Anhydride Groups Research Articles

Supramolecular semicrystalline polyolefin elastomer blends with triple‐shape memory effects

AbstractSupramolecular polyolefin elastomer blends possessing triple‐shape memory effects were prepared by melt blending of two semicrystalline maleated elastomers (maleated ethylene‐propylene‐diene rubber (mEPDM) and maleated polyethylene‐octene elastomer (mPOE)) in the presence of a small amount of 3‐amino‐1,2,4‐triazole (ATA). The amino group of ATA reacted with the maleic anhydride groups of both elastomers during melt blending to form supramolecular hydrogen‐bonded networks. Dynamic mechanical analysis of the blends showed drops in the storage modulus at two different transition temperatures (Ttrans) belonging to the crystalline melting temperatures of each phase as well as a plateau above these two Ttrans. This is an essential property for triple‐shape memory behavior. Dual‐shape memory properties of the blends were determined using one‐step programming under three different temperature ranges. When an individual crystalline phase is used for the fixing process, the switching temperature (Tsw) relates to the melting temperature of a particular phase during the recovery process. However, if both crystalline phases are used simultaneously for the fixing process, then the Tsw relates to the higher melting temperature. Cyclic two‐step programming revealed that two different shapes can be fixed, one by EPDM crystallization and the other by POE crystallization, and both programmed shapes can be recovered upon heating above a specific Tsw. © 2016 Society of Chemical Industry

Biobased Microspheres Consisting of Poly(trans-anethole-co-maleic anhydride) Prepared by Precipitation Polymerization and Adsorption Performance

This paper reports the first biobased microspheres derived from phenylpropenic resources. To explore the potentials of biomass derived trans-anethole (ANE) and to develop new biobased polymeric materials, ANE was used for preparing an unprecedented kind of polymeric microspheres constructed by poly(trans-ANE-co-maleic anhydride) [poly(ANE-co-MAH)] through free radical precipitation polymerization in methyl ethyl ketone/n-heptane mixed solvent with 2,2′-azobis(isobutyronitrile) as the initiator. Microspheres (about 1 μm in size) with spherical morphology and narrow size distribution were obtained under appropriate conditions. Following the same preparative strategy, cross-linked microspheres were further prepared with divinylbenzene as a cross-linking agent and then subjected to hydrolyzation of the surface anhydride groups into carboxyl groups, aiming at developing microsphere adsorbents. The hydrolyzed microspheres exhibited considerable adsorption ability toward trivalent chromic ion [Cr(III)] and an or...

Thermal evaluation of PHB/PP-g -MA blends and PHB/PP-g -MA/vermiculite bionanocomposites after biodegradation test

This study aimed to evaluate the thermal behavior of polyhydroxybutyrate (PHB)/polypropylene grafted with maleic anhydride (PP-g-MA) blends and PHB/PP-g-MA/vermiculite bionanocomposites submitted to the biodegradation test according to ASTM G 160-03. The blends and bionanocomposites were prepared by melt intercalation method using a single screw extruder, and then, compression molded. The thermal analyzes were performed by thermogravimetry (TG) and differential scanning calorimetry. It was verified the decrease of onset degradation temperature and the melting temperature mainly after 86 days of exposure to the simulated soil. This behavior was more pronounced in bionanocomposites because of interactions between the maleic anhydride groups and the clay favoring biodegradation, making the systems more amorphous and propitious to the attack of microorganisms. POLYM. ENG. SCI., 56:555–560, 2016. © 2016 Society of Plastics Engineers

An efficient nanofiltration membrane based on blending of polyethersulfone with modified (styrene/maleic anhydride) copolymer

In this study, styrene–maleic anhydride (SMA) copolymer was modified by ring opening reaction of its anhydride groups with diethanolamine (DEA). The modified SMA copolymer was blended in different concentrations (2.5, 4 and 5.5 %) with Polyethersulfone (PES) to improve the hydrophilicity of PES membranes and the corresponding blend membrane was prepared through phase inversion. The influence of SMA copolymer on morphology, mechanical properties, water flux, rejection and anti-fouling properties of blend membrane were investigated. The modified SMA and their composition were confirmed by FT-IR and 1HNMR techniques. The asymmetric structure of membrane was revealed by SEM. The water flux and contact angle results show that the hydrophilicity of membrane surface was increased by addition of SMA copolymer. The better anti-fouling properties of the PES/modified SMA blend membranes in comparison with the PES membrane also confirmed that the hydrophilicity of blend membrane enhances.

