2.8. Low-density polyethylene (LDPE) is used in food packaging because of its high-impact resistance and good resistance to a wide range of chemicals. In a study, the stress relaxation behavior of LDPE at high temperature (115°C) was examined under constant strain of 0.01 and the data are given in Table P.2.8.1.
(a) Determine the relaxation time for LDPE. If the viscosity of LPDE at 115°C is 200 kPa ■ s, calculate its corresponding G value.
(b) Calculate the Deborah number of the LDPE sample and compare the Deborah number of glass at 27°C having a relaxation time of 105 s for the same observation time with the LDPE.
2.9. To determine the influence of glutaraldehyde as a crosslinking agent to increase the strength of collagen, 1% collagen solution was treated with 0.09% of glutaraldehyde. Then, the viscoelas-ticity of the resulting collagen gel was examined by using the creep compliance data given in Table P.2.9.1. Examine the creep behavior of the collagen gel with the Kelvin-Voight model and obtain the values of G, A.ret, and p.
Was this article helpful?