Skin/core crystallinity of injection-molded poly (butylene terephthalate) as revealed by microfocus X-ray diffraction and fast scanning chip calorimetry
详细信息 查看全文
- 作者：Alicyn Marie Rhoades ; Jason Louis Williams…
- 关键词：Poly (butylene terephthalate) ; Injection molding ; Crystallization ; Skin/core crystallinity ; Microfocus X ; ray diffraction ; Fast scanning chip calorimetry
- 刊名：Journal of Thermal Analysis and Calorimetry
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：127
- 期：1
- 页码：939-946
- 全文大小：
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Physical Chemistry; Analytical Chemistry; Polymer Sciences; Inorganic Chemistry; Measurement Science and Instrumentation;
- 出版者：Springer Netherlands
- ISSN：1588-2926
- 卷排序：127
文摘
The semicrystalline morphology of a poly (butylene terephthalate) was formed under the shear, pressure, and thermal gradients of the injection-molding process, and subsequently studied regarding the crystallinity of the skin layer and the core using fast scanning chip calorimetry (FSC) and microfocus X-ray diffraction. Test bars of 3 mm thickness were molded via a broad tab gate at one end of the part, designed to facilitate a linear flow path and to minimize shearing of the polymer as it passes through the gate. Simulation of the injection-molding process suggests a gradient in the cooling rate through the test part that varies from 50 K s−1 100 µm below the surface to 10 K s−1 in the core, at the temperature of crystallization after the cessation of flow. Analysis of the crystallinity reveals skin and core crystallinities of 35 and 46 %, respectively, near the gate, while there were observed values of 42 and 48 % at the end of fill; XRD data consistently confirmed the crystallinity difference between skin and core, and between the near and far gate positions. The observed cooling-rate-controlled crystallinity values are in excellent agreement with data of the degree and kinetics of quiescent melt-crystallization obtained in a former study. For the first time, the reliability of FSC data obtained during first heating, in order to gain thermal-history/processing-controlled structure information, is demonstrated.