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Characterization of molecular orientation in injection‐molded thermoplastics by transmission and reflection infrared spectroscopy
Author(s) -
Houska M.,
Brummell M.
Publication year - 1987
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760271208
Subject(s) - materials science , composite material , molding (decorative) , polypropylene , phase (matter) , polystyrene , reflection (computer programming) , amorphous solid , infrared spectroscopy , perpendicular , orientation (vector space) , infrared , spectroscopy , optics , crystallography , polymer , geometry , chemistry , mathematics , physics , organic chemistry , quantum mechanics , computer science , programming language
Orientation in injection moldings of polypropylene (PP), polyethylene (PE), polyamide 6 (PA‐6), and polystyrene (PS) was investigated by transmission and reflection infrared spectroscopy. Orientation of the surface was measured by the reflection method, the depth profiles of orientation and of the fraction of the crystalline phase were measured by the transmission spectroscopy of microtome sections. The maximum of orientation of PP lies in the subsurface layer (ca. 250 μm); the crystalline phase is oriented more than the amorphous one. The maximum of the depth profile of orientation corresponds to the minimum of the fraction of the crystalline phase in PP. The profile of orientation of PE Is similar; at the beginning (to a depth of about 500 μm) the parallel orientation of the c axis of the crystalline phase is the most distinct one, towards the center the orientation of the a axis passes from the perpendicular to the parallel one. Under the described molding conditions PA‐6 is not significantly oriented, the fraction of the crystalline phase increases towards the center of the molding. Unoriented PA‐6, the surface layer of which was removed by milling, has a highly oriented surface due to its mechanical treatment. No pronounced orientation of PS was observed under the molding conditions used.