Methylhexahydrophthalic Anhydride Research Articles

Kinetic Study of Epoxy Resin Decomposition in Near‐Critical Water

AbstractA diglycidyl ether type epoxy resin from bisphenol A, E‐51, was cured by methylhexahydrophthalic anhydride (MeHHPA) and then decomposed in near‐critical water without any additives. The effects of the experimental parameters such as the reaction temperature, reaction time, pressure, and feedstock ratio on the percentage of decomposition were investigated to obtain optimized reaction conditions. The results revealed that the percentage of decomposition can be enhanced by increasing either temperature or reaction time. At 260 °C, it initially increased with higher pressure and then decreased dramatically when the pressure further was reduced to the saturated water vapor pressure. The kinetics study of the epoxy decomposition was also carried out by monitoring the glass transition temperature of the solid product using differential scanning calorimetry. The decomposition equation was established and the activation energy was calculated to be 123.5 kJ mol–1.

Curing Behavior and Thermal Properties of Autocatalytic Cycloaliphatic Epoxy

Cycloaliphatic epoxy resin containing hydroxyl group (DMTMP) was prepared by the transesterification between methyl-3,4-epoxycyclohexane carboxylate (MEC) and trimethylolpropane (TMP), which was then thermally cured with methylhexahydrophthalic anhydride (MHHPA). As comparison, a commercial available cycloaliphatic epoxy 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (ERL-4221) cured with the same curing agent was also investigated. The chemical structure was characterized by FT-IR and 1H-NMR. And the curing behavior and the thermal properties were studied by DSC and TGA. The DSC results showed that the DMTMP systems exhibited higher reactivity than the ERL-4221 systems due to the autocatalysis of hydroxyl group of DMTMP. While the glass temperature transitions (Tg s) of DMTMP systems were much lower than ERL-4221 systems, and the Tg s of DMTMP and ERL-4221 systems both reduced after introducing n-dodecyl trimethylammonium bromide (DTAB) as catalyst. The decomposition behavior from TGA shows that the DMTMP epoxy resins exhibited a relative slow weight decreasing tendency in comparison with ERL-4221 epoxy resins, but initial degradation temperatures of DMTMP systems were lower than ERL-4221 systems.

Mechanical and dielectric properties of epoxy resin modified using reactive liquid rubber (HTPB)

AbstractIn the present study, hydroxyl‐terminated polybutadiene (HTPB) liquid rubber was employed to modify epoxy resin using 2,4,6‐tri (dimethylaminomethyl) phenol as a catalyst, and methyl hexahydrophthalic anhydride as a curing agent. The reactions between HTPB and epoxy were monitored by Fourier transform infrared (FTIR); the mechanical and dielectric properties of HTPB modified epoxies were evaluated and the morphology was investigated through scanning electronic microscopy (SEM). The FTIR analysis evidenced the occurrence of a chemical reaction between the two components. The mechanical results indicated that the impact strength of HTPB‐modified epoxy was superior to that of the pure epoxy. As the HTPB content increased up to 10 phr the best mechanical performances in terms of tensile and flexural properties were achieved when compared to the unmodified epoxy. Higher concentration of HTPB resulted in larger particles and gave lower mechanical strength values. The incorporation of HTPB into epoxy decreased the dielectric constant and dissipation factor over a wide frequency range from 1 to 106 Hz, and improved the electrical resistivity. SEM micrographs showed that the modified epoxy exhibited a two‐phase morphology where the spherical rubber domains were dispersed in the epoxy matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Studies on Polysiloxane-based Alicyclic Episulfide Resin

