Maleic Polypropylene Research Articles

Efeito do Co-Intercalante CIS-13-Docosenamida na Morfologia e Propriedades Mecânicas de compósitos Polipropileno/Argila Organofílica

PP/organoclay/PP-g-MA/erucamide composites with 5% commercial organo-montmorillonite (Cloisite 20A), 5 and 15% maleated polypropylene as compatibilizer, and 0, 0.5 and 1% erucamide as a co-intercalating agent were prepared by melt intercalation. A masterbatch of compatibilizer and organoclay was compounded in an internal mixer and then diluted in the polypropylene matrix in a corotating twin-screw extruder. The compounds were characterized by x-ray diffraction, optical microscopy and mechanical properties. Results indicate that the organoclay acted as a reinforcer. Addition of the co-intercalating agent significantly increased the interlayer spacing of the clay, without notably affecting the mechanical behavior of the composites. Optical microscopy showed the dispersive effect of the screw profile used, which promoted the breaking of clay agglomerates.

Waste chestnut shell as a source of reinforcing fillers for polypropylene composites

In this study, we evaluated dimensional stability and some mechanical properties of polypropylene composites filled with chestnut shell flour (CSF). To meet this objective, CSF was compounded with polypropylene with and without coupling agent in a twin screw corotating extruder and then were manufactured by injection molding process. The thickness swelling and water absorption of the samples increased with increasing CSF content. The flexural and tensile modulus improved with increasing CSF content, while the flexural and tensile strengths of the samples decreased. The use of maleic anhydride polypropylene had a positive effect on the dimensional stability and mechanical properties of the polypropylene composites filled with CSF. This work showed that the composites treated with maleated polypropylene could be efficiently used as decking products, due to high-dimensional stability and satisfactory mechanical properties of the composites.

Influence of Twin-Screw Processing Conditions on Structure and Properties of Polypropylene – Organoclay Nanocomposites

Abstract This study looks at the influence of extrusion parameters such as screw speed, feed rate and barrel temperature on the nanocomposite structure (size of agglomerates, level of intercalation and exfoliation) and its consequences on final mechanical properties. Nanocomposites of polypropylene, maleated polypropylene and organomodified montmorillonite, with respective mass fractions of 85/10/5, were prepared in a co-rotating twin-screw extruder using a masterbatch dilution method. The nanocomposites structure was quantified by scanning and transmission electron microscopy, X-ray diffraction and dynamic rheometry. Relationships between the microstructure at different levels (size and number of agglomerates, interlayer distance, melt yield stress to quantify the exfoliation level) and the processing conditions were established, revealing that specific mechanical energy received during extrusion was the key parameter controlling this microstructure. Mechanical properties in uniaxial tension (apparent Young's modulus) were measured and related to the microstructural parameters resulting from extrusion conditions.

Characterization of microstructures in sisal fiber composites by Voronoi diagram

In this article, the microstructures of sisal fiber composites were analyzed. The porous structure of sisal fiber, crystalline morphology of matrix and fiber distribution in composites were characterized by Voronoi diagram. The tensile properties of composites were also measured. The results show that the maleated polypropylene compatibilizer can accelerate the formation of transcrystalline interface between fibers and matrix. Improvement of interface adhesion and reduction of fiber polarity can lead to better fiber distribution in the matrix. The tensile moduli of composites are related to the degree of fiber distribution.

Using master curves based on time–temperature superposition principle to predict creep strains of wood–plastic composites

To verify master curves obtained based on time–temperature superposition principle for wood–plastic composites (WPCs), a 220-day long-term creep test was conducted under an unconditioned environment. In this study, WPCs were made by extrusion with various formulations; using mountain pine beetle-attacked lodgepole pine flour and high-density polyethylene as raw materials, as well as maleated polypropylene as coupling agent. The results showed that the effect of naturally elevated temperature during the summer months caused additional increases in creep strain. The information obtained from the conventional creep study method may be insufficient to reflect the practical application. Comparisons between long-term data and the master curves showed that the master curves tended to overestimate the real creep strain of large specimens and that the deviation increased with time. The prediction of the master curve agreed more reasonably with the long-term data for coupled WPC products, whereas the master curves showed considerable overestimation for the uncoupled ones. In general, the master curves cannot precisely predict the long-term creep strain, but merely provide conservative estimations.

