Maleic Anhydride Groups Research Articles

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.

Dynamic mechanical analysis of recycled polystyrene composites reinforced with wood flour

AbstractThe dynamic mechanical properties of wood flour (WF) reinforced recycled expanded polystyrene (r‐EPS) composites were investigated as a function of the WF content and coupling agent used. With the incorporation of WF into the polystyrene the storage modulus (E′) and loss modulus (E″) were found to increase and the mechanical damping (tan δ) decreased. The use of coupling agents improved the storage modulus and reduced the damping peak values of the composites because of the improved WF/matrix interfacial adhesion. The height of the damping peaks was found to be dependent on the content of maleic anhydride groups and the weight average molecular weight (Mw) of the coupling agent used. Finally, the experimental results were compared with the theoretical predictions for tan δ and the storage modulus. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Synthesis and physicochemical evaluation of maleic anhydride-grafted-poly(d,l-lactide-co-glycolide) as functional stent coating for localized gene delivery

The present study describes a novel strategy to covalently immobilize genes onto inert PLGA films via -CONH-cross-links. PLGA with functional carboxylic acid groups was synthesized using free-radical grafting maleic anhydride (MA) groups onto the polymer backbone. Cationic PEI/DNA complexes were successfully immobilized onto the functional PLGA films and characterized by ATR-FTIR and SEM analysis. We conclude that robust PLGA with functional carboxylic groups is a suitable platform for localized gene delivery.

Tuning the localization of functionalized MWCNTs in SAN/PC blends by a reactive component

The influence of the reactive component (N-phenylmaleimide styrene maleic anhydride) on the blend morphology, the localization of functionalized multiwalled carbon nanotubes (MWCNTs), and the electrical resistivity of MWCNT filled blend systems of polycarbonate (PC) and poly(styrene-co-acrylonitrile) (SAN) was investigated. SAN, PC, amino-functionalized MWCNTs (Nanocyl™ NC3152) and the reactive component (RC) were melt mixed in a DSM Xplore microcompounder using different mixing sequences. The RC containing maleic anhydride (MA) groups is miscible with SAN and is assumed to act as linking agent to the functionalized MWCNTs. The morphology of the SAN/PC blends was studied depending on the concentration of the RC. Thereby co-continuous morphologies were found for all blends with 40 wt.% SAN and 60 wt.% PC. In all nonmodified blends the MWCNTs were localized within the PC phase. After the addition of RC the MWCNTs migrated completely into the miscible SAN–RC phase. Consequently, the electrical resistivities of the blends changed in dependence on the localization. Whereas the SAN/PC/MWCNT blends showed low electrical resistivity values, much higher values were found for SAN–RC/PC/MWCNT blends. This was assigned to a coupling or strong interaction of MA groups to the nanotubes disturbing electrical contacts and percolation between them. The occurrence of the MWCNT migration from PC towards SAN was found to be dependent on the concentrations of RC and MWCNTs. By adapting that ratio and the mixing strategy, the localization of the carbon nanotubes in the blend phases can be tuned. The investigations indicated that MWCNTs once coupled with the RC remain in the SAN–RC phase. Thus, a chemical reaction or strong interactions seem to be the driving forces for localization of the MWCNTs in the SAN–RC blend phase.

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

Effect of maleic anhydride modified MWCNTs on the morphology and dynamic mechanical properties of its PMMA composites

This study successfully grafted multiwalled carbon nanotubes (MWCNTs) with maleic anhydride (Mah-g-MWCNTs) via Friedel–Crafts acylation with the aluminum chloride catalyst (AlCl 3), investigated by Raman and TGA analysis. The covalent bonds and carboxylic groups of maleic anhydride provided additional active species, improving adhesion between the MWCNTs and poly(methyl methacrylate) (PMMA). This investigation also studied the morphology and dynamic mechanical properties of pristine MWCNTs (P-MWCNTs) and modified MWCNTs (Mah-g-MWCNTs) reinforced with PMMA. Findings show a homogeneous distribution of MWCNTs throughout the matrix for Mah-g-MWCNTs/PMMA composites, as revealed by transmission electron microscope (TEM). The addition of both MWCNTs influenced the molecular arrangement of the PMMA matrix and also increased the dynamic mechanical properties of MWCNTs/PMMA composites. Glass transition temperature (Tg) and storage moduli (E′) of the Mah-g-MWCNTs/PMMA composites increased significantly comparing with P-MWCNTs/PMMA composites, attributed to improved interfacial adhesion between the reinforcement and the matrix. DMA studies revealed that adding 4.76 wt% Mah-g-MWCNTs into PMMA generates a 184% enhancement in the storage modulus and a 19 °C increase in Tg. However, adding 4.76 wt% P-MWCNTs into PMMA only generates 108% enhancement in the storage modulus and a 14 °C increase in Tg.

