Utilization of Recycled Polypropylene for Production of Eco-Composites

Nowadays natural fiber and polymer matrix are being extensively used as alternatives in producing furniture like ceiling, floor and etc. to fulfill society demand instead of environmental friendly and saving cost. The objective of this study is to investigate the effects of maleic anhydride grafted polypropylene (MAPP) as a coupling agent for reinforcement between kenaf fiber (KF) and polypropylene (PP). The ratio of MAPP between 3% and 5% was observed to determine which composition ratio is better. The tensile strength for both 30% KF and 40% KF was treated through the alkali treatment process with 5% sodium hydroxide (NaOH). Kenaf fiber reinforced polypropylene (PP/KF) composites were melt blended and then used hydraulic molding test press machine for characterization to observe their tensile strengths by measuring their threshold. Tensile test was carried out to determine the tensile stresses of the composite at the best composition ratio of kenaf fiber that are 30% KF and 40% KF instead of MAPP ratio. The result shows 40% KF (5% MAPP) lead to better tensile performance compared to 40% KF (3% MAPP), 30% KF (5% MAPP) and 30% KF (3% MAPP). Meanwhile, Scanning electron microscopy (SEM) is used to observe the morphological comparison between untreated KF and treated KF as well as PP/KF. The good interfacial bonding between KF and PP was 5% MAPP rather than 3% MAPP due to the optimum strength received. Overall 5% MAPP with 40% PP/KF had shown the best result compared to others with the estimated tensile strength value of 21.38 MPa.

Nanocomposites polypropylene (PP) with 3 and 7 wt % of clay were prepared by melt mixing. Four types of maleic anhydride grafted PP (MAPP) in broad range of MA groups content (0.3–4 wt %) and molecular weights (MW) were used as polar compatibilizers. The effect of the MAPP kind on both the clay dispersion and miscibility with PP was studied. The mixed intercalated/exfoliated morphologies of nanocomposites in the presence of all studied compatibilizers were revealed by XRD and TEM. The oligomer compatibilizer with 4 wt % of MA groups increases the intercalation ability of polymer into clay galleries but this one has limited miscibility with PP and worsens crystalline structure of polymer matrix. The MAPPs with 0.3–1.3% of MA are characterized by the lower intercalation ability but well cocrystallize with PP. Maximum reinforcing effect is attained using high MW MAPP with 0.6% MA and for nanocomposite with 7 wt % (3.8 vol %) of clay it averages almost 1.7 times relative to neat PP and 1.3 times relative to noncompatibilized composite. Dynamic storage moduli of nanocomposites compatibilized by MAPPs with 0.3–1.3% of MA containing 7 wt % of clay increase up to 1.4–1.5 around 30–75°C and over the whole temperature range remain higher compared with both neat PP and uncompatibilized composite. On the contrary, the oligomer MAPP with 4 wt % of MA groups decreases the thermal–mechanical stability of nanocomposite at high temperature compared with both PP and uncompatibilized composites. The study of nanocomposites flammability showed that creating complex composites containing both layered silicate and relatively small amount of magnesium hydroxide can be a successful approach to reduce the combustibility of PP‐based nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Composites of untreated and treated kenaf fibres with recycled polypropylene were fabricated by melt-cast technique with and without using maleic anhydride-grafted polypropylene. To improve interfacial bonding between kenaf fibres and recycled polypropylene, surface modifications of fibres were performed through ultrasound, enzyme and alkali pre-treatments. Klason lignin test, Fourier-transform infrared spectroscopy and scanning electron microscopy were used for the characterization of fibres. For characterization of composites, the samples were examined by density measurements, mechanical tests, field-emission scanning electron microscopy, X-ray diffraction study, differential scanning calorimetry and thermogravimetric analysis. Results revealed that ultrasound was able to remove the highest amount of lignin (32%). Tensile strength of the composites was increased by 57%, 58% and 40% due to the treatment with alkali, ultrasound and enzyme, respectively. Optimization of treatment parameters was carried out by means of the design expert software. The optimum treatment parameters, such as alkali concentration, soaking time in alkali, sonication power, temperature, enzyme concentration and soaking time in enzyme were found to be 4.6 wt%, 4.95 h, 99.96%, 94.46℃, 1.26 wt% and 3.89 h, respectively, which are reasonably close to the experimental ones. The preferential b-axis orientation in recycled polypropylene crystal was found to be more apparent due to treated kenaf fibres with maleic anhydride-grafted polypropylene than untreated kenaf fibres with maleic anhydride-grafted polypropylene. A correlation among crystallinity, surface morphology, and tensile and thermal properties of composites with the fibre-matrix interactions has been established.

