Viscoelastic properties of kenaf reinforced unsaturated polyester composites

Abstract

In order to quantify the effect of temperature on the mechanical and dynamic properties of kenaf fiber unsaturated polyester composites, formulations containing 10 wt.% to 40 wt.% kenaf fiber were produced and tested at two representative temperatures of 30°C and 50°C. Dynamic mechanical analysis was performed, to obtain the strain and creep compliance for kenaf composites at various styrene concentrations. It is possible to obtain creep curves at different temperature levels which can be shifted along the time axis to generate a single curve known as a master curve. This technique is known as the time–temperature superposition principle. Shift factors conformed to a William–Landel–Ferry (WLF) equation. However, more long term creep data was needed in order to further validate the applicability of time-temperature superposition principle (TTSP) to this material. The primary creep strain model was fitted to 60 min creep data. The resulting equation was then extrapolated to 5.5 days; the creep strain model of power-law was successfully used to predict the long-term creep behavior of natural fiber/thermoset composites.

Polyamide 6 nanocomposites incorporating cellulose nanocrystals prepared by In situ ring‐opening polymerization: Viscoelasticity, creep behavior, and melt rheological properties

“…Time‐temperature superposition (TTS) principle has been successfully and widely used to predict the viscoelastic behavior of polymeric materials at long times or elevated temperatures that are experimentally inaccessible . In the current research, the creep experiments were performed on all samples at five different temperatures namely 25°, 50°, 75°, 90°, and 105°C which covers a temperature range ( T ) below and above the glass transition ( T g ∼ 65°C) (i.e., T = T g ± 40°C).…”