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Orientation and crystalline morphology of blow molded polyethylene bottles
Author(s) -
Choi KyungJu,
Spruiell Joseph E.,
White James L.
Publication year - 1989
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.760290706
Subject(s) - materials science , high density polyethylene , bottle , polyethylene , linear low density polyethylene , composite material , low density polyethylene , lamellar structure , blow molding , extrusion , crystallization , orientation (vector space) , geometry , chemical engineering , mold , mathematics , engineering
A study was carried out of the development of orientation during processing of conventional blow molded bottles made from low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE). The level of molecular orientation was found to be relatively low in all of the polyethylene bottles examined; it increased with increasing inflation pressure and decreasing extrusion temperature. Pole figures for the HDPE bottles indicated a slight a‐axis orientation toward the circumferential direction of the bottle. The b‐axes, which correspond to the lamellar growth direction, tend to be parallel to the bottle thickness direction. A comparison was made of the structure developed in blow molded bottles and blown films. The results for both films and bottles indicate that crystallization during processing involves both an increase in level of molecular orientation and an increased tendency toward biaxiality. Based on pole figures and small angle X‐ray scattering patterns, a morphological model for HDPE blow molded bottles is proposed.