Properties of polypropylene filled with chemically treated rice husk

Finely ground rice husk was used as a filler in two commercial grades of polypropylene (PP) in different amounts. Rice husk powder was chemically treated with dilute hydrochloric acid, dilute sodium hydroxide solution, and dimethyl sulfoxide. The mechanical, thermal, and rheological properties of PP filled with untreated and treated rice husk powder were determined. Effectiveness of PP grafted with acrylic acid, PP‐g‐AA, as a compatibilizer was examined. Rice husk powder treated with acid showed significant improvement in the flexural modulus of PP and also less water absorption. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of a silane coupling agent on the properties of white rice husk ash–polypropylene/natural rubber composites

White rice husk ash (WRHA)–polypropylene (PP)/natural rubber (NR) composites were prepared using a Brabender Plasticorder at 180 °C and a rotor speed of 50 rev min^?1. The mechanical and water‐absorption properties were studied. The incorporation of WRHA into the PP/NR matrix has resulted in the improvement of the tensile modulus; however, the tensile strength, elongation at break and stress at yield decreased with increasing WRHA loading. Poor filler matrix interactions are believed to be responsible for the decrease in the properties. Incorporation of a silane coupling agent, 3‐aminopropyl triethoxysilane (3‐APE), improved tensile modulus, tensile strength and stress at yield of the composites. Water‐absorption studies indicate that the use of the coupling agent reduced the amount of water absorbed by the composites. © 2001 Society of Chemical Industry     

Water absorption and hygrothermal aging study on organomontmorillonite reinforced polyamide 6/polypropylene nanocomposites

The water absorption and hygrothermal aging behavior of organomontmorillonite (OMMT) reinforced polyamide 6/polypropylene (PA6/PP ratio = 70/30), with and without maleated PP (MAH‐g‐PP), was studied at three different temperatures (30, 60, and 90°C). The water absorption and hygrothermal aging response of the composites was studied and analyzed by tensile tests and morphology assessment (scanning electron microscopy and transmission electron microscopy), indicating the effect of the immersion temperature, OMMT, and MAH‐g‐PP compatibilizer. The mathematical treatment used in analyzing the data was the single free phase model of diffusion, which assumed Fickian diffusion and utilized Fick's second law of diffusion. The kinetics of water absorption of the PA6/PP nanocomposites conformed to Fickian law behavior, whereby the initial moisture absorption follows a linear relationship between the percentage gain at any time t and t^1/2 (the square root of time), followed by saturation. It was found that the equilibrium moisture content and the diffusion coefficient are dependent on the OMMT loading, MAH‐g‐PP concentration, and immersion temperatures. Both the tensile modulus and strength of the PA6/PP nanocomposites deteriorated after being exposed to hygrothermal aging. MAH‐g‐PP acted as a good compatibilizer for PA6/PP/OMMT nanocomposites, which was attributed to its higher retention ability in modulus and strength (in the wet and redried states), lower equilibrium moisture content, and reduced water diffusivity of the nanocomposites. Morphological sketches for both uncompatibilized and MAH‐g‐PP compatibilized PA6/PP/OMMT nanocomposites, toward water uptake are proposed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 780–790, 2005     

Hygrothermal aging and tensile behavior of injection‐molded rice husk‐filled polypropylene composites

The effect of the filler volume fraction on the tensile behavior of injection‐molded rice husk‐filled polypropylene (RH–PP) composites was studied. Hygrothermal aging behavior was also investigated by immersing the specimens in distilled water at 30 and 90°C. The kinetics of moisture absorption was studied from the amount of water uptake by specimens at regular interval times. It was found that the diffusion coefficient and the maximum moisture content are dependent on the filler volume fraction and the immersion temperatures. Incorporation of RH into the PP matrix has led to a significant improvement in the tensile modulus and a moderate improvement in the tensile strength. Elongation at break and energy at break, on the other hand, decreased drastically with the incorporation of the RH filler. The extent of deterioration incurred by hygrothermal aging was dependent on the immersion temperature. Both the tensile strength and tensile modulus deteriorated as a result of the combined effect of thermal aging and moisture attack. Furthermore, the tensile properties were not recovered upon redrying of the specimens. Scanning electron microscopy was used to investigate the mode of failure of the RH–PP composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 742–753, 2001     

Silica‐filled polypropylene composites: The effect of ethylene diamine dilaurate and maleic anhydride grafted polypropylene on mechanical properties,water absorption,morphology, and thermal properties