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

P‐155: Analysis of Solubilization of Surface‐Modified Carbon Nanotube in Nematic Liquid Crystal Using Flory‐Huggins Theory

AbstractAn analytic study on the solubility behavior between 4′‐n‐pentyl‐4‐cyano‐biphenyl (5CB) liquid crystal and Maleic anhydride (MA) grafted surface‐modified single walled carbon nanotube (CNTs‐MA) using the prestigious Flory‐Huggins model is presented. The statistical thermodynamics of the Flory‐Huggins mean‐field theory is for the first time, applied in the solubility study of the ill‐famed issue of blending liquid crystals with carbon nanotubes. In conjunction with the Monte Carlo calculations, we discovered that at room temperature, this functionalized carbon nanotube can dissolve in the 5CB nematogens when the grafting ratio of the MA functional groups reaches up to 20 atomic wt%. Although it may not be for a perfectly exact prediction with respect to the mixture of liquid crystal combined with carbon nanotubes, we believe this mesoscale simulation can still offer reliable tends and directions toward the analysis of designing “liquid crystal‐soluble” carbon nanotubes in order for this novel composite to become a practical homogeneous nanosolution, and realize its promises in the future.

Polyethylene nanocomposite dielectrics: Implications of nanofiller orientation on high field properties and energy storage

Nanocomposite formation, through the incorporation of high aspect ratio nanoparticles, has been proven to enhance the dielectric properties of thermoplastic polymers, when the mitigation of internal charges and the nature of the interfacial regions are properly adjusted. Here, we explore polyethylene/montmorillonite nanocomposites, and we specifically investigate how to impart desirable dielectric behavior through controlled nanoscale texturing, i.e., through control of the spatial arrangement of the high aspect ratio nanofiller platelets. In particular, it is shown that filler alignment can be used to improve the high electric-field breakdown strength and the recoverable energy density. The origins of the improved high field performance were traced to improved charge-trapping by a synergy of nanofillers and polar maleic anhydride (MAH) groups—introduced via polyethylene-MAH copolymers—as templated by the inorganic nanofillers. Further, it is conclusively demonstrated that the alignment of the two-dimensional nanoparticles has a measurable positive effect on the breakdown strength of the materials and, consequently, on the maximum recoverable energy density.

Antibacterial activity and antistatic composites of polyester/Ag‐SiO2 prepared by a sol–gel method

AbstractPoly(butylene adipate‐co‐terephthalate) (PBAT) composites containing silver‐silica (Ag‐SiO2) were prepared using an in‐situ sol–gel process. Maleic anhydride‐grafted PBAT (PBAT‐g‐MA) and multihydroxyl‐functionalized Ag‐SiO2 were used to improve the compatibility and dispersibility of Ag‐SiO2 within the PBAT matrix. The composites were characterized morphologically using transmission electron microscopy and chemically using Fourier transform infrared spectrometry. The existence of Ag‐SiO2 nanoparticles on the substrate was confirmed by the ultraviolet–visible absorption spectra. The antibacterial and antistatic properties of the composites were evaluated whether SiO2 enhanced the electrical conductivity was tested as well as whether Ag enhanced the antibacterial activity of the PBAT‐g‐MA/SiO2 or PBAT/SiO2 composites. The PBAT‐g‐MA/SiO2 or PBAT/SiO2 composite that contained Ag had better antibacterial activity (more than 1.3‐fold). The functionalized PBAT‐g‐MA/Ag‐SiO2 composite can markedly enhanced antibacterial and antistatic properties due to the carboxyl groups of maleic anhydride, which acted as coordination sites for the Ag‐SiO2 phase, allowing the formation of stronger chemical bonds. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Solubilization of functionalized (5, 5) single-walled carbon nanotubes in 5CB nematic liquid crystals: simulation using Flory–Huggins theory

This work analyzes the solubility behavior between a 4′-n-pentyl-4-cyano-biphenyl (5CB) liquid crystal and a maleic anhydride (MA)-grafted surface-modified (5, 5) single-walled carbon nanotube (SWCNT-MA) using the Flory–Huggins model. The statistical thermodynamics of the Flory–Huggins mean-field theory, and its extension to modeling of macromolecular or polymer solutions, is adopted for the first time to investigate solubility as it is related to blending of liquid crystals with carbon nanotubes. This theory incorporated with Monte Carlo calculation reveals that, at room temperature, this functionalized carbon nanotube with all regular commonly seen CNT lengths can spontaneously and fully dissolve in 5CB nematogen when the grafting ratio of the MA functional group reaches 30 at. wt%. We believe that this mesoscale simulation offers a reliable and useful analytical method for ‘liquid crystal soluble’ carbon nanotubes, since this novel composite material can form a homogeneous nanosolution, and realize its potential in the future.