Nanoscale characterization of interphase properties in maleated polypropylene‐treated natural fiber‐reinforced polymer composites

AbstractContact resonance force microscopy has been used to evaluate the effect of maleated polypropylene (MAPP) concentration on interphase thickness as well as the spatial distribution of mechanical properties within the interphase of cellulose fiber‐reinforced polypropylene composites. The average interphase thickness values ranged from 25 nm to 104 nm for different concentrations of MAPP. The interphase region showed a gradient in the elastic modulus, with a gradual decrease in modulus from fiber to matrix. The interphase region in the specimen containing 0% MAPP showed a narrow interphase with steep gradient in modulus from fiber to matrix, whereas the use of MAPP significantly increased the interphase thickness which resulted in a more gradual change in modulus from fiber to matrix. POLYM. ENG. SCI., 2013. © Society of Plastics Engineers

Extruder‐made TPO nanocomposites. I. Effect of maleated polypropylene and organoclay ratio on the morphology and mechanical properties

AbstractPP/PP‐g‐MA/MMT/EOR blend nanocomposites were prepared in a twin‐screw extruder at fixed 30 wt % elastomer and 0 to 7 wt % MMT content. Elastomer particle size and shape in the presence of MMT were evaluated at various PP‐g‐MA/organoclay masterbatch ratios of 0, 0.5, 1.0, and 1.5. The organoclay dispersion facilitated by maleated polypropylene serves to reduce the size of the elastomer dispersed phase particles and facilitates toughening of these blend nanocomposites. The rheological data analysis using modified Carreau‐Yasuda model showed maximum yield stress in extruder‐made nanocomposites compared with nanocomposites of reactor‐made TPO. Increasing either MMT content or the PP‐g‐MA/organoclay ratio can drive the elastomer particle size below the critical particle size below which toughness is dramatically increased. The ductile‐brittle transition shift toward lower MMT content as the PP‐g‐MA/organoclay ratio is increased. The D‐B transition temperature also decreased with increased MMT content and masterbatch ratio. Elastomer particle sizes below ∼1.0 μm did not lead to further decrease in the D‐B transition temperature. The tensile modulus, yield strength, and elongation at yield improved with increasing MMT content and masterbatch ratio while elongation at break was reduced. The modified Mori‐Tanaka model showed better fit to experimental modulus when the effect of MMT and elastomer are considered individually. Overall, extruder‐made nanocomposites showed balanced properties of PP/PP‐g‐MA/MMT/EOR blend nanocomposites compared with nanocomposites of reactor‐made TPO. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012

Crystallization, shrinkage and mechanical characteristics of polypropylene/CaCO3 nanocomposites

Nanocomposites based on polypropylene (PP) containing 5–15 wt% of nano-calcium carbonate (CaCO3) particles and 1–3 wt% of maleated PP as compatibilizer were prepared by melt compounding followed by injection molding. The crystallinity, shrinkage behavior and mechanical properties were characterized, and the morphology was studied using scanning electron microscopy. Inclusion of 5 wt% of nano-CaCO3 interfered with PP crystallization and lowered the thermal contraction. Incorporation of higher fraction of nano-CaCO3 (10 wt%) raised the effective ability to nucleate PP crystals and hence increased the crystallization and shrinkage rates. The presence of 10 wt% CaCO3 nanoparticles raised the impact strength and elongation at break to as high as 77.4% and 115%, respectively, when compared with pure PP. A trend of CaCO3 particles agglomeration was observed at 15 wt% loading that led to the reduction in crystallinity and elongation at break.

Influence of two compatibilizers on clay/PP nanocomposites properties

This article investigates the influence on mechanical properties of using a two compatibilizer system. Cloisite-Na Clay (ClNa) was organically modified in different ways with a polyethermonoamine and maleated polypropylene (MA-g-PP) added as a second compatibilizer. A corotating twin-screw extruder was used to obtain nanocomposites based on polypropylene via the melt intercalation technique. X-ray diffraction and differential scanning calorimetric results showed that intercalated nanocomposites with improved thermal stability were obtained. Increases of 8% in tensile strength, 34% in modulus, and 20% in crystallinity were observed. Also an increase of 23% in creep properties was observed when using these two compatibilizer system and 1% clay. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Dispersion of nano-clay at higher levels into polypropylene with carbon dioxide in the presence of maleated polypropylene