The effect of two compatibilizers, i.e. ethylene diamine dilaurate (EDD) and maleic anhydride grafted polypropylene (MAPP) on the mechanical properties, water absorption, morphology, and thermal properties of silica‐filled polypropylene (PP/Sil) composites were studied. The results show that the tensile, impact and flexural strengths (up to 2 php), Young's modulus, and elongation at break (Eb) increased with increasing EDD content. However, increasing MAPP content increases the tensile strength, Young's modulus, impact and flexural strengths, and water absorption resistance. At a similar compatibilizer content, EDD exhibits higher Eb, impact and flexural strengths but lowers tensile strength, Young's modulus, and water absorption resistance compared with MAPP. Scanning electron microscopy study of tensile fractured surfaces exhibits the evidence of better silica‐PP adhesion with MAPP and EDD compared with the similar composites but without compatibilizer. Fourier transform infra red spectra provide an evidence of interaction between EDD or MAPP with PP/Sil composites. Termogravimetry analysis results indicate that the addition of EDD or MAPP slightly increases the thermal stability of PP/Sil composites. Differential scanning calorimetry also indicates that PP/Sil composites with EDD or MAPP have higher heat fusion (ΔH_f(com)) and crystallinity (X_com) than similar composites but without compatibilizer. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Effect of interfacial interaction on the crystallization and mechanical properties of PP/nano‐CaCO3 composites modified by compatibilizers

To investigate the effect of interfacial interaction on the crystallization and mechanical properties of polypropylene (PP)/nano‐CaCO₃ composites, three kinds of compatibilizers [PP grafted with maleic anhydride (PP‐g‐MA), ethylene–octene copolymer grafted with MA (POE‐g‐MA), and ethylene–vinyl acetate copolymer grafted with MA (EVA‐g‐MA)] with the same polar groups (MA) but different backbones were used as compatibilizers to obtain various interfacial interactions among nano‐CaCO₃, compatibilizer, and PP. The results indicated that compatibilizers encapsulated nano‐CaCO₃ particles, forming a core–shell structure, and two interfaces were obtained in the compatibilized composites: interface between PP and compatibilizer and interface between compatibilizer and nano‐CaCO₃ particles. The crystallization and mechanical properties of PP/nano‐CaCO₃ composites were dependent on the interfacial interactions of these two interfaces, especially the interfacial interaction between PP and compatibilizer. The good compatibility between PP chain in PP‐g‐MA and PP matrix improved the dispersion of nano‐CaCO₃ particles, favored the nucleation effect of nano‐CaCO₃, increased the tensile strength and modulus, but reduced the ductility and impact strength of composites. The partial compatibility between POE in POE‐g‐MA and PP matrix had little effect on crystallization and mechanical properties of PP/nano‐CaCO₃ composites. The poor compatibility between EVA in EVA‐g‐MA and PP matrix retarded the nucleation effect of nano‐CaCO₃, and reduced the tensile strength, modulus, and impact strength. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of compatibilizer on the dispersion of untreated silica in a polypropylene matrix

BACKGROUND: A new processing method for polypropylene–untreated precipitated silica (PP/SiO₂) composites based on the incorporation of a second polymer phase of polyamide 6 (PA6) is presented and compared with a more classic one making use of compatibilizers: glycerol monostearate (GMS), ethylene acrylic acid ionomer (IAAZE) and maleic anhydride grafted polypropylene (MA‐graft‐PP). The effects of processing methods and conditions on the microstructure and properties of PP/SiO₂ composites prepared by melt compounding are investigated with a view to reduce the size of aggregates of silica from the micrometre to the nanometre scale and to improve the link between filler and matrix. RESULTS: On the one hand, the presence of GMS and IAAZE compatibilizers significantly improves the dispersion of the silica particles. On the other hand, when using a PA6 second phase, the SiO₂ particles are dispersed in PA6 nodules. Within these nodules, SiO₂ appears dispersed at the nanoscale but with larger particles (‘aggregates’) of about 200 nm. Significant improvements in tensile strength and modulus are obtained using MA‐graft‐PP compatibilizer. An increase in impact strength is observed in the case of GMS compatibilizer. Thermal parameters indicate also that silica plays the role of nucleation agent for PP matrix. All improvements (tensile strength, modulus and impact strength) increase with the addition of compatibilized PA6 second phase. CONCLUSION: By the incorporation of masterbatch of silica in PA6 as a second polymer polar phase, a successful new production method for PP/SiO₂ nanocomposites has been developed. Interestingly, this method does not require any (expensive) pre‐treatment of the silica. Copyright © 2007 Society of Chemical Industry     

