Preparation and thermal properties of bismaleimide blends based on hydroxyphenyl maleimide

N‐(4‐hydroxyphenyl)maleimide was melt‐blended with the glycidyl ether of bisphenol‐A and various mole percentages of 4, 4′‐(diaminodiphenylsulfone) bismaleimide. The cure behaviour of the resins was evaluated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The blends showed distinct reductions in the onset of cure (T_o) and peak exothermic (T_exo) temperatures. The blends cured at low temperatures exhibited glass transition temperatures (T_gs) higher than the cure temperatures. The cured blends showed high moduli, glass transition temperatures in excess of 250 °C and good thermal stabilities up to 400 °C. Copyright © 2005 Society of Chemical Industry     

Phosphonate‐containing bismaleimide resins. II. Preparation and characteristics of reactive blends of phosphonate‐containing bismaleimide and epoxy

Two kinds of phosphonate‐containing bismaleimide (BMI) monomers, phenyl‐(4,4′‐bismaleimidophenyl) phosphonate and ethyl‐(4,4′‐bismaleimido‐phenyl) phosphonate, were synthesized and added through blending to two epoxy systems for the study of their applications as reactive flame retardants. The thermal behaviors of the BMI monomers in both kinds of epoxy systems, bisphenol and phenol–novolac, were similar. An increase in the BMI contents increased the storage modulus and glass‐transition temperature but slightly reduced the mechanical strength of the epoxy blends. The pyrolysis models of both BMI blends in the two epoxy systems were quite alike. Although the initial pyrolysis temperatures of all the blending systems gradually decreased as the phosphorous content increased, the flame retardancy of all the phosphonate‐containing epoxy systems was promoted significantly by increasing contents of BMI. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2375–2386, 2004     

Preparation and properties of high performance phthalide‐containing bismaleimide reinforced polydicyclopentadiene

A series of phenolphthalein‐containing bismaleimide (PPBMI) reinforced polydicyclopentadiene blends (PPBMI/polyDCPD) were prepared via the ring‐opening metathesis polymerization of DCPD in the presence of PPBMI. The crosslinked networks between PPBMI and polyDCPD backbones resulted in the reinforced structures. The curing behavior, thermal, and mechanical properties were investigated. Differential scanning calorimetry investigations showed the samples exhibit similar singular exothermic peak, and the exothermic peak of the PPBMI/polyDCPD blends slightly shifted to a lower temperature direction compared with the unfilled polyDCPD, meanwhile, the exothermic peak of the PPBMI/polyDCPD blends slightly shifts back to a higher temperature direction with the PPBMI content increased. Both dynamic mechanical analysis and thermo gravimetric analysis measurements revealed the optimal thermal performance of PPBMI/polyDCPD was obtained with 20 wt % loading of PPBMI. In addition, while PPBMI content increased, the weight loss peak at 100–200°C disappeared and the temperature of maximum rate of decomposition (T_d,max) increased. Moreover, bending tests showed the best mechanical performance was achieved at 5 wt % loading of PPBMI in blends. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40474.     

Preparation and characterization of siliconized epoxy/bismaleimide (N,N′‐bismaleimido‐4,4′‐diphenyl methane) intercrosslinked matrices for engineering applications

Novel hybrid intercrosslinked networks of hydroxyl‐terminated polydimethylsiloxane‐modified epoxy and bismaleimide matrix systems have been developed. Epoxy systems modified with 5, 10, and 15 wt % of hydroxyl‐terminated polydimethylsiloxane (HTPDMS) were developed by using epoxy resin and hydroxyl‐terminated polydimethylsiloxane with γ‐aminopropyltriethoxysilane (γ‐APS) as compatibilizer and dibutyltindilaurate as catalyst. The reaction between hydroxyl‐terminated polydimethylsiloxane and epoxy resin was confirmed by IR spectral studies. The siliconized epoxy systems were further modified with 5, 10, and 15 wt % of bismaleimide (BMI). The matrices, in the form of castings, were characterized for their mechanical properties. Differential scanning calorimetry and thermogravimetric analysis of the matrix samples were also performed to determine the glass‐transition temperature and thermal‐degradation temperature of the systems. Data obtained from mechanical studies and thermal characterization indicate that the introduction of siloxane into epoxy improves the toughness and thermal stability of epoxy resin with reduction in strength and modulus values. Similarly the incorporation of bismaleimde into epoxy resin improved both tensile strength and thermal behavior of epoxy resin. However, the introduction of siloxane and bismaleimide into epoxy enhances both the mechanical and thermal properties according to their percentage content. Among the siliconized epoxy/bismaleimide intercrosslinked matrices, the epoxy matrix having 5% siloxane and 15% bismaleimide exhibited better mechanical and thermal properties than did matrices having other combinations. The resulting siliconized (5%) epoxy bismaleimide (15%) matrix can be used in the place of unmodified epoxy for the fabrication of aerospace and engineering composite components for better performance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 38–46, 2001     

