Organic/inorganic hybrid bismaleimide resin with octa(aminophenyl)silsesquioxane

Octa(aminophenyl)silsesquioxane (OAPS) was prepared in two steps by the nitration of octaphenylsilsesquioxane (OPS) in fuming nitric acid to form octa(nitrophenyl)silsesquioxane (ONPS), followed by the mild reduction of ONPS with Pd/C as a catalyst. OPS, ONPS and OAPS were characterized by FTIR, ¹H NMR, and ²⁹Si NMR techniques. Modification of a bismaleimide (BMI) resin with OAPS and dipropargyl ether of bisphenol A (DPBPA) was investigated. The modified resins, OAPS/DPBPA/BMI, were characterized with DSC, FTIR and rheology analyses. The results showed that the modified resins have good processability. The DMA results indicated that the glass transition temperature (T_g) of the cured OAPS/DPBPA/BMI hybrid resins reached 350°C. The decomposition temperature (T_d5) of the cured resins decreased but the char yield (Y_c, 800°C) increased as the OAPS loading increased, especially in air. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Bismaleimides,bisnadimides, and polyaspartimides containing ether and ester linkages and pyridine

A series of bismaleimides (BMI) and bisnadimides (BNI) containing pyridine ring and flexible linkages were prepared and the structural characterization of the resins was carried out by elemental analysis, FTIR, ¹H NMR, and ¹³C NMR spectroscopy. Their curing behavior were characterized by differential scanning calorimetry and thermal stability of the cured resins were investigated by thermogravimetric analysis. In addition, a series of polyaspartimides were prepared by the polyaddition of the bismalemide with various dimaines. The polymers were characterized by FT‐IR, inherent viscosity, and molecular weight measurements. All the polyimides were soluble in many organic solvents, the glass transition temperature of the polyaspartimides are in the range of 194–231°C, 10% weight loss (T₁₀) takes place in the temperature range of 379–482°C in N₂ and char yield in the range of 44.31–53.31%. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel propargylether‐terminated monomers containing pyridine and phenyl pendent group: Synthesis,cure, and properties

Two novel propargylether‐terminated resins containing pyridine and bulky phenyl pendent group were prepared from propargyl bromide and different diphenols, and highly thermal stable polymers were obtained by the thermal cure of the monomers. The chemical structures of these novel monomers were well confirmed by FTIR, ¹H‐NMR and elemental analysis. Curing and thermal behavior of the resins were investigated using differential scanning calorimetry (DSC) and dynamic thermogravimetry in argon atmosphere. DSC curves of these two monomers showed a single endothermic peak corresponding to the conformation of chromene ring and homopolymerization of the chromene ring. The temperature at 5% weight loss (T_d5) was higher than 440°C under argon and the highest glass transition temperature (T_g) reached 362°C. The rheological behavior and solubility of the monomer were also investigated. The monomers showed excellent flow‐ability, broad processing window, and great solubility. These results showed that the two resins could be ideal candidates for high‐temperature resistant resins. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40469.     

High-performance poly(methylsilane arylether arylacetylene) resins with low curing temperatures and weak secondary relaxations

A series of poly(methylsilane arylether arylacetylene) (PSEA-H) resins were synthesized from methyldichlorosilane and isomeric arylether arylacetylenes, and characterized by ¹H-NMR and FT-IR spectroscopies. The effect of reactive Si-H groups and the linking positions of benzene rings in the arylether arylacetylene units on the properties of the resins were investigated. The results show that PSEA-H resins possess good processability with processing windows of over 80°C. The introduction of Si-H groups reduces the curing temperatures for PSEA-H resins and weakens the secondary relaxation for the cured PSEA-H resins. The cured resins and T300 carbon fiber (T300CF) reinforced composites display high mechanical properties. The flexural strengths of a cured PSEA-H resin and its T300CF composite at room temperature reach 64.2 and 426.5 MPa, respectively. The flexural properties depend on the linking positions of benzene rings. The cured PSEA-H resins show excellent heat resistance with a temperature of 5% weight loss (T_d5) above 500°C.     