Preparation and morphological,thermal, and physicomechanical properties of polypropylene‐potato peel biocomposites

Potato peel powder (POPL), which is biodegradable, has been used as filler material in polypropylene (PP) matrix in varying concentration from 10 to 40% by weight to prepare biocomposites and investigated water absorption, physicomechanical and thermal properties. Scanning electron microscopy and X‐ray diffraction has been used for morphological characterization and crystallization studies. Flexural modulus of biocomposites increased by 40% compared with neat PP at 30% loading of POPL. Flexural strength also increased with increasing filler loading. Tensile strength of biocomposites has been observed to be comparable with neat PP up to 20% filler loading and increase in tensile modulus up to 40% was seen in biocomposites with 20% filler loading. Impact strength of biocomposites up to 20% filler loading was found to be at par with neat PP. Use of MA‐g‐PP compatibilizer in the biocomposites yielded better physico‐mechanical and thermal properties than biocomposites without compatibilizer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42445.     

Water absorption behavior and its effect on tensile properties of ethylene–propylene–diene–terpolymer/polypropylene/filler ternary composites: a preliminary study

The water absorption behavior of white rice husk ash (WRHA) and silica filled ethylene-propylene-diene-terpolymer/polypropylene (EPDM/PP) ternary composites was studied with special reference to filler type, test specimen preparation (die cut or molded), and dynamic vulcanization of elastomer phase. The water uptake of composites was recorded as a function of them over 40 days of immersion period in distilled water. The influence of final water uptake on tensile properties of the composites was also studied. White rice husk ash filled composites and molded composites exhibit lower water uptake when compared to silica and die cut composites, respectively. All vulcanized composites showed lower water uptake than the unvulcanized composites. After the immersion period in water, tensile properties of unvulcanized composites were almost unaffected while vulcanized composites exhibit an increase in the tensile properties. None of the composites reached the equilibrium state within the immersion period. The results of this preliminary study suggest the importance of in-depth study of water absorption–tensile property correlation of this ternary system over a large span of time till the equilibrium state is reached. It is further revealed that the water absorption behavior depends on the characteristics of the test specimen used.     

Morphological,mechanical, and physical properties of composites made with wood flour‐reinforced polypropylene/recycled poly(ethylene terephthalate) blends

Wood flour (WF)‐filled composites based on a polypropylene (PP)/recycled polyethylene terephthalate (r‐PET) matrix were prepared using two‐step extrusion. Maleic anhydride grafted polypropylene (MAPP) was added to improve the compatibility between polymer matrices and WF. The effects of filler and MAPP compatibilization on the water absorption, mechanical properties, and morphological features of PP/r‐PET/WF composites were investigated. The addition of MAPP significantly improved mechanical properties such as tensile strength, flexural strength, tensile modulus, and flexural modulus compared with uncompatibilized composites, but decreased elongation at break. Scanning electron microscopic images of fracture surface specimens revealed better interfacial interaction between WF and polymer matrix for MAPP‐compatibilized PP/r‐PET/WF composites. MAPP‐compatibilized PP/r‐PET/WF composites also showed reduced water absorption due to improved interfacial bonding, which limited the amount of absorbable water molecules. These results indicated that MAPP acts as an effective compatibilizer in PP/r‐PET/WF composites. POLYM. COMPOS., 38:1749–1755, 2017. © 2015 Society of Plastics Engineers     

Effect of maleic‐anhydride‐grafted polypropylene as a compatibilizer on the properties of polypropylene/(modified carbon black) composites

Maleic‐anhydride‐grafted polypropylene (PP‐g‐MAH) was added, as a compatibilizer, to polypropylene (PP) composites filled with a hindered phenol and modified carbon black (CB). The interaction between the modified CB and PP‐g‐MAH, as proved by Fourier transform infrared spectroscopy, had a beneficial effect on the mechanical properties of the PP/(modified CB) composites and prevented the sharp decrease of the mechanical properties of these composites at higher filler concentration. The storage modulus of PP/(modified CB) was increased significantly by the incorporation of PP‐g‐MAH, especially when the temperature was lower than 0°C. When the content of PP‐g‐MAH was 5 wt% and the loading of the modified CB was 2 wt%, the best tensile strength was obtained. The system showed the best flexural strength and impact strength when the loading of the modified CB was 1 wt%. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Morphological and mechanical properties of PP/ABS blends compatibilized with PP‐g‐acrylic acid