Maleic anhydride functionalization of multi-walled carbon nanotubes by the electron beam irradiation in the liquid media

In this work, maleic anhydride groups were introduced onto multi-walled carbon nanotubes (MWNTs) by electron beam treatment in liquid media. FTIR, XPS and Raman analysis showed that reactive groups were covalently attached to the MWNTs and the content of the active groups were determined by TGA. HRTEM characterization showed that a layer of maleic anhydride was wrapped on the surface of the MWNTs with thickness of ∼1.5 nm. It was proved that the one-step radiation grafting procedure was effective on functionalization of MWNTs.

A facile route for preparing stable co-continuous morphology of LLDPE/PA6 blends with low PA6 content

A facile method is employed to prepare a series of LLDPE/PA6 blends with co-continuous morphology with low PA6 content via reactive extrusion. In these blends, co-continuous morphology is obtained by introducing graft copolymers with both high and low molecular weight trunk chains to the interface simultaneously. Maleic anhydride functionalized polybutadine (PB-g-MAH, Mn¯≈3000g/mol and MAH content=10 wt%) is first melt grafted onto the LLDPE backbones with dicumyl peroxide (DCP) as an initiator. Part of PB-g-MAH is grafted onto LLDPE to form LLDPE-g-PB-g-MAH copolymer. During reactive extrusion, in-situ formed Copolymer II (polybutadiene-graft-polyamide, PB-g-PA6) with a low molecular weight trunk chain (PB) is obtained from the reaction between the maleic anhydride group of free or non-grafted PB-g-MAH and the amino group on PA6 molecules; while Copolymer I (LLDPE-g-PB-g-PA6) is obtained via the reaction between the maleic anhydride group of the grafted PB-g-MAH (i.e., LLDPE-g-PB-g-MAH) and the amino group of PA6. Copolymer I with a high molecular weight trunk chain, LLDPE, should strengthen the interface and favor stress transfer, enabling the deformation of PA6; and Copolymer II (PB-g-PA6) with a low molecular weight trunk chain, PB, facilitates the formation of a flat interface between LLDPE and PA6, thus promoting an elongated PA6 phase. Therefore, co-continuous morphology of LLDPE/PA6 blend is successfully prepared with only 25 wt% PA6 by controlling suitable amounts of Copolymers I and II in the blend.

Property control of enzyme coatings on polymer nanofibers by varying the conjugation site concentration

Trypsin was coated onto electrospun polystyrene–poly(styrene-co-maleic anhydride) (PS–PSMA) nanofibers with varied concentrations of maleic anhydride group, which enables an easy conjugation of enzymes onto PS–PSMA nanofibers. The concentration of maleic anhydride group, determined by the amount of PSMA in the mixture of PS and PSMA for electrospinning, correlated well with the enzyme loading and activity of covalently attached trypsin. Trypsin-coated nanofibers, prepared via covalent attachment of seed enzyme molecules and follow-up enzyme cross-linking, resulted in highly stable nanobiocatalytic systems, irrespective of added PSMA amounts. The variation of PSMA amounts enables the facile control of various properties of trypsin-coated nanofibers, such as enzyme loading, activity, structure, and mass transfer limitation. Especially, the mass transfer limitation of substrate through the enzyme coating matrix correlated well with the conjugation site concentration, and this feature would be useful in optimizing the enzyme coatings for the biocatalytic conversion of large-size substrates, such as protein digestion as an example. Facile property control of highly stable enzyme coatings would provide a powerful tool for more successful applications of enzyme coatings in various fields.

Reactive blending of polypropylene and butadiene-acrylonitrile elastomer

Graft copolymer of polypropylene and butadiene-acrylonitrile random copolymer was prepared by reactive polymer blending in a melt without solvents. The process was performed by preliminary grafting of maleic anhydride groups to polypropylene and of isocyanate groups to butadiene-acrylonitrile copolymer, followed by blending of the modified polymers. The chemical reactions occurring in the process and the fraction composition of the copolymer were studied.

Modified and functionalized maleimide copolymers for paper coatings

New functional aqueous dispersions of poly(styrene-co-maleimide) (SMI) and poly(octadecene-co-maleimide) (OMI) have been prepared by grafting different functional additives into the copolymers side chains to explore the possibility of tailoring the properties of these auxiliary pigments for applications in paper coating formulations. Modifications were carried out by reacting the corresponding maleic anhydride (MA) copolymer with ammonia and small amounts of various functional primary amines such as 4-amino-2,2,6,6,-tetramethylpiperidine (TAD), l(+)-aspartic acid (ASP), 2,2,2-trifluoroethylamine (TFEA) and 2,2,3,3,4,4,4-heptafluorobutylamine (HFBA) to investigate opportunities to fine-tune weathering stability (TAD), adhesion properties (ASP) or hydrophobicity (TFEA, HFBA) of the coated paper board. The thermal imidazation reaction of MA groups was carried out at 155 °C for 6 h in organic solvent-free process using high shear forces. The obtained functional nanoparticles varied in size from 50 to 217 nm and exhibited high glass transition temperatures (Tg) ranging from 150 to 180 °C. Paper board coating trials are also reported in this article.

