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.

The combustion of a typical thermoplastic polymer, Polypropylene mixed with three additive fire retardants, magnesium hydroxide, aluminium hydroxide and antimony trioxide, was assessed in a cone calorimeter. It is found that the increased MS(OH)(2) content in Polypropylene, further increases the ignition time and reduces the heat release rate. its effect on smoke density is found to be somewhat different, when present at lower percentages it increases the smoke density of fire effluents.

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.

Due to environmental, health, and economic concerns, recycling plastic waste has increased significantly in recent years. Numerous mixes and composites of recycled polymer materials have been studied. Unfortunately, Polypropylene makes up a very small portion of the five primary polymers that make up polymer waste. This study aims to research the usage of recycled Polypropylene (rPP) in combination with virgin Polypropylene (PP) and to use electron radiation to improve the mixture's characteristics for potential applications. After electron radiation exposure, mixtures containing rPP at 0, 5, 10, and 15 wt.% were examined to determine gel content, melt flow index, mechanical properties, and structural characteristics. The irradiation results in crosslinking in the PP mixture, as evidenced by the decrease in melt flow index and the increase in gel content of the irradiated mixes. The tensile strength and elongation at break are unaffected by increasing the amount of rPP, but after exposure to radiation, the tensile strength of samples containing 0 to 10 wt.% of rPP declines by 10% and that of samples with 15% by weight reduces by 15%. In comparison to samples not exposed to radiation, the elongation-at-break increase was also reduced, which appears to be a result of developing a crosslinking net in the polymer's structure. The polymer mixture still exhibits reasonable hammering behavior. The decrease caused by rPP and irradiation is of an appropriate magnitude. The irradiation sample's analysis using a scanning electron microscope also demonstrates improved interaction of PP with rPP. Based on the findings, it appears that the irradiation combination containing 10 wt.% rPP is the optimal sample to use for environmentally recycling post-consumer PP waste, creating new, high-performing products for a variety of applications, Cost reduction, and sustainable production.

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%.