Maleic Polypropylene Research Articles

Effect of hybridization and compatibilization on the mechanical properties of recycled polypropylene‐hemp composites

AbstractHemp fibers and particles, with different sizes and contents, were used to make hybrid composites based on recycled polypropylene (PP). In particular, the effect of maleated polypropylene (MAPP) addition on the morphology and mechanical properties is reported. The results show that better adhesion is obtained with MAPP addition. In general, fiber content and size had a substantial effect on the tensile, flexural, torsion, and impact properties of the resulting composites. Although, adding MAPP to the samples improved the impact strength of the composites, the values were always lower than neat PP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Polypropylene-elastomer (TPO) nanocomposites: 2. Room temperature Izod impact strength and tensile properties

Room temperature Izod impact strength was determined for polypropylene (PP)/ethylene-co-octene elastomer (EOR) blends and nanocomposites, containing organoclays based on montmorillonite (MMT), at fixed elastomer content of 30 wt% and 0–7 wt% MMT. A ratio of maleated polypropylene, PP-g-MA to organoclay of unity was used as a compatibilizer in the nanocomposites. The organoclay serves to reduce the size of the EOR dispersed phase particles and facilitates toughening. The Izod impact strength is also influenced by the molecular weight of PP, elastomer octene content, elastomer MFI in addition to MMT content. Nanocomposites based on a low molecular weight polypropylene (L-PP) containing a higher octene content elastomer showed higher impact strength at lower MMT contents compared to those based on a low octene content elastomer. The effect of elastomer octene content on impact strength of high molecular weight polypropylene (H-PP) nanocomposites is not so significant. Elastomers having a melt flow index (MFI) in the range of 0.5–1.0 showed significant improvement in the impact strength of L-PP based nanocomposites. Most H-PP/EOR blends gave ‘super-tough’ materials without MMT and maintain this toughness in the presence of MMT. The critical elastomer particle size below which the toughness is observed is reduced by decreasing the octene content of the elastomer. For the similar elastomer particle sizes in nanocomposites, the impact strength varies as H-PP > M-PP > L-PP. The tensile modulus and yield strength improved with increasing MMT content; however, elongation at break was reduced. The extruder-made TPO showed a good-balance of properties in the presence of MMT compared to reactor-made TPO having similar modulus and elastomer content.

Preparation and Properties of Polypropylene/Clay Nanocomposites for Food Packaging

Polypropylene (PP)/clay nanocomposites based on PP, organic clay (montmorillonite; MMT), and maleated polypropylene (MAPP) were prepared by melt compounding. The mechanical, thermal, morphological, and gas barrier properties of the resulting PP/clay nanocomposites were investigated at varying concentrations of the components for food packaging. The results revealed that the mechanical strengths, including tensile, flexural, and Izod impact strength, were increased for PP/clay nanocomposites compared to neat PP. The thermal properties showed a tendency for the melting and degradation temperatures to increase with the clay concentration. The effect of the compatibilizer was observed using scanning electron microscopy (SEM). The X-ray diffraction pattern of the nanocomposites revealed increased d-spacing of the MMT layers, indicating that the compatibility of neat PP and clay was improved by the addition of MAPP, and the intercalation and partial exfoliation of the layers. The use of clay increased the mobility distance of the gas molecules, leading to the oxygen permeability of neat PP being reduced by 26% to 55%.

Rice husk/poly(propylene‐co‐ethylene) composites: Effect of different coupling agents on mechanical, thermal, and morphological properties

AbstractPoly(propylene‐co‐ethylene) composites with rice husk were prepared in a corotating intermeshing twin‐screw extruder using four different coupling agents. While modified maleic anhydrides such as maleated polypropylene (MAPP) and maleated polyethylene (MAPE) are commonly used as compatibilizers to improve interfacial adhesion between lignocellulosic filler and matrix, in this study, polypropylene grafted with acid comonomer (CAPP) and high‐density polyethylene grafted with acid comonomer (CAPE) were also used. The morphologies and the thermal and mechanical properties of the composites were characterized using scanning electron microscopy, thermogravimetric analysis, differential scanning analysis, tensile and impact tests. The results indicate that the base resin of the compatibilizer is an important factor in determining the effectiveness of compatibilizers for composites. Composites with PP‐based compatibilizers are more effective than PE‐based compatibilizers due to the improved wetting of the former compatibilizer in the matrix polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Oil palm fiber reinforced polypropylene composites: effects of fiber loading and coupling agents on mechanical, thermal, and interfacial properties

