Mechanical Properties of Kenaf/Polypropylene Nonwoven Composites

With an industrial trend of going green, the use of natural fibers in polymer composites is growing rapidly, especially in the automotive industry. The objectives of this research are to investigate mechanical performance of kenaf/polypropylene nonwoven composites (KPNCs) in production of automotive interior parts, and to develop preliminary linear models for quantifying elastic range of the KPNCs under various loading conditions. Using polypropylene (PP) fiber as bonding fiber, the KPNCs were fabricated with 50/50 blend ratio by weight. Unlike the manufacturing method of fiber reinforced plastics, all KPNCs were produced by carding and needle-punching techniques and thermally bonded by a panel press with 3-mm thickness gauge. Mechanical properties of the KPNCs in terms of uniaxial tensile, open-hole tensile, tensile at different strain rates, flexural, and in-plane shear were measured instrumentally. It was found that sample which was processed at higher temperature (230?°C) but shorter time (60?s) had the best mechanical performance. KPNCs were relatively insensitive to the notch but sensitive to strain rates. The linear elastic finite element model of KPNCs agreed well with the experimental results in the valid strain range of 0?C0.5?% for uniaxial tensile test and 0?C1?% for flexural test.     

Feather Fiber Reinforced Light-Weight Composites with Good Acoustic Properties

Three to four billion pounds of chicken feathers are wasted in the United States annually. These feathers pose an environmental challenge. In order to find a commercial application of these otherwise wasted feathers, composites have been prepared from feathers. Flexural, impact resistance, and sound dampening properties of composites from chicken feather fiber (FF) and High Density Polyethylene/Polypropylene (HDPE/PP) fiber have been investigated and compared with pulverized chicken quill-HDPE/PP, and jute-HDPE/PP composites. Sound dampening by FF composites was 125% higher than jute and similar to quill although mechanical properties were inferior to the latter two. In ground form, FF and jute composite properties were similar except for 34% higher modulus of jute; under the same formulation and processing conditions, ground FF composites had nearly 50% lower mechanical properties compared with ground quill composites. It was found that voids and density of composites have effect on mechanical and sound dampening properties; however, no direct relationship was found between mechanical properties and sound dampening.     

The Effect of Fiber Pretreatment and Compatibilizer on Mechanical and Physical Properties of Flax Fiber-Polypropylene Composites

Recently, investigations have been conducted on the use of natural fibers as reinforcement in low-melting point thermoplastics to improve mechanical properties of composites. However, due to some limitations of natural fibers, composite formulation and processing parameters must be controlled to produce a product with improved properties. This study was conducted to investigate the influence of flax fiber loading, use of compatibilizer and pretreatment on physical and mechanical properties of compression-molded composite. In this study, untreated and treated (sodium hydroxide-treated and mild-bleached flax fibers) fibers at 15% and 30% of the total product mass were used in formulations. To investigate the effect of compatibilizer on product properties, maleic anhydride grafted polypropylene (MAPP) was added at 5% by mass in the formulations. After extrusion of composites formulations, they were formed using compression molding. Results indicated that using flax fiber in composites without pretreatment and compatibilizer could result into products with inferior physical and mechanical properties; this could be compensated by the use of a compatibilizer. However, the use of compatibilizer had some negative effects on some other physical properties like color and melt flow index (MFI).     

Mechanical, Thermal and Water Absorption Properties of Kenaf-Fiber-Based Polypropylene and Poly(Butylene Succinate) Composites

The use of composites made from non-biodegradable conventional plastic materials (e.g., polypropylene, PP) is creating global environmental concern. Biodegradable plastics such as poly(butylene succinate) (PBS) are sought after to reduce plastic waste accumulation. Unfortunately, these types of plastics are very costly; therefore, natural lignocellulosic fibers are incorporated to reduce the cost. Kenaf fibers are also incorporated into PP and PBS for reinforcing purposes and they have low densities, high specific properties and renewable sourcing. However without good compatibilization, the interfacial adhesion between the matrix and the fibers is poor due to differences in polarity between the two materials. Maleic anhydride-grafted compatibilizers may be introduced into the system to improve the matrix-fiber interactions. The overall mechanical, thermal and water absorption properties of PP and PBS composites prepared with 30 vol.% short kenaf fibers (KFs) using a twin-screw extruder were being investigated in this study. The flexural properties for both types of composites were enhanced by the addition of compatibilizer, with improvements of 56 and 16 % in flexural strength for the PP/KF and PBS/KF composites, respectively. Good matrix-fiber adhesion was also observed by scanning electron microscopy. However, the thermal stability of the PBS/KF composites was lower than that of the PP/KF composites. This result was confirmed by both DSC and TGA thermal analysis tests. The water absorption at equilibrium of a PBS composite filled with KFs is inherently lower than of a PP/KF composite because the water molecules more readily penetrate the PP composites through existing voids between the fibers and the matrix. Based on this research, it can be concluded that PBS/KF composites are good candidates for replacing PP/KF composites in applications whereby biodegradability is essential and no extreme thermal and moisture exposures are required.     

