Sisal Fiber Reinforced Polypropylene Composites Research Articles

Investigations on Tribological Performance of Sisal Fiber Reinforced Polypropylene Composites

There has been an increase in global interest in the development of natural fiber-reinforced composites. Natural fibers extracted from plants are receiving more attention from researchers, scientists, and academics due to their use in polymer composites and their environmentally friendly nature and sustainability. Recently, sisal fiber-reinforced polymer composites have been used in a variety of engineering applications like aerospace, automotive, marine, and other mechanical components, where tribological properties are of prime consideration. In this endeavor, experiments have been conducted to determine the tribological behavior of sisal fiber-reinforced polypropylene composite. Pin-on-disc wear tests have been conducted on specimens at various combinations of sliding velocities (1-3 m/s), sliding distances (1000-3000 m), and applying normal loads (10-30N). Using Response Surface Method (RSM), a mathematical model has been developed to predict the friction and wear loss behavior of the sisal fiber-reinforced polypropylene (PP) composites. To ensure the validity of the developed model, the Analysis of variance (ANOVA) technique has been applied. Important process parameters and material variables that exert significant influence on sliding wear loss have been determined with the help of systematic experimentation. Scanning Electron Microscope (SEM) has been used to probe morphological observation of the worn surface. Results revealed that the highest volumetric wear loss has been recorded at the highest values of applied load and this has been supported by the morphological study demonstrated by the scratches, as well as wider and deeper plowing marks on the worn surfaces.

Effects of Hyperbranched Polyamide on the Properties of Sisal Fiber Reinforced Polypropylene Composites

ABSTRACT In this paper, the effects of hyperbranched polyamide on the properties of sisal fiber reinforced polypropylene composites were studied. And the microstructure, fluidity, mechanical properties, and thermal stability of the composites were characterized. The results show that hyperbranched polyamide can significantly improve the interfacial bonding between fiber and matrix. When the fiber content is 20%, the melt flow rate can increase by 54%. Meanwhile, the tensile property of the composite increases by 50%, the impact strength of silane-treated fiber composite increases by 24%. However, the thermal stability of the composite decreases slightly after the addition of hyperbranched polyamide.

Recycling of sisal fiber reinforced polypropylene and polylactic acid composites: Thermo-mechanical properties, morphology, and water absorption behavior

The effect of recycling on the thermo-mechanical and water absorption behavior of polypropylene (PP)/sisal fiber and polylactic acid (PLA)/sisal fiber composites were studied. The PP-based non-biodegradable composites and PLA-based biodegradable composites were recycled for four times. The effect of recycling was determined by examining the morphology, thermo-mechanical properties, and water absorption behavior and the obtained results were compared. The results showed that the incorporation of sisal fibers in the PP and PLA matrix enhances the tensile modulus and percentage crystallinity of the composites. The tensile strength and modulus of the sisal fiber reinforced PP composites were not affected with recycling. Even though the tensile properties of PLA and PLA/sisal fiber reinforced composites are superior to PP and PP/sisal fiber composites, the PLA-based composites show a dramatic decrease in tensile strength and modulus after the first recycling due to the degradation of the polymer. The thermal stability of the PP/sisal fiber composites was not affected by the repeated recycling process. On the other hand, the PLA-based composites with higher sisal fiber content show a bit lower thermal stability after recycling. The PP-based composites show fluctuations in percentage crystallinity with recycling. On the other hand, a remarkable increase in percentage crystallinity for PLA and PLA-based composites was observed with increasing recycling times. Water diffusion study divulges that the diffusion of water into the polymer composites was reduced with recycling, irrespective of the polymer matrix.

Effect of Fiber Content and Screw Speed on Mechanical Characterization of Sisal Fiber Reinforced Polypropylene Composites

The present paper researches the impact of differing fiber content and speed on tensile flexural, HDT and effect properties of characteristic fiber (sisal) fortified polypropylene composites (NF). The support fiber (Sisal-Fiber) was gathered from the foliage of locally accessible tree through the procedure of water retting and mechanical extraction. Poor adhesion among fiber and matrix is regularly experienced issue in characteristic fiber-strengthened composites and to conquer this issue, physical and substance medicines were performed for surface adjustment of fibers. The expansion of compatibilizer to the matrix like, is enhanced the adhesion attributes of the fiber. The outcomes it proposes that the high level of fibers combined with a higher screw speed improves the mechanical properties of the Sisal Fiber-Polypropylene plastic composite due to a high interaction between the fiber and the matrix and an even distribution of the fiber in the matrix.

