Bismaleimide modified bis propargyl ether bisphenol A resin: Synthesis,cure, and thermal properties

Bis propargyl ether bisphenol A (PBPA) was synthesized and blended with 4,4′‐bismaleimide diphenyl methane (BDM) at different molar ratios. The cure behavior of the blend resins was measured by DSC and FTIR spectra. The results indicated that the onset cure temperatures of the blend resins were about 20–30°C lower than that of pure PBPA, and the cure exothermic enthalpy of the resins also significantly reduced from 1320 (PBPA) to 493 J/g (PBPA–BDM (1.0:2.0)). The thermal stabilities and dynamic mechanical properties of the cured resins were characterized by TGA and DMA, respectively. The thermal stability of the resins improved markedly with the increase in BDM content, and the glass transition temperature increased from 306°C for PBPA–BDM (1.0:0.5) to 358°C for PBPA–BDM (1.0:2.0). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3610–3615, 2006     

Sequential interpenetrating polymer networks from bisphenol A based cyanate ester and bimaleimide: Properties of the neat resin and composites

Blends of varying composition of a bisphenol A based cyanate ester—viz., 2,2‐bis‐(4‐cyanatophenyl) propane (BACY)—and a bisphenol A based bismaleimide—viz., 2,2‐bis[4‐(4‐maleimido phenoxy) phenyl] propane (BMIP)—were cured together in a sequential manner to derive bismaleimide–triazine network polymers. Enhancing the bismaleimide content was conducive for decreasing the tensile properties and improving both the flexural strength and fracture toughness of the cyanate ester‐rich neat resin blends. Although DMA analyses of the cured blend indicated a homogeneous network for the cyanate ester dominated compositions, microphase separation occurred on enriching the blend with the bismaleimide. Addition of bismaleimide did not result in any enhancement in T_g of the blend. Interlinking of the two networks and enhancing crosslink density through coreaction with 4‐cyanatophenyl maleimide impaired both the mechanical and fracture properties of the interpenetrating polymer network (IPN), although the T_g showed an improvement. Presence of the bismaleimide was conducive for enhancing the mechanical properties of the composites of the cyanate ester rich blend, whereas a higher concentration of it led to poorer mechanical properties due to the formation of a brittle interphase. The IPNs showed reduced moisture absorption and low dielectric constant and dissipation factor, the latter properties being independent of the blend composition. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2737–2746, 1999     

Blends of bisphenol A‐based cyanate ester and bismaleimide: Cure and thermal characteristics

A dicyanate ester, namely, 2,2‐bis‐(4‐cyanatophenyl)propane, and a bismaleimide, namely, 2,2‐bis[4‐(4‐maleimido phenoxy)phenyl]propane, possessing closely resembling backbone structures, were cured together to derive bismaleimide–triazine network polymers of varying compositions. The blend manifested a eutectic melting behavior at a 1 : 1 composition with a eutectic melting point of 15°C. The cure characterization of the blends was done by DSC and dynamic mechanical analyses (DMA). The near simultaneous cure of the blend could be transformed to a clear sequential one by catalyzing the dicyanate cure to lower temperature using dibutyl tin dilaurate. The two‐stage, independent cure of the components of the blend evidenced in DSC was confirmed by DMA. The cure profile of the bismaleimide component predicted from the kinetic data derived from nonisothermal DSC was found to be in league with the isothermal DMA behavior. Both techniques led to optimization of the cure schedule of the blends. The cured polymers were characterized by FTIR and TGA. The cured blends underwent decomposition in two stages, each corresponding to the polycyanurate and polybismaleimide. Enhancing the bismaleimide component did not alter the initial decomposition temperature, but led to reduced rate of thermal degradation at higher temperature. Interlinking of the two networks and enhancing crosslink density through coreaction of the blend with 4‐cyantophenylmaleimide unaffected the initial decomposition properties but was conducive for increasing the char residue significantly. Computation of activation parameters for the thermal decomposition of the polymers confirmed that the first step in the degradation of the blends is caused by the polycyanurate component. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3365–3375, 1999     

