The barrier polypropylene (PP) films were prepared via REACTIVE blending of PP with polyethylene terephthalate (PET) in an intermeshed co-rotating twin-screw extruder. Films were prepared via EXTRUSION through a flat die followed by postEXTRUSION stretching. The effects of compatibilizer, PP-g-MA, content and draw ratio were investigated. SEM micrographs showed that the dispersed phase inclusion size decreases significantly upon the addition of compatibilizer. Morphological studies of the films have shown that laminar morphology was developed in the machine direction rather than in transverse direction. The optimum morphology was observed at 5% compatibilizer concentration. Tensile tests showed that melt stretching has resulted to the inferior properties except modulus. Mechanical properties of blends decreased significantly upon the addition of PET and increased as the compatibilizer content was raised to 10%. Higher contents, however, showed no improvement, as it just improves the physical properties of the blends. Blending results in 200% improvement in the oxygen barrier properties. Permeability of the stretched films and compression moulded films showed 25-35% improvement in the oxygen barrier properties. The maximum barrier property of the extruded films was observed at 5% compatibilizer and draw ratio of 2. Higher contents (up to 15%) resulted in decreased oxygen barrier properties.

Aseries of PE/SiO2 nanocomposites, namely PE2D, PE5D, PE7D and PE10D, were prepared via REACTIVE EXTRUSION from the mixtures of vinyl functionalized nano-SiO2 (v-SiO2), Dicumyl peroxide and PE. For comparison, PE/SiO2 nanocomposite (PE7) was also prepared by the same method from a mixture of v-SiO2 and PE. SEM and TEM micrographs showed that the above products were composed of nanocomposite. Xylene extraction results showed that, except PE7, nanocomposites contained gel. FTIR Spectra showed the existence of SiO2 in the gels, meaning that SiO2 nanoparticles were covalently bonded to PE chains, i.e., PE2D, PE5D, PE7D and PE10D were nanocomposites formed by covalent bonds between SiO2 and PE.Studies based on DSC show that all the nanocomposites have Tm of close values and PE7 has higher crystallinity than other nanocomposites. Mechanical properties were investigated through tensile tests and the results show that covalently bonded PE/SiO2 nanocomposites have better performance compared to PE7. In this respect, the tensile strength, modulus, and elongation-at-break of PE7D are given as 41.5 MPa, 349 MPa and 1060% which are as high as 170%, 126% and 125% of the values for pure PE.While the tensile strength, modulus, and elongation-at-break of PE7 are only 109%, 108% and 109% of the values for pure PE, indicating the significant effect of covalent bond between polymer matrix and nanoparticles.

The effects of an ε,-caprolactam (CL) modified nanosilica (MNS) component on thermal properties, morphology and rheological behavior of PA6/SiO2 nanocomposites were investigated. Star-shaped PA6/SiO2 nanocomposites were synthesized through a two-step in situ anionic ring-opening polymerization (AROP) of CL monomer by hexamethylene diisocyanate (HDI) linking the nanoparticles and CL in a REACTIVE melt blending. The star-shaped structure was observed by field emission scanning electron microscope (FESEM) and elemental mapping. Moreover, the study on chemical structure of the samples was carried out by Fourier transform infrared (FTIR), energy-dispersive X-ray spectroscopy (EDX) and carbon nuclear magnetic resonance (13C NMR) spectroscopy. Incorporating MNS increased γ,-crystal and arm numbers of the star-shaped structure. Thermal degradation increased in the star-shaped samples due to the effects of MNS and molecular weight (MW). However increasing the number of arms was effective in increasing the temperature of degradation. In addition, the crossover of storage modulus (Gʹ, ) and loss modulus (Gʺ, ) shifted to higher frequencies in the low-and lower frequencies in the multi-arms star-shaped samples. Shear viscosity and glass transition temperature (Tg) of the multi-arms samples with maximum MNS loading were lower than those of other samples. Furthermore, dispersity, and their MWs were higher than those of other samples. Therefore, the resulting multi-arms star-shaped nanocomposites may be desirable for industrial productions in absence of solvents and lowering cost and energy rather than linear PA6.