The use of supercritical carbon dioxide (scCO2) has proven to be beneficial for surface modified montmorillonite (MMT) nano-clay dispersion up to 6.6 wt% in a polypropylene (PP) matrix and lead to improved material mechanical properties in our earlier research. Our further modifications of the processing procedure including a sequential mixing technique successfully extended the technique to PP composites with as much as 10 wt% of clays and continuously increasing mechanical properties. In order to obtain additional enhancements of the composite properties at this clay level, polypropylene grafted with maleic anhydride (PP-g-MA) is included in this work. The results from the studies of the mechanical properties, rheological properties, and transmission electron microscopy (TEM) show that PP-g-MA is greatly beneficial in generating an exfoliated nano-clay morphology. Greater enhancements in the mechanical properties and nano-clay dispersion in the polymer matrix are observed when PP-g-MA is combined with the scCO2 and sequential mixing techniques. The PP-g-MA based nano-clay composites have a high degree of exfoliated structure even with the addition of up to approximately 10 wt% nano-clay when using this technique, with mechanical properties such as yield strength and Young's modulus being increased by as much as 12 and 88%, respectively, relative to the polymer matrix. It is believed that the modulus reported here is the highest reported in the literature for conventional PP's.

Spatially Resolved Characterization of Cellulose Nanocrystal–Polypropylene Composite by Confocal Raman Microscopy

Raman spectroscopy was used to analyze cellulose nanocrystal (CNC) -polypropylene (PP) composites and to investigate the spatial distribution of CNCs in extruded composite filaments. Three composites were made from two forms of nanocellulose (CNCs from wood pulp and the nano-scale fraction of microcrystalline cellulose) and two of the three composites investigated used maleated PP as a coupling agent. Raman maps, based on cellulose and PP bands at 1098 and 1460 cm(-1), respectively, obtained at 1 μm spatial resolution showed that the CNCs were aggregated to various degrees in the PP matrix. Of the three composites analyzed, two showed clear existence of phase-separated regions: Raman images with strong PP and absent/weak cellulose or vice versa. For the third composite, the situation was slightly improved but a clear transition interface between the PP-abundant and CNC-abundant regions was observed, indicating that the CNC remained poorly dispersed. The spectroscopic approach to investigating spatial distribution of the composite components was helpful in evaluating CNC dispersion in the composite at the microscopic level, which helped explain the relatively modest reinforcement of PP by the CNCs.

Epoxidized natural rubber–toughened polypropylene/organically modified montmorillonite nanocomposites

The objective of this study is to toughen organically modified montmorillonite (OMMT)-filled polypropylene (PP) nanocomposites with epoxidized natural rubber (ENR). PP, ENR (10–20 wt%), OMMT (6 wt%) and maleated PP (PP-g-MA; 10 wt%) were melt blended using counterrotating twin extruder, followed by injection molding to prepare test samples. X-ray diffraction results revealed that the OMMT platelets in PP/OMMT nanocomposites were intercalated and the incorporation of ENR into the nanocomposites further increased the d-spacing of OMMT layers. The Fourier transform infrared spectra showed that the maleic anhydride group in PP-g-MA reacted in situ with the epoxy groups of ENR, which demonstrates the occurrence of grafting reaction. With slight decrease in stiffness and strength, the addition of 20 wt% ENR increased the impact strength of PP/ENR/OMMT nanocomposites by 521% compared to PP/OMMT nanocomposites. Scanning electron microscopy images revealed that the ENR particle size increased with increasing ENR contents in PP/ENR/OMMT nanocomposites. Differential scanning calorimetry results revealed that the presence of ENR and OMMT had slightly increased the crystallization temperature as well as the degree of crystallinity of PP. Thermogravimetric analysis showed that the blending of ENR decreased the thermal stability of PP/OMMT nanocomposites.

Investigation on the competing effects of clay dispersion and matrix plasticisation for polypropylene/clay nanocomposites. Part I: morphology and mechanical properties

The key compatibiliser role of maleated polypropylene (MAPP) to improve the clay dispersability has been explicitly addressed in the fabrication process and material characterisation of polypropylene (PP)/clay nanocomposites. However, its matrix plasticiser role, which has been rarely mentioned, could adversely influence the excellent mechanical properties of such nanocomposites, resulting from the homogeneous clay dispersion. PP/clay nanocomposites in the presence of MAPP were prepared by twin screw extrusion and subsequently injection moulded with three typical material formulations in fixed parametric settings: (1) weight ratio (WR) of clay and MAPP, WR = 1:2; (2) MAPP content of 6 wt% and (3) clay content of 5 wt%. The morphological structures and mechanical properties of PP/clay nanocomposites were examined by using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and universal mechanical testing. The further improvement of mechanical properties was evidently hindered with very inconsiderable alteration of morphological structures in terms of the clay dispersion level. This observation could be ascribed to the change of MAPP role from a compatibiliser to a plasticiser because of its excessive amount used above a certain saturation level, which was found in the range of 3–6 wt% in MAPP contents for the enhancements of tensile and flexural properties of PP/clay nanocomposites.