The aminolysis of styrene–maleic anhydride copolymers for a new modifier used in urea-formaldehyde resins

Styrene (St) and maleic anhydride (MA) alternating copolymers with different molecular weights (MW) were synthesized via radical copolymerization. The copolymers were subsequently transferred into water-soluble maleic amic acid derivatives (SMAA) via the aminolysis of anhydride groups using (NH4)2CO3 as the ammonia sources. The synthesized polymers were applied as a new kind of macromolecular modifier and added into the reaction system during the synthesis of urea-formaldehyde (UF) resins via the traditional alkaline–acidic–alkaline three-step process. The UF resins modified with SMAA were characterized using Fourier Transform Infrared Spectroscopy (FT-IR), 13C nuclear magnetic resonance (13C-NMR) spectroscopy, and thermal gravimetric analysis (TGA). All the results confirmed the successful incorporation of SMAA chains into the crosslinking network of the UF resins. The modified UF resins were further employed as wood adhesives and the effect of synthesis parameters on their performance was investigated. Meanwhile, the influence of SMAA molecular weight (MW) on the properties of the modified UF resins was also studied. When the UF resins were synthesized with a low molar ratio of formaldehyde/urea (F/U) and a predetermined amount of SMAA added into the reaction system at the second step, plywood bonded using these modified UF resins showed much improved bonding strength (BS) and depressed formaldehyde emission. Moreover, the as-modified UF resins showed good storage characteristics.

Dual-component collagenous peptide/reactive oligomer hydrogels as potential nerve guidance materials - from characterization to functionalization.

Toward a new generation of improved nerve guidance conduits (NGCs), novel biomaterials are required to address pressing clinical shortcomings in peripheral nerve regeneration (PNR) and to promote biological performance. A dual-component hydrogel system formed by cross-linking reaction between maleic anhydride groups in an oligomeric building block for cross-linking of free amine functionalities in partially hydrolyzed collagen is formulated for continuous processing and NGC fabrication. The influence of the gelation base is optimized for processing from a double syringe delivery system with a static mixer. A hydrophilic low-concentrated base was introduced to control network formation and to utilize highly reactive macromers for gelation. Cross-linking extent and building block conversion were improved and homogenous monoliths were fabricated. Chemically derivatized hydrogels were obtained by conversion of a fraction of anhydride groups in the oligomeric precursor with monovalent primary amine-containing grafting molecules prior to gelation. Network stability in functionalized hydrogels was maintained and cationic moieties were implement to the gel that promoted in vitro cell attachment and spreading irrespective of mechanical stiffness. A molding strategy was introduced that allowed for fabrication of flexible tubular conduits in tunable dimensions and with chemically patterned structures. These hydrogel-based conduits hold promise for the next generation NGCs with integrated chemical cues for PNR.