This study investigates the effects of fiber type, fiber loading, and coupling agent on the performance of oil palm biomass (OPB) fiber composites. Fiber composition and fiber morphology were evaluated by scanning electron microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDAX). Grinded fiber was compounded into polypropylene by means of a twin-screw compounder. Maleated polypropylene (MAPP) was used as a coupling agent during compounding. The incorporated fiber contents for OPB composites were up to 40% (by weight). The compounded samples were prepared into test specimens by injection moulder. The composites were characterized by tensile testing, flexural testing, impact testing, melt flow index, SEM, thermogravimetric analysis (TGA), and differential scanning calorimeter (DSC). The most significant effect on strength and modulus were found by the addition of coupling agent. This was attributed to the thermodynamic segregation of the MAPP toward the interface, resulting in the formation of covalent bonding to the –OH groups of the fiber surface. Composites with MAPP also provided better thermal stability.

The impact of the nature of nanoclay on physical and mechanical properties of polypropylene/reed flour nanocomposites

In this study, the effect of nanoclay on the physical and mechanical properties of nanocomposites was investigated. Composites based on polypropylene, reed fiber, coupling agent (maleated polypropylene, MAPP) and nanoclay were made by melt compounding and then injection molding. The mass ratio of reed fiber to polypropylene was controlled at 60/40 for all blends. The concentration was varied and set to 0, 2 and 4 per hundred compounds (phc) for nanoclay and 0 and 2 phc for MAPP. Results indicated that the tensile modulus and strength of PP/reed flour composites significantly increased with nanoclay loading. However, the impact strength and water uptake of the composites decreased by addition of nanoclay. Finally, the mechanical and physical analyses showed that the biggest improvement of these properties can be achieved for the nanoclay loading at 4 phc. The morphology of the nanocomposites has been examined by using X-ray diffraction. The morphological findings revealed that intercalation from the sample with 4 phc concentration of clay, which implies the formation of intercalation morphology and better dispersion, and the d-spacing of clay layers were improved in the composite in the presence of MAPP. Additionally, the coupling agent improved the mechanical and physical properties of the composites.

Thermal, dynamic‐mechanical, and dielectric properties of surfactant intercalated graphite oxide filled maleated polypropylene nanocomposites

AbstractGraphite oxide (GO) and amine surfactant intercalated graphite oxide (GOS) filled maleated polypropylene (PPgMA) nanocomposites were prepared directly by solution blending. In this study, the effects of the surfactant intercalation on the crystalline structure, thermo‐mechanical, and dielectric properties of PPgMA/GO and GOS composites are reported. Wide‐angle X‐ray diffraction exhibited a lower intensity diffraction peak of the monoclinic (α) phase of PPgMA for PPgMA/GOS composites compared with the unfilled sample. Differential scanning calorimetry exhibited a single characteristic melting peak of monoclinic (α) crystalline phase. The incorporation of GOS hardly showed any change in Tm. However, the significant decrease in the melting enthalpy of PPgMA/GOS composite, which was lower than that of GO filled PPgMA, demonstrated the high degree of dispersion of the GOS flakes in the PPgMA matrix. Dynamical mechanical analysis indicated that incorporation of GO or GOS into PPgMA increased both the storage modulus and the glass transition temperature, due to the hydrogen bonding between GO and the maleic anhydride group of PPgMA. Dielectric analyzer showed significant increase in both dielectric permittivity and dielectric loss at high temperature regimes in the GOS nanocomposites. The finely dispersed GOS in the PPgMA matrix manifested the interfacial polarization, which gave rise to much greater ε′ and ε″ than that of PPgMA/GO hybrid. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Optimization of Dispersion of Nanosilica Particles in a PP Matrix and Their Effect on Foaming

Abstract Nanocomposites based on isotactic polypropylene (PP) and nanosilica (SiO2) were prepared using a co-rotating twin-screw extruder (TSE). The effect of operating variables, such as screw speed and screw configuration on the dispersion of nanosilica in the polymer matrix has been studied, using TEM imaging. High shear stress, sufficient residence time, and high fill ratio in the melting section of the screw were the most important factors in achieving good nanosilica dispersion. Furthermore, the effects of filler loading and amount of a maleated polypropylene (PP-g-MA) compatibilizer on the degree of SiO2 dispersion were investigated. The foaming performance of the composites was evaluated using a batch foaming simulation system, and an extrusion foaming setup that employed respectively N2 and CO2 blowing agents. Well-dispersed surface-modified hydrophobic SiO2 particles acted as effective nucleating agents for foaming, when used at loadings below 1 phr.