Investigation on the competing effects of clay dispersion and matrix plasticisation for polypropylene/clay nanocomposites. Part II: crystalline structure and thermo-mechanical behaviour

In view of the structure–property relationship, the mechanical property enhancement of polypropylene (PP)/clay nanocomposites can also be associated with the alterations of their crystalline structures and behaviour in addition to the general interpretation of intercalation/exfoliation level and uniform dispersion of more rigid clay platelets with higher aspect ratios in the PP matrix. Wide-angle X-ray diffraction (WAXD) was utilised to evaluate the effects of clay content, maleated PP (MAPP) content (MAPP as the compatibiliser) on PP crystalline structures of nanocomposites. Furthermore, the melting and crystallisation behaviour of PP/clay nanocomposites was also investigated by conducting differential scanning calorimetry (DSC). The thermo-mechanical properties were characterised via dynamic mechanical thermal analysis (DMTA). It is observed that enhancement of mechanical properties are mainly affected by the preferred orientation of PP crystals, the growth of α-PP phase and effective nucleating agent role of additional clay while the excessive amount of MAPP becomes detrimental to these crucial aspects, which is also evidently revealed in DMTA measurements.

Nanodiamond‐based PP/EPDM thermoplastic elastomer composites: Microstructure, tribo‐dynamic, and thermal properties

AbstractAttempts have been made for the first time to employ graphitized nanodiamond with the cage‐like structure to prepare thermoplastic elastomer (TPE) nanocomposites based on polypropylene (PP) and ethylene‐propylene‐diene rubber (EPDM), with improved tribo‐dynamic properties. Samples were prepared via melt mixing process, and maleated polypropylene (PP‐g‐MAH) was used to promote the interfacial interactions between the components and partitioning of nanodiamond particles in polymer phases. Microstructure characterization revealed significant reduction in the size of EPDM droplets if nanodiamond particles are preferentially wetted by the polypropylene phase. Nanoindentation and scratch tests performed on the surface of prepared nanocomposites exhibited enhanced surface stiffness and scratch resistance. Rheomechanical spectroscopy (RMS) and dynamic mechanical analysis (DMTA) showed enhanced melt elasticity for the interfacially compatibilized nanocomposites, which is attributed to the antiplasticizing characteristics of the caged shape nanodiamond particles. More interestingly, nanodiamond particles exhibited plasticizing behavior for the nanocomposite in molten state. All interfacially compatibilized nanodiamond composites showed enhanced thermal resistivity. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Interfacial enhancement of maleated polypropylene/silica composites using graphene oxide

AbstractGraphene oxide (GO) is derived from oxidization of natural graphite and contains many active groups. These active groups make GO a potential compatibilizer for polymer blends or coupling agent for polymer composites. In this work, a novel core‐shell structured hybrid submicroparticles of graphene oxide‐encapsulated silica (GO‐SiO2) were fabricated using GO sheets via an electrostatic assembly between ultrathin negatively charged graphene oxide sheets and positively charged amino‐modified silica. The possible application of this new hybrid filler was explored in preparation of maleated polypropylene (PP‐g‐MA)/GO‐SiO2 composites. The microstructure and interface enhancement of the prepared composites were analyzed by SEM, TEM, OM, TGA, FTIR, and DMA measurements. A uniform dispersion of GO‐SiO2 hybrids, enhanced interfacial adhesion and improved mechanical property were evidenced. The reason might be that graphene oxide can be covalently assembled onto the amino‐modified silica surface, and simultaneously it provides strong interaction with the PP‐g‐MA due to similar polarity or possible hydrogen bonding. This work suggests a potential application of graphene oxide‐encapsulated particle in preparation of high performance polymer composites. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Experimental Investigation of a Novel Polymeric Heat Exchanger Using Modified Polypropylene Hollow Fibers

Plastic heat exchangers have attracted more and more attention because of their superior resistance to chemicals and fouling. However, the thermal conductivity of plastic materials is much lower than that of metal, which limits the wider application of plastic heat exchangers. In this study, polypropylene-based hollow fibers as a heat-conducting medium for heat exchangers was developed by melt-mixing polypropylene with graphite particles and maleated polypropylene (PP-g-MA). Results show that the addition of graphite fairly improved the crystalline, thermal stability and conductivity of the polypropylene resin and further improved the heat transfer efficiency of polypropylene-based hollow fiber heat exchangers. The overall heat transfer coefficient of 15.0 wt % graphite modified polypropylene hollow fiber heat exchangers reached 1228.7 W/(m2·K), which is 5 times higher than that of pure PP-based hollow fiber heat exchangers, and the overall conductance per unit volume reached 1.1 × 106 W/(m3·K). Further, ...