Biodegradable anhydride-based reconfigurable shape memory elastomer

Event Abstract Back to Event Biodegradable anhydride-based reconfigurable shape memory elastomer Melodie I. Lawton1, 2, Halimatu S. Mohammed3, Wenbin Kuang1, 2, Devon A. Shipp3 and Patrick T. Mather1, 2 1 Syracuse University, Department of Biomedical and Chemical Engineering, United States 2 Syracuse University, Syracuse Biomaterials Institute, United States 3 Clarkson University, Department of Chemistry and Biomolecular Science, United States Introduction: Shape memory polymers are a class of smart materials capable of transitioning from a programmed temporary shape back to its permanent shape when stimulated[1]. While shape memory polymers have been developed to be degradable and biocompatible, none feature a reconfigurable permanent shape. We have developed a new, soft, biocompatible and biodegradable reconfigurable shape memory elastomeric composite[2] featuring a polyanhydride (PAH) matrix[3]-[6] and electrospun poly(ε-caprolactone) (PCL) fibers. This composite is capable of resetting its permanent shape as well as triggering shape recovery at body temperature. Materials: PCL, 4-pentenoic anhydride (PNA), pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), azobisisobutyronitrile (AIBN), chloroform, N,N-dimethylformamide (DMF), trimethylolpropane diallyl ether (TMPDAE), and 1,6-hexanediol diacrylate (HDDA) were used as received. Thermoplastic polyurethane PCL was synthesized using 3,4-dihydroxy-1-butene, hexamethylene diisocyanate, toluene and poly(ε-caprolactone) diol. Methods: PCL was electrospun from solution prepared by dissolving PCL in chloroform/DMF. The PAH monomer was prepared by mixing PNA with PETMP (2:1 molar ratio) and AIBN. The PCL fiber mat was then imbibed with the PAH monomer, followed by UV and thermal curing of the PAH matrix. The shape memory properties were characterized quantitatively using a defined thermomechanical cycling method using a dynamic mechanical analyzer. Degradation of the composite was monitored by measuring the mass loss over time and evaluating the PCL content using differential scanning calorimetry. Scanning electron microscopy (SEM) was used to evaluate the morphological changes during degradation. Results and Discussion: The PAH elastomer was found to reconfigure its crosslinked structure toward a stress-free state when strained at temperatures greater than 40 °C, with stress relaxation completing over a time that decreased with increasing temperature. This reconfiguration in the solid state is due to dynamic covalent exchange reactions involving anhydride groups. Such reconfiguration did not occur when the elastomer was synthesized devoid of anhydride groups; i.e., using HDDA or TMPDAE instead of PNA. When combined with PCL fibers, PAH-PCL composite exhibited one way shape memory before and after shape resetting through melting and recrystallization of PCL. The thermal parameters of these shape memory cycles can be tuned by replacing PCL with a hard-block-free PCL-based polyurethane exhibiting a lower melting transition. Near-complete degradation of the PAH matrix occured after approximately four days, with about 92% of composite comprised of PCL compared to 18% prior to degradation. Microstructural analysis reveals a change in the erosion mechanics from surface erosion of the pure matrix to apparent bulk degradation for the composite. The composite maintained its fixed shape throughout degradation. Conclusions: Our polyanhydride elastomer is capable of resetting new permanent shapes, erasing any ‘memory’ of previous shapes. Incorporation of this elastomer as a matrix structured with PCL fibers provides a new reconfigurable elastomeric shape memory biomaterial capable of reprogramming its original shape as well as degrading in PBS at physiological conditions while maintaining a programmed shape.

Ageing phenomena in high-voltage aqueous supercapacitors investigated by in situ gas analysis

High-voltage aqueous electrolyte based supercapacitors (U > 1.23 V) attract significant attention for next-generation high power, low cost and environmentally friendly energy storage applications. Cell ageing is however markedly pronounced at elevated voltages and results in accelerated overall performance fade and increased safety concerns. Online electrochemical mass spectrometry, combined with cell pressure analysis, is for the first time shown to provide a powerful means for in situ investigation of degradation mechanisms in aqueous electrolyte/carbon based supercapacitors. The activated carbon electrodes possess high specific surface area and oxygen-based surface functionalities (mainly phenol, lactone and anhydride groups), which are oxidized already at a cell voltage of 0.6 V to provoke the evolution of minor amounts of CO and CO2. Noticeable water decomposition starts at a high voltage of 1.6 V with the evolution of H2 on the negative electrode and carbon corrosion on the positive electrode with the generation of predominantly CO. In this paper we also report that short-term cycling leads to partly reversible gas evolution/consumption side-reactions giving negligible capacitance. On the other hand, long-term cycling causes irreversible side-reactions, deteriorates the electrochemical performance, and increases the internal pressure of the cell. Repeated cycling (U < 2 V) is confirmed as a more harmful technique for the electrode integrity compared to the voltage holding in a floating test. In situ gas analysis is shown to provide valuable insights into the electrochemical cell ageing aspects, such as the nature and potential onsets of side-reactions, hence paving the way for fundamental understanding and mitigating the performance and safety loss of high-energy aqueous supercapacitors.

Biodegradation Studies in Vitro of Novel Poly(adipic anhydride-co-mannitol)-N-maleoyl Chitosan Networks

In this work, novel copolymers of poly(adipic anhydride-co-mannitol) were synthesized by melting condensation polymerization of poly(adipic anhydride) with five percentages of mannitol sugar, 1 to 5 Wt.%. These copolymers were purified and then, characterized by FT-IR, which was proved that the cross-linking reaction was caused by nucleophilic attack of mannitol hydroxyl group to acidic anhydride groups of poly(adipic anhydride) backbone and new ester groups were formed and appeared. Also, modified organic-soluble chitosan, N-maleoyl-chitosan, were synthesized by grafting reaction of chitosan with maleic anhydride in DMF as solvent, and it was also purified and characterized by FT-IR. Biodegradation in vitro of the IPNs of poly(adipic anhydride-co-mannitol)-N-maleoyl chitosan networks were evaluated by hydrolytic degradation studies at three different media (PBS, SIF and SGF) for 18 weeks with 92% as maximum degradation and it was found that minimum weight loss of IPNs was noticeably shown in SIF. In addition, hydrolytic degradation percent was decreased with increasing mannitol proportions.