Synthesis and characterization of poly(dihalophenylene oxide)s by solid-state thermal-decomposition of manganese phenolate complexes with tetramethylethylenediamine

The characterization of poly(dihalophenylene oxide)s synthesized by solid-state thermal decomposition of manganese phenolate complexes with tetramethylethylenediamine (TMEN) ligand is reported. The complexes prepared with 2,4,6-trichlorophenol (TCP) and 2,4,6-tribromophenol (TBP) have been characterized by FTIR spectroscopy, elemental analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The dependence of the polymerization yield on temperature and decomposition time of the complexes has been investigated. Maximum polymerization yield is obtained at 220°C and 48 h. The polymers synthesized from the complexes have been characterized by ¹H-NMR and FTIR spectroscopy, DSC, and viscometric measurements. All polymers have a branched structure, a high T_g and low intrinsic viscosity. © 1999 Society of Chemical Industry     

Synthesis of soluble and thermally stable polyimides from 3,5‐diamino‐N‐(4‐(8‐quinolinoxy) phenyl) aniline and various dianhydrides

Three novel polyimides (PIs) having pendent 4‐(quinolin‐8‐yloxy) aniline group were prepared by polycondensation of a new diamine with commercially available tetracarboxylic dianhydrides, such as pyromellitic dianhydride, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride, and bicyclo[2.2.2]‐oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride. These PIs were characterized by FTIR, ¹H NMR, and elemental analysis; they had high yields with inherent viscosities in the range of 0.4–0.5 dl g⁻¹, and exhibited excellent solubility in many organic solvents such as N,N‐dimethyl acetamide, N,N′‐dimethyl formamide, N‐methyl pyrrolidone (NMP), dimethyl sulfoxide, and pyridine. These PIs exhibited glass transition temperatures (T_g) between 250 and 325° C. Their initial decomposition temperatures (T_i) ranged between 270 and 450°C, and 10% weight loss temperature (T₁₀) up to 500°C with 68% char yield at 600°C under nitrogen atmosphere. Transparent and hard polymer films were obtained via casting from their NMP solutions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and properties of bismaleimide resins of aromatic sulfone ether diamine

Aromatic sulfone ether diamine, bis[4-(4-aminophenoxy)phenyl]-sulfone (SED), was prepared by the nucleophilic aromatic substitution of 4,4′-dichlorodiphenylsulphone by p-aminophenolate. The reaction was conducted in the presence of excess potassium carbonate as a weak base, toluene as the dehydrating agent and N-methylpyrrolidone as the dipolar aprotic solvent. SED showed good solubility in common organic solvents, such as dioxan, tetrahydrofuran, butanone and acetone. SED was reacted with maleic anhydride to obtain aromatic sulfone ether bismaleimide, bis[4-(4-maleimidophenoxy)phenyl]-sulfone (SEM). The compounds were characterized by FTIR and ¹H NMR analysis. Furthermore, copolymer resins of SED with 4,4′-bismaleimidodiphenyl methane (BMI) and SEM were prepared. After curing, crosslinked resins with better thermal stability resulted. The temperature at maximum rate of weight loss (T_max) and the heat-resistant temperature index (T_i) in air were found to be 426°C, 208°C and 579°C, 221°C for BMI/SED and SEM/SED resins, respectively. Compared with the corresponding 4,4′-diaminodiphenyl methane (DDM) system, BMI/SED and SEM/SED showed a slight decrease in T_max and T_i SED-modified BMI/amine resin based glass cloth laminates for printed circuit boards showed higher mechanical properties than those of the corresponding unmodified system. With SED instead of the original amine component in 3–5% weight fraction, the tensile strength, flexural strength and impact strength of the laminates increased markedly. Meanwhile, the stripping strength and weld resistance were also improved by the addition of SED.     