Effects of sol-gel modification on the interfacial and mechanical properties of sisal fiber reinforced polypropylene composites

In order to prepare high performance sisal fiber reinforced polypropylene composites, this paper pays special attention to the changes of intrinsic mechanical properties of the sisal fiber so as to achieve the maximum reinforcing effect of the fiber. For achieving this aim, the sisal fibers were modified by tetraethylorthosilicate (TEOS) sol-gel method to form SiO2-based organic-inorganic hybrid materials. For a better result, a novel combined modification method by TEOS precursor solution and γ-aminopropyltriethoxysilane solution for the fibers was put forward and performed. Then the relevant mechanism was also analyzed in detail. The corresponding composites were prepared by melt blending with polypropylene matrix and polypropylene-graft-maleic anhydride (MAPP) compatibilizer, and the interfacial and mechanical properties of composites were studied by single fiber fragmentation test and mechanical test, respectively. The results show that the mechanical and thermal properties of the modified fiber composites are improved compared with the untreated fiber composite. The combined modification composite presents the highest interfacial shear strength, which increases by 259.49% compared with the untreated fiber composite. A good interfacial bonding is obviously observed in the combined modification composite by the analysis of scanning electron microscope (SEM). The tensile strength and modulus of the composite with the combined treatment (20 wt% fiber loading) increase by 21.72% and 28.18%; the flexural strength and modulus increase by 3.61% and 16.02%; and the impact strength increases by 21.28%.

Vibration damping and acoustic characteristics of sisal fibre–reinforced polypropylene composite

Natural fibre composites attract industries because of their low density, low cost and the specific mechanical properties they possess in comparison to synthetic fibres. In this work, the randomly oriented sisal fibre–reinforced polypropylene composites are fabricated using extrusion–injection moulding technique. The aim of this study is to experimentally investigate the effect of fibre weight fraction (0%–30% in step of 10%) on vibrational damping and acoustic characteristics. The impulse hammer excitation technique is used to evaluate the free vibrational characteristics, namely, natural frequency and damping. An impedance tube is used in evaluating the acoustic properties, namely, sound absorption coefficient and transmission loss. Experimental results reveal that increase in fibre loading significantly alter the vibrational and acoustic response of the polypropylene composite. Modal analysis shows that incorporation of sisal fibres by 30 wt.% to polypropylene made the natural frequency superior when compared with other compositions. However, damping becomes worse with higher fibre content. In case of acoustic properties, incorporation of fibres at higher fraction enhances the sound absorption coefficient and transmission loss. Experimental results drive the research in development of such new materials system towards the application of vibration and sound diminutions.

Effect of grafting generations of poly(amidoamine) dendrimer from the sisal fiber surface on the mechanical properties of composites

ABSTRACTIn order to improve the mechanical properties of sisal fiber-reinforced polypropylene composites, the sisal fibers were grafted with poly(amidoamine) dendrimer and the effects of grafting generations on the mechanical properties of composites were studied. The results reveal that the tensile, flexural, and impact strength of the composites are improved considerably with the poly(amidoamine) dendrimer grafting treatment. For the 2.0 generation treatment with the poly(amidoamine) dendrimer, the tensile, flexural, and impact strength of the composites at 30 wt% fiber loading increase by 29%, 13%, and 54%, respectively. However, the thermal and mechanical properties of the sisal fibers decrease after prolonged grafting treatment.

Effect of mesostructure on the tensile properties of sisal fiber-reinforced polypropylene composites

In this paper, the effects of fiber shape, fiber distribution, fiber size and fiber hybridization on the tensile properties of short sisal fiber-reinforced polypropylene composites were studied by the generalized method of cells and laminate analogy approaches. It is found that the fiber distribution has a large effect on the axial Young’s modulus. The fiber shape and fiber size have stronger influences on the transverse Young’s modulus and axial Poisson’s ratio than the fiber distribution. The fiber type hybridization and fiber shape are shown to be important factors in affecting the axial shear modulus. Hybridization with glass fiber is found to be an efficient method of creating high-performance composites.