Effect of styrene maleic anhydride on physical and mechanical properties of recycled polystyrene wood flour composites

In this work, the influence of three types of styrene maleic anhydride (SMA) oligomers on the adhesion of polystyrene wood plastic composites (WPC) was investigated. The composites were processed on a twin-screw co-rotating extruder below 200°C using 20 wt% of wood flour. The styrene maleic anhydride with different content of maleic anhydride groups, 30%, 25% and 20% (w/w) and levels of 1, 2 and 4% of coupling agents (styrene maleic anhydride 2000, styrene maleic anhydride 3000 and styrene maleic anhydride EF40) in the composite formulations were tested. Mechanical, physical and morphologic properties were evaluated. The styrene maleic anhydride improves the compatibility of hydrophilic wood flour with hydrophobic polystyrene matrix. It has been observed that the addition of styrene maleic anhydride increased the wood plastic composites mechanical properties with the incorporation of 2% wt of styrene maleic anhydride 2000. The mechanical properties showed to be dependent on content of maleic anhydride in the coupling agent. Treated and non-treated wood plastic composites showed similar density values, but the void content was reduced for treated composites. Scanning electron microscopy revel the better adhesion between polymer and matrix when coupling agent were used.

Color Bricks: Building Highly Organized and Strongly Absorbing Multicomponent Arrays of Terpyridyl Perylenes on Metal Oxide Surfaces.

Terpyridine-substituted perylenes containing cyclic anhydrides in the peri position were synthesized. The anhydride group served as an anchor for assembly of the terpyridyl-crowned chromophores as monomolecular layers on metal oxide surfaces. Further coordination with Zn(2+) ions allowed for layer-by-layer formation of supramolecular assemblies of perylene imides on the solid substrates. With properly selected anchor and linker molecules it was possible to build high quality structures of greater than ten successive layers by a simple and straightforward procedure. The prepared films were stable and had a broad spectral coverage and high absorbance. To demonstrate their potential use, the synthesized dyes were employed in solid-state dye-sensitized solar cells, and electron injection from the perylene antennas to titanium dioxide was observed.

Stable hydrophilic surface of polycarbonate

In this report we present a simple method for preparation of stable hydrophilic surface modification of polycarbonate. The method uses branched polyethyleneimine (BPEI) and poly(ethylene-alt-maleic anhydride) (PEMA) as the reagents for the first steps of modification, followed by hydrolysis of maleic anhydride groups on the polymer surface. The method yields the polymer surface rich in carboxylic acid groups and may thus be also useful for further surface modification protocols (e.g. immobilization of enzymes on the surface of the polymer). The method has been designed particularly for use in microfluidics applications. The surfaces obtained via the method are extremely durable and can be stored without any special conditions for at least one year.

Reversible shape‐memory properties of surface functionalizable, crystallizable crosslinked terpolymers

There is a high demand for polymer actuators comprising reactive groups at their surface in biotechnological or bioanalytical devices especially in microfluidics. In this work, we explored whether a thermoplastic poly[ethylene‐co‐(ethyl acylate)‐co‐(maleic anhydride)] (PEEAMA) terpolymer can be converted to a multifunctional shape‐memory actuator by introducing covalent netpoints. In crosslinked PEEAMA (cPEEAMA) crystalline polyethylene (PE) domains with melting temperatures below 70°C should serve as actuation domains, responsible for the reversible shape change during cyclic heating and cooling, while higher melting PE crystals act as skeleton forming domains; finally maleic anhydride (MAH) groups enable surface modification of the polymeric substrate. cPEEAMAs with a fixed composition and various crosslink densities were prepared by thermally crosslinking of PEEAMA using different dicumyl peroxide (DCP) concentrations in the starting reaction mixture. A broad melting transition in the range of 50 to 90°C with a melting temperature interval of ∆Tm = 40°C, related to the crystalline PE domains, was observed for all polymer networks in differential scanning calorimetric experiments. Cyclic, thermomechanical uniaxial tensile tests revealed high reversible strains up to 17 ± 2%. A reversible change in long period during repetitive heating and cooling was observed in in situ small angle X‐ray scattering experiments. Finally, a successful functionalization of the MAH groups at the cPEEAMA surface by reaction with ethylene diamine was confirmed by infrared spectroscopy analysis. The presented amino functionalized cPEEAMA substrates could be a candidate material for the preparation of adaptive microfluidic devices. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Characterization and adsorption properties of a lanthanum-loaded magnetic cationic hydrogel composite for fluoride removal

