Reinforcement Of Polypropylene Matrix Research Articles

Utilization of flours from hemp stalks as reinforcement in polypropylene matrix

Utilization of hemp stalks (HS) was investigated as filler and maleic anhydride-grafted polypropylene (MAPP) as a coupling agent relative to some mechanical, physical, morphological, and thermal properties of polypropylene (PP) composites. The test sample manufacturing used 10, 15, 20, 25, 30, and 35 wt% of HS and 0 wt% or 3 wt% of MAPP. Test specimens were manufactured by combining extrusion and injection molding processes. Results showed that incorporating filler and MAPP increased the mechanical properties significantly. The utilization of HS filler or MAPP provided an improvement of 11.7% (samples containing 35 wt% HS and 3 wt% MAPP) improvement in tensile strength, 44.2% (samples containing 35 wt% HS and 3 wt% MAPP) in flexural strength, and 60.2% (samples containing 30 wt% HS and 0 wt% MAPP) in impact strength compared to neat PP. The scanning electron microscopy analysis provided visual evidence that MAPP improved adhesion between the filler and the polymer matrix. This study showed that using hemp stalks in composite manufacturing provided good overall properties.

Effect of particle sizes on the mechanical behaviour of limestone-reinforced hybrid plastics

The present research has been made to investigate the characteristics of a new composite material made up of limestone as particle reinforcement. New composites are made by taking limestone particles in five different sizes and jute as woven reinforcement in polypropylene matrix. Mechanical characteristics of the composites that include strengths against tension, compression, flexural, impact and hardness are evaluated and a comparative investigation is made among the composites. The effect of particle size on the properties is analysed and found that the composite with medium particle size bears the highest strength in all aspects. In addition, microscopic image analysis is carried out to investigate the distribution of particles, bonding capacity and other morphologies. The results showed that limestone will be apt particle reinforcement and its presence enhances all the characteristics of the composite.

Response surface methodology based analysis of the impact of nanoclay addition on the wear resistance of polypropylene

The addition of nanoclay in the polypropylene matrix has many applications in the field of automotive, packaging and aeronautical industry. Nanocomposites of polypropylene with nanoclay phr (part per hundred of resin) of 2.5, 5.0, 7.5 and 10 are prepared using melt mixing in twin-screw extruder and injection molding. The dispersion of nanoclay in the polypropylene matrix played a significant role in the preparation of nanocomposites. The freeze-fractured microstructures of the 5 phr of nanoclay composites shows better dispersion of clay particles in the polypropylene matrix. Tensile testing is performed to quantify the strength with respect to nanoclay phr in the nanocomposites. Stress strain behaviors during the tensile testing along with critical examining using field emission scanning electron microscope of the fracture surface have evolved that phr value around 5 provide maximum strength. In addition to this, surface roughness of these nanocomposites also indicate that the nanocomposites formed by 5 phr nanoclay give better surface finish. The wear behavior of nanocomposites is investigated using pin-on-disc tribo-tester at different loads (10, 20 and 30 N) and sliding speeds (0.5, 1.5 and 2.5 m/s). A response surface methodology based model is developed to explore the impact of nanoclay phr along with load and sliding speed on the wear behavior of these nanocomposites. Response surface methodology is a statistical technique in which the interaction among process variables is studies. It uses a sequence of design experiments to get an optimal response. It was found that 4.19 phr provides to be optimal value of nanoclay content exhibiting better wear resistance. Present study of composites with nanoclay reinforcement in polypropylene matrix concludes that phr value ranging around 4 to 5 gives best results.