Phosphogypsum Waste Used as Reinforcing Fillers in Polypropylene Based Composites: Structural,Mechanical and Thermal Properties

The industrial production of wet phosphoric acid in Morocco led to controversial stockpiling of waste phosphogypsum by-products resulting in the release of significant amounts of toxic impurities in salt marshes. In the framework of fighting against global climate change and efforts to reduce toxic industrial wastes (phosphate industry), this work presents a new polymer composite based on phosphogypsum (PhG) and polypropylene (PP).The compounds were produced by twin-screw extrusion and injection molding. The morphological results show that good affinity between PhG and PP led to good particle dispersion/distribution in the polymer matrix. Thermal characterizations showed that PhG particles improved the thermal stability of PP with a 50 °C increase at 40 wt%. The optimum tensile modulus was also obtained at 40 wt% with a 74 % increase over neat PP. Dynamical mechanical analysis showed that PhG addition can improve the viscoelastic properties of PP for potential applications under dynamic stress. Overall, it can be concluded that PhG is potential reinforcing filler for the production of PP composites and represents a promising avenue for the valorization of this waste as a new raw material while resolving some environmental issues.     

Rheological, Mechanical and Thermal Behaviour of Wood Polymer Composites Based on Recycled Polypropylene

The aim of this paper was to investigate the effect of recycled polypropylene (PP) on the rheological, mechanical and thermal properties of wood flour polypropylene composites. Beforehand, the influence of wood flour treated with a coupling agent on the rheological behaviour had been looked at. By analysing moduli and viscosity curves and studying the thermal and mechanical properties of samples with 10% filler it was possible to see that the recycled PP that was added change in either its physical properties or its rheology. In the other wood plastic composites (WPC) studied, slight changes in the rheology behaviour were observed. However, the same processing parameters may be used with and without recycled PP. Recycled PP is appropriate for these kinds of composites to maintain the optimal rheological properties that make it easier to process the material by extrusion. Furthermore, it is also possible to maintain the thermal and mechanical properties in comparison with the behaviour of virgin PP/wood flour composites.     

Influence of Hygrothermal Ageing on the Physico-Mechanical Properties of Alkali Treated Industrial Hemp Fibre Reinforced Polylactic Acid Composites

30 wt% aligned untreated long hemp fibre/polylactic acid (AUL) and aligned alkali treated long hemp fibre/polylactic acid (AAL) composites were produced by film stacking and subjected to hygrothermal ageing environment along with neat polylactic acid (PLA). Hygrothermal ageing was carried out by immersing samples in distilled water at 25 and 50 °C over a period of 3 months. It was found that both neat PLA and composites followed Fickian diffusion. Higher temperature generally increased the Diffusion coefficient, D of neat PLA and composites, as well as shortening the saturation time. Neat PLA had the lowest D value followed by AAL composites and then AUL composites. After hygrothermal ageing, tensile and flexural strength, Young’s and flexural modulus and K _Ic were found to decrease and impact strength was found to increase for both AUL and AAL composites. AUL composites had greater overall reduction in mechanical properties than that for AAL composites after hygrothermal ageing. Crystallinity contents of the hygrothermal aged composites support the results of the deterioration of mechanical properties upon exposure to hygrothermal ageing environment.     

Mechanical Properties of Poly (Lactic Acid)/Hemp Fiber Composites Prepared with a Novel Method

This research dealt with a novel method of fabricating green composites with biodegradable poly (lactic acid) (PLA) and natural hemp fiber. The new preparation method was that hemp fibers were firstly blending-spun with a small amount of PLA fibers to form compound fiber pellets, and then the traditional twin-screw extruding and injection-molding method were applied for preparing the composites containing 10–40 wt% hemp fibers with PLA pellets and compound fiber pellets. This method was very effective to control the feeding and dispersing of fibers uniformly in the matrix thus much powerful for improving the mechanical properties. The tensile strength and modulus were improved by 39 and 92 %, respectively without a significant decrease in elongation at break, and the corresponding flexural strength and modulus of composites were also improved by 62 and 90 %, respectively, when the hemp fiber content was 40 wt%. The impact strength of composite with 20 wt% hemp fiber was improved nearly 68 % compared with the neat PLA. The application of the silane coupling agent promoted further the mechanical properties of composites attributed to the improvement of interaction between fiber and resin matrix.     

