A numerical investigation of the use of novel melt processed PET-hemp fiber composites for thermoforming applications

Abstract

The mechanical and structural properties of five formulations of a novel melt processed poly-ethylene terephthalate (PET)-hemp fibers composite were determined, followed by a numerical investigation of their thermoformability using the ThermoForm® code. The composites' linear viscoelastic properties were determined by small amplitude oscillatory shear tests and their viscoelastic behavior characterized by the Christensen's model. The forming pressure load required by the numerical analysis was derived from the Redlich–Kwong's real gas equation of state. The air flow's influence on the thickness of the thermoformed part, as well as the stress and the energy required for the process were analyzed. Our observations indicate little influence of the constitutive equations of the investigated formulations on the final thickness distribution of the thermoformed part; moreover, the time and energy required for the process showed no clear variation with the fiber load. POLYM. ENG. SCI. 56:1021–1030, 2016. © 2016 Society of Plastics Engineers.