On-line Monitoring of Films during Stretching by an Optical Fiber Type Spectrometer
| Autor: | Han-Yu Fang, 方瀚宇 |
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| Rok vydání: | 2009 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 In this study, the on-line monitoring of light transmittance of films during stretching was carried out by an optical fiber type spectrometer to investigate the formation of crazes, and microvoids. Two semi-crystalline film materials, polypropylene (PP) and poly(4-methylpentene) (TPX), were used respectively. The film were stretched at various stretching rates, and the change in light transmittance at different strains was analyzed by the optical fiber type spectrometer. Microvoids, crazes, or orientation of crystallites might be generated during stretching, and might cause whitening. The phenomena can be confirmed by the observation of the morphology through polarized optical microscopy (POM), atomic force microscopy (AFM) and X-ray diffractometer (XRD). When TPX film was stretched, crazes were generated first to cause whitening. Afterwards, voids were formed, and cracks took place up to the break point. The generation of whitening for TPX was be affected by the stretching rate significantly. The strain of first appearance of whitening increased as the stretching rate increased. In the stretching of PP film, microvoids were formed and this caused whitening. It seemed that the stretching rate had little effect on the strain of first appearance of whitening of PP. Shrinkage was obvious after releasing the stress of PP film. Moreover, the degree of whitening of PP film decreased and even vanished after releasing the stress, and the increase in transmittance could be observed. The results of POM, AFM, XRD could confirm the structure of microvoids and crazes when films were stretched. The above results indicated that the on-line monitoring by the optical fiber type spectrometer can be used to observe the formation of microvoids, crazes, or whitening behavior during stretching. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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