Recycled Natural Fiber Polypropylene Composites: Water Absorption/Desorption Kinetics and Dimensional Stability

Detailed analysis of the effects of recycling process on long-term water absorption, thickness swelling and water desorption behavior of natural fiber polypropylene composites is reported. Composite materials containing polypropylene and wood flour, rice hulls or bagasse fibers were produced at constant fiber loading and were exposed to a simulated recycling process consisting of up to five times grinding and reprocessing under controlled conditions. A wide range of analytical methods including water absorption/desorption tests, thickness swelling tests, density measurement, scanning electron microscopy, image analysis, contact angle, fiber length analysis and Fourier transform infrared spectroscopy was employed to understand the hygroscopic behavior of the recycled composites. Water absorption and thickness swelling behaviors were modeled using existing predictive models. Results indicated that generally the recycled composites had considerably lower water absorption and thickness swellings as compared with the original composites which were attributed to changes in physical and chemical properties of the composites induced by the recycling process.     

Natural Fiber Reinforced Poly(vinyl chloride) Composites: Effect of Fiber Type and Impact Modifier

Poly(vinyl chloride) (PVC) and natural fiber composites were prepared by melt compounding and compression molding. The influence of fiber type (i.e., bagasse, rice straw, rice husk, and pine fiber) and loading level of styrene-ethylene-butylene-styrene (SEBS) block copolymer on composite properties was investigated. Mechanical analysis showed that storage modulus and tensile strength increased with fiber loading at the 30% level for all composites, but there was little difference in both properties among the composites from various fiber types. The use of SEBS decreased storage moduli, but enhanced tensile strength of the composites. The addition of fiber impaired impact strength of the composites, and the use of SEBS led to little change of the property for most of the composites. The addition of fiber to PVC matrix increased glass transition temperature (T_g), but lowered degradation temperature (T_d) and thermal activation energy (E_a). After being immersed in water for four weeks, PVC/rice husk composites presented relatively smaller water absorption (WA) and thickness swelling (TS) rate compared with other composites. The results of the study demonstrate that PVC composites filled with agricultural fibers had properties comparable with those of PVC/wood composite.     

Effect of Alkaline Treatment and Coupling Agent on Thermal and Mechanical Properties of Macadamia Nutshell Residues Based PP Composites

Journal of Polymers and the Environment - The influence of alkaline treatment on the thermal and mechanical properties of polypropylene (PP) reinforced with fibers from macadamia nutshell (5 to 30...     

Mechanical and Thermal Properties of Bamboo Microfibril Reinforced Polyhydroxybutyrate Biocomposites

In the present investigation, microfibrils were extracted from raw bamboo and characterized using scanning electron microscope. Composites based on polyhydroxybutyrate (PHB) and bamboo microfibril were prepared with various microfibril loading. The mechanical and thermal properties of the resulting composites were measured. Tensile strength and impact strength of the composites were found to be increasing with increase in the loading of bamboo microfibrils, reached an optimum and thereafter decreased with further increase in microfibril loading. Percentage crystallinity was found to be increasing with increase in fibril loading. Thermal stability of the composite was higher than that of pure PHB. The composite could be developed further for various structural applications.     

Processing and Morphology Impacts on Mechanical Properties of Fungal Based Biopolymer Composites

Fungal based biopolymer matrix composites with lignocellulosic agricultural waste as the filler are a viable alternative for some applications of synthetic polymers. This research provides insight into the impact of the processing method and composition of agriwaste/fungal biopolymer composites on structure and mechanical properties. The impact of nutrition during inoculation and after a homogenization step on the three-point bend flexural modulus and strength was determined. Increasing supplemental nutrition at inoculation had little effect on the overall composite strength or modulus; however, increasing carbohydrate loading after a homogenization step increased flexural stress at yield and bulk flexural modulus. The contiguity of the network formed was notably higher in the latter scenario, suggesting that the increase in modulus and strength of the final composite after homogenization was the result of contiguous hyphal network formation, which improves the integrity of the matrix and the ability to transfer load to the filler particles.     

Mechanical Properties and Morphology of Polypropylene/Poly(ethylene-co-octene) Blends

The polypropylene (PP)/poly(ethylene-co-octene) (POE) blends was prepared by means of a twin screw extruder in a range of temperature from 185 to 195 °C. The mechanical properties including tensile, flexural and impact of the PP/POE blends were measured at room temperature to identify the effect of the POE content on the mechanical properties. It was found that the Young’s modulus, tensile strength and tensile elongation at break decreased nonlinearly with increasing the POE weight fraction. While the V-notched and unnotched impact fracture strength increased nonlinearly with an increase of the POE weight fraction. The flexural modulus and strength decreased roughly linearly with increasing the POE weight fraction. Furthermore, the impact fracture surface of the blends was observed by using a scanning electronic microscope and the toughening mechanisms were discussed.     