The polysiloxane-based alicyclic episulfide resin (PSCER) was synthesized through substitution of oxygen atoms in 1,3-bis[2-(3{7-oxabicyclo[4,1,0]hepyl})ethyl]-tetramethyldisiloxane with sulfur atoms using potassium thiocyanate (KSCN) as the reagent. The product was purified by column chromatography, and the by-products were isolated. It was found by 1H-NMR and 13C-NMR that the by-products were cycloolefins formed by desulfurization of the episulfide groups. PSCER was unstable; desulfurization took place easily, especially at high temperatures. The PSCER resin could not be cured with methylhexahydrophthalic anhydride (MeHPPA). When m-phenylenediamine or isophorondiamine was used as curing agent, PSCER showed a higher reactivity compared with the parent epoxide. However, the reactivity of the alicyclic episulfide was much lower than the polysiloxane based aliphatic episulfide for the steric hindrance of the six member ring. Desulfurization took place upon curing of the alicyclic episulfide resin, therefore the cured resin showed poor mechanical properties. Thermal stability of cured PSCER resin was also poor on account of low bonding energy of C-S and crosslinking density.

Preparation and Properties of Halogen-Free Flame Retardant Epoxy Resins with Aryl Phosphinate Dianhydride Hardener

Two halogen-free flame retardant epoxy resins were prepared by diglycidyl ether of bisphenol A (DGEBA) epoxy with two compound hardeners. The aryl phosphinate dianhydride BPAODOPE was used as a hardener and flame retardant when coupled with two curing agents, such as methylhexahydrophthalic anhydride (MeHHPA) and maleic anhydride (MA). The effect of the BPAODOPE contents on the fire resistance, thermal properties and mechanical properties of halogen-free flame-retardant epoxy resins were investigated in detail. The results showed that the phosphorus-containing epoxy resin composites had a higher UL-94 grade and char yield, furthermore, the flame retardation and the char yield of the cured epoxy resins increased with an increase of the phosphorus content, the phosphorus content of 1.75% was enough to achieve UL-94 V-1 grade and the best combination properties for the two composites with different hardeners.

Preparation and Properties of Rigid Cross-Linked PVC Foam

High performance rigid cross-linked PVC foam has been prepared by molding process and boiling foam process with the main materials including polyvinyl chloride paste resin (PVC), liquefied methylene bis-phenyl diisocyanate (MDI-L) and methylhexahydrophthalic anhydride (MHHPA). The chemical structure, cellular structure and thermal properties were respectively characterized by fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), thermomechanical analyzer (TMA) and thermogravimetric analyzer (TGA). Results showed that the foam had a uniform cellular structure, and cell size was about 760μm. The glass transition temperature (Tg) was 81°C and 5% weight loss temperature (T5d) was 252°C.

Morphology and Properties of Bisphenol-A Novolac Epoxy Resin with Polysulfone Blends

Polysulfone (PSF) was blended into bisphenol-A novolac epoxy resin (bis-ANER) diluted with vinyl cyclohexene dioxide (VCD), and the mixture was cured with methylhexahydrophthalic anhydride (MHHPA). The cured bis-ANER/VCD/MHHPA/PSF developed a bi-continuous morphology consisting of two distinct domains: one of the domains is an epoxy-rich matrix containing PSF particles, while the other consisted of a dispersion of epoxy particles within a PSF-rich phase. The mechanical properties of cured bis-ANER/VCD/MHHPA/PSF are enhanced with the increase of the PSF content, while the thermal degradation temperature decreases with the addition of PSF.

Preparation and Properties of Epoxy Matrix for Composite Cable Core

According to the requirements of aluminum conductor composite cores, a kind of resin system was developed with TGDDM as main body, and self-made flexible epoxy SUC-1 as auxiliary, plus methyl hexahydrophthalic anhydride as curing agent. The gel rate of the system was high enough to meet the demands of pultrusion technique. The heat deformation temperature of cured sample reached 194°C, and the tensile strength achieved 62.95Mpa. The elongation at break matched that of carbon fibers. The interfacial bonding between the matrix and the fibers, observed by scanning electron microscope, was tight without debonding phenomenon.

Thermal properties, curing characteristics and water absorption of soybean oil-based thermoset

Epoxidized soybean oil (ESO) was successfully thermal-cured by using methylhexahydrophthalic anhydride (MHHPA) curing agent, in the presence of tetraethylammonium bromide (TEAB) catalyst of varied concentration (0.3-0.8 phr). The polyesterification process of ESO thermoset was proven and supported by Fourier transforms infrared spec- troscopy (FTIR) and gas chromatography-mass spectroscopy analysis (GC-MS). A possible chemical reaction of the MHHPA, TEAB and ESO was proposed based on the experimental work. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) revealed that there is a positive relationship between the degree of conversion and crosslink density of ESO thermoset with TEAB concentration. The kinetics of water absorption of the ESO thermoset were found to conform to Fickian law behavior.

Curing Characteristics and Thermal Properties of Epoxidized Soybean Oil Based Thermosetting Resin

AbstractEpoxidized soybean oil (ESO) was thermally cured using methylhexahydrophthalic anhydride (MHHPA) curing agent in the presence of 2‐ethyl‐4‐methylimidazole (EMI) catalyst. The curing characteristics of ESO/MHHPA/EMI systems were characterized using Fourier transform infrared spectroscopy (FTIR), a dynamic mechanical analyzer (DMA) and a differential scanning calorimeter (DSC). FTIR spectra showed that the polyesterification rate in ESO/MHHPA/EMI systems increased with increasing of the catalyst concentration. DSC thermograms indicated that EMI‐catalyzed ESO/MHHPA systems experienced enthalpy relaxation at low EMI concentration whereas the extent decreased with increasing of the EMI concentration. There is a direct relationship between the degree of conversion and crosslink density of the thermal cured ESO/MHHPA/EMI systems with EMI concentration. The curing characteristics of thermal curable ESO thermosetting resins were found to have influence on the thermal properties of the ESO systems. It was determined that the glass transition temperature (Tg) and storage modulus (E′) of cured ESO increased with increasing the EMI concentration whereas the damping properties of the ESO/MHHPA/EMI systems exhibited the reverse trend. It was found that the thermally curable ESO thermosetting resins experienced a two‐stage thermal decomposition process.

Research on Pavement Characteristics of Epoxy Resin and Rubber Modified Asphalt

An asphalt modified by epoxy resin and rubber has the following improved properties: the softening point is 70 , elastic recovery rate is 80%, and kinematic viscosity at 175 is 2879.1mm2 /s. In order to solve the early curing in the process of mixing, storage and transportation, methyl hexahydrophthalic anhydride(MHHPA) was used as the curing agent. A reflective cracking caused by traffic load simulation test was established with the objective to compare the propagation speed of reflective crack of three different structure asphalt mixture samples. The results showed that the sample with epoxy resin and rubber used as stress-absorbing layer can obviously delay reflective cracking, improve the pavement performance and prolong the road life. Furthermore, the results of Marshall test, immersion Marshall test and Rutting test were consistent with the results of the reflective crack simulation test.

Synthesis and characterization of epoxy with improved thermal remendability based on Diels‐Alder reaction

AbstractTo produce an epoxy resin with high intrinsic self‐healing efficiency, furfurylglycidyl ether (FGE) was synthesized following a two‐step route. It carried one furan and one epoxide on each of its molecules. Having been cured using N,N′‐(4,4′‐diphenylmethane)bismaleimide and methylhexahydrophthalic anhydride, FGE was then polymerized with two types of intermonomer linkages. That is, thermally reversible Diels–Alder (DA) bonds from the reaction between furan and maleimide groups, and thermally irreversible bonds from the reaction between epoxide and anhydride groups. These two types of bonds provide the polymer with thermal remendability and load‐bearing capacity, respectively. Compared with N,N‐diglycidylfurfurylamine, which was previously developed by the authors and has a similar structure to FGE but with fewer furan rings, FGE can react with maleimide with lower activation energy and the DA bonds formed exhibit higher reversibility. Consequently, improved crack healability of the cured FGE characterized by nearly full recovery of fracture toughness was revealed using double cleavage drilled compression tests. Copyright © 2010 Society of Chemical Industry

Thermal resistance of cycloaliphatic epoxy hybrimer based on sol‐gel derived oligosiloxane for LED encapsulation

AbstractCycloaliphatic epoxy hybrimer bulk was successfully fabricated by thermal curing of cycloaliphatic epoxy oligosiloxane resin synthesized by a sol‐gel condensation reaction with methylhexahydrophthalic anhydride (MHHPA) and tetrabutylphosphonium methanesulfonate (TBPM). The composition of MHHPA and TBPM in the resin was optimized to minimize yellowness of the cycloaliphatic epoxy hybrimer bulk. The sample with the optimized composition showed little discoloration upon thermal aging at 120°C for 360 h under an air atmosphere. On the basis of its high thermal stability with appropriate hardness and a high refractive index of 1.55, cycloaliphatic epoxy hybrimer bulk can be used as a LED encapsulant for white LEDs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Synthesis, characterization and properties of the polysiloxane-based episulfide resin

The polysiloxane episulfide resin (PSER) was synthesized through replacement of the oxygen atoms in 1,3,5,7-tetra-(3-glycidoxypropyl) tetramethylcyclotetrasiloxane (TGCS) with sulfur atoms using potassium thiocyanate (KSCN). It was characterized by FT-IR, 1H NMR, MS and elemental analysis. The PSER resin was a low viscosity liquid, stable at room temperature. The polysiloxane episulfide resin was very reactive: a mixture of PSER and isophorondiamine gelated in a few seconds at room temperature. When m-phenylenediamine ( m-PDA) or 2-ethyl-4-methylimidazole (2E4MZ) was used as curing agent, PSER exhibited higher reactivity compared with the parent polysiloxane epoxy resin. The reaction heat of the PSER resin was much lower in comparison with TGCS. The cured polysiloxane episulfide resin showed higher glass transition temperature and much lower water absorption, while the thermal stability was lower. It was found that methylhexahydrophthalic anhydride (MeHHPA) is not effective for curing the episulfide resin, although it is commonly used for curing epoxy resins.

Rubber‐like thermosetting epoxy asphalt composites exhibiting atypical yielding behaviors

AbstractRubber‐like thermosetting epoxy asphalt composites (REACs) were prepared by curing epoxy resin (diglycidyl ether of bisphenol A) with curing agents system made up of maleated petroleum asphalt, adipic acid, and methylhexahydrophthalic anhydride. REACs' glass transition temperatures (Tg) and mechanics performances were investigated by differential scanning calorimetry (DSC) and universal tester, respectively. DSC results indicated that REACs had homogeneous phase structures, and theirTgwere lower than room temperature. Large elongation at break (εb), as high as 150–286%, and atypical yielding behaviors similar to so‐called “hard elastic” thermoplastics were observed simultaneously for the first time as to thermosetting epoxy composites at room temperature. The striking characteristics of REACs were ascribed to the formation of unique asphalt‐filled bimodal networks, consisting of simultaneous cured maleated asphalt short‐chain and dicarboxylic acid long‐chain interpenetrating bimodal networks and wherewith filled unmaleated asphalt. The experimental results suggest that these inexpensive REACs may find promising applications in many engineering fields. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Methylhexahydrophthalic anhydride adducted albumin tryptic peptides in nasal lavage fluid

Methylhexahydrophthalic anhydride (MHHPA) is a reactive, low molecular weight chemical used in products such as plastics, paints, and electronic components. Exposure to MHHPA may lead to work-related airway diseases such as rhinitis, conjunctivitis, and asthma. Twelve subjects employed at a plant manufacturing electrical capacitors using MHHPA were included in this study. Nasal lavages were collected from subjects before work Monday morning and after work Tuesday afternoon. The levels of MHHPA adducted to serum albumin were analyzed with a straightforward work-up method. The samples were trypsinated before being analyzed with a liquid chromatography–triple quadrupole mass spectrometer. The mass spectrometer was run using selected reaction monitoring for six adducted peptides. Also, some biomarkers of effect (albumin, total protein, eosinophil cationic protein, and tryptase) were analyzed in nasal lavages. Furthermore, the metabolite MHHP acid in urine after work on Tuesday was analyzed by gas chromatography–mass spectrometry. Symptoms from the airways and the eyes and sensitization were registered. The main result of this study is that protein adducts can be analyzed in vivo after low occupational exposures to MHHPA. The results also show a correlation between adducted peptides and albumin in nasal lavage. Furthermore, there may be a difference in the potential to induce hyperresponsiveness between adducts bound to different amino acids.