Styrenic thermoplastic vulcanizates (STPV) consist of polypropylene (PP) and linear low density polyethylene (LLDPE) as the continuous phases and a crosslinked hydrogenated styrene block copolymer (SEBS) as the dispersed phase were prepared in an industrial scale using a corotating twin-screw extruder. Morphological study of the TPVs was carried out using a scanning electron microscope (SEM). Rheological study of the SEBS compounds carried with different content of 2,5-Dimethyl-2,5-di(tert-butylperoxy) hexane peroxide (0.5, 1, 2 and 4 wt. %). T90 appeared with 4 w% peroxide shows that curing has been completed. Effect of peroxide content (0.5 to 1.2 wt.%) on properties of the TPVs was led to an increase in tensile strength (from 5.6 to 7.4 MPa) and hardness to a certain extent (74 shore A). On the other hand, mechanical properties such as the elongation at break (from 592% to 284%), the melt flow index (MFI) (from 29.6 to 3.14 g/10 min at 190 °C, 10 kg) and tear strength (from 35 to 30 kg f/cm) are decreased. The compression set at low temperature (70 °C) is not changed so much, at high temperature (120 °C), while, is reduced due to higher curing (from 69% to 46%). Heat aging was carried out (at 85 °C for 168 h) on the TPVs which were prepared via the different content of peroxide (0.5 wt. % to 1.2 wt. %). It was found that the results of elongation and the hardness after aging have the lowest amount using 0.9 wt.% peroxide. However, the tensile strength after aging decreased with increasing the content of peroxide. As a result of increasing curing with increasing content of peroxide, the melting point of the prepared TPVs was disappears. The results of using triallylcyanurate (TAC) and bismaleimide (BMI) as a co-curing agent in peroxide curing indicate that all of the tensile strength, hardness and elongation at break (from 897 to 1082%) of the STPV were increased with BMI. Heat ageing study and compression set on the STPV with TAC was slightly raised compared to BMI. Also, the results of dynamic vulcanization on the properties of TPV based on SEBS/LLDPE/PP indicate that Crosslink density and gel content of TPV are close to that of EPDM rubber (fully crosslinked) and higher than that of TPE (without crosslinking). The results show that the tensile strength and density of the dynamically crosslinked blend have not changed significantly under peroxide curing.

Nanocomposites based on high-density polyethylene-grafted maleic anhydride (HDPE-g-MA) were prepared by in situ REACTIVE melt mixing using a twin-screw extruder. The effects of different modified clays and maleic anhydride content on intercalation and mechanical properties were studied. The nanocomposites were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy techniques and tensile testing. The results show that clay I.30TC is suitable for preparation of HDPE-g-MA/clay nanocomposites. Grafting HDPE with MA contributed to higher degree of intercalation in clay particles and increases the tensile modulus of nanocomposite. MA content should be maintained at a certain level to improve the extent of intercalation. During the process, grafted maleic anhydride groups on HDPE backbone are converted to acid pendant groups. In order to determine the extent of cross-linking as a function of MA content, the gel content of the samples were measured. A significant improvement in the tensile modulus of the HDPE/clay nanocomposites was observed without changes in tensile strength and elongation-at-break values. 

Vortex EXTRUSION (VE) is a severe plastic deformation technique which is based on the synergies between high strain accumulation and high hydrostatic pressure. Such a high amount of pressure places a mandate to seek the method for investigation of the load under processing conditions. For this, kinematically admissible velocity field and upper bound terms based on Bezier formulation are developed in order to investigate relative pressure in the VE process. Effects of reduction in area, relative length, twist angle, and friction factor in power dissipation terms are systematically analyzed. It is demonstrated that the increase in twist angle, area reduction and friction factor in the VE process increases the relative pressure, which the rates of these increase vary with twist angle. Moreover, the effect of the relative length is different in various frictional conditions. Results of conventional EXTRUSION (CE) are in good agreement with those found by Avitzur for the effect of slug length and friction factor on the relative EXTRUSION stress.