateau region, corresponded to regime III condition in which the crystals were imperfect. In the fourth region, the cooling was so fast that crystallization was incomplete during the cooling for the melting condition of 400 degrees C for 15 min.