Synthesis and properties of methyl hexahydrophthalic anhydride‐cured fluorinated epoxy resin 2,2‐bisphenol hexafluoropropane diglycidyl ether

The fluorinated epoxy resin, 2,2‐bisphenol hexafluoropropane diglycidyl ether (DGEBHF) was synthesized through a two‐step procedure, and the chemical structure was confirmed by ¹H n uclear magnetic resonance (NMR), ¹³C NMR, and Fourier transform infrared (FTIR) spectra. Moreover, DGEBHF was thermally cured with methyl hexahydrophthalic anhydride (MHHPA). The results clearly indicated that the cured DGEBHF/MHHPA exhibited higher glass transition temperature (T_g 147°C) and thermal decomposition temperature at 5% weight loss (T₅ 372°C) than those (T_g 131.2°C; T₅ 362°C) of diglycidyl ether of bisphenol A (DGEBA)/MHHPA. In addition, the incorporation of bis‐trifluoromethyl groups led to enhanced dielectric properties with lower dielectric constant (D_k 2.93) of DGEBHF/MHHPA compared with cured DGEBA resins (D_k 3.25). The cured fluorinated epoxy resin also gave lower water absorption measured in two methods relative to its nonfluorinated counterparts. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2801–2808, 2013     

High glass transition temperature bismaleimide‐triazine resins based on soluble amorphous bismaleimide monomer

A novel bismaleimide (DOPO‐BMI) with unsymmetrical chemical structure and DOPO pendant group has been prepared. The particular molecular structure makes DOPO‐BMI show an intrinsic amorphous state with a T_g about 135°C and excellent solubility in most organic solvents, which is beneficial to the processability of bismaleimide composite materials. A series of bismaleimide‐triazine (BT) resins have been prepared based on DOPO‐BMI and 2,2‐bis(4‐cyanatophenyl)propane at various weight ratios. The prepared BT resins show outstanding solubility in organic solvent and low viscosity about 10–671 mPa s at 180°C. The cured BT resins exhibit high glass transition temperature (T_g) over 316°C. As the weight ratio of DOPO‐BMI increases to 80% (BT80), the T_g can rise to 369°C (tan δ). The cured BT resins also show good thermal stability with the 5% weight loss temperature over 400°C under both nitrogen and air atmosphere. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42882.     

Preparation,characterization, and polymerization of novel maleimidobenzoxazine containing carboxylic moiety and its cocuring behaviors with epoxy resin

A novel benzoxazine containing maleimide and carboxylic moieties, 1‐[3‐(4‐carboxylphenyl)‐3,4‐dihydro‐2H‐benzo[e][1,3]‐oxazin‐6‐yl]maleimide (Mal‐Bz‐Co), was synthesized and the structure was identified by ¹H‐NMR and FTIR. Mal‐Bz‐Co exhibited good solubility in common organic solvents. The cure behavior of Mal‐Bz‐Co and cocure behavior of Mal‐Bz‐Co with o‐cresol formaldehyde epoxy resin were investigated by differential scanning calorimetry. Results indicated that Mal‐Bz‐Co showed a single curing exothermic peak at about 238.3°C. However, the maximum curing temperature (T_p) decreased to 146.1°C when Mal‐Bz‐Co cocured with o‐cresol formaldehyde epoxy resin in the molar ratio of 1 : 1. The T_p was about 92°C lower than that of Mal‐Bz‐Co. Thermogravimetric analysis showed that high‐decomposition temperature and char yield were observed for the cured resins of Mal‐Bz‐Co and Mal‐Bz‐Co/o‐CFER. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Amorphous polyamide coating resins from sugar-derived monomers

In this article, the synthesis of bio-based polyamides for powder coating applications and their evaluation in a solventborne coating system are reported. The M _n values of the resins were between 3000 and 4000 g mol^?1 and the resins displayed T _g values from 60 to 80°C. Both amine and carboxylic acid functionalities (total ~0.6 mmol g^?1) were introduced for curing purposes. The resins were cured with triglycidyl isocyanurate (TGIC) or N,N,N′,N′-tetrakis(2-hydroxyethyl)adipamide (Primid XL-552). The curing reaction was followed using rheology which indicated that TGIC achieved higher reaction rates and higher gel contents. The DSC analysis of the cured disks showed that all cured samples were amorphous as is desired for the targeted coating application. The resins required a curing temperature higher than 150°C. Aluminum panels were coated using a solventborne approach and the coatings were cured at 180°C during 1 h. Dewetting was observed on all panels. Network formation was adequate for an amine-functional resin cured with TGIC as indicated by solvent resistance testing. In conclusion, the developed bio-based polyamide resins are promising materials to be used as binder resins in powder coating applications.     

Methacrylate/acrylate terminated derivatives of diglycidyl hexahydrophthalate: Synthesis,structural, and thermal characterization

Mono‐ or di(meth)acrylate‐terminated derivatives of diglycidyl hexahydrophthalate (ER) were prepared by reacting 1 : 1 or 1 : 2M ratio of ER and methacrylic acid or acrylic acid. These vinyl ester (VE) resins were characterized by determining epoxy equivalent weight, acid number, and molecular weight by gel permeation chromatography. Structural characterization was done by FTIR and ¹H NMR spectroscopy. In the ¹H NMR spectra of acrylate‐terminated VE resins, three proton resonance signals were observed in the region 5.8–6.4 ppm due to vinyl group while in methacrylate‐terminated VE resins only two proton resonance signals due to vinylidene protons were observed at 5.6–6.1 ppm. The Brookfield viscosity (room temperature (25 ± 2)°C) of these resins diluted with varying amounts of MMA was determined at 20 rpm. Curing behavior was monitored by determination of gel time and differential scanning calorimetry. An exothermic transition was observed in the DSC scans in the temperature range of (81–150)°C. Isothermal curing of MMA‐diluted VE resins containing AIBN as an initiator was done at 60°C for 2 h in N₂ atmosphere, and then heating for another 2 h in static air atmosphere. Thermal stability of isothermally cured resins in N₂ atmosphere was evaluated by thermogravimetric analysis. All cured resins decomposed above 310°C in single step. Thermal stability of the cured resins having acrylate end caps was marginally higher than the resins having methacrylate end groups. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Synthesis and properties of silicon-containing bismaleimide resins

Two novel bismaleimide (BMI) monomers containing silicon atom in the structure, i.e., bis[4-(4-maleimidophenylcarbonyloxy)phenyl]dimethylsilane (BMI-SiE1) and bis[4-(4-maleimidophenyloxycarbonyl)phenyl]dimethylsilane (BMI-SiE2), were designed, synthesized, and polymerized with and without the use of diamine as comonomers to yield novel silicon-containing BMI resins. Both monomers obtained are readily soluble in organic solvents, such as chloroform and N, N-dimethylformamide. Differential scanning calorimetry and thermogravimetric analysis investigation of these two monomers indicated a high polymerization temperature (T_p > 240°C) and a good thermal and thermo-oxidative stability of cured BMI resins. The onset temperature for 5% weight loss was found to be above 450°C in nitrogen and above 400°C in the air. Polymerization of BMI-SiE1 and BMI-SiE2 with 4,4′-diaminodiphenylether (DPE) yielded a series of polyaspartimides that had good solubility and could be thermally cured at 250°C. TGA investigations of the cured diamine-modified BMI resins showed onset of degradation temperatures (T_ds) in the range of 344–360°C in nitrogen and 332–360°C in the air. Composites based on the cured diamine-modified BMI resins and glass cloth were prepared and characterized for their dynamic mechanical properties. All the composites showed high glass transition temperatures (e.g., >190°C) and high bending modulus in the range of 1000–2700 MPa. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of LC p-Biphenyl di{4-[2-(2,3-epoxypropyl)ethoxy] benzoate} and Curing Kinetics with Succinic Anhydride

A liquid crystalline (LC) diepoxide of p-biphenyl di{4-[2-(2,3-epoxypropyl)ethoxy] benzoate} (p-BPEPEB) was synthesized from allyl 2-hydroxyethyl ether, 4-hydroxy ethyl benzoate, 4,4-biphenol and m-chloroperoxybenzoic acid (MCPBA). Its structure was characterized by FTIR, ¹HNMR. The thermal properties and liquid crystalline behavior were investigated by using DSC, POM and XRD. The results show that the p-BPEPEB has a smectic liquid crystalline structure, and the melting point is 155°C. The curing kinetics of p-BPEPEB with succinic anhydride was investigated by nonisothermal DSC method. The results show that the cured system's initial temperature T_i is 90.8°C; peak temperature T_p is 128.4°C and finishing temperature T_f is 144.7°C. The apparent activation energy Ea is 213.69 KJ/mol, and with the increase of conversion rate the value reduces.     

Synthesis and characterization of poly(arylene ether) containing cyanate ester networks

A series of bisphenols containing ether linkage were prepared from halo phenol/dihalo compound and dihydroxy compounds in the presence of K₂CO₃. The bisphenols were transformed to cyanate esters by treatment with cyanogen bromide using triethyl amine catalyst. The structure of all the five bisphenols and the cyanate esters were structurally confirmed by FT-IR, ¹H-NMR and ¹³C-NMR spectral methods and elemental analysis. The cyanate esters were cured at 100 °C (30 min) → 150 °C (30 min) → 200 °C (60 min) → 250 °C (3 hr). The thermal properties of the cured resins were studied by DSC and TGA. DSC analysis shows that these cyanate esters exhibit T _g in the range of 203–234 °C. The CE(c) has the highest glass transition temperature. The cyanate ester CE(e) shows the lowest T _g which is due to its asymmetric structure. The initial degradation temperature of the cured resins was found to be in the range of 324–336 °C. The Limiting Oxygen Index (LOI) value, determined by Van Krevelen’s equation, is in the range of 35.5–38.7.     

Mechanical and thermal properties of epoxy resins with reversible crosslinks

The tensile properties: Young's modulus, ultimate tensile strength, ultimate elongation, the glass transition temperature, and the dynamic mechanical properties (dynamic shear modulus (G'), loss tangent (Tan δ)), of three epoxy resins (Epon 828, Epon 836, Epon HPT 1071) cured with the disulfide-containing crosslinking agent—4.4-dithiodianilme (DTDA) have been characterized. The results show that DTDA is a satisfactory crosslinking agent for the epoxide resins that have been studied as compared to the well-known curing agent methylene dianiline (MDA). There are no significant differences between the properties of Epon 828 cured with DTDA at stoichiometric ratio (2:1) and Epon 828 cured with DTDA at small amine excess ratio (1.75:1). The glass transition temperature of the cured tetrafunctional epoxy resin Epon HPT 1971 (235°C) is significantly higher than that of difunctional epoxy resins such as Epon 828 (T_g–175°C), but the product is too brittle to be used without plasticizer.     

Thermal and mechanical properties of tetra‐functional mesogenic type epoxy resin cured with aromatic amine

A novel tetra‐functional epoxy monomer with mesogenic groups was synthesized and characterized by ¹H‐NMR and FTIR. The synthesized epoxy monomer was cured with aromatic amine to improve the thermal property of epoxy/amine cured system. The glass transition temperature (T_g) and coefficient of thermal expansion (CTE) of the cured system were investigated by dynamic mechanical analysis and thermal mechanical analysis. The properties of the cured system were compared with the conventional bisphenol‐A type epoxy and mesogenic type epoxy system. The storage modulus of the tetra‐functional mesogenic epoxy cured systems showed the value of 0.96 GPa at 250 °C, and T_g‐less behavior was clearly observed. The cured system also showed a low CTE at temperatures above 150 °C without incorporation of inorganic components. These phenomena were achieved by suppression of the thermal motion of network chains by introduction of both mesogenic groups and branched structure to increase the cross linking density. The temperature dependency of the tensile property and thermal conductivity of the cured system was also investigated. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46181.     

