INEB
INEB
TitleEnhancement of the mechanical properties of a high-density polyethylene
Publication TypeJournal Article
1999
AuthorsKalay, G, Sousa, RA, Reis, RL, Cunha, AM, Bevis, MJ
JournalJournal of Applied Polymer ScienceJ. Appl. Polym. Sci.
Volume73
Issue12New York, NY, United States
Pagination2473 - 2483
Date Published1999///
00218995 (ISSN)
differential scanning calorimetry, Elastic moduli, High density polyethylenes, Injection molding, morphology, Optimization, Shear controlled orientation in injection molding, Shear flow, Shish kebab structure, Stiffness, Strength of materials, tensile strength, Tensile testing, Toughness, Wide angle X ray diffraction, X ray diffraction analysis
This paper describes the process optimization in injection molding of high-density polyethylene (HDPE). Both conventional injection molding and shear controlled orientation (SCORIM) were employed in processing. The process optimization was based on design of experiments and complemented with analysis of variance. Mechanical characterization was carried out by tensile testing. Wide-angle X-ray diffraction and differential scanning calorimetry were used for the structural characterization of the moldings. High-density polyethylene exhibits 7.2 GPa Young's modulus and 155 MPa of ultimate tensile strength following the application of SCORIM processing. These results account for a fourfold increase in Young's modulus and a fivefold increase in ultimate tensile strength compared to conventional injection molding. The maintenance of toughness while enhancing stiffness and strength of the SCORIM moldings is attributable to an oriented morphology developed during shear flow, i.e., shish-kebab structure. The frequency of shearing action has the strongest influence on the morphology development. It is also demonstrated that the studied parameters are very much interdependent. It is possible to achieve substantial gains in mechanical properties of HDPE in SCORIM processing without causing a substantial increase in cycle time.
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