Polypropylene-elastomer (TPO) nanocomposites: 1. Morphology

PP/PP-g-MA/MMT/elastomer nanocomposites were prepared in a twin-screw extruder at fixed 30 wt% elastomer and 0–7 wt% MMT content. The ratio of maleated polypropylene, PP-g-MA and organoclay was maintained at 1. Elastomer particle size and shape in the presence of MMT were evaluated for three different molecular weight grades of polypropylene (PP) and five different ethylene-co-octene elastomers (EOR) with different melt flow index (MFI) and octene contents. The MMT particles are located exclusively in the PP phase in the PP/PP-g-MA/MMT/EOR nanocomposites as seen from TEM images. Injection molded nanocomposite samples show significant decreases in elastomer particle size and increases in elastomer aspect ratio and particle density compared to as-extruded or pelletized samples. The elastomer particle size decreased significantly with increased MMT content and the molecular weight of PP. Low molecular weight PP based nanocomposite showed a greater reduction in elastomer particle size compared to medium and high molecular weight PP based nanocomposites. Elastomers having MFI in the range of 0.5–1.0 gave minimum elastomer particle sizes in the PP/PP-g-MA/MMT/EOR nanocomposite. The elastomer particles were deformed during injection molding leading to an increase in their aspect ratio. The nanocomposites containing high octene content elastomer gave smaller elastomer particle size and higher elastomer aspect ratios compared to nanocomposites containing low octene content elastomer.

Effect of γ-Radiation on the Property of Polypropylene/Nylon-6 Blends

Blends PP/PA (100:18) was prepared by means of melt-mixing using a twin- screw extruder, and the effects of γ-radiation in air on their stability under lower radiation dose (≤5kGy) at a fixed dose rate of 110Gy/min have been researched. The effects of nylon-6 (PA-6), trimethyrol-propane trimethacrylate (TMPTA), maleated polypropylene (mPP) and γ-radiation dose (D) on melt flow ability, mechanical property, thermal property and morphology of the blends were investigated. It was noted that its tensile strength (σs) and Young’s modulus (E) increased with the addition of TMPTA, while its elongation (ε) and melt flowing rate (MFR) decreased. Compatibilizer mPP and TMPTA could improve the compatibility of the PP/PA-6. Its heat resistance was superior to PP. There was little effect of γ-radiation in air on their σs, E and ε when irradiation dose ranged from 0.1 to 5.0kGy.

Preparation and Characterization of Clay Nanocomposites of Plasticized Starch and Polypropylene Polymer Blends

Plasticized starch (PLS) is a renewable, degradable, and inexpensive polymer, but it suffers from poor mechanical properties. The mechanical properties can be improved by blending PLS with polyolefins, nonetheless, at high PLS content, the mechanical properties remain poor. Here we show that addition of clay can greatly improve the mechanical properties of PLS/polypropylene blends at high starch content. Unmodified and organically modified montmorillonite clays, MMT and Cloisite 30B respectively, were added to blends of glycerol-plasticized starch and polypropylene, compatibilized using maleated polypropylene. TEM indicates that MMT is well dispersed in the PLS phase of the blends, while Cloisite 30B is located both within the PLS phase as well as at the interface between PLS and PP. At high PLS content, the addition of clay increased the tensile strength and tensile modulus by an order of magnitude, while reducing the ultimate elongation only slightly. Such improvements are attributable to both the addition of clay as a reinforcing component, as well as to the change in the two phase morphology due to addition of clay.

Investigation of tensile properties and dyeing behavior of various polypropylene/polyamide 6 blends using a mixture experimental design

Polypropylene has many advantages over other polymeric fibers such as high tensile strength, good abrasion resistance, high chemical resistance and very competitive price. However, the use of polypropylene fiber is restricted by the lack of affinity of conventional dyestuffs for this fiber. Many attempts have been made to improve the dyeability of polypropylene by various techniques. It must however, be noted that enhanced dyeability of polypropylene should not adversely impair its other properties, in particular its mechanical properties. To this end, in the present investigation, a mixture experimental design was used in order to attain an optimal region of proportions of three components namely polypropylene (PP), maleated polypropylene (polypropylene grafted with maleic anhydride (MAH-PP) as a compatibilizing agent) and polyamide 6 (PA6); where enhanced dyeability as well as retained mechanical properties would be achieved. Additionally, in order to analyze the morphology of the blends, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were used. Finally, in order to evaluate effect of each component on fastness properties of the blends, wash, rub and light fastnesses were determined by the corresponding standard test methods.