Comparison of thermoset soy protein resin toughening by natural rubber and epoxidized natural rubber

Fully bio‐based soy protein isolate (SPI) resins were toughened using natural rubber (NR) and epoxidized natural rubber (ENR). Resin compositions containing up to 30 wt % NR or ENR were prepared and characterized for their physical, chemical and mechanical properties. Crosslinking between SPI and ENR was confirmed using ¹H‐NMR and ATR‐FTIR. All SPI/NR resins exhibited two distinctive drops in their modulus at glass transition temperature (T_g ) and degradation temperature (T_d ) at around ?50 and 215 °C, corresponding to major segmental motions of NR and SPI, respectively. SPI/ENR resins showed similar T_g and T_d transitions at slightly higher temperatures. For SPI/ENR specimens the increase in ENR content from 0 to 30 wt % showed major increase in T_g from ?23 to 13 °C as a result of crosslinking between SPI and ENR. The increase in ENR content from 0 to 30 wt % increased the fracture toughness from 0.13 to 1.02 MPa with minimum loss of tensile properties. The results indicated that ENR was not only more effective in toughening SPI than NR but the tensile properties of SPI/ENR were also significantly higher than the corresponding compositions of SPI/NR. SPI/ENR green resin with higher toughness could be used as fully biodegradable thermoset resin in many applications including green composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44665.     

Biobased thermosetting resins composed of L‐lysine methyl ester and bismaleimide

Lysine methyl ester (LME), which was generated in situ by the reaction of lysine methyl ester dihydrochloride and triethylamine in dimethyl sulfoxide (DMSO), was prepolymerized with 4,4′‐bismaleimidodiphenylmethane (BMI) at 80°C for 2 h in DMSO. Then, the formed prepolymer was precipitated in water. The obtained LME/BMI prepolymers with molar ratios of 2:2, 2:3, and 2:4 were compression‐molded at a final temperature of 230°C for 2 h to produce cured lysine methyl ester/4,4′‐bismaleimidodiphenylmethane resins (cLBs; cLB22, cLB23, and cLB24, respectively). Fourier transform infrared (FTIR) analyses revealed that the Michael addition reaction of amino groups to the C?C bonds of the maleimide group occurred in addition to the homopolymerization of the maleimide group. The glass‐transition temperature (T_g) and 5% weight loss temperature (T₅) of the cured resin increased with increasing BMI feed content, and cLB24 showed the highest T_g (343°C) and T₅ (389°C). The flexural strengths (131–150 MPa) and moduli (3.0–3.6 GPa) of the cLBs were comparable to those of the conventionally cured resins of BMI and 4,4′‐diaminodiphenylmethane. Field emission scanning electron microscopy analysis revealed that there was no phase separation for all of the cured resins. Although cLB23 and cLB24 were not biodegradable, cLB22 had a biodegradability of 8.5% after 30 days in an aerobic aqueous medium containing activated sludge. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40379.     

Silicon-containing fluorenylacetylene resins with low curing temperature and high thermal stability

Silicon-containing arylacetylene resins (PSAs) are promising thermal stability polymers for many applications. However, the controllability of curing reaction limited their application because of the high curing temperature and enthalpy. In this study, Materials Genome Initiative was utilized to screen out a target monomer, 2,7-diethynyl-9H-fluorene (DEF), for design of new PSAs with low curing temperature and enthalpy. After incorporation of DEF, the obtained silicon-containing fluorenylacetylene resins (PSA-VBF) could be cured at a lower temperature of 149.2 °C with lower enthalpy (239.8 J g⁻¹) than the reported PSA-V (190.0 °C, 368.3 J g⁻¹). Moreover, the thermal curing behavior and mechanism were investigated by differential scanning calorimetry, Fourier transform infrared, and pyrolysis-gas chromatography–mass spectrometry. The results revealed that with the increased of DEF, the curing reaction of PSA-VBF became dominated by Diels–Alder reaction. And the formed aromatic fused rings endowed the cured PSA-VBF with excellent thermal stability, which were proved by thermogravimetric analysis results that the temperature at 5% weight loss (T_d5) of the cured copolymers ranged from 630 to 639 °C, and the char yield at 1000 °C was above 90%. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48262.