In this study, a novel lanthanum-loaded magnetic cationic hydrogel (MCH-La) was synthesized for fluoride adsorption from drinking water. The adsorption kinetics, isotherms, and effects of pH and co-existing anions on fluoride uptake by MCH-La were evaluated. FTIR, Raman and XPS were used to analyze the fluoride adsorption mechanism of MCH-La. Results showed that MCH-La had positive zeta potential values of 23.6–8.0 mV at pH 3.0–11.0, with the magnitude of saturation magnetization up to 10.3 emu/g. The fluoride adsorption kinetics by MCH-La fitted well with the fractal-like-pseudo-second-order model, and the adsorption capacity reached 93% of the ultimate adsorption capacity within the first 10 min. The maximum fluoride adsorption capacity for MCH-La was 136.78 mg F−/g at an equilibrium fluoride concentration of 29.3 mg/L and pH 7.0. Equilibrium adsorption data showed that the Sips model was more suitable than the Langmuir and Freundlich models. MCH-La still had more than 100 mg of F−/g adsorption capacity at a strongly alkaline solution (pH > 10). The adsorption process was highly pH-dependent, and the optimal adsorption was attained at pH 2.8–4.0, corresponding to ligand exchange, electrostatic interactions, and Lewis acid–base interactions. With the exception of both anions of HCO3− and SiO44−, Cl−, NO3−, and SO42− did not evidently prevent fluoride removal by MCH-La at their real concentrations in natural groundwater. The fluoride adsorption capacity of the regenerated MCH-La approached 70% of the fresh MCH-La from the second to fifth recycles. FTIR and Raman spectra revealed that C–O and CO functional groups on MCH contributed to the fluoride adsorption, this finding was also confirmed by the XPS F 1s spectra. Deconvolution of C 1s spectra before and after fluoride adsorption indicated that the carboxyl, anhydride, and phenol groups of MCH were involved in the fluoride removal.

Grafting of adipic anhydride to carbon nanotubes through a Diels-Alder cycloaddition/oxidation cascade reaction

Different reactions have been reported for the successful functionalization of carbon nanotubes (CNT). The Diels-Alder cycloaddition is recognized as a plausible chemical approach, but few reports are known where this strategy has been used. In this study, the functionalization was performed by 1,3-butadiene generated from 3-sulfolene under heating conditions in diglyme. This simple and easily scalable method resulted in functionalized CNT with mass losses of 10–23% by thermogravimetric analysis (nitrogen atmosphere). The functionalization was also supported by acid-base titration, elemental analysis, temperature programmed desorption and X-ray photoelectron spectroscopy. The high content in oxygen detected on the CNT surface was assigned to anhydride formation due to a cascade oxidation of the alkene groups generated in the cycloaddition reaction. The complete evolution of the alkene leads to a grafting density of 4.2 mmol g−1 for the anhydride moiety. Ab-initio calculations in CNT model systems indicate that the Diels-Alder addition of butadiene is a feasible process and that subsequent oxidation reactions may result in the formation of the anhydride moiety. The presence of the anhydride group is a valuable asset for grafting a multitude of complex molecules, namely through the nucleophilic addition of amines.

Strained ring motif at silica surfaces: A quantum mechanical study of their reactivity towards protic molecules

The ring opening reactions of (SiO)n ring motifs (n=2, 3 and 4) at the silica surfaces by the interaction with H2O (forming two SiOH silanol groups) and HCOOH (forming a SiOH group and a SiOC(O)H surface mixed anhydride group) has been studied by means of quantum chemical methods. Results are based on a cluster approach adopting the B3LYP-D2/6-311++G(d,p) level of calculations for computing the energetics of reaction. All reactions envisage an activated complex in which the nucleophilic part of the molecules (O atom for H2O and the carbonyl O atom for HCOOH) attacks the Si atoms of the (SiO)n moiety followed by a proton transfer from the molecules towards an O atom of the ring. Opening of the most strained two-membered (SiO)2 ring by the considered molecules is highly exoergic. For the medium strained three-membered (SiO)3 ring, two different Si atoms can react, one exposed to the exterior part of the surface and the other buried in the inner region of the surface. Reaction with the outer Si atom is exoergic, whereas that with the inner Si atom is endoergic, indicating the role of possible constraints enforced on the reaction products by the silica surroundings. Opening the regular four-membered (SiO)4 ring is an endoergic process for the both probe molecules. Calculations also show that the energy barriers for reactions with HCOOH are lower than with H2O because the transition state structures involving HCOOH exhibited a 6-membered ring, far less strained than the 4-membered ring found with H2O. A further reason is the more acidic character of the HCOOH compared to H2O, favoring the proton release towards the silica surface oxygen. Furthermore, it was shown that the energy barriers of the ring opening reactions with H2O is significantly lowered by the presence of an additional H2O molecule acting through the proton relay mechanism. Reaction energies, in contrast, are less favorable with HCOOH than with H2O, thus indicating that the formation of SiOH groups is favored with respect to the SiOC(O)H moiety. Finally, population analysis indicate that the electrophilic character of the C atom in the SiOC(O)H moiety is higher than for the isolated HCOOH, thereby making it more prone to undergo nucleophilic attack bringing an easier formation of amides.