Correlation of morphological, dynamic mechanical, and thermal properties in compatibilized polypropylene/ethylene-vinyl acetate copolymer/organoclay nanocomposites

Compatibilized and noncompatibilized nanocomposites based on polypropylene (PP)/ethylene–vinyl acetate copolymer (EVA) blends, having 75/25 (wt %/wt %) PP/EVA ratio, with different contents of organoclay (OMMT) and maleated polypropylene as compatibilizer were made through a melt-mixing process with a twin-screw microcompounder, and their properties were investigated. X-ray analysis revealed mainly intercalated/partially exfoliated structures for the blend-based nanocomposites. Through a thermodynamic theoretical approach and transmission electron microscopy investigation, it was shown that the OMMT nanoparticles were mainly placed at the EVA phase of the nanocomposites. Also, scanning electron microscopy analysis showed that OMMT acted like a compatibilizer and reduced the average size of the EVA dispersed phase by preventing coalescence. Dynamic mechanical analysis revealed that the addition of OMMT in the presence of the compatibilizer increased both the storage modulus and damping factor of the corresponding blends. The critical interparticle distance of the EVA domains for achieving supertoughening behavior was obtained at about 100 nm. The addition of OMMT led to a significant improvement in the thermal stability of the blends, especially in the presence of the compatibilizer. A correlation between the morphological, dynamic mechanical, and thermal properties was established to determine the best performing composition, in which desirable damping and stiffness and good thermal stability could be achieved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Multiwalled carbon nanotubes functionalized with maleated poly(propylene) by a dry mechano-chemical process

Ball milling was used to graft maleated polypropylene (MAPP) on the surface of multiwalled carbon nanotubes (MWCNTs), with a view to preparing MWCNT/polypropylene composites with improved matrix/nanotube compatibility. The occurrence of the grafting reaction was evaluated by FTIR spectroscopy and the yield was quantified by thermogravimetric analysis, as a function of the milling time. Dispersion experiments confirmed the nanotube surface modification of the nanotubes since functionalized MWCNTs remained stably dispersed in an ethanol/xylene solution for more than 48 h after sonication. No evidences of significant structural damage after the mechano-chemical treatment were shown by Raman spectroscopy. Moreover, a layer attributable to the presence of grafted MAPP chains on MWCNT walls was clearly detected by transmission electron microscopy. The average thickness of this amorphous layer was evaluated and compared with quantitative TGA data.

Polypropylene/organically modified Sabah montmorillonite nanocomposites: Surface modification and nanocomposites characterization

AbstractThe aim of the work is to extract, purify, and organically modify montmorillonite (MMT) of Lahad Datu, Sabah bentonite. The octadecylamine treated Sabah MMT (S‐OMMT) (2–8 wt%) was then melt blended with polypropylene (PP) and maleated polypropylene (PPgMAH) (10 wt%) via single screw nanomixer extruder followed by injection molding into test samples to examine the mechanical, thermal, and morphological properties of PP/S‐OMMT nanocomposites. Unmodified Sabah MMT (S‐MMT) and commercial grade MMT (Nanomer 1.30P) filled PP nanocomposites were also characterized for comparison purpose. X‐ray diffraction results showed that the interlayer spacing of S‐MMT increased after organic modification as Fourier transform infra‐red and elemental analysis evidenced the presence of octadecylamine. PP/S‐OMMT nanocomposites showed a better dispersion and strength compared to PP/Nanomer 1.30P nanocomposites due to its smaller MMT platelet size. differential scanning calorimetry and Thermogravimetry analysis revealed that the thermal stability and crystallinity of neat PP improved with the addition of all types of MMT. Dynamic mechanical analyzer showed that PP nanocomposites have higher storage modulus (E′) values than the neat PP over the whole temperature range. The new PP/S‐OMMT nanocomposites showed a comparable performance with PP/Nanomer 1.30P nanocomposites exhibiting promising future applications of S‐MMT in polymer/MMT nanocomposites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers