Curing and thermal behaviour of a flame retardant cycloaliphatic epoxy resin based on phosphorus containing poly(amide–imide)s

The curing behaviour of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate was investigated by the dynamic differential scanning calorimetry (DSC) using phosphorus-containing poly(amide–imide)s (PAIs) having free amine groups, 4,4′-diaminodiphenylmethane (PM) and p-phenylenediamine (PA), in the ratio of 1:1. The PAIs were prepared by co-polymerization of diimide–diacid (DIDA) and phosphorus-containing triamines having phenylene moiety. l-Tryptophan and pyromellitic anhydride were used to synthesize DIDA. Triamines used in the synthesis PAIs were tris(3-aminophenyl) phosphine (TAP), tris(3-aminophenyl) phosphine oxide (TAPO) and bis(3-aminophenyl) aminotolyl phosphine (BAP). TAP-, TAPO- and BAP-containing PAIs were designated as PTAP, PTAPO and PBAP, respectively. These PAIs with free amine groups were characterized by FTIR, ¹H NMR, ¹³C NMR spectroscopic techniques and elemental analysis. The mixture of PAIs and PM or/and PA in the ratios of 0:1, 1:0 and 0.5:0.5 was used for investigation. DSC was used to study the curing of epoxy by recording the DSC scans at heating rates of 10 °C min^?1. Thermal stability of epoxy resin cured isothermally was evaluated by recording thermo gravimetric traces in nitrogen atmosphere at the heating rate of 20 °C min^?1. All samples are highly stable, and the 10 % mass loss found was in the range of 335–520 °C. The percent char yield was highest in case of resin sample E/PM/PTAPO. The flame-retardant properties of cured epoxy resins were investigated by the limiting oxygen index test (LOI) and UL94 test. When phosphorus was incorporated in epoxy resin, the epoxy resin system met the UL94 V-0 classification and the LOI reached at 37.8, because of nitrogen–phosphorus synergistic effect.     

UV固化超支化聚酯树脂的制备研究

以双季戊四醇（DPE）为超支化核心，与偏苯三酸酐（TMA）和甲基丙烯酸缩水甘油酯（GMA）反应合成了超支化聚酯树脂。偏苯三酸酐半酯化后产生羧基，羧基再与GMA中的环氧基反应提供UV固化性能。同时研究了温度、催化剂等因素对反应的影响。     

Synthesis of p,p ′-Phenolphthaleinbis(trimellitic) Dianhydride

p,p′-Phenolphthalein-bis(trimellitic) dianhydride was obtained by the reaction of diacetyloxyphenolphthalein with trimellitic anhydride. The structure of the new compound was proved by elementary analysis, infrared spectroscopy, and acid value determination. The course of acidolysis reaction was examined in the temperature range of 240–280°C. The compound obtained is a powder having a melting point of 135–138° C, has high thermal stability, and is easily soluble in many organic solvents and low-molecular epoxy resins. Application of p,p′-phenolphthalein-bis(trimellitic) dianhydride in synthesis of soluble polyester-imides and as a hardening agent for low molecular weight epoxy resins is proposed.     

Thermal and mechanical properties of epoxy resin toughened with epoxidized soybean oil

A series of new modified epoxy resin (EP) cured products were prepared from epoxidized soybean oil and commercial epoxy resin, with methyl nadic anhydride as curing agent and 1-methylimidazole as promoting agent. The thermal properties of the resins were characterized by DMA and TG; DSC was used to determine the curing process. Fourier transform infrared spectroscopy was utilized to investigate their molecular structures and scanning electron microscopy was used to observe the micro morphology of their impact fracture surfaces. Tensile and impact testing was employed to characterize the mechanical properties of the cured products. The combination of commercial EP with 20 wt% ESO resulted in a bioresin with the optimum set of properties: 130.5 °C T _g, 396.9 °C T _50 %, 74.89 MPa tensile strength, and 48.86 kJ m^?2 impact resistance.     

Synthesis and thermal behaviour of silicon containing poly(ester imide)s

A series of silicon containing poly(ester imide)s [PEIs] were synthesized using novel vinyl silane diester anhydride (VSEA) and various aromatic and aliphatic dimines by two-step process includes ring-opening polyaddition reaction to form poly(amic acid) and thermal cyclo-dehydration process to obtain poly(ester imide)s. VSEA was synthesized by using dichloro methylvinylsilane and trimellitic anhydride in the presence of K₂CO₃ by nucleophilic substitution reaction. The PEIs were characterized by FTIR spectroscopy. The thermal properties of PEIs were investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) methods. The prepared PEIs showed glass transition temperatures in the range of 320–350°C and their 5% mass loss was recorded in the temperature range of 500–520°C in nitrogen atmosphere. These had char yield in the range of 45–55% at 800°C.     

Synthesis and characterization of polyurethane ionomers with trimellitic anhydride and dimethylol propionic acid for waterborne self‐emulsifying dispersions

A new synthesis for polyurethane dispersions was developed using both trimellitic anhydride alone and in combination with dimethylol propionic acid as internal emulsifiers. During synthesis of the polyurethane ionomer, Fourier transform infrared spectroscopy was used for monitoring and characterizing both the polyaddition step and the anhydride ring opening process. Depending on the synthesis route, the carboxylic groups are either located at the end of the polymer backbone or additionally statistically distributed within the polymer chain itself. The effect of the carboxylic group's position on the chemical and physical properties, with particular reference to particle size and pH, was analyzed. Three different polyols were used to synthesize the polyurethane dispersions. Driven by the current trend to find renewable alternatives to petrochemical‐based raw materials, one bio‐based polyol was included for the synthesis. The effect of the different structures of the polyurethane dispersions (petrochemical‐ or bio‐based polyols) on mechanical properties and thermal behavior was investigated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 680–690     

Chemical Modification of Polystyrene. VI. Thermal Stability Studies of Sulfonic Acid Resins from Anhydride Modified Polystyrene

Thermal stabilities of the H form of sulfonic acid resins from polystyrene electrophilically substituted with phthalic anhydride, pyro-mellitic dianhydride, trimellitic anhydride, and cis-1,2,3,6-tetra-hydrophthalic anhydride have been studied and compared by DTA and TGA. Isothermal degradation studies of these resins at 150 ± 10°C for 72 h in air and nitrogen reveal significant changes in IR, decreases in sulfur content, and increases in ion-exchange capacity values. The pH-metric titration characteristics of the pyro-mellitic-dianhydride-modified sulfonated polystyrene after isothermal heating under the above conditions indicate weak acid behavior, in contrast to the strong acid nature of the original resin.     

LC polyimides. XXI. Thermotropic poly(amide-imide)s based on trimellitimides

Polycondensation of α, ω-bis(-4-aminophenoxy) alkanes with trimellitic anhydride chloride (TMA-Cl) in m-cresol yielded a new class of poly(amideimide)s. Starting from the same diamine spacers poly(amideimides) with a more regular sequence of amide and imide groups were prepared by another synthetic method. All these poly(amide-imide)s are semi-crystalline and melt in the range of 250–300°C. They form a smectic-A phase over a narrow temperature range and suffer thermal degradation at the isotropization temperature (330–350°C). The smectic-A phase was characterized by optical microscopy (“batonnet texture”) and by synchrotron radiation measurements conducted at a heating rate of 20°C. Furthermore, it is demonstrated that slight variation of the chemical structure, such as methyl substituents or meta positions in the spacer prevent the formation of a LC phase. © 1995 John Wiley & Sons, Inc.     

Synthesis of aromatic polyamide-phthalimidines from chloroformylphthalides and aromatic diamines

New polymer-forming monomers, 3-benzylidene-5-chloroformylphthalide and 3-benzylidene-6-chloroformylphthalide, were synthesized by the Perkin reaction of trimellitic anhydride with phenylacetic acid, followed by chlorination. The polycondensation of these monomers with aromatic diamines in N-methyl-2-pyrrolidone at 200°C afforded aromatic polyamide-phthalimidines having inherent viscosities of 0.2-0.5 dL/g. All the polymers were readily soluble in m-cresol, pyridine, dimethylformamide, and dimethyl sulfoxide. Glass transition temperatures of some of the polymers were in the range of 255–282°C. The polyamide-phthalimidines began to lose weight at around 300°C in both air and nitrogen atmospheres, with 10% weight losses being recorded at 435–475°C in nitrogen by thermogravimetry.     

