Time–temperature superposition principle applied to a kenaf‐fiber/high‐density polyethylene composite

Abstract

ABSTRACT:The time-temperature superposition principle was applied to the viscoelastic properties of a kenaffiber/high-density polyethylene (HDPE) composite, and its validity was tested. With a composite of 50% kenaf fibers, 48% HDPE, and 2% compatibilizer, frequency scans from a dynamic mechanical analyzer were performed in the range of 0.1-10 Hz at five different temperatures. Twelve-minute creep tests were also performed at the same temperatures. Creep data were modeled with a simple two-parameter power-law model. Frequency isotherms were shifted horizontally and vertically along the frequency axis, and master curves were constructed. The resulting master curves were compared with an extrapolated creep model and a 24-h creep test. The results indicated that the composite material was thermorheologically complex, and a single horizontal shift was not adequate to predict the long-term performance of the material. This information will be useful for the eventual development of an engineering methodology for creep necessary for the design of structural building products from these composites.

Thermo-viscoelastic and viscoplastic behavior of high-density polyethylene

“…Fig. 7 demonstrates that the apparent activation energy of HDPE far below the melting temperature is about 78 kJ/mol, which is lower than the values provided in some studies grounded on the standard method of superposition of observations in dynamic tests: E a ¼ 110-140 (Zamfirova et al, 2002), E a ¼ 137 (Pegoretti et al, 2000), E a ¼ 150-170 (Mano et al, 2001), E a ¼ 174 (Djokovic et al, 2000), and E a ¼ 207 kJ/mol (Tajvidi et al, 2005), but agrees well with the activation energies E a ¼ 50-140 (Stadler et al, 2005), E a ¼ 65-80 (Boiko et al, 1995), E a ¼ 79-106 (Matsuo et al, 1988), and E a ¼ 89 kJ/mol (Ohta and Yasuda, 1994). The fact that the apparent activation energy of HDPE in the solid state exceeds that of HDPE melt by twice [in the latter case, the activation energy belongs to the interval between 27 and 32 kJ/mol (Bin Wadud and Baird, 2000)] appears to be natural, whereas rather high values of the activation energies (close to the activation energies for thermal degradation of this polymer [E a ¼ 210-270 (Sinfronio et al, 2005) and E a ¼ 260-290 kJ/mol (Marazzato et al, 2007)] ''shows that the physical significance of E a .…”

Evaluation of Time Dependent Behavior of a Wood Flour/High Density Polyethylene Composite

“…They found that the horizontal superposition was not satisfactory and two-dimensional superposition method was somewhat preferable. Comparing the results of this study with that of Tajvidi et al (2005), it can be suggested that the equivalency between stress level and time may be more than the equivalency between temperature and time. …”

“…Tajvidi et al (2005) investigated the time temperature response of kenaf-fiber/high density polyethylene composites. Short duration (12 min) creep tests were performed at five different temperatures.…”

Effect of Chemical Treatment of Flax Fiber and Resin Manipulation on Service Life of Their Composites Using Time-Temperature Superposition

“…TTS is valid when temperature dependence of horizontal shift factors are in the form of either Williams-Landel and Ferry (WLF) [50] or Arrhenius [51] Equations, the creep tests temperature range should be below material degradation, and there should be no residual curing of the resin occurring during the creep tests. In addition, for crystalline and semi-crystalline materials, the deformation should be kept in the linear viscoelastic range by applying low strains [52].…”