Short‐term creep experiments and modeling on the effect of nano-sized calcium carbonate particles and applied stress on nonlinear viscoelastic behavior of high-density polyethylene

• Published in: Journal of polymer research 2022-04, Vol.29 (4), Article 126
• Main Authors: Sepetcioglu, Harun, Aydemir, Bulent
• Format: Article
• Language: English
• Subjects: Calcium carbonate; Chain mobility; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Creep strength; Creep tests; High density polyethylenes; Industrial Chemistry/Chemical Engineering; Injection molding; Mechanical properties; Microcracks; Original Paper; Polyethylene; Polymer Sciences; Polymers; Raw materials; Strain rate; Stress; Stress transfer; Yield stress
• ISSN: 1022-9760; 1572-8935
• DOI: 10.1007/s10965-022-02985-9

In selecting uses areas engineering parts obtained from polymer materials, they have been decisive their mechanical behavior. Creep behavior is one of the crucial mechanical properties to evaluate polymeric matrix exposed to a constant loading in a short time. In this study, the effect of applied stress and nano-sized calcium carbonate particles (nano-CaCO 3 ) on the short-term creep of the HDPE matrix was studied, and the particle size, morphology, and dispersion within the HDPE matrix were characterized by transmission electron microscopy. The filled HDPE granules were prepared by the melt-mixing method using a compounder system and then were molded as plates through an injection molding. The short-term creep tests were performed at three stress levels as 8 MPa, 12 MPa, and 16 MPa for 600 s at the strain rate of 1E − 4 1/s for short-term creep behavior characterization of the unfilled and filled samples. The instantaneous deformation of all nano-CaCO 3 filled and unfilled HDPE samples increased at all applied stress levels. The creep performance of the HDPE has increased with the addition of nano-CaCO 3 particles at a stress level of 8 MPa, which is below the yield stress of unfilled and filled HDPE samples. However, creep resistance and creep modulus decreased at 12 MPa and 16 MPa stress levels due to the presence of the nano-CaCO 3 particle within the HDPE matrix. This decrement was attributed to decreased interaction between filler/polymer matrix resulting in an incremental in polymer chain mobility and microcrack formation. Besides, a reduction in the creep strain's resistance occurred because the stress transfer decreased. Consequently, the creep test results can be employed to adapt to creep phenomena in the design of engineering parts or semi-products produced from nano-CaCO 3 filled HDPE raw materials.