Laminating resins obtained from 2,2′-(1,4-phenylenedivinylene)bispyridine bismaleimides and maleimide-terminated styrylpyridine prepolymers

A new bismaleimide (2a) , biscitraconimide (2b) , and bisnadimide (4) were synthesized by reacting 2-amino-6-methylpyridine with an equimolar amount of maleic, citraconic, or nadic anhydride, respectively, and then with a half molar amount of 1,4-benzenedicarbaldehyde in the presence of acetic anhydride. They, as well as the intermediate amic acids ( 1a, 1b, and 3 ) were characterized by IR and ¹H-NMR spectroscopy. The DTA thermograms showed that crosslinking of polymer precursors started at 180–212°C. The crosslinked resins obtained from 2a and 2b were stable up to 300–313°C and afforded anaerobic char yield of 53–60% at 800°C. The cured resin of 4 was less thermostable. In addition, end-capping of styrylpyridine prepolymers was accomplished by reacting 2,6-dimethylpyridine (n mol) with 1,4-benzenedicarbaldehyde (n + 1 mol) in acetic anhydride to yield a formyl-terminated styrylopyridine prepolymer. The latter reacted with the maleamic acid 1a (2 mol) to afford a series of maleimide-terminated styrylpyridine prepolymers MTSOs. They showed lower curing temperatures than did the ordinary poly(styrylpyridine). Their cured resins did not lose weight up to 310–344°C both in N₂ or air and afforded anaerobic char yield of 66-72% at 800°C.     

Preparation of copoly(amide-imide)s via direct polycondensation

Preparation of various kinds of copoly(amide-imide) was carried out via direct polycondensation of trimellitic anhydride (TMA) with the corresponding diamine mixture in the presence of an equimolar amount of thionyl chloride (TC) as a condensing agent followed by thermal imidization. The resulting copoly(amide-imide)s had inherent viscosities in the range of 41 to 68 mL g⁻¹ and glass transition temperatures of 215°C to 291°C. These copoly(amide-imide)s had relatively good thermomechanical properties. That is, the initial decomposition temperature (IDT) and tensile strength were 350–409°C and 104–121 MPa, respectively. The melt viscosities of the copoly(amide-imide)s measured at 345°C under a frequency of 10² rad s⁻¹ were in the range of 4.8 × 10² ∼ 4.5 ˜ 10³ Pa s depending on comonomers, which are somewhat lower than that commerciallized PAI with 5.6 × 10³ Pa s.     

Preparation and characterization of CaCu3Ti4O12 powders by non-hydrolytic sol–gel method

CaCu₃Ti₄O₁₂ (CCTO) powders were prepared via a non-hydrolytic sol–gel (NHSG) method by using acetylacetone as chelating agent and ethylene glycol as solvent. The samples were characterized by TG–DSC, Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscope. The dielectric properties of ceramics were also measured. The pure perovskite-like CCTO powders were obtained by heat treatment at 800 °C for 2 h. The average particle sizes of CCTO powders calcined at 800 °C were approximately 350–450 nm. The samples sintered at 1,000 °C showed the mean grain size of 2.5–4 μm. Specially, the ceramics exhibited high dielectric constant (1.19 × 10⁵–1.40 × 10⁵) and low dielectric loss (0.051–0.1) in the temperature range of 30–110 °C. Moreover, with the NHSG method the period of synthesis process was greatly shortened.     

Adhesives and coatings based on phenolic/epoxy resins

Low molecular weight epoxy resin based on bis (4‐hydroxy phenyl) 1,1 cyclohexane was prepared and modified with various types of the prepared phenolic resins. Phenol–, cresol–, resorcinol–and salicylic acid–formaldehyde resins were used. The optimum conditions of formulation and curing process were studied to obtain modified wood adhesives characterized by high tensile shear strength values. This study indicated that the more suitable conditions are 1:2 weight ratio of phenol–or cresol–formaldehyde to epoxy resin in the presence of phthalic anhydride (20 wt%) of the resin content as a curing agent at 150°C for 80 min. Resorcinol–or salicylic acid–formaldehyde/epoxy resins formulated at 1:2 weight ratio were cured in the presence of paraformaldehyde (20 wt%) at 150°C for 60 min. The effect of the structure of phenolic resins on the tensile shear strength values of formulated resin samples, when mixed with the epoxy resins and cured under the previously mentioned optimum conditions for different times, was investigated. Metallic and glass coatings from the previous resins were also prepared and evaluated as varnishes or paints. Copyright © 1999 John Wiley & Sons, Ltd.     

