descriptive and historical account with experimental evidence is provided for the production feasibility of micro- and nanofibrils from structured-fibres using existing technologies. Blends of 6.25% POLYPROPYLENE, 87.5% nylon 6 and 6.25% POLYPROPYLENE grafted with maleic anhydride as compatibilizer (N6/PP-g -MAH/PP) were spun into continuous filaments yarns using a melt spinning unit (pilot plant) at the speed of 2000 m/min. The yarn samples were drawn in a drawing unit with draw ratios of 1.3 and 2.6. Samples were treated with formic acid (98%) to dissolve the nylon component that forms the matrix of the bi-constituent filaments. Different analytical techniques including polarizing microscopy, scanning electron microscopy, FTIR spectroscopy, differential scanning calorimetry and wide angle X-ray diffraction were used to examine the filaments and fibrils. It is shown that by existing technology it is possible to produce polyblend filaments from two rather incompatible polymers, while the extraction of POLYPROPYLENE micro and nanofibrils is possible either by decantation or Soxhlet using formic acid as solvent for nylon 6. The extracted fibrils were partially crystalline having melting temperature close to neat POLYPROPYLENE. The fibrils have diameters less than one micrometer, down to less than 100 nm. By examining the fibrils, it was found that fibrils are partially crystalline with considerable molecular orientation.

POLYPROPYLENE-clay nanocomposites were prepared in solution and followed by a melt mixing process. The nanocomposites were prepared for 5% (by weight) organoclay with varying amounts of two oxidized POLYPROPYLENE waxes (OPPWs) as compatibilizer. The clay dispersion was analyzed by X-ray diffraction (XRD), transmission electron microscopy and melt rheology technique. The extent of intercalation in clay platelets was quantified by XRD analysis based on interactions between OPPW and clay layers. A maximum of ca.10% increase in clay basal spacing was observed. It was revealed that the degree of clay intercalation in solution technique varies by the polarity of OPPW. In subsequent melt mixing process, the clay dispersion was evaluated by XRD which correlated well with the variations of storage moduli at low frequency region and displayed a pseudo solid-like behaviour. The rheological measurements also showed higher dispersion of clay platelets in PP matrix in the presence of OPPW. The increase in storage moduli especially at low frequency region implied that there were stronger interactions between Cloisite® 15A organoclays and polymer chains when OPPW is present. The TEM images mainly suggested to com-patibilizing effect of OPPW in clay intercalation. In spite of low mechanical properties of OPPW, the DMTA showed the highest modulus of glassy region in nanocomposites with maximum OPPW content. These findings agreed well with each other in co-intercalation effect of OPPW in PP nanocomposites.

Observations are reported on isotactic POLYPROPYLENE in uniaxial tensile relaxation tests on specimens subjected to tension up to various maximum strains and retraction down to various stresses. Noticeable evolution of shapes of relaxation curves under retraction is revealed with stress at the beginning of relaxation process: with a decrease in this stress, relaxation diagrams characterized by a monotonic decay of stress with time (simple relaxation) become, first, non-monotonic (mixed relaxation), and, finally, monotonically increasing (inverse relaxation). A thorough investigation is performed on the effect of multi-cycle preloading (maximum strain per cycle, minimum stress per cycle, number of cycles, and strain rate) on transition from simple to mixed and to inverse relaxation. It is found that (1) intensity of mixed relaxation increases with maximum strain when this parameter remains below the yield strain and decreases in the post-yield region of deformations, (2) an increase in number of cycles under preloading leads to reduction of intensity of mixed relaxation and transition from mixed to inverse relaxation, (3) inverse relaxation diagrams of specimens subjected to the same preloading program with various strain rates can be superposed to construct a master-curve. A constitutive model is developed in cyclic viscoelastoplasticity of semi crystalline polymers. A polymer is thought of as two-phase continuum composed of amorphous and crystalline regions. Both phases were treated as viscoelastoplastic media whose response was governed by different kinetic equations for evolution of plastic strains and different kinematic equations for changes in relaxation rates and relaxation spectra driven by plastic flow. Good agreement is demonstrated between the experimental data in relaxation tests under retraction and the results of numerical simulation.

In this research, influence of thermo-mechanical degradation of POLYPROPYLENE (PP) on physical and mechanical properties of wood- PP composites made from virgin and degraded PP blends was studied. For this purpose, a virgin PP was thermo-mechanically degraded by twice extrusion under controlled conditions with a twin-screw extruder. Virgin PP and degraded PP in each stage were mixed and the blends and beech sawdust (-40/+60 mesh) were compounded (at 60% weight sawdust loading) in a counter-rotating twin-screw extruder in presence and absence of compatibilizer to produce the sawdust-PP composites. The results showed that replacing 50% of virgin PP by degraded PP, impact strength of wood-PP composites decreases but water absorption, thickness swelling, flexural modulus and hardness increase. Compatibilizer improved the mentioned properties.