Investigating the influence of mercerization treatment of sisal fiber on the mechanical properties of reinforced polypropylene composites and modeling of the properties

This work was centered on investigating the influence of mercerization treatment of sisal fiber on the mechanical properties of reinforced polypropylene (PP) composites and modeling of the mechanical properties. The sisal fiber was sourced from their plantation and was extracted by soil retting process. The extracted fibers were divided into three from where two parts were subjected to mercerization treatment with sodium hydroxide (NaOH) and potassium hydroxide (KOH) in a shaker water bath at 50°C for 4 hours respectively. The third part was left as untreated fibers. Both the treated and untreated fibers were cut into 10 mm lengths and were used for the production of the composites. The fibers and the polypropylene were blended in predetermined proportions in a randomly dispersed mode and were subjected to heat and pressure in a heating compression molding machine maintained at 170°C for 10 minutes. Tensile and flexural properties were observed from universal testing machine and a mathematical response surface methodology model (RSM) was developed. From the flexural and tensile results, it was observed that, KOH treated sisal fiber reinforced polypropylene composites gave the best flexural and tensile properties when compared to NaOH treated sisal fiber reinforced polypropylene composites and untreated sisal fiber reinforced polypropylene composites. The developed RSM models reveal high degree of correlation between the experimental values and the predicted values. This implies that, the model can be used to predict the mechanical properties of the sisal fiber reinforced polypropylene composite materials.

Predicting the elastic properties of sisal fiber reinforced polypropylene composites by a new method based on generalized method of cells and laminate analogy approach

Abstract In this paper, a new method based on generalized method of cells and laminate analogy approach was used to predict the elastic properties of short sisal fiber reinforced polypropylene composites. The effects of fiber volume fractions and fiber aspect ratios on the elastic properties of composites were studied by the new model and other models. Continuous fiber composite and layered composite, as two special cases were analyzed in detail by this new model. The results show that both fiber volume fraction and fiber aspect ratio have significant effects on the axial Young’s modulus. However, the fiber volume fraction has very small effects on the transverse Young’s modulus, axial shear modulus and axial Poisson’s ratio. The new model agrees better than other models with the experimental data. The elastic properties of composites with complex microstructures can be predicted efficiently by this new model.

Effect of fibre loading on mechanical and thermal properties of sisal and kenaf fibre-reinforced injection moulded composites

Kenaf and sisal fibres were selected for the development of natural fibre-reinforced thermoplastic composites because they are in abundance in South Africa. These materials can be used in the building industry, where good mechanical and fire resistance properties are required for structural and non-structural applications. High load bearing, moisture and fire can negatively affect the properties of these composites and decrease their performance. The effect of water glass, maleic anhydride-grafted-polypropylene (MAPP) treatment and fibre loadings on mechanical and thermal properties as well as fire resistance of kenaf and sisal fibre-reinforced polypropylene composites were investigated. The fibre-reinforced polypropylene composites were produced by injection and compression moulding processes. A significant improvement of the tensile strength and modulus of kenaf fibre composites was more pronounced when compared to sisal fibre composites. However, the water glass has a slight negative influence on mechanical properties of fibre/polypropylene matrix composites but showed better fire resistance and thermal properties when compared to the untreated fibre/polypropylene composites. Generally, the impact strength of fibre/polypropylene composites decreased with the addition of MAPP. The low impact strength could be the results of weak interfacial bond strength between the fibre and the matrix. The total heat release was reduced by water glass treatment due to the non-flammable polysilicate coating, while the average mass loss rate was slightly reduced by MAPP.

Role of Cenosphere Addition on Dielectric Properties of Sisal Fiber-Polypropylene Composites

This research investigates the influence of addition of porous additives on dielectric constant of polypropylene. Composite composed of PP matrix with sisal fiber having cylindrical pores and cenospheres having spherical pore, presents low dielectric constant. A new relation concerning porosity is proposed by modifying the usual mixing rule to predict the dielectric constant of PP composite. This research presents the dielectric properties of sisal fiber-reinforced PP composites with and with out cenospheres. Treated and untreated cenospheres with different concentration were loaded in chopped sisal fiber-reinforced polypropylene. The loading of the polypropylene with the sisal fiber, increases the dielectric constant ε′ and improves the ac conductivity σac. The effect of temperature on the dielectric spectrum of polypropylene composites was investigated in the frequency range ranging from 1–10 kHz. Sisal fiber-reinforced polypropylene composites having 20% sisal fiber with and without cenospheres were developed and electrical properties such as dielectric constant (ϵ′), dissipation factor (tanδ) and ac conductivity (σac) of these composites were determined. Dielectric constant, tan δ, and a.c. conductivity increases with increase in temperature at different frequencies.