Macroporous zirconia particles prepared by subcritical water in batch and flow processes

Porous zirconia particles were synthesized through a low-temperature hydrothermal synthesis process. Under hydrothermal conditions, water can control the direction of crystal growth, morphology, particle size, and size distribution because thermodynamics and transport properties can be controlled by pressure and temperature. In a batch process, the hydrothermal synthesis was conducted at 200–300 °C and 30 MPa with an SUS-304 tube as the reactor. At the same reaction pressure, experiments were also performed for a flow process with temperatures of 180–200 °C. The synthesized products were calcined and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The results showed that the macroporous zirconia particles that were formed had pore diameters around 419 nm. The XRD pattern indicated that the products were composed of zirconium oxide particles with monoclinic, tetragonal, and cubic structures.     

Preparation and properties characterization of gallic acid epoxy resin/succinic anhydride bionanocomposites modified by green reduced graphene oxide

Graphene oxide was reduced into reducing-graphene oxide (r-GO) successfully using gallic acid (GA) as a green reducing agent. Biobased gallic acid epoxy resin (GAER) was synthesized from renewable GA, and the biobased GAER/r-GO nanocomposites and glass fiber-reinforced composites were prepared with succinic anhydride as a curing agent. The dynamic mechanical, thermal, and mechanical properties of the composites with varying r-GO contents were characterized. When the content of r-GO was 0.5 wt%, the glass transition temperature was 10.4°C higher than the pure resin system. The thermal and mechanical properties were increased with increasing r-GO content; when the r-GO content was 1.0 wt%, the initial degradation temperature was enhanced by approximately 6.8°C, the tensile and impact strengths were 34.5% and 49.1% higher, respectively, than the pure cured GAER. The impact strength of GAER was higher than that of the bisphenol A epoxy resin/SUA curing system, but the tensile strength was lower than it.     

New poly(amide-imide)s syntheses. VII. Preparation and properties of poly(amide-imide)s derived from 1,5-bis(4-aminophenoxy) naphthalene,trimellitic anhydride,and various aromatic diamines

New bis(phenoxy)naphthalene-containing poly(amide-imide)s having an inherent viscosity in the range of 0.62–1.09 dL/g were prepared by the direct polycondensation of 1,5-bis(4-trimellitimidophenoxy) naphthalene ( I ) and various aromatic diamines using triphenyl phosphite and pyridine as condensing agents in N-methyl-2-pyrrolidone (NMP) in the presence of calcium chloride. The diimide-diacid (I) was prepared by the condensation of 1,5-bis(4-aminophenoxy) naphthalene and trimellitic anhydride. Most of the polymers were soluble in aprotic solvents such as NMP and N,N-dimethylacetamide (DMAc), and afforded transparent, flexible and tough films upon casting from DMAc solutions. Measurements of wide-angle X-ray diffraction revealed that those polymers containing p-phenylene or oxyphenylene groups were characterized as crystalline polymers. Tensile strength and initial moduli of the polymer films ranged from 61–86 MPa and 1.83–2.21 GPa, respectively. Glass transition temperatures of the polymers were in the range of 231–340°C. The melting points of the crystalline polymers ranged from 375–430°C. The 10% weight loss temperatures were above 512°C in nitrogen and 481°C in air. © 1993 John Wiley & Sons, Inc.     