Preliminary Study of Non-woven Composite: Effect of Needle Punching and Kenaf Fiber Loadings on Non-woven Thermoplastic Composites Prepared From Kenaf and Polypropylene Fiber

Non-woven composites were produced using kenaf (bast) fiber and polypropylene (PP) fiber. The effects of needle punching process, number of needle and kenaf fiber loadings on the properties of non-woven composite were studied. The aspect ratio of kenaf fiber was also measured in this study. The aspect ratio of most of kenaf fiber used was in the range of 200–400. The results indicated that the mechanical strength of the non-woven composite was significantly influenced by the percentage of kenaf fiber. This may due to the evenly mixed kenaf and PP fibers during carding process prior to the mechanical interlocking by needle punching process. The tensile strength, modulus and toughness were enhanced with the incorporation of carded and needle punched fibers. The number of needle used in needle punching process had a significant effect on the strength of the composite. This was evident in SEM micrograph where composite prepared from carded to needle punched non-woven web showed better wettability as compared to composite prepared from carded non-woven web only. However, no significant difference was observed in water absorption and thickness swelling tests for composites prepared with different number of needles.     

Tensile,Flexural and Chemical Resistance Properties of Sisal Fibre Reinforced Polymer Composites: Effect of Fibre Surface Treatment

In this study, effect of fibre surface treatment on tensile, flexural and chemical resistance properties were studied for sisal fibre reinforced composites. Natural ligno cellulosic sisal fibre reinforced composites were prepared by different surface treatments by hand lay-up method. Fibre surface treatments were carried out to produce good interface between the fibre and the matrix to improve the mechanical properties. Fibre surface treatments were done by boiled the sisal fibres in different % of NaOH and treated the fibres in different % of NaOH, treated in acetic acid and methanol. Unsaturated polyester resin was used as the matrix for preparing the composites. For comparison, these properties for untreated sisal fibre reinforced composites were also studied. From the results it was observed that 18% aqueous NaOH boiled sisal fibre reinforced composites have higher tensile, flexural properties than other composites. Untreated sisal fibre composites show lower properties than treated composites. Chemical resistance properties indicate that all sisal fibre reinforced composites are resistance to all chemicals except carbon tetra chloride. The tests are carried out as per the ASTM standards.     

Effect of Agar and Cotton Fiber on Properties of Thermoplastic Waxy Rice Starch Composites

Biodegradable polymer from thermoplastic waxy rice starch (TPWRS) was prepared by internal mixer and compression molding. Since tensile properties and water uptake of the TPWRS was still the main disadvantages, the TPWRS sample was, therefore, modified by agar and/or cotton fibers. The effect of different ratios of agar:cotton fibers on properties of the TPWRS matrix were also studied. It was found that new hydrogen bonds could be found for the TPWRS matrix with the addition of different ratios of agar: cotton fibers by the detection of IR peak shift. Tensile properties of the TPWRS sample were significantly improved by the addition of agar or cotton fibers and the highest tensile properties were obtained from the TPWRS composite modified with 4:6 agar:cotton fibers. In addition, thermal degradation temperature and thermal stability of the starch were improved by the incorporation of agar and/or cotton fibers. Moreover, color measurement, morphology, water uptake and biodegradability from soil burial test were also examined.     

Mechanical,Morphological and Dynamic Mechanical Analysis of Pineapple Leaf/Washingtonia Trunk Fibres Based Biophenolic Hybrid Composites

In this article, flexural, impact and dynamic mechanical properties of the Pineapple leaf fibres (PALF) and Washingtonia trunk fibres (GW) based bio-phenolic hybrid composites were examined. The pure and hybrid composites were fabricated using the hand lay-up technique with an overall fibre weight ratio of 50% in which GW and PALF were maintained in the fibre weight ratios of 50:50, 30:70, and 70:30 denoted as 1G1P, 3G7P, and 7G3P, respectively. Hybrid composites displayed better flexural strength, flexural modulus and impact strength than the GW composites and better viscoelastic properties than the PALF composites. Results revealed that 1G1P hybrid composites exhibited 25% and 12% improvements in flexural strength and modulus compared to the GW composites. 3P7K composites showed a twofold increase in impact strength than GW composites. The storage modulus of the pure and hybrid composites declined rapidly beyond the glass transition temperature. Furthermore, it was observed that the values of storage modulus for all the composites at 150 °C were similar regardless of the composite configuration. The Peak of loss modulus was found to increase in the following order: GW?>?7G3P?>?3G7P?>?1G1P?>?PALF. Furthermore, the temperature at the peak tan delta was improved, and a reduction in the tan delta peak was observed for hybrid composites compared to the pure composites. Finally, the PALF and GW hybrid combinations can be suitable for use in various applications such as textiles, machinery part production industries, medicine, automobiles, etc.