Comparative study of maleated polypropylene as a coupling agent for recycled low‐density polyethylene/wood flour composites

AbstractThe effects of the type of coupling agent and virgin polypropylene (PP) content on the mechanical properties and water absorption behavior of recycled low‐density polyethylene/wood flour (WF) composites were investigated. The fractured surfaces of these recycled wood/plastic composites (rWPCs) were examined to gain insight into the distribution and dispersion of WF within the polymer matrix. The results indicate that the use of 100% recycled polymer led to inferior mechanical properties and to a greater degree of moisture absorption and swelling when compared to recycled polymer–virgin PP wood/plastic composites. This could have been related to the poor melt strength and inferior processability of the recycled polymer. The extent of improvement of the mechanical properties depended not only on the virgin PP content in the matrix but also on the presence of maleic anhydride (MA) modified PP as the coupling agent. Higher concentrations of MA group were beneficial; this improvement was attributed to increased chemical bonding (ester linkages) between hydroxyl moieties in WF and anhydride moieties in the coupling agent. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Effects of fiber loading, fiber type, its mesh sizes, and coupling agent on the properties of oil palm biomass/polypropylene composites

This study investigates the effects of fiber type, mesh size, fiber loading, and coupling agent on the performance of oil palm biomass (OPB) fiber composites. The dried OPB fibers were ground and screened into 63, 150, 250, 450, and 500 µm meshes for composite production. Fiber composition and fiber morphology were evaluated by scanning electron microscope (SEM) and energy disperse analysis of X-Ray. Ground fiber was compounded into polypropylene (PP) by means of a twin-screw compounder. Maleated polypropylene (MAPP) was used as a coupling agent during compounding. The incorporated fiber contents for OPB composites were 10%, 20%, 30%, and 40% (by weight). The compounded samples were prepared into test specimens by injection molder. The composites were characterized by tensile testing, flexural testing, impact testing, melt flow index, and SEM. The analysis of variance of the effects of fiber types, fiber mesh sizes, and fiber contents and their interactions on the OPB–PP composite properties were studied and found to affect on composite properties significantly. The most significant effect on strength and modulus was found by the addition of coupling agent which was suggested to be due to the thermodynamic segregation of the MAPP toward the interface resulting in covalent bonding to the −OH groups on the fiber surface.

Effects of maleated polypropylene on the morphology, thermal and mechanical properties of short carbon fiber reinforced polypropylene composites

The aim of this study was to determine the effect of the maleic anhydride grafted polypropylene (PP-g-MAH) on the properties of short carbon fiber (CF) reinforced polypropylene (PP) composites. The composites were prepared by melt blending and injection molding techniques at different percentages of CF. Tensile tests, hardness, differential scanning calorimeter (DSC) and scanning electron microscopy (SEM) were performed to characterize the physical and morphological properties of the prepared composites. It was observed from SEM photographs that modification with PP-g-MAH improved the interfacial adhesion between the carbon fibers and PP matrix. The ultimate tensile strength, hardness and modulus values of modified PP composites were higher compared to the values of CF reinforced PP composites. Melting temperature of all composites was not changed significantly with increasing CF content; however degree of crystallinity values were decreased with the increasing CF content level.

Effect of the tie‐layer thickness on the delamination and tensile properties of polypropylene/tie‐layer/nylon 6 multilayers

AbstractThis study examined the effect of the tie‐layer thickness on the delamination behavior of polypropylene/tie‐layer/nylon 6 multilayers. Various maleated polypropylene resins were compared for their effectiveness as tie‐layers. Delamination failure occurred cohesively in all the multilayer systems. Two adhesion regimes were defined according to the change in the slope of the linear relationship between the delamination toughness and the tie‐layer thickness. The measured delamination toughness of the various tie‐layers was quantitatively correlated to the length of the damage zone that formed at the crack tip. In addition, the effect of the tie‐layer thickness on the multilayer tensile properties was correlated with the delamination behavior. The fracture strain of the multilayers decreased with decreasing tie‐layer thickness. An examination of the prefracture damage mechanism of the stretched multilayers revealed a good correlation with the delamination toughness of the tie‐layers. In thick tie‐layers (>2 μm), the delamination toughness was great enough to prevent the delamination of the multilayers when they were stretched. In thin tie‐layers (<2 μm), the delamination toughness of all the tie‐layers was low; consequently, delamination led to premature fracture in the stretched multilayers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Effects of coupling agent on oil palm clinker and flour-filled polypropylene composites