Blended resins based on a new propargyl‐functional resin: Synthesis,cure, and thermal properties

A new propargyl‐functional resin, propargyl ether bisphenol A novolac (PBPN), was synthesized, and the structure of PBPN were characterized using ¹H NMR and FTIR spectra. The PBPN was blended with 4,4′‐bismaleimide diphenyl methane (BDM) at different molar ratio to obtain the blends. Differential scanning calorimetry (DSC) was used to characterize the cure behavior of PBPN and the blends. Thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) were performed, respectively, to evaluate thermal stability and dynamic mechanical properties of the cured resins. The results indicate that the PBPN presented better cure and thermal properties than do traditional propargyl resins; furthermore, the cure behavior and thermal properties of PBPN could be improved remarkably by blending with BDM. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4207–4212, 2006     

Diallyl bisphenol A—novolac epoxy system cocured with bisphenol‐A‐bismaleimide—cure and thermal properties

Novolac epoxy (EPN)—2,2′‐diallyl bisphenol A (DABA) resin system was modified by cocuring it with bisphenol A bismaleimide (BMI). Molar concentration of BMI in the stochiometric blend of EPN and DABA was varied from 0.5 to 2.0. The cure optimization was done using DSC, IR spectroscopy, and rheological studies. The curing proceeded by phenol‐epoxy and Alder‐ene reactions. The performance of the ternary Epoxy‐Allyl phenolic‐Bismaleimide system was evaluated through their thermal and dynamic mechanical characterization. BMI improved the overall thermal stability and the modulus of the resultant composites. The increase in BMI concentration in the system resulted in enhanced glass transition temperature with a consequent improvement in high temperature performance typically estimated by their lap shear strength at high temperatures. The high temperature performance of the epoxy‐phenol‐bismaleimide (EPB) system was found to be far superior to the epoxy‐phenol (EP)system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Rapid monitoring of bisphenol‒A diglycidyl ether formation through byproduct estimation: A study by Fourier transform infra‐red spectroscopy

For identification and quantification of desired and undesired products during epoxy resin formation, polymerization of bisphenol‐A with the stoichiometric excess of epichlorohydrin is carried out using catalytic excess of alkali. The reaction is monitored using Fourier transform infra‐red (FT‐IR) spectroscopy technique. Major undesired products are unreacted monomers (bisphenol‐A and epichlorohydrin) and byproducts (chlorine and α‐glycol substituted diglycidal ether of bisphenol‐A), whereas the desired product is only diglycidal ether of bisphenol‐A. Molar concentrations of epichlorohydrin, bisphenol‐A, diglycidal ether of bisphenol‐A, chlorine substituted resin, and α‐glycol substituted resin in the polymerization mixture are analyzed and quantified using FT‐IR characteristic frequency bands at 925, 3448, 1344, 773, and 3641 cm^?1, respectively. For optimal determination of process parameters on polymerization, effect of temperature and alkali loading on epoxy polymerization is carried to maximize the yield of diglycidal ether of bisphenol‐A with simultaneous minimizing the byproducts formation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Bismaleimide resin modified with diallyl bisphenol A and diallyl p‐phenyl diamine for resin transfer molding

O,O′‐diallyl bisphenol A (DBA) and N,N′‐diallyl p‐phenyl diamine (DPD) were used for the reactive diluents of 4,4′‐bismaleimidodiphenol methane (BDM). The objective was to obtain a modified BDM resin system suitable for resin transfer molding (RTM) process to prepare the advanced composites. The processing behavior was determined by time–temperature–viscosity curves, gel characteristics, and differential scanning calorimetry (DSC). The injection temperature of the resin system in RTM could be 80°C, at which its apparent viscosity was only 0.31 Pa/s, and the apparent viscosity was still less than 1.00 Pa/s after the resin was held at 80°C for 16 h. The gel time test result indicated that at low temperatures, the reactivity of the resin system is low, whereas at high temperatures, the resin could cure very fast, which was beneficial to RTM. The postcure of the cured resin at a given temperature was necessary because the resin had a wide and flat cure exothermic peak, observed by DSC curve. The cured resin displayed both high heat and hot/wet resistance and high mechanical properties, especially tensile strength, tensile modulus, and flexural strength at room temperature, which reached 96.2 MPa, 4.8 GPa, and 121.4 MPa, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2245–2250, 2001     