Amphiphilic protic anionic oligomeric ionic liquids of hyperbranched structure

The method of synthesizing anionic amphiphilic protic hyperbranched ionic liquids with the controlled ratio between hydrophilic ionic-liquid groups and hydrophobic alkyl urethane fragments in the oligoester nucleus shell is developed. These compounds are synthesized by the interaction of excess hyperbranched polyesterpolyol containing 32 terminal hydroxyl groups with n-octadecyl isocynate followed by the acylation of hydroxyl groups by phthalic anhydride or 2-sulfobenzoic anhydride and the neutralization of the formed carboxyl or sulfonic groups by N-methylimidazole or 1,2,4-1H-triazole. With a rise in the content of alkyl urethane fragments, the synthesized compounds form the crystalline phase. Structuring of the system leads to different effects of the degree of ionicity of ionic-liquid groups on proton conductivity, which is within 10^–7–10^–4 S/cm at 100–120°C under anhydrous conditions. The thermal stability of the hyperbranched ionic liquids is determined by the nature of ionic-liquid groups and the amount of the introduced alkyl urethane fragments; it is in the range of 170–270°C.     

Synthesis and anti-aging property in acrylonitrile-butadiene rubber of non-aromatic dendritic antioxidant with amine groups

A novel kind of antioxidant with dendritic structure and amine groups for acrylonitrile-butadiene rubber (NBR) was synthesized via the combination of Michael addition and nucleophilic reactions. Structures of the synthesized non-aromatic dendritic antioxidants, namely first-generation (1.0 G), second-generation (2.0 G), third-generation (3.0 G) dendritic polyamidoamine (DPAMAM) and hyperbranched polyamidoamine (HPAMAM), were confirmed by Fourier Transform Infrared Spectroscopy (FT-IR) and Hydrogen Nuclear Magnetic Resonance Spectroscopy (¹H NMR). Anti-aging properties of the antioxidants for NBR vulcanizates were evaluated by accelerated thermal aging tests and extraction resistance tests. The decomposition of vulcanizates containing dendritic antioxidants were investigated by thermogravimetric (TGA) curves, and the thermo-oxidative aging kinetic parameters were calculated by the Dakin-Ozawa-Doyle (DOD) method. Compared with conventional aromatic antioxidant N-isopropyl-N′-phenyl-p-phenylene diamine (4010NA), the anti-aging properties of 1.0 G and 2.0 G DPAMAM were at the same level, while that of 3.0 G DPAMAM and HPAMAM were further improved. Meanwhile, HPAMAM and 3.0 G PAMAM showed better extraction resistance in NBR vulcanizates than 4010NA, thus indicating superior anti-aging performances. Maximum service temperatures (T_max) under 30 years of service life span of NBR vulcanizates containing HPAMAM and 3.0 G DPAMAM were 219°C and 221°C, 15°C and 17°C higher than that of sample with 4010NA respectively.     

Synthesis of autophotosensitive hyperbranched polyimides based on 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride and 1,3,5‐tris(4‐aminophenoxy)benzene via end capping of the terminal anhydride groups by ortho‐alkyl aniline

Benzophenone‐containing, anhydride‐terminated hyperbranched poly(amic acid)s were end‐capped by ortho‐alkyl aniline in situ and then chemically imidized, yielding autophotosensitive hyperbranched polyimides. The polyimides were soluble in strong polar solvents, such as N‐methyl‐2‐pyrrolidone, N‐dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. Thermogravimetric analysis revealed their excellent thermal stability, with a 5 wt % thermal loss temperature in the range of 527–548 °C and a10 wt % thermal loss temperature in the range of 562–583 °C. The strong absorption of the polyimide films in ultraviolet–visible spectra at 365 nm indicated that the hyperbranched polyimides were patternable. Highly resolved images with a line width of 6 μm were developed by ultraviolet exposure of the polymer films. A well‐defined image with lines as thin as 3 μm was also patterned, but the lines were rounded at the edges. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2026–2035, 2003     

Hyperbranched epoxy resins prepared by proton transfer polymerization from an A<Subscript>2</Subscript> + B<Subscript>3</Subscript> system

Epoxy-terminated hyperbranched polymers(EHBPs)were prepared by proton transfer polymerization and characterized by FT-IR,~1H-NMR and GPC.The solution and thermal properties of the uncured samples and mechanical properties of cured samples were examined.The thermo-stable products had good solubility in polar solvents,low solution viscosity and T_gs ranging from 15℃to 33℃depending on their molecular weights.The mechanical properties of cured films were studied and compared with those of a bisphenol-A type epoxy resin.The films of EHBPs had good impact resistance and high gloss values without sacrificing hardness and adhesion.