MECHANICAL PROPERTIES OF THE VIET NAM SISAL FIBRE REINFORCED POLYPROPYLENE COMPOSITE

The static mechanical and dynamic mechanical properties of the treated sisal fiber reinforced polypropylene composites were improved by adding the compatiblizer PPgMA (polypropylene-grafted-maleic anghydride). The mechanical properties of the composites have been evaluated. By increasing PPgMA dosages from 2% and 3.5% by weight of PP matrix; the impact strength of the composites were significantly improved by 27% and 38%; the elongation increased by 21% and 36%; the tensile strength increased by 35% and 95%; the elastic modulus increased by 21% and 94% and the flexural modulus increased by 2% and 83% respectively. The dynamic mechanical properties (the storage modulus E’, the loss modulus E” and the loss factor tanδ) have been investigated in relation to the compatibility between the PP matrix and the treated sisal fibers. E’ and E” increased by increasing dosage of PPgMA and Tg decreased a little when increasing the contents of PPgMA. At higher temperatures, tanδ increased and at lower temperature tanδ decreased when increasing dosage of PPgMA. It is shown that PP/treated sisal fibers/PPgMA composites have shown the effects of cohesion when increasing the PPgMA. The fiber dispersion was studied by the transmission optical microscope (TOM). The morphology of the composites samples fractured by the impact strength tests have been studied using scanning electronic microscopy (SEM). The results show the improvement of the interaction forces between treated sisal fibers and PP matrix at higher levels of PPgMA.

Effect of Heat Treated Sisal Fiber on Physical Properties of Polypropylene Composites

Sisal fiber reinforced polypropylene composites were prepared using an internal mixer. Heat treatred sisal fibers were performed by heating the fibers in an oven at 150, 170, and 200°C under an atmospheric pressure and a presence of air. The composites prepared at a fiber content of 20 wt% were molded by an injection molding machine for mechanical tests including tensile and impact properties. Morphologies of the composites were examined using a scanning electron microscope (SEM). Viscosity at various shear rate of the composites were also investigated. Tensile strength and impact strength of heat treated sisal fiber/polypropylene composites were slightly higher than that of the untreated sisal fiber/polypropylene composite. However, no remakable effect of treatment temperatures on the mechanical and rheological properties of the composites was observed. SEM micrographs revealed that the heat treatment improved adhsion between the fiber and PP matrix.

Influence of MA-g-PP on abrasive wear behaviour of chopped sisal fibre reinforced polypropylene composites

In this paper, chopped sisal fibre reinforced polypropylene composites with and without maleic anhydride grafted polypropylene (MA-g-PP) were developed. Different amounts of MA-g-PP, e.g. 1, 2 and 5-wt% were added to modify the composites. Abrasive wear and mechanical properties of sisal fibre reinforced polypropylene composites were determined. Addition of MA-g-PP improved the mechanical properties of the composite. Effects of MA-g-PP coupling agent, sliding distance and load on abrasive wear behaviour of sisal fibre reinforced PP composites were studied by using a SUGA abrasion tester. Addition of MA-g-PP coupling agent has significantly influenced the wear resistance of sisal fibre reinforced PP composites. It is observed in chopped sisal fibre reinforced polypropylene composite that initially at low loads (i.e. 1 N and 3 N), sample having 1-wt% MA-g-PP exhibited maximum wear resistance but at higher applied loads (i.e. 5 N and 7 N), sample having 2-wt% MA-g-PP offered maximum wear resistance. The higher concentration of MA-g-PP, i.e. 5-wt% has increased the internal slippage of chain molecules, leading to lowering the wear resistance of composite. Worn and fractured surfaces were analyzed and discussed using SEM.

Mechanical Properties of Injection-molded Natural Fiber-reinforced Polypropylene Composites: Formulation and Compounding Processes

In this study, the effects of material optimization and compounding processes on the properties of natural fiber composites were studied. The thermal stabilities of sisal fiber and jute fiber were compared by thermogravimetric analysis. The influences of fiber content, coupling agent, fiber geometry, and fiber distribution on the properties were also researched. It was observed that sisal fiber had more thermal stability than jute fiber. Addition of coupling agent, long fiber length, and uniform fiber distribution led to higher performance composites. For the sisal fiber-reinforced polypropylene composites, the critical fiber length was 2.27 mm and the interfacial shear strength was 22.03 MPa with MAPP. The tensile strength of composites was also theoretically predicted based on Kelly—Tyson model.