Synthesis and characterization of tetrakis‐ derivatives of bisphenol‐A with 4‐phenylazoaniline and 5‐(4‐aminophenylazo)‐25,26,27‐tribenzoyloxy‐ 28‐hydroxycalix[4]arene

The synthesis of tetrakis‐ derivatives of bisphenol‐A containing azo groups at their 2,2′,6,6′‐positions is reported. Novel examples of bisphenol‐A, coupled with diazonium salts and derived from 4‐phenylazoaniline and 5‐(4‐aminophenylazo)‐25,26,27‐tribenzoyloxy‐28‐hydroxycalix [4]arene, have been synthesized. It has been observed that the coupling reaction of diazonium salt obtained from 4‐phenylazoaniline with bisphenol‐A gives tetrakis‐ while those derived from 5‐(4‐aminophenylazo)‐25,26,27‐tribenzoyloxy‐28‐hydroxycalix [4]arene give partially substituted bisphenol‐A analogues. The newly prepared tetrakis‐azo substituted bisphenol‐A compounds ( 1 and 2 ) are characterized by using UV‐vis, FT‐IR, ¹H‐NMR spectroscopic methods as well as elemental analysis techniques. These azo compounds give rise to bathochromic shifts in the absorption spectra, which can even be detected by “naked eye.” © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal properties of new bismaleimide resins containing hydrogen silsesquioxane and diallyl bisphenol A

Bismaleimide (BMI) resins modified with hydrogen silsesquioxane (HSQ) and diallyl bisphenol A (DABPA) (BMI‐HSQ‐DABPA resins) were prepared. DSC, FTIR, and TGA were used to characterize the curing behaviors, structures, and thermal properties of the BMI‐HSQ‐DABPA resins, respectively. The results showed that the glass transition temperatures and thermal stabilities of the cured BMI‐HSQ‐DABPA resins increased with the rise of the contents of HSQ. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

In situ FT‐IR and DSC investigation on the cure reaction of the dicyanate/diepoxide/diamine system

Cure reactions of a liquid aromatic dicyanate ester (1,1′‐bis(4‐cyanatophenyl)ethane, BEDCy) with a liquid bisphenol A epoxide (2,2‐bis(4‐glycidyloxyphenyl)propane, BADGE) and 4,4′‐diaminodiphenyl sulfone (DDS) were studied through correlation of the in situ FT‐IR spectroscopy and DSC in dynamic scanning mode. Before this system was examined, cure reactions of precursory systems of BADGE/DDS, BEDCy/BADGE and BEDCy/DDS were investigated separately. Cure reaction paths for each system are proposed. Some reactions in the precursory systems, such as polycyclotrimerization of dicyanate to form sym‐triazine and formation of alkyl isocyanurate, were not observed in the combined curing system BEDCy/BADGE/DDS. Four principal reaction paths are proposed for this curing system: (1) formation of oxazoline from the reaction between the epoxide and cyanate group; (2) reaction of epoxide with primary amine to form a hydroxyl group; (3) reaction of epoxide with the hydroxyl group to form an ether linkage; and (4) rearrangement of oxazoline to form oxazolidinone. Two distinct, but somewhat overlapping, exothermic peaks were observed on the DSC thermogram. The lower temperature peak on the DSC thermogram was primarily contributed by the first reaction path, whereas the higher temperature peak can mainly be attributed to the reaction paths 2, 3 and 4. © 2001 Society of Chemical Industry     

Bisphenol A dicyanate–novolac epoxy blend: Cure characteristics,physical and mechanical properties,and application in composites

