Investigation of tensile behavior and molecular structure of the thermoplastic polyurethane sheets injection molded at different mold temperatures

Abstract

This paper aims to investigate the influence of the mold temperature on the mechanical responses at different ambient temperature and molecular structure of the injection molded TPU sheets. The tensile properties of the TPU sheets prepared at different mold temperatures were obtained at different ambient temperatures. As the mold temperature increases, both the elongation at break and tensile strength of the specimens increase. The specimens show yield behavior during stretching at −30 and −50°C. The microstructure of the TPU sheets was characterized by DMA, AFM, and birefringence. The results show that the higher mold temperature can reduce the aggregation of hard domains because of the higher mobility of the hard segments. In‐situ SAXS and WAXS measurements were carried out at −30°C test temperature to exhibit the evolution of the microstructure during stretching. When the specimens are prepared at 40°C mold temperature, the hard domains are destroyed and difficult to orient along the stretching direction. In contrast, the hard domains begin to be deformed and oriented along the stretching direction above the yield strain when the specimens molded at higher mold temperature. The above microstructure evolution is consistent with the tensile behavior of the TPU specimens.

A Review of Research on the Effect of Temperature on the Properties of Polyurethane Foams

“…The general results show that with the increase in mold temperature, the mechanical properties of polyurethane foams materials such as compression, tensile, shear strength and elastic modulus have a significant decreasing trend. Furthermore, Xiang [ 47 ] investigated the effect of mold temperature (40 °C, 60 °C, 80 °C, 100 °C) on the mechanical response of injection molded polyurethane foams materials at different ambient temperatures and molecular structures, and the stress–strain curves obtained indicated that the increase in mold temperature led to a decrease in tensile strength, as well as tensile modulus and an increase in tensile yield strain. Some scholars have come to different conclusions.…”

A novel multi‐functional model thermoset and PDA‐coated PU nanocomposite based on graphene and an amphiphilic block copolymer

“…Regarding to the Young's modulus, for the common TPUs, it usually falls in the range of 1.5–30.0 MPa based on their chemical nature and processing conditions 38,39 . However, the graphene‐based tPU nanocomposites showed a relatively high modulus, which falls in the range of 38.5–96.2 MPa.…”

“…Regarding to the Young's modulus, for the common TPUs, it usually falls in the range of 1.5-30.0 MPa based on their chemical nature and processing conditions. 38,39 However, the graphene-based tPU nanocomposites showed a relatively high modulus, which falls in the range of 38.5-96.2 MPa. The high modulus of the specimens is due to the presence of graphene nanoparticles with 0.50 wt.%, which is in accordance with the Young's modulus of TPU/graphene nanocomposites.…”

Molecular dynamics simulation study of the joining strength of different polymer‐aluminum heterointerfaces in nano‐injection molding

“…It was revealed by observing the morphological changes during the separation process that the PE layer was divided into two parts, indicating that cohesive damage occurred in the PE body, and the stresses within the PE layer changed. [35,36] This provided a reference for the selection of the joining strength of the integrated structure according to the elastic modulus of the material.…”