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Anisotropy and dimensions of blow‐molded polyethylene bottles
Author(s) -
Kamal Musa R.,
Kalyon Dilhan,
Tan Victor
Publication year - 1982
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.760220504
Subject(s) - materials science , composite material , crystallinity , blow molding , reciprocating motion , birefringence , extrusion , anisotropy , polyethylene , molding (decorative) , bottle , high density polyethylene , crystallization , optics , mold , mechanical engineering , chemistry , physics , organic chemistry , engineering , gas compressor
A commercial blow‐molding grade, high‐density polyethylene resin was employed to produce cylindrical bottles in a commercial reciprocating screw‐extrusion blow‐molding machine. The distributions of thickness, crystallinity, birefringence, and impact strength were obtained at various positions. The thickness is greatest near the parting lines, while minimum thickness occurs at the top and bottom of the bottle. The thickness tends to be uniform in the middle section, in agreement with earlier studies of the parison during processing. Density and crystallinity distributions are closely associated with the distribution of thickness and its effect on the cooling rates prevailing during molding. Frozen stresses and birefringence are largest at the outer surface, where cooling rates are highest. The impact strength is lowest near the parting line. Photomicrographs suggest that this is associated with internal flow and crystallization phenomena.