This study gives the comparative analysis of polypropylene (PP)/oil palm flour (OPF) and PP/oil palm clinker (OPC) composites using maleated polypropylene (MAPP) as a coupling agent. Ground flour and crashed OPC were compounded separately into polypropylene with and without MAPP using a twin-screw compounder. The incorporated OPF and OPC in the composites were up to 40 wt%. The compounded samples were prepared into test specimens by injection molder. The composites were characterized by tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength, and melt flow index. The surface morphology of composites was evaluated by scanning electron microscope. Incorporation of coupling agent showed better result than that of without coupling agent. Various properties of composites incorporated with OPC represented considerably close to the composites with OPF.

Thermo-oxidative stability of polypropylene/layered silicate nanocomposites

Several series of experiments were carried out to check the effect of components on the stability of PP/layered silicate nanocomposites. The amount of organophilic montmorillonite (OMMT) changed between 0 and 6, while that of maleated polypropylene (MAPP) between 0 and 50vol%. The composites were prepared in an internal mixer at 190°C. Mixing speed and time were changed to study the effect of processing conditions on stability. The structure of the samples was characterised by various methods, while stability by the induction time of oxidation (OIT), the onset temperature of degradation (OOT) and by colour. Contrary to numerous claims published in the literature, which indicate the positive effect of layered silicates on the stability of polymer nanocomposites, our results clearly proved that both OMMT and MAPP accelerate degradation during processing and deteriorate the properties of PP composites. Residual stability decreases drastically with increasing amounts of both components, chain scission leads to the decrease of viscosity and to inferior strength and deformability. In spite of expectations, the effect of the components is independent of each other. Discoloration is caused mainly by the inherent colour of the filler and it decreases with increasing exfoliation. The most probable reason for decreased stability is the reaction of the components with the stabilisers, but this explanation needs further verification. Processing conditions influence degradation considerably, increasing shear rate and longer residence times lead to more pronounced degradation. The basic stabilization of commercial grade polypropylenes is insufficient to protect the polymer against degradation and without additional stabilization processing under normal conditions results in products with inferior quality.

Influence of coupling agents in the preparation of polypropylene composites reinforced with recycled fibers

The use of coupling agents based on polyolefins is an interesting strategy for the preparation of composites with marked different chemical structure between their components. That is the case of polypropylene-based composites reinforced with lignocellulose fibers. In this work a deep study of the influence of the intrinsic parameters of maleated polypropylene (MAH-PP) has been carried out in order to determine the effect of its acid number as well as molecular weight in mechanical properties of composites reinforced with low cost reinforcements, under tensile, flexural and impact stresses, flow capacity, water absorption behavior and surface morphology. The use of high functionalized MAH-PP coupling leaded to important improvements in mechanical stresses and also a lower capacity of water absorption due to the formation of thinner interfaces. In the case high molecular weight MAH-PP agents, even higher than plain polymer matrix, conducted to an interesting increase in unnotched Charpy Impact Strength attributed to a low dispersion of the coupling agent in the matrix during mixing process keeping microdomains that help to avoid crack propagation.

Biocomposites from Musa textilis and polypropylene: Evaluation of flexural properties and impact strength

Abaca ( Musa textilis)-reinforced polypropylene composites have been prepared and their flexural mechanical properties studied. Due to their characteristic properties, M. textilis has a great economic importance and its fibers are used for specialty papers. Due to its high price and despite possessing very distinctive mechanical properties, to date abaca fibers had not been tested in fiber-reinforced composites. Analysis of materials prepared showed that, in spite of reduced interface adhesion, flexural properties of the PP composites increased linearly with fiber content up to 50 wt.%. Addition of a maleated polypropylene coupling agent still enhanced the stress transfer from the matrix to the reinforcement fiber. As a result, composites with improved flexural properties were obtained. The mechanical properties of matrix and reinforcing fiber were evaluated and used for modelling both the flexural strength and modulus of its composites. In addition, the impact strength of materials was evaluated. Comparison with mechanical properties of composites reinforced with fiberglass points out the potentiality of abaca-reinforced polypropylene composites as suitable substitutes in applications with low impact strength demands.