Polypropylene (PP) and acrylonitrile–butadiene–styrene (ABS) blends were prepared by a melt extrusion process. PP‐g‐acrylic acid was used as a compatibilizer. Blends with various compositions of PP, compatibilizer, and ABS were prepared and studied for morphological and mechanical properties. PP‐rich ternary blends showed good morphological and mechanical properties. The use of 5 wt % PP‐g‐acrylic acid as a compatibilizer resulted in a fine and homogeneous dispersion of the ABS phase in the PP phase. The experimental data of the tensile modulus showed good agreement in PP‐rich compositions with that generated from Kerner's model with perfect adhesion. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1731–1741, 2001     

Lewis acidic polypropylene for compatibilization of polypropylene/microsilica composites

Polypropylene (PP) was compounded with submicron size silica filler particles (microsilica, μSi) up to 30 wt‐%. In addition, three external compatibilizers, with characteristic functionalities, were studied to examine their influence in the mechanical properties of the PP/μSi composites. As a result, the modulus of the composite increased while the other tensile values deteriorated in correlation with increased filler concentration. The addition of an external compatibilizer reduced this deterioration, but the reduction was dependent on the type of the compatibilizer used. The influence of an acid functionalized compatibilizer was unsubstantial while the fluorosilane and the Lewis acidic phenylsilane functionalized polypropylenes acted as effective compatibilizers. In addition to examining the tensile properties, the toughness of the composites was evaluated as well. The microsilica filler was found to act as toughening agent since the Brittle‐to‐Ductile transition point of the composite increased by 2‐3 orders of magnitude at high filler concentrations. However, this increase in the toughness was rapidly lost when an effective compatibilizer was used to bind the filler with the matrix. This observation was consistent with the common understanding of the filler toughening mechanism, where particle‐matrix debonding is a prerequisite for facilitating the plastic stretch of the polymer ligaments between filler particles. In our case, however, the few filler aggregates in the polymer matrix also played a crucial role. While in uncompatibilized composites the filler aggregates remained passive (could not be seen at the fracture surface), the addition of an effective compatibilizer activated these aggregates to promote crack initiation and/or propagation. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Effect of compatibilizing agents on the mechanical property of rice husk flour as nano-potential filler in polypropylene biocomposite

In this article, rice husk flour filler/polypropylene (RH/PP) composites with different ratios of the filler were prepared without and with maleated PP, which was used as a compatibilizer. The RH filler in the RH/PP composites was treated with acid and alkali, and their mechanical properties were measured. The mechanical properties were improved with the addition of the compatibilizer. In this study, grafting of maleic anhydride (MA) onto PP with different ratios of benzoyl peroxide (BPO) and MA was prepared. Infrared analysis showed characteristic bands at 1786 and 1863 cm⁻¹ for the grafted sample (maleated PP). Also, from chemical titration, the optimum MA and BPO contents were 4 and 1 part per hundred parts (php of polymer), respectively. The results showed that the morphology of the grafted sample was a flat with coarse surface, and that of the composite clearly elucidated that the interfacial bonding between RH and PP was enhanced by the presence of the compatibilizer. Thermal stability of the grafted PP was enhanced by the grafting process. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Investigation on the use of coir fiber as alternative reinforcement in polypropylene

Polypropylene/coir fiber composites were prepared according to an experimental statistical design, in which the independent variables, coir fiber, and compatibilizer content, were varied. The compatibilizer used was maleic anhydride grafted polypropylene (PP‐g‐MA). Compatibilizer free composites were also prepared. Composites were processed in a corotating twin‐screw extruder and submitted to mechanical and morphological analyses. The effects of the independent variables on the mechanical properties were assessed through tensile strength, elongation at break, flexural modulus, and impact strength. The morphological properties were assessed by scanning electron microscopy (SEM). The results indicated the need for using compatibilizers in the composites due to the incompatibility of PP and coir fiber. The variable with the strongest effect on the properties was coir content, whose increase caused increase in tensile strength, impact strength and elastic modulus, and decrease in elongation at break. The presence of PP‐g‐MA was fundamental to achieving the aforementioned results. The effect of increasing compatibilizer content was only observed for the elastic modulus. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Role of reactive compatibilization in preparation of nanosilica/polypropylene composites

The effect of reactive compatibilization on the mechanical properties of nanosilica filled polypropylene (PP) composites was studied in this work. First, the nanoparticles were grafted with poly(glycidyl methacrylate) (PGMA) by solution free‐radical polymerization, and then melt blended together with PP matrix and aminated PP (PP‐g‐NH₂) that acts as reactive compatibilizer. The reaction between epoxide groups of the grafted PGMA on the nanoparticles and amine groups of PP‐g‐NH₂ during compounding greatly improved interfacial interaction in the composites. As a result, tensile strength, Young's modulus, and notch impact strength of PP composites were increased at rather low filler content. The experimental results indicated that the reinforcing and toughening effects were controlled by flexibility of the grafted polymer as well as processing methods. POLYM. ENG. SCI., 47:499–509, 2007. © 2007 Society of Plastics Engineers.     