Reactive blends of bisphenol A dicyanate (BACY) and a novolac epoxy resin (EPN) were investigated for their cure behavior and the mechanical, thermal, and physical properties of the cocured neat resin and glass‐laminate composites. Contrary to the apparent observation in DSC, the dynamic mechanical analysis confirmed a multistep cure reaction of the blend, in league with an established reaction path for similar systems. The cured matrix was found to contain both polycyanurate and oxazolidinone networks that existed in discrete phases exhibiting independent glass transitions in dynamic mechanical analysis (DMA). The flexible and less crosslinked oxazolidinone network contributed to enhanced flexural strength at the cost of the tensile strength of the neat resin. The increased resin flexibility was, however, not translated to the glass‐laminate composite for which the flexural strength decreased with the oxazolidinone content, although the latter was conducive for rendering a stronger interphase. The presence of oxazolidinone adversely affected the thermal stability of the cured resin and the high‐temperature performance of both neat resin and the composites. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1675–1685, 1999     

Transesterifications of poly(bisphenol A carbonate) with aromatic and aliphatic segments in ethylene terephthalate–caprolactone copolyester

In this article, transesterification of poly(bisphenol A carbonate) (PC) with a ethylene terephthalate–caprolactone copolyester at a weight ratio 50/50 (TCL50) was investigated by infrared spectroscopy (IR), proton nuclear magnetic resonance spectroscopy (¹H‐NMR), and a model compound. The IR and ¹H‐NMR results showed that transesterification occurred between PC and ethylene terephthalate (ET) segments in TCL50 and resulted in the formation of bisphenol A–terephthalate ester units as in the annealed blend of PC with the PET homopolyester. By comparison with a model compound, the new signal at 2.55 ppm in the ¹H‐NMR spectrum confirmed the appearance of bisphenol A–caprolactone ester units resulting from the exchange reaction of PC with caprolactone (CL) segments. The ¹H‐NMR analysis of the transesterification rates revealed that the reactions of PC with aromatic and aliphatic segments in TCL50 proceeded in a random or free manner. In addition, we separately examined the interchange reaction between a PC and poly(ε‐caprolactone) (PCL) homopolyester in an annealed blend. It was found that in the presence of a Ti compound catalyst the predominant reaction was a transesterification rather than a thermooxidative branching reaction. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1558–1565, 2001     

Synthesis and epoxy curing of Mannich bases derived from bisphenol A and poly(oxyalkylene)diamine

A family of Mannich bases were prepared from the reaction of 2,2‐bis‐(4‐hydroxyphenyl)propane (bisphenol A or BPA), formaldehyde, and poly(oxyalkylene)diamines at 1 : 1 : 1 or 1 : 2 : 2 molar ratio. By varying the molar ratio of bisphenol A to amine and the chemical structures of poly(oxyalkylene)diamines, a series of products with multiple functionalities of primary/secondary amines, phenols, and poly(oxyalkylene) were prepared. The curing profiles of these products toward the diglycidyl ether of bisphenol A (DGEBA) were examined by a differential scanning calorimeter (DSC). The physical properties of these cured materials were correlated with the chemical structures of the Mannich bases. Compared with the poly(oxyalkylene)diamines, the built‐in phenol moiety in Mannich bases accelerated the curing rate. Both amine and phenol functionalities could be reactive sites toward diglycidyl ethers in a step‐wise fashion under catalytic (triphenylphosphine) and different temperature conditions. Furthermore, the cured polymers demonstrated improved properties including tensile and flexural strength in comparison with those cured by the corresponding poly(oxyalkylene)diamines. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 615–623, 2000     

Curing behaviour of syndiotactic polystyrene–epoxy blends: 1. Kinetics of curing and phase separation process