Fiber reinforced concrete (FRC) has been used widely due to its advantages over plain concrete such as high energy absorption, post cracking behavior, flexural and impact strengths, arresting shrinkage crack.This research discusses the effect of increasing the percentage of POLYPROPYLENE fiber on flexural toughness and strength of FRC. Three percentages of POLYPROPYLENE fiber were substituted in 1% steel fiber reinforced concrete (SFRC). Finally, the mechanical properties of three types of hybrid fiber reinforced concretes were compared with each other and with steel fiber reinforced concrete by measuring their flexural toughness and flexural strength. A four-point bending test was adopted to determine the effect of hybrid fibers on crack arresting and post crack behavior.The research results show that the more the percentage of POLYPROPYLENE fiber which is substituted in SFRC is, the less the amount of energy absorption and flexural toughness with FRC will be.

The influence of maleic anhydride-POLYPROPYLENE (MAPP) (0, 2, 3 and 5%) as a compatibilizer on the wettability of POLYPROPYLENE/wood flour/glass fiber hybrid composites was studied by using the contact angle determination technique. Sample slats with a cross section of 10×70 mm were made by a twin screw extruder. Specimens were conditioned at room temperature and the angles between the water droplets and surfaces of the hybrid composites were measured. Results revealed that the wettability of the composites was significantly decreased as the MAPP was increased to 3%. However, no significant decreasing effect was observed at MAPP contents above 3%.

In this work rheological behavior of polyethylene/POLYPROPYLENE blends produced by Arak and Bandar Imam Petrochemical complexes was investigated. The viscosity of homopolymers, PE and PP, and their blends at different concentration proportions were measured. The measurements have been carried out by using a capillary rheometer. The results for the blends show that when two homopolymers with great difference in shear viscosity form a blend, the viscosity of the blends are intermediate between the viscosity of homopolymers. On the other hand, for the two homopolymers (PE and PP) with viscosities close to each other, the curve of viscous homopolymer falls down quickly below the viscosity of blends with high shear rate. It has been shown that the viscosity of the blends versus PE content has negative deviation from logarithmic addition rule. The modeling of viscosity of blends in respect to concentration of homopolymers has been produced and it is shown that the modified Kulezner model can predict the viscosity of the blends in terms of viscosities of original resins with very good precision.

The main goal of this work was to examination the structural and compositional changes in the POLYPROPYLENE (PP) fabrics caused by ion irradiation. In this work, the PP fabric was irradiated with CO2 ions. The implantation conditions (i.e, exposure time, beam current, and discharge power) were changed to control the extent of surface modification. Dye ability of the untreated sample and treated sample under different conditions were investigated by using a 3% wt aqueous solution of a basic dyestuff.The obtained data show that, ion beam processing of PP fabrics allows an adjustable modification of their surface properties. The functional groups on the surface of samples were examined using FTIR spectrometer. Moreover, dyeing properties for treated fabrics has been tested. Significant increase in color strength has been achieved. Morphology of samples was examined by Scanning Electron Microscopy (SEM).

The compatibilizing effect of hyperbranched poly(amide-ester) grafted POLYPROPYLENE (PP-HBP) had been investigated in POLYPROPYLENE (PP)/poly(vinyl chloride) (PVC) blends. In this work, PP/PVC/PP-HBP blends were prepared by melt mixing. Mechanical and rheological properties and phase morphologies of the blends were studied as a function of PP-HBP. The results showed that the tensile strength of the blends reached the maximum value when the content of PP-HBP was 5 phr and then dropped on the increase of PP-HBP. The impact strength of the blends showed a small change as that of pure PP/PVC blend, and the viscosity of the PP/PVC/PP-HBP blends was higher than that of pure PP/PVC when the amount of PP-HBP added was£ 5 phr. The viscosity of the PP/PVC/PP-HBP blends was lower than that of pure PP/PVC blend when PP/PVC blend contained PP-HBP > 5 phr. The scanning electron microscopy (SEM) showed that a two-phase morphology was characteristic of all blends. In presence of PP-HBP, the PVC spherical droplets of the minor phase dispersed in a PP continuous matrix phase, whereas there was a large difference among the minor-phase particle sizes. The SEM photos also confirmed that PP-HBP could enhance the adhesion at the interface and reduce the phase separation of PP/PVC blend. The tensile strength of the blends was in accordance with their morphology.