Rigidity analysis of polypropylene/vegetal fibre composites after recycling

Polypropylene/hemp or sisal fibre composites exhibit interesting recyclability [Bourmaud A, Baley C. Investigations on the recycling of hemp and sisal fibre-reinforced polypropylene composites. Polymer Degradation and Stability 2007;92(6):1034–45]. The obtained results prove that the tensile modulus of these polypropylene/vegetal fibre composites is well conserved with the number of reprocessing cycles. In this work, we investigated the relationship between the mechanical properties of the fibres and those of the composites by taking the influence of the recycling into account. In the first part of this study we carried out nanoindentation and tensile tests on vegetal fibres to obtain transversal and longitudinal Young's moduli. The experimental values were then introduced into micromechanical models, taking the aspect ratio changes into account, to estimate the stiffness of the PP/vegetal fibre injected composites before and after recycling. The first results show an interesting correlation between experimental results and model predictions; however a general underestimation of tensile stiffness of composites can be noticed.

Dielectric Behavior of Maleic Anhydride Grafted Polypropylene (MAgPP) Modified Sisal Fiber Reinforced PP Composites

ABSTRACT Sisal fiber reinforced polypropylene composites having different weight percent sisal fiber with and without Maleic anhydride grafted polypropylene (MAgPP) have been developed by melt mixing method. Dielectric properties such as ϵ′, tanδ, and a.c. conductivity of sisal fibers reinforced polypropylene composites with and without MAgPP have been determined. Dielectric constant, tan δ, and a.c. conductivity increases with increase in temperature at different frequencies. 10 wt% sisal fiber addition to PP gave two tanδ peaks. First peak appears at 90°C, which is similar to 5 wt% sisal fiber PP composite. Another peak appears at 105°C, which is due to the sisal fiber. MAgPP addition to sisal-PP composite suppresses the first 90°C peak. There is a peak that appears at 123°C, 126°C, 135°C, and 140°C in 1 phr (parts per hundred) MAgPP added sisal-PP composite. On adding 2 phr maleic anhydride grafted polypropylene (MagPP) to 5wt% sisal-PP composite the peak appears at 125°C, 128°C, 132°C, and 135°C. Peak is shifted to higher temperature side due to the improved bonding between the sisal fiber and PP matrix. The relaxation time values calculated at 70°C for sisal fiber/PP composites with and without MAgPP show that addition of sisal fiber decreases the relaxation time due to shortening of PP chains. Addition of low concentration of coupling agent increased the relaxation time and further increase of MAgPP concentration decreased the relaxation time value, increase is due to increased bonding between sisal fiber and polypropylene chains. Better bonding between fiber and polypropylene would have created hindrance in the movement of the dipoles, which would have increased the relaxation time.

Investigations on the recycling of hemp and sisal fibre reinforced polypropylene composites

Microscopic, mechanical, rheological and thermal tests were carried out in order to determine the recycling behaviour of PP/vegetal fibre composites. Different composites using hemp and sisal were characterized. All results were compared with PP- g-MA/hemp composites and PP/glass fibre composites. The results prove that mechanical properties are well conserved with the reprocessing of PP/vegetal fibre composites but that there is poor adhesion between the fibres and PP without any treatment. The addition of PP- g-MA shows an improvement of the bonding evidenced by MEB pictures. Vegetal fibres induce an increase in the percentage of crystallinity χ c and in the crystallization temperature T c which can be explained by the nucleating ability of the fibres improving crystallization of PP. The Newtonian viscosity η 0 decreases with cycles, indicating a decrease in molecular weight and chain scissions induced by reprocessing. The decrease of fibre length with reprocessing could be another reason for viscosity decrease.

Moisture absorption studies of sisal fibre reinforced polypropylene composites

In this research, sisal fibre reinforced polypropylene (SF/PP) composites were prepared by injection moulding using a pre-coating technique that we have developed earlier. The composite specimens were subjected to hot water immersion treatment at 90 °C for different durations. The effects of the immersion treatment on the tensile and impact fracture characteristics were investigated. The apparent weight gain and weight loss curves were constructed. From the weight loss curves for the individual composites, the weight loss within the induction period was negligible. At the end of the induction period, the weight loss increased sharply. Due to the weight loss and the formation of additional moisture diffusion paths as immersion treatment proceeds, the apparent weight gain was non-Fickian. Both the tensile modulus and tensile strength of the SF/PP composites decreased continuously with increasing water immersion time. On the contrary, the Izod impact strength increased initially with immersion treatment. After reaching the maximum impact strength, the impact strength was found to decrease with further increase in immersion time. These contradictory behaviours between the tensile and impact properties were explained by the plasticization of the SF/PP interface and the swelling of the reinforcing sisal fibres.