The modification of the curing behaviour and the phase separation process for an epoxy resin blended with a crystalline thermoplastic was investigated in the case of the diglycidylether of bisphenol‐A (DGEBA)/4,4′‐methylene bis(3‐chloro‐2,6‐diethylaniline) (MCDEA) blended with syndiotactic polystyrene (sPS) and cured at 220 °C. Phase separation taking place during curing of the blend was investigated by differential scanning calorimetry (DSC) and optical microscopy in order to get a better understanding of the complex interactions between cure kinetics of epoxy matrix and crystallisation of sPS, both influenced by blend composition. Results suggested that phase separation and crystallisation of sPS occurred at almost similar times, with phase separation just being ahead of crystallisation. DSC and near‐infrared measurements were used for the determination of the cure kinetics. Slow delays on the cure reactions were observed during the first minutes for the sPS‐containing blends compared with the neat DGEBA/MCDEA system but, after some time, the reaction rate became faster for the blends than for the neat matrix. Phase separation occurring in the mixtures may explain this particular phenomenon. Copyright © 2004 Society of Chemical Industry     

Transformation products of bisphenol A by a recombinant Trametes villosa laccase and their estrogenic activity

A Trametes villosa laccase, produced as a recombinant protein in Aspergillus oryzae, was purified to an electrophoretically homogeneous state and employed in studies on the metabolism of bisphenol A. Structural analysis of the bisphenol A reaction products by the enzyme indicated that the dimer, trimer, tetramer, pentamer, and hexamer of bisphenol A with C? C and/or C? O bonds between phenol moieties, were formed as the result of successive oxidative‐condensation. The reaction mixture also contained oligomers fragments, each with phenol molecules, suggesting the occurrence of cleavage of the formed oligomers to release 4‐isopropenylphenol. A luciferase reporter assay using COS‐7 cells revealed that both the soluble and insoluble fractions of the bisphenol A reaction products had no estrogenic activity even at rather high concentrations. Copyright © 2004 Society of Chemical Industry     

Studies on new type of phenolic resin (IX) curing reaction of bisphenol A‐based benzoxazine with bisoxazoline and the properties of the cured resin. II. Cure reactivity of benzoxazine

Bisphenol A‐based benzoxazine that contained oligomers (oligo‐Ba) was prepared from bisphenol A, formaline, and aniline. Curing reaction of oligo‐Ba with bisoxazoline and the properties of the cured resin were investigated. Consequently, the ring‐opening reaction of benzoxazine ring occurred, and then the phenolic hydoroxyl group generated by the ring‐opening reaction of benzoxazine ring reacted with oxazoline ring. It was found that the cure induction time and cure time of the molten mixture from oligo‐Ba and bisoxazoline could be reduced and also the cure temperature could be lowered, compared with those from bisphenol A‐based benzoxazine, which contained no oligomers (Ba), and bisoxazoline. The melt viscosity of the molten mixture from oligo‐Ba and bisoxazoline was kept 0.1–10 [Pas] at 140°C even after 40 min, the molten mixture from oligo‐Ba and bisoxazoline showed good flowability below 140°C as well as that from Ba and bisoxazoline. However, above 160°C the curing reaction of oligo‐Ba with bisoxazoline proceeded more rapidly than that of Ba with bisoxazoline. The cured resin from oligo‐Ba and bisoxazoline showed good heat resistance and water resistance, compared with the cured resin from Ba and bisoxazoline. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2331–2339, 2001     

Synthesis and properties of a novel bismaleimide resin containing 1,3,4‐oxadiazole moiety and the blend systems thereof with epoxy resin