Mechanical Properties of Chemically Treated Coir and Betel Nut Fiber Reinforced Hybrid Polypropylene Composites

Natural fiber reinforcement in polymer is one of the best ways to enhance mechanical properties of polymer. Hybrid composites provide the potential of achieving a balanced a pursuit of stiffness, strength, ductility and other mechanical properties. For this purpose coir and betel nut fiber were used as reinforcement in polypropylene matrix in present research. Raw coir and betel nut husk fiber were chemically treated with sodium hydroxide to increase adhesion of those fibers with polypropylene. Both raw and alkali treated fibers were utilized during composite preparation with the help of hot press technique. Fiber loading were varied at 5, 10 and 15 wt%, while coir and betel nut husk fiber ratios were varied at 1:1, 3:1 and 1:3. Tensile, flexural, impact, hardness and water absorption tests of prepared composites were subsequently conducted. All mechanical properties except tensile strength increased with increase in fiber loading. Properties of prepared composites were found better as compared to polypropylene matrix. Composites containing coir and betel nut at same ratio had better mechanical properties than composites containing those fibers at 1:3 and 3:1 ratio. On the other hand, sodium hydroxide treatment of raw coir and betel nut fiber increased mechanical properties of treated fiber composites as compared to raw fiber reinforced composite. Thus alkali treated 15 wt% coir and betel but fiber (at 1:1) reinforced polypropylene composite had the optimum set of mechanical properties among all prepared composites.

Jute–polypropylene composites using m-TMI-grafted-polypropylene as a coupling agent

Jute fiber filled polypropylene composites were prepared using m-isopropenyl-α-α-dimethylbenzyl-isocyanate (m-TMI)-grafted-polypropylene as the coupling agent. The effect of filler concentration and coupling agent on mechanical properties (tensile, flexural, impact strengths and tensile modulus) of the composites were investigated. Fourier transform infra red (FTIR) spectroscopy of the coupling agent and composites revealed effective coupling between jute fibers and polypropylene. The coupling agent was found to be effective in improving the strength and stiffness properties of the composites. Thus, at 50wt% jute content, the tensile strength exhibited 87% increase and flexural strengths exhibited about 95% increase over virgin polypropylene. The tensile modulus of the composite with 50wt% jute content was nearly five times of virgin polypropylene (6.7GPa vs. 1.4GPa). The improvement in properties indicated reinforcement of polypropylene matrix by the jute fibers with an effective transfer of load from matrix to fibers. Significantly without coupling agent, the strength properties did not exhibit any improvement with increasing filler content. However, only the tensile modulus exhibited an increasing trend with filler content. The elongation at break and the unnotched impact strength of the composites decreased whereas the notched impact strength increased with increasing filler content. The moisture absorption in composites without the coupling agent, measured over 600h, was two to three folds higher as compared to composites with the coupling agent.

Biocomposites from abaca strands and polypropylene. Part I: Evaluation of the tensile properties

In this paper, abaca strands were used as reinforcement of polypropylene matrix and their tensile mechanical properties were studied. It was found relevant increments on the tensile properties of the abaca strand-PP composites despite the lack of good adhesion at fiber–matrix interface. Afterwards, it was stated the influence of using maleated polypropylene (MAPP) as compatibilizer to promote the interaction between abaca strands and polypropylene. The intrinsic mechanical properties of the reinforcement were evaluated and used for modeling both the tensile strength and elastic modulus of the composites. For these cases, the compatibility factor for the ultimate tensile strength was deduced from the modified rule of mixtures. Additionally, the experimental fiber orientation coefficient was measured, allowing determining the interfacial shear strengths of the composites and the critical fiber length of the abaca strand reinforcement. The mechanical improvement was compared to that obtained for fiberglass-reinforced PP composites and evaluated under an economical and technical point of view.

Influence of Water on Properties of Cellulosic Fibre Reinforced Polypropylene Composites

Flax fibers with different moisture content were used as reinforcement in polypropylene matrix with maleic anhydride grafted polypropylene coupling agent. Mechanical properties-three point bending and Izod impact strength-were investigated as a function of moisture content of the fiber, and amount of applied coupling agent. By decreasing the moisture content of the fiber all the investigated properties can be improved. Using PPgMA as coupling agent the three point bending characteristics (flexural strength, flexural modulus, and ultimate bending stress) were better, while the impact strength decreased.