Neat polypropylene (PP)- and post-industrial recycled polypropylene (rPP)-based wood-plastic composites (WPC) were manufactured using 40% mahogany wood flour (WF). The effect of particle size (0.074 to 0.149 mm, 0.177 to 0.250 mm, and 0.400 to 0.841 mm) on the selected properties of PP and rPP composites was studied. The influence of 3% maleic anhydride grafted polypropylene (MAPP) presence in the formulation was also evaluated. Test specimens were manufactured using a combination of extrusion and injection molding processes. The density and mechanical properties, such as flexural strength, flexural modulus, tensile strength, tensile modulus, elongation at break, hardness and impact strength values were determined. Morphology of the manufactured composites was also studied using scanning electron microscopy (SEM) analysis. Results showed that the particle size, polypropylene type (neat or recycled), and presence of MAPP had important effects on WPC’s properties. Density, flexural modulus, tensile modulus, and impact strength values increased with decreased particle size regardless of the presence of MAPP. Flexural strength values increased with decreased particle size without MAPP. Regardless of particle size, addition of MAPP in composites provided higher flexural strength, flexural modulus, tensile strength, and tensile modulus values but lower elongation at break values compared to composites without MAPP.

Recycled carbon fibre (RCF) and Kenaf fibre (KF) have been used as reinforcement materials in combination with recycled polypropylene (RPP) matrix to manufacture a sustainable composite. Maleic anhydride grafted polypropylene (MAPP) has also been used as a compatibilizer to modify the interface between fibres and matrix composites, resulting in improved composite strength and thermal resistance. After modified with MAPP, the recycled carbon fibre was combined with KF fiber to improve the KF/RPP composite properties such as mechanical and thermal stability. The results were indicated that the mechanical properties of RCF/RPP composite was improved with increasing of MAPP when MAPP added 8 Wt. %, these reached a Maximum of 77.6 MPa and 271.4 MPa, respectively. When the RCF combined with the KF hybrid composite, the mechanical strength of the hybrid composite was improved with the amount of RCF. The DSC results showed that the MAPP could reduce the Tc of RPP and increase the crystallization degree. The hybrid composite presented that the crystallization degree was increased with the increment of RCF content. The DMA results showed that the RCF can influence the β translation of RPP.

The growing amount of plastic and food waste has become a serious problem around the worldwide. As a byproduct of milling rice, rice husk is an agricultural waste that is produced in bulk quantities. Rice husk has been used as filler in polymer composites in a variety of ways. However, there have only been a few reports of using rice husk as reinforcement in composites made of recycled polypropylene. The limited interfacial reaction between natural fibre and polymer is the fundamental issue in natural fibre-based composites. This prompted the development of sustainable composite manufactured from recycled polypropylene(rPP) and rice husk (RH). Thus, we investigated the intermolecular adhesion between rPP–RH composite with maleic anhydride grafted polypropylene (MAPP) as a coupling agent. Varied compositions of RH in the range of 10–40 wt% with 4 wt% of MAPP were fabricated. The rPP, RH and MAPP were blended and executed in injection moulding. The mechanical properties will be analysed through differential scanning calorimetry, rheology, tensile, flexural, impact and hardness tests. The result shows RH agglomeration and limited dispersion in the composite cause a reduction of up to 40% for tensile strength compared to neat rPP. Despite this, it demonstrates improvements in tensile modulus, flexural modulus, impact, and hardness. It is evidence of a good intermolecular between rPP matrix and RH. In conclusion, the ideal RH loading for composites occurs at a fillercontent of 40% and has acceptable mechanical properties for various composite applications.