A new bismaleimide monomer, 2‐((4‐maleimidophenoxy)methyl)‐5‐(4‐maleimidophenyl)‐1,3,4‐oxadiazole (Mioxd), was designed and synthesized. The chemical structure of the monomer was confirmed by means of Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (¹H NMR) spectroscopy and elemental analysis, and its thermal properties were characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Mioxd as a reactive modifier was blended with epoxy resin based on bisphenol A diglycidyl ether (DGEBA) in weight ratio of 5, 10, and 15%, using 4,4′‐diaminodiphenyl sulfone (DDS) as hardener. The effect of Mioxd addition on the cure behavior and thermal properties of the blend resins was studied by DSC, TGA, and dynamic mechanical analysis (DMA). DSC investigations showed that the main exothermic peak temperature (T_p) of the blend systems did not obviously shift with increasing Mioxd content whereas a new shoulder appeared and gradually grew on the high temperature side of the exothermic peak. The results of DMA measurements exhibited the glassy storage modulus (G') and glass transition temperatures (T_g) increased as the Mioxd content was increased, the cured blends investigated were miscible and no phase separation occurred. Further, the thermal decomposition temperature first decreased and then increased, but the char yield at 600°C increased with an increase in Mioxd content. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Hydrogen‐bonding interaction between poly(ε‐caprolactone) and low‐molecular‐weight amino compounds

The specific interactions between several low‐molecular‐weight diamino compounds and poly(ε‐caprolactone) (PCL) have been investigated by FT‐IR. It was found that PCL and 3,3′‐diaminodiphenylmethane (3,3′‐DADPM) interact through strong intermolecular hydrogen bonds in the blend. Thermal and mechanical properties of PCL/3,3′‐DADPM blends were investigated by DSC and tensile measurements, respectively. The glass transition temperature of the blend increases while both the melting point and the elongation‐at‐break of the blend decrease with the increase of 3,3′‐DADPM content. Besides 3,3′‐DADPM, several other low‐molecular‐weight compounds containing two amino groups, such as o‐phenylenediamine or 1,6‐diaminohexane, were also added into PCL and the corresponding blend systems were investigated by FT‐IR and DSC. The effect of the chemical structure of the additives on the properties of PCL is discussed. © 2001 Society of Chemical Industry     

Thermal and dielectric properties of bismaleimide‐triazine resins containing octa(maleimidophenyl)silsesquioxane

Octa(maleimidophenyl)silsesquioxane (OMPS) was synthesized, characterized, and employed to modify the BT resin which composed of 4,4′‐bismaleimidodiphenylmethane (BMI) and 2,2′‐bis(4‐cyanatophenyl)propane (BCE). The curing reaction between OMPS and BT resin was first investigated. It was found that OMPS accelerate the curing reaction of BCE, and the onset temperature of the cyclotrimerization was reduced up to 95.5°C (by DSC). As demonstrated by DSC and FTIR, there was no evidence that indicated the coreaction between maleimide and cyanate ester. 2,2′‐diallyl bisphenol A (DBA) and diglycidyl ether of bisphenol A (E‐51) (Wuxi Resin Factory, Jiangsu Province, China) were also used to enhance the toughness of BT resin, and the formulated BTA (containing DBA) and BTE (containing E‐51) resins were obtained. The thermal properties of BT, BTA, and BTE resins incorporated with OMPS were then investigated. The results of DMA and TG showed that the BT, BTA, and BTE resins containing 1 wt % of OMPS exhibit enhanced thermal properties in comparison with their pristine resins respectively, while more contents of OMPS may impair the thermal properties of the polymer matrix, though the effect of OMPS was slight. Finally, the dielectric constant of these hybrid materials were detected, and their dielectric constant were distinctly reduced by the incorporation of OMPS, while overmuch contents of OMPS were disadvantageous for dielectric constant because of the aggregation of OMPS. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Epoxy resin cured by bisphenol A based benzoxazine

Bisphenol A based benzoxazine was prepared from bisphenol A, formaline, and aniline. This benzoxazine was used as a hardener of the epoxy resin. Curing behavior of the epoxy resin and the properties of the cured resin were investigated. Consequently, curing reaction proceeded without a curing accelerator. The molding compound showed good thermal stability under 150°C, which corresponded to the temperature in the cylinder of injection molding. Above 150°C, the curing reaction proceeded rapidly. The cured epoxy resin showed good heat resistance, water resistance, electrical insulation, and mechanical properties compared with the epoxy resin cured by the bisphenol A type novolac. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1903–1910, 1998