Microstructure and tensile properties of injection molded thermoplastic polyurethane with different melt temperatures

Abstract

The use of injection molding technology to prepare heterogeneous interlayer film of laminated glass holds strong applicable potential. This article aims to investigate the effects of melt temperature and melt flow on the microstructure evolution and tensile properties of thermoplastic polyurethane (TPU) specimens during the injection molding process. The tensile properties of the TPU specimens show dependency on the melt temperature and melt flow direction. The results of birefringence indicate that melt flow and lower melt temperature induce higher stretching deformation of the molecular chain network. Small-angle X-ray scattering analysis approves that besides the melt temperature and flow direction, the testing position on the cross section of the specimen has great influence on the microstructure of the TPU sheet. Further analysis and conclusions can be made using wide-angle X-ray scattering method. The above results demonstrate that both the tensile properties and microstructure of the injection molded TPU specimens tend to be isotropic with the increase of melt temperature.

Long-Term In Vivo Response of a Polyurethane Gastric Implant for Treating Gastro-Oesophageal Reflux Diseases: A Comparison of Different Surface Treatments

“…Since the peak area was directly proportional to the crystallinity of polymers, the peak changes may indicate the processing and sterilisation influences on the gastric implant structure as the implant's crystallinity significantly increased after the injection moulding compared with unprocessed thermoplastic polyurethane. The increased orientation degree of thermoplastic polyurethane long molecule chains has been reported previously due to the shearing and heat [77]. As reported by others, gamma radiation causes crosslinking of long polymer chains, where there is a limiting chain's free motion, and therefore prohibited crystallite regions [78,79].…”

Preparation of laminated safety glass based on high strength polyurethane film by solution annealing

“…16 On the premise of maintaining the high light transmittance, it is an effective way to enhance the safety characteristics of laminated glass by improving the tensile strength and elongation at break of polyurethane intermediate film. 17 The excellent mechanical properties of polyurethane are attributed to their regulation of intermolecular hydrogen bonding, the crystallization of molecular segments and phase separation morphology. The results have verified that additives and molecular crosslinking structure have been considered as an effective way to improve the properties of polyurethane film.…”

“…The impact resistance of laminated glass is depended on the mechanical and bonding properties of polyurethane intermediate film 16 . On the premise of maintaining the high light transmittance, it is an effective way to enhance the safety characteristics of laminated glass by improving the tensile strength and elongation at break of polyurethane intermediate film 17 . The excellent mechanical properties of polyurethane are attributed to their regulation of intermolecular hydrogen bonding, the crystallization of molecular segments and phase separation morphology.…”

Injection molding and shear‐induced stress simulation of poly (styrene‐ethylene‐butylene‐styrene) and polypropylene blends

“…In injection molding, high‐speed shear can untie the entangled molecular chains of the triblock copolymer, reduce its melt viscosity, improve its mold filling ability, and obtain good mechanical properties 22 . However, the anisotropy caused by shearing makes the polymer chain in an unbalanced stress conformation, 23 which is prone to form microscopic defects and macroscopic dimensional changes under external stimulation. Very high‐shear rate may also cause slippage between molecular chains in the blend, and composite systems with different phase structures and heterogeneous relaxation spectra may form unstable interface coupling and additional residual stress 24 …”