Nonisothermal crystallization behavior of PP/rubber/clay nanocomposite

Two different PP/rubber/clay nanocomposites, one having maleic anhydride in the PP matrix and the other having maleic anhydride in the rubber phase, were prepared by melt mixing using Brabender mixer. To enhance the dispersion of organoclay, the organoclay was treated further by amines as intercalating agent, which can react with a maleic anhydride group in the compatibilizer. The presence of maleic anhydride either in the PP phase or rubber phase could help disperse the clay selectively in the PP phase or rubber phase. Two different amines (HMDA and Jeffamine D230) Polybond3200 and Exxellor VA1803 were used. The amine treated silicate layers were made by melt intercalation using a Brabender mixer. The insertion of amine groups was checked by XRD. The nonisothermal crystallization behavior of these nanocomposites was examined to determine the effect of the location of the silicate layers. POM(polarized optical microscopy) showed that the silicate layers retarded spherulite growth rate because the clay could act as an obstacle against the movement of chain. A nanocomposite with silicate layers in the PP matrix showed a higher overall crystallization rate than the reference samples due to the larger number of effective nuclei.

Carboxylate clays: A model study for polypropylene/clay nanocomposites

Sodium-montmorillonite was intercalated by carboxylate salts to prepare carboxylate clays. The intercalation of sodium acetate doubles the clay basal spacing and no degradation of the carboxylate clay is noticed in the extrusion temperature range. These carboxylate clays were used to synthesize polypropylene-graft-maleic anhydride (PP-g-MA)/clay nanocomposites. Nanocomposites were also produced by a one-pot process using in situ prepared carboxylate clay. The carboxylate salts within the clay layers partially neutralize the maleic anhydride groups of the PP-g-MA matrix, in situ during the melt compounding. The ionic groups of the partially neutralized polymer offer favourable interactions with the clay, hence reinforcing the interfacial bond between the polymer and the clay and improving the composite properties. The use of carboxylate clay clearly improves the clay dispersion into the PP-g-MA matrix and improves the nanocomposite’s thermal and rheological properties.

Preparation and characterization of polypropylene/silica nanocomposites by gamma irradiation via ultrafine blend

Polypropylene/silica nanocomposites were prepared by gamma irradiation via ultrafine blend so that the silica at 3% loading level can be well dispersed to polymeric materials for improving their mechanical performance. First, ultrafine blend processing in the melt state is an effective method for improving physical dispersion of nanosilica. Then irradiation technique generates firm and impervious joint between polypropylene and silica, due to the adding of the compatibilizer, maleic anhydride grafted polypropylene. The reaction of maleic anhydride groups with the hydroxyl groups on the surface of nanosilica was characterized by Fourier Transform Infrared Spectra (FTIR). Scanning electronic microscopy (SEM), X-ray diffraction analysis (XRD), differential scanning calorimeter (DSC) and polarized optical microscope (POM) were introduced to characterize the polypropylene/silica nanocomposites. Also the mechanical properties of the nanocomposites were evaluated by tensile strength, young’s modulus and elongation at break, which showed good enhancement due to well dispersed silica and improving interface combination.

Flame-Retardant Polypropylene Composites with Magnesium Hydroxide Encapsulated by Polypropylene Grafted with Maleic Anhydride

A novel surface-treated magnesium hydroxide (MH) was prepared through the encapsulation of polypropylene grafted with maleic anhydride (PP-g-MA) for the flame retardance of polypropylene (PP). Compared with surface-treating inorganic flame retardants by using conventional modifiers, this method possesses lower cost and better effects. Due to the interaction between maleic anhydride group and hydroxyl group and the similarity for the resin encapsulating inorganic particles (PP-g-MA) and matrix resin (PP), better compatibility and dispersion of MH in PP can be obtained. Therefore, it showed that MH encapsulated by PP-g-MA significantly improved the processablity, flame retardancy, and mechanical properties of the flame retardant composites. Additionally, the effects of the modified MH on the crystallization behavior of PP were also investigated through differential scanning calorimetry (DSC). Interesting results that PP-g-MA and MH had heterogeneous nucleation effect were found. Both the crystallization temperature and the crystallinity were increased by addition of MH encapsulated by PP-g-MA.