Noncatalytic curing of an epoxy siloxane monomer with 1,2,4‐cyclohexanetricarboxylic anhydride: Properties and light‐emitting diode encapsulation

AbstractThe noncatalytic anhydride curing of an epoxy siloxane monomer, 1,3‐bis[2‐(3‐{7‐oxabicyclo[4.1.0]heptyl})ethyl]tetramethyldisiloxane, with 1,2,4‐cyclohexanetricarboxylic anhydride (H‐TMAn) and methyl hexahydrophthalic anhydride (MeHHPA) was studied. Different H‐TMAn concentrations, ranging from 13 to 58 mol %, were evaluated. The highest curing exotherm and highest glass‐transition temperature were both found at 50 mol %. MeHHPA showed a sharp dependence of the thermal stability and thermal discoloration on the anhydride concentration. In contrast, the H‐TMAn concentration did not much affect the thermal stability or thermal discoloration. H‐TMAn could be diluted up to 3 times with MeHHPA to reduce the initial viscosity without a loss of noncatalytic reactivity. Unlike MeHHPA, H‐TMAn experienced very little anhydride evaporation and weight reduction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Occupational contact urticaria caused by cyclic acid anhydrides

Cyclic acid anhydrides often cause allergic respiratory diseases, but contact urticaria because of these anhydrides has been considered rare. We describe 21 patients diagnosed with occupational contact urticaria at the Finnish Institute of Occupational Health during the period 1990-2006. Prick test with human serum albumin (HSA)-acid anhydride conjugates, determination of specific immunoglobulin E (IgE), and open application were used in the diagnosis. The majority of the patients worked in the manufacture of electrical machines and were exposed to an epoxy hardener containing methyl hexahydrophthalic anhydride. The largest prick test reaction was often noted for the acid anhydride the patient had been exposed to. The specific IgE results were mostly in line with the prick test reactions. Phthalic anhydride IgE was determined in 20 patients and was found positive in 19 patients. In open application, a positive test result often required the use of the undiluted hardener. Contact urticaria may be more common than previously believed. Prick tests with HSA-acid anhydride conjugates were a useful test method for detecting immediate sensitization to acid anhydrides. The determination of the specific IgE gave almost equal results. The open application test often had to be performed with the undiluted anhydride product to obtain a positive test result.

A thermally remendable epoxy resin

To provide epoxy resin with crack healing capability, an epoxy containing both furan and epoxide groups, N,N-diglycidyl-furfurylamine (DGFA), was synthesized through a two-step approach. When it reacted with N,N′-(4,4′-diphenylmethane) bismaleimide (DPMBMI) and methylhexahydrophthalic anhydride (MHHPA), respectively, a crosslinked polymer with two types of intermonomer linkage was yielded. That is, thermally reversible Diels–Alder (DA) bonds from the reaction between furan and maleimide groups, and thermally stable bonds from the reaction between epoxide and anhydride groups. In this way, cured DGFA possessed not only similar mechanical properties as commercial epoxy, but also thermal remendability that enabled elimination of cracks. The latter function took effect as a result of successive retro-DA and DA reactions, which led to crack healing in a controlled manner through chain reconnection.

Toughened epoxy resin matrix for a membrane shell by wet filament winding

AbstractA toughened epoxy resin matrix was obtained with a reactive toughening agent and methyl hexahydrophthalic anhydride as a curing agent. The mechanical properties of the modified epoxy resin and its glass‐fiber‐reinforced composites were investigated systematically. The modified epoxy resin matrix possessed many good properties, including a high flexural strength (138 MPa), high elongation at break (5.2%), low viscosity, long pot life at room temperature, and good water resistance. In addition, the glass‐fiber‐reinforced composites showed a high strength conversion ratio of the glass fiber (86.7%) and good fatigue resistance. The results demonstrated that the modified epoxy resin matrix is very suitable for applications in reverse osmosis membrane shell products fabricated with wet filament winding for water treatment. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009