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Mechanical and surface properties are considered important in governing the physical strength of polymers. A commercially available oxo-biodegradable polymer additive, which has induced surface and mechanical property changes during photo-oxidation in low-density polyethylene (LDPE) films, has been studied. LDPE films containing the oxo-biodegradable additive were irradiated with ultraviolet (UV)-B lamps at 30 ± 1 1C for an extended time period. The changes manifested on the polymer surface and in the mechanical properties were studied with respect to surface wettability, surface morphology using scanning electron microscope, surface topology by atomic force microscopy, functional groups by Fourier transformed infrared spectroscopy, absorbance spectra by UV-visible spectroscopy and elongation at break and tensile strength through mechanical testing. The increase in the wettability and surface-free energy of the irradiated samples was attributed to the formation of hydrophilic groups on the polymer surface by photo-oxidation, which occurs by the exposure of PE to UV irradiation in the presence of air. The degree of reduction in the mechanical strength and surface property modifications in our study are appreciable through the use of an oxo-biodegradable additive added to LDPE film samples.

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Ester-based thermoplastic polyurethane (TPU) nanocomposites were prepared by melt blending at 1908C, using 3 wt% Cloisite 10A (organically modified montmorillonite clay) as the nanoscale reinforcement [TPU(C10A)]. The nanocomposites were subsequently melt-blended with polypropylene (PP) using maleic anhydride-grafted polypropylene (MA-g-PP) as a compatibilizer [in the ratio of 70/30-TPU/PP, 70/25/5-TPU/PP/ MA-g-PP, 70/25/5-TPU (C10A)/PP/MA-g-PP]. Besides giving substantial increase in modulus, tensile strength, and other properties, organoclay reinforcement functions as a surface modifier for TPU hard segment resulting in improved dispersion. The morphology and other characteristics of the nanocomposite blends were investigated in terms of X-ray diffraction, fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, tensile properties, scanning electron microscopy, and atomic force microscopy. The results indicate that the ester-TPU(C10A)/PP/MA-g-PP exhibited better dispersion than other blend systems; abrasion resistance and water absorption resistance were also better for this system.

The flame retardancy, mechanical properties of a pure polypropylene (PP)/(thermoplastic polyurethane) (TPU) blend, and PP/TPU blends containing nanoclay as flame retardants, were investigated by the limiting oxygen index (LOI) test, vertical burning test (UL-94), rate of burning test (ASTM D 635), and their effect on relevant mechanical properties. The LOI value of the neat PP/TPU blend was 18% and those of the halogenbased bromine-containing (flame retardant)-based PP/ TPU blend and PP/TPU(5% nanoclay-filled)/MA-g-PP (maleic anhydride-grafted-PP) blends were increased by 32% and 28.5% as compared with that of the pure PP/TPU blend, which showed that the above flame retardants and nanoclay could greatly increase the LOI value of the system. However, deterioration of mechanical properties is observed for brominecontaining (flame retardant)-based compositions. The introduction of the nanoclay as the flame retardant to the TPU/PP blend system increased the mechanical properties along with flame-retardant properties. The tensile stress required to make 200% strain in 5% nanoclay added TPU/PP/MA-g-PP nanocomposite increased by 120%, and the flexural modulus increased by 80%-90%. J. VINYL ADDIT. TECHNOL., 00:000-000, 2015.

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The mechanical properties of thermoplastic polyurethane (TPU)/polypropylene (PP) blends were investigated with special reference to the effect of type of polyurethane (ester-or ether-based), blend ratio, compatibilizer, and sequence addition of nanoclay. Tensile strength, stress at different elongations, flexural modulus, and abrasion resistance were analyzed and correlated with morphology. Blends of nanoclay filled thermoplastic polyurethane (TPU)/polypropylene (PP) of various compositions were evaluated by dynamic mechanical properties such as storage modulus (E′), loss modulus (E″), and dissipation factor (tan δ), at a frequency of 10 Hz over a temperature range from −100 to 200 °C. Finally different theoretical models were used to compare the experimental results with theoretical predictions.