The effects of dynamic vulcanization and compatibilizer on properties of paper sludge‐filled polypropylene/ethylene propylene diene terpolymer composites

The effects of dynamic vulcanization (DV) and dynamic vulcanization plus compatibilizer (DVC) of paper sludge (PS) filled polypropylene/ethylene propylene diene terpolymer (PP/EPDM) composites on torque development, mechanical properties, water absorption, morphology, and thermal properties were studied. Results show that DV and DVC composites exhibit higher stabilization torque than unvulcanized composites (UV). The dynamic vulcanized (DV) and dynamic vulcanized plus compatibilizer (DVC) composites exhibit higher tensile strength, elongation at break, and Young's modulus but lower water absorption than unvulcanized composites. The scanning electron microscopy (SEM) study of tensile fracture surface of DV and DVC composites shows the improved interfacial interaction between PS and PP/EPDM matrix. The DV and DVC composites also exhibit better thermal stability and higher crystallinity than unvulcanized PP/EPDM/PS composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The effects of PHBV-g-MA compatibilizer on morphology and properties of poly(3-hydroxybutyrate-Co-3-hydroxyvalerate)/olive husk flour composites

The paper provides some experimental data on the effects of a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) grafted maleic anhydride (PHBV-g-MA) used as the compatibilizer for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/olive husk flour (OHF) composites prepared by melt compounding. The natural filler was added to PHBV at various contents, i.e. 10, 20, and 30 wt%, while the amount of PHBV-g-MA was 5 wt% based on neat PHBV. Morphology, contact angle measurements, water absorption (WA), mechanical, viscoelastic, and barrier properties of the various composites were investigated with and without the compatibilizer. The study showed through scanning electron microscopy that the addition of PHBV-g-MA to PHBV/OHF composites resulted in better and finer dispersion of the filler in the matrix, even at a higher content ratio, indicating improved affinity between the components. This is in agreement with the decrease in both surface energy and WA. Furthermore, tensile and dynamic mechanical measurements indicated a reinforcing effect of OHF in PHBV composites, being more pronounced in the presence of PHBV-g-MA. The barrier properties against oxygen and water vapor were also improved for the compatibilized composites.     

Effects of interfacial adhesion on properties of polypropylene/Wollastonite composites

Wollastonite reinforced polypropylene (PP/CaSiO₃) composites were prepared by melt extrusion. A silane coupling agent and a maleic anhydride grafted PP (PP‐g‐MA) were used to increase the interfacial adhesion between the filler and the matrix. The increased adhesion observed by scanning electron microscopy (SEM) resulted in improved mechanical properties. A model was applied to describe the relationship between the interfacial adhesion and tensile properties of PP/CaSiO₃ composites. There is stronger interfacial adhesion between silane‐treated CaSiO₃ and polymer matrix containing PP‐g‐MA as a modifier. Results of dynamic mechanical thermal analysis (DMTA) showed that stronger interfacial adhesion led to higher storage modulus. The influence of CaSiO₃ particles on the crystallization of PP was studied by using differential scanning calorimetry (DSC). The introduction of CaSiO₃ particles does not affect the crystallization temperature and crystallinity of PP matrix significantly. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Properties of Paper Sludge Filled Polypropylene (PP)/Ethylene Propylene Diene Terpolymer (EPDM) Composites: The Effect of Silane-Based Coupling Agent

Paper sludge was used as a filler in PP/EPDM composites and 3-aminopropyl triethoxysilane (3-APE) was used in this study as a coupling agent. The effects of filler loading and 3-APE on the mechanical properties, water absorption, morphology, and thermal properties of the composites were investigated. It was found that incorporation of a silane coupling agent (3-APE) increased the stabilization (equilibrium) torque, tensile strength, and Young's modulus but decreased the elongation at break and water absorption. Scanning electron microscopy (SEM) study of the tensile fracture surface of the composites indicated that the presence of 3-APE increased the interfacial interaction between paper sludge and PP/EPDM matrix. The addition of a silane coupling agent also increased the crystallinity of PP and thermal stability of PP/EPDM/PS composites.