Polymer nanocomposites: functionalisation of the nanofiller and control of the interface

Two different examples of compatibilisation strategies used to enhance filler/matrix interfacial adhesion in polymer nanocomposites are discussed. The first strategy was based on the surface modification of multiwalled carbon nanotubes (MWCNT) by a dry mechano-chemical process. The modified nanotubes were used for the realisation of polypropylene/MWCNT composites with improved matrix/nanotubes compatibility. The second compatibilisation strategy was based on the synthesis of a proper coupling agent, realised by modifying polyethyleneterephthalate (PET) chain ends with anhydride groups. This coupling agent was used as a third component for the realisation of PET-based nanocomposites reinforced with precipitated calcium carbonate.

Chemical modification of palygorskite with maleic anhydride modified polypropylene: Mechanical properties, morphology, and crystal structure of palygorskite/polypropylene nanocomposites

Maleic anhydride modified polypropylene (PP) (PP-g-MAH) was chemically grafted onto palygorskite (Pal) via the bridge linking of [3-(2-aminoethyl)aminopropyl]trimethoxysilane (Z-6020) and PP-g-MAH in the presence of ultrasonic oscillation. The modified Pal was added to a PP matrix as a nano-filler to prepare Pal/PP nanocomposites by melt blending. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to discern that PP-g-MAH and Z-6020 were chemically grafted onto Pal via acrylation between NH2 and anhydride groups. The Pal/PP nanocomposites were characterized by Scanning electron microscopy, transmission electron microscopy and wide angle X-ray diffraction. The toughness and strength of PP could be improved markedly by the addition of modified Pal. The modified Pal was dispersed uniformly in the PP matrix in the form of individual crystal needles, which demonstrated the presence of strong interactions between the modified Pal and PP. The modified Pal could induce the formation of β-form PP crystals and promote the motion of PP chains during crystallization.

In situ FT-IR spectroscopic studies on thermal decomposition of the weak covalent bonds of brown coal

In situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) was used to characterize the thermal decomposition of the functional groups in Huolinhe brown coal. The PeakFit program for curve fitting was used to analyze the overlapped IR bands. The formation and decomposition of the functional groups show different trends during the heat treatment. The methyl and carboxyl groups decomposed with increasing the temperature, which is closely related to the release of CO2, CH4. The amounts of ester and anhydride groups rise reach a maximum then fall. Different types of OH hydrogen bonds were also observed after the absorbed water was removed at high temperature. The results indicate that the curve-fitting analysis well represents the change in the chemical bonds in coal.

Crosslinking and ozone degradation of thermosetting resins based on maleic anhydride/diene copolymer and polyfunctional alcohols

ABSTRACTCrosslinking and de‐crosslinking reactions of an alternating copolymer of maleic anhydride (MAn) and 2,4‐dimethyl‐1,3‐pentadiene (DMPD) by thermal curing with polyfunctional alcohols as the crosslinkers and subsequent ozone degradation are reported in this article. The ring‐opening reaction of an anhydride group by polyfunctional alcohols produces network polymers with an ester linkage. The rate of crosslinking reaction depends on the curing conditions, i.e. the structure of the used alcohols and the curing temperature and time. The crosslinking density of the alcohol‐cured copolymers is low due to a slow reaction between the anhydride and hydroxy groups, being different from the corresponding epoxy‐cured copolymer with a dense network structure reported in a previous article. The insoluble resins are readily de‐crosslinked and solubilized by ozone degradation. The polymer surface modification by ozone is also investigated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42763.