ABSCRACT Renewable raw materials and recyclable thermoplastic polymers provide attractive eco-friendly quality as well as environmental sustainability to the resulting recycled cotton/polyester and polypropylene fiber reinforced nonwoven composites. We studied the possibility of using recycled polypropylene (PP) for the production of nonwoven composites based on recycled cotton (RC) and recycled polyester (RP) as reinforcements. This research focuses on optimizing the manufacturing techniques and testing of both air-laid nonwoven and melt-bonded recycled nonwoven composite materials. Each series of experimentation was to be combined with a specific amount of copolymer chemical agent, the recycled post-industrial polypropylene powder, and recycled fiber. The physical and mechanical properties can be tested in accordance with ASTM standards. The results exposed that physical properties can be determined for both conditions like 24 h soak and 2 h boil. The air-laid materials have more properties than melt extrusion. The air-laid and melt- bond has deviation likewise coupling agent can change the properties. The results obtained report the possibility of exploitation of recycled PP for the production of recycled cotton/polyester reinforcements based on nonwoven composites with good mechanical characteristics to utilize as construction building materials in housing systems.

The interest in natural fiber-reinforced polymer composites is growing rapidly due to their high performance in terms of mechanical properties, significant processing advantages, excellent chemical resistance, low cost and low density. In this study, the compression and injection molding of polypropylene (PP) and polylactic acid (PLA) based composites reinforced with rice hulls or kenaf fibers was carried out and their basic properties were examined. Rice hulls from rice processing plants and natural lignocellulosic kenaf fibers from the bast of the plant Hibiscus Cannabinus represent renewable sources that could be utilized for composites. Maleic anhydride grafted PP (MAPP) and maleic anhydride grafted PLA (MAPLA) were used as coupling agents (CA) to improve the compatibility and adhesion between the fibers and the matrix. Composites containing 30 wt % reinforcement were manufactured by compression and injection molding, and their mechanical and thermal properties were compared. It was found that the techniques applied for manufacturing of the eco-composites under certain processing conditions did not induce significant changes of the mechanical properties. The flexural strength of the compressed composite sample based on PP and kenaf is 51. 3 MPa in comparison with 46.7 MPa for the same composite produced by injection molding technique. Particularly, PP-based composites were less sensitive to processing cycles than PLA-based composites. The experimental results suggest that the compression and injection molding are promising techniques for processing of eco-composites. Moreover, the PP-based composites and PLA-based composites can be processed by compression and injection molding. Both composites are suitable for applications as construction materials.

BACKGROUND: Renewable resources and recyclable thermoplastic polymers provide an attractive eco‐friendly quality as well as environmental sustainability to the resulting natural fibre‐reinforced composites. The properties of polypropylene (PP)‐based composites reinforced with rice hulls or kenaf fibres were investigated with respect to their recyclability. Rice hulls from rice processing plants and natural lignocellulosic kenaf fibres from the bast of the plant Hibiscus cannabinus represent renewable sources that could be utilized for composites. Maleic anhydride‐grafted PP was used as a coupling agent to improve the interfacial adhesion between fillers and matrix. Composites containing 30 wt% reinforcement were manufactured by melt mixing and their mechanical and thermal properties were determined. The composites were then pelletized and reprocessed by melt mixing. Finally, structure/properties relationships were investigated as a function of the number of reprocessing cycles. RESULTS: It is found that the recycling processes do not induce very significant changes in flexural strength and thermal stability of the composites. In particular PP‐based composites reinforced with kenaf fibres are less sensitive to reprocessing cycles with respect to PP‐based composites reinforced with rice hulls. CONCLUSION: The response of PP‐based composites reinforced with rice hulls or kenaf fibres is promising since their properties remain almost unchanged after recycling processes. Moreover, the recycled composites are suitable for applications as construction materials for indoor applications. In fact, the flexural strength and modulus of these materials are comparable to those of conventional formaldehyde wood medium‐density fibreboards. Copyright © 2008 Society of Chemical Industry

Virgin polypropylene (PP), recycled polypropylene (RPP) and acrylonitrile butadiene rubber (NBR) were mixed together to prepare ternary blends (PP/RPP/NBR) of thermoplastic vulcanisates (TPVs). The blends comprised 30 parts per hundred (phr) NBR and 70 phr PP and RPP. Sulphur was used to dynamically crosslink the NBR during the blending process. Maleic anhydride grafted polypropylene (MA-g-PP) was used as compatibiliser to enhance the interaction of the polypropylene and the rubber. In this study, the loading of RPP in the TPVs was varied and the effects on mechanical and rheological properties were studied. The hardness and the tensile strength of the TPVs increased upon increasing the RPP loading. The RPP exhibited an adverse effect on elongation-at-break of the vulcanisates, with the pseudo-plastic flow behaviour and the viscosity of the vulcanisates increasing with the increased loading of RPP.

