Polybutylene terephthalate modulus

TPUs and polycarbonate blends and TPU/polycarbonate/ABS blends are used with the addition of the polycarbonate giving higher modulus and solvent stress cracking resistance as well as making processing of the TPU much easier. TPU/polycarbonate/polybutylene terephthalate blends are superior to their ABS analogue for resistance to environmental stresscracking resistance. 

Reinforced polymers that combine high tensile strength with high flexural modulus include polybutylene terephthalate, polyether ether ketone, polyamide-imide, and polyethylene terephthalate (see Table 3.3). 

The speeds of testing for stress and elongation measurements were the same for both ASTM and ISO specimens. The polycarbonate (PC), polybutylene terephthalate (PBT), and high impact polystyrene (HIPS) resins were tested at 50 mm/min. For the acrylonitrile-butadiene-styrene (ABS) resins a speed of testing of 5 mm/min was used. Modulus measurements for ASTM specimens were conducted at these same speeds. For the ISO specimens, a separate set of ten specimens were tested at 1 mm/min. In addition to the difference in speed of testing, tangent modulus was reported for ASTM specimens, and chord modulus at 0,05 and 0.25 percent strains was reported for ISO specimens. 

The need for mechanical reinforcement has been the driving force for most of the reported work on polymer/CNT composites. In an attempt to investigate the mechanical properties of electrospun PAN/SWNT nanofibers, Ko et al. (75) have used an atomic force microscope (AFM) to measure the elastic modulus of the electrospun composite nanofibers. The obtained fiber modulus was 140 GPa, a value which is much higher than that of conventional PAN fibers (60 GPa) (75). In a somewhat related but independent study, Mathew et al. (92) also used AFM to measure the mechanical properties of electrospun polybutylene/MWNT terephthalate nanofibers. Elastic deformation of MWNTs in electrospun PEO/MWNT and PVA/MWNT nanofibers was studied by Zhou and co-workers (84), and was found to increase with an increase in the modulus of the polymer matrix. In the same study, a simplified model was also proposed to estimate the elastic modulus ratio of MWNT and polymers. To confirm the validity of their model, these authors compared the model predictions with experimental data obtained from AFM measurements. 

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