Different properties (tensile strength, elongation, modulus, impact strength) of rice husk (RH) reinforced polypropylene (PP) coupled by Maleic-Anhydride grafted Polypropylene (MAgPP) have been investigated. MAgPP is an effective coupling agent, not only in cellulosic-fibre filled polyolefine composites, but in rice husk flour filled polypropylene composite systems as well. It gives a utilizable construction polymer matrix composite (PMC) material even at a 40 wt.% RH filling degree. The strength and modulus increases by adding the rice husk but the elongation decreases in a non-monotonic way. Micrographs shows weak coupling in between RH and PP without MAgPP.

Rice husk (RH) is an agricultural waste that is gaining importance as fillers for polymers due to its abundant advantages such as light weight, low cost and environmentally friendly. This study investigates the tensile and impact properties of rice husk waste (RH) filled polypropylene (PP) composites with ethylene-acrylic ester maleic anhydride (E-AE-MA) as compatibilizer. The compatibilizer agent is used to improve compatibility between the RH which is hydrophilic and non-polar PP. Tensile test and impact strength test were conducted according to ASTM D638 and ASTM D256 standards. The incorporation of 15 wt% of RH into PP increased the Young's modulus of PP by 28 % but decreased the tensile strength and impact strength by 10 % and 31 % compared to neat PP. The elongation at break was observed to decrease by approximately 4 %. The addition of E-AE-MA at 4 parts per hundred (phr) to the composite increased the impact strength and elongation at break of RH-PP composite by 18 % and 22 % , but decreased the Young's modulus and tensile strength by 18 % and 5 %. The overall results showed that the elongation at break and Young's modulus of the compatibilized RH-PP composite is higher than neat PP, including that E-AE-MA is an effective compatibilizer between RH filler and PP due to its ability to improve adhesion between the two phases.

Preparation, structure and properties of dynamically vulcanized polypropylene/acrylonitrile butadiene rubber/zinc dimethacrylate ternary blend composites containing maleic anhydride grafted polypropylene

Previously, Polyvinyl Alcohol (PVA) and phenolic resin were used for resin impregnated bamboo fiber reinforced PP composites which was manufactures for resin impregnated bamboo fiber with polypropylene (PP). Resin impregnation method can show improvement on tensile strength of fiber. However, to reduce the contact surface area and low inter-facial shear strength (IFSS) between impregnated resin and matrix, using 40% weight fraction of bamboo fiber in PP matrix, PVA impregnated composites with mean flexural and tensile strength 10% higher than untreated composites were produced butphenolic resin impregnated fiber reinforced composition’s mechanical properties were decreased. In this study maleic anhydride grafted polypropylene (MAPP) was used to increase interfacial shear strength between resin impregnated fiber and PP. With 10% MAPP, IFSS between resin impregnated fiber and PP increased more than 100% and reinforced composites. MAPP with untreated, phenolic resin and PVA impregnated cases showed similar mechanical properties. Yet in water absorption test, the PVA treatment with bamboo/PP composites increased water absorption ratio. But with 10% MAPP, matrix PP water absorption ratio decreased like phenolic resin impregnated fiber reinforced composites. 10% MAPP with resin impregnated bamboo fiber reinforced PP composites can improve IFSS, mechanical properties of composite and can decrease water absorption PVA resin impregnated bamboo fiber reinforced composites.

Poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) was melt blended with polypropylene (PP) with maleic anhydride grafted PP (MPP) used as the reactive compatibiliser. The PHBV/PP (97·5/2·5) blend exhibited optimum elongation at break. Scanning electron microscopy exhibited that the PP phase was dispersed evenly within the PHBV matrix; a reduction in the domain size of the PP phase and plastic deformation of PP were observed with the addition of MPP. Differential scanning calorimetry studies showed that PP enhanced the crystallisation of PHBV, while MPP weakened it. Polarised optical microscopy results demonstrated that small spherulites of PP were effective PHBV nucleation agents, whereas MPP restrained the nucleation of PHBV. The results of tensile tests revealed that the elongation of the blends improved after the addition of MPP and increased with increasing concentration of MPP. The blend containing 2·5 wt-%PP with MPP content of 3 wt-% exhibited the best toughness, increasing 295·7% compared with pure PHBV.