Fracture properties of epoxy/poly(styrene‐co‐allylalcohol) blends

The epoxy/polystyrene system is characterized by a poor adhesion between the constituent phases, which determines its mechanical properties. The adhesion can be improved via blends based on epoxy resin and random copolymers, poly(styrene‐co‐allylalcohol) (PS‐co‐PA). In this work, the influence of PS‐co‐PA content and the good adhesion between the phases on the tensile properties and the fracture toughness achieved through instrumented Charpy tests have been investigated. The tensile strength and the deformation at break showed an increase in the PS‐co‐PA content while the Young's modulus remained the same. The tensile fracture surfaces revealed that the improvement of these magnitudes was mainly due to a crack deflection mechanism. Also, the fracture toughness of the blends was superior to that of the pure epoxy resin. The main operating toughening mechanism was crack deflection. The fractographic analysis showed that ～ 80% of the particles were broken, and the crack tended to divert from its original path through the broken PS‐co‐PA particles. The remaining particles were detached from the epoxy resin, and the holes left suffered plastic deformation. Analytical models were used to predict successfully the toughness due to these mechanisms. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis of a bifunctional epoxy monomer containing biphenyl moiety and properties of its cured polymer with phenol novolac

A new type of epoxy resin containing a 4,4′‐biphenylene moiety in the backbone (Bis‐EBP) is synthesized and confirmed by elemental analysis, infrared spectroscopy, and ¹H‐nuclear magnetic resonance spectroscopy. In addition, to evaluate the influence of the 4,4′‐biphenylene group in the structure, an epoxy resin having a 1,4‐phenylene group in place of the 4,4′‐biphenylene moiety (Bis‐EP) is synthesized. The cured polymer obtained through the curing reaction between the new biphenyl‐containing epoxy resin and phenol novolac is used for making a comparison of its thermal and physical properties with those obtained from Bis‐EP and bisphenol‐A (4,4′‐isopropylidenediphenyl)‐type epoxy resin (Bis‐EA). The cured polymer obtained from Bis‐EBP shows markedly higher fracture toughness of 1.32 MPa m^1/2, higher glass transition temperature, lower moisture absorption, and higher thermal decomposition temperature. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 690–698, 1999     

Synthesis and properties of novel phosphorus‐containing bismaleimide/epoxy resins

A novel soluble phosphorus‐containing bismaleimide (BMI) monomer, bis(3‐maleimidophenyl)phenylphosphine oxide (BMIPO), was synthesized by the imidization of bis(3‐aminophenyl) phenylphosphine oxide, in which its structural characterization was identified with ¹H‐NMR, ¹³C‐NMR, and Fourier transform infrared spectra. The BMIPO resin, with five‐membered imide rings and high phenyl density, was an excellent flame retardant with a high glass‐transition temperature (T_g), onset decomposition temperature, and limited oxygen index. In phosphorus‐containing BMI/epoxy/4,4′‐methylene dianiline (DDM)‐cured resins, homogeneous products were obtained from all proportions without phase separation. Because of the higher reactivity of BMIPO/DDM relative to that of 4,4′‐bismaleimidodiphenylmethane (BMIM)/DDM, the increase in the BMIPO/BMIM ratio in this blending resin increased the recrosslinking hazards of the postcuring stage and so lowered the T_g value and thermal stability. The thermal stability of the BMI/epoxy‐cured system was lower than that of the epoxy‐cured system because of the introduction of a phosphide group into BMIPO, whereas for the T_g value and flame retardancy, the former was significantly higher than the latter: the higher the BMIPO content in the blend, the higher the flame retardancy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2080–2089, 2002; DOI 10.1002/app.10607     

Mechanical properties of poly(styrene‐co‐acrylonitrile)‐modified epoxy resin/glass fiber composites

Poly(styrene‐co‐acylonitrile) was used to modify diglycedyl ether of bisphenol‐A type epoxy resin cured with diamino diphenyl sulfone and the modified epoxy resin was used as the matrix for fiber‐reinforced composites (FRPs) to get improved mechanical properties. E‐glass fiber was used as fiber reinforcement. The tensile, flexural, and impact properties of the blends and composites were investigated. The blends exhibited considerable improvement in mechanical properties. The scanning electron micrographs of the fractured surfaces of the blends and tensile fractured surfaces of the composites were also analyzed. The micrographs showed the influence of morphology on the properties of blends. Results showed that the mechanical properties of glass FRPs increased gradually upon fiber loading. Predictive models were applied using various equations to compare the mechanical data obtained theoretically and experimentally. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

新型双马来酰亚胺改性环氧树脂体系性能研究

用含二氮杂萘联苯结构的双马来酰亚胺(DHPZ-BM I)与4,4'-二氨基二苯砜(DDS)为复合固化剂固化环氧树脂(E-51)。采用示差扫描量热仪(DSC)研究了该体系的固化反应动力学,求得固化反应表观活化能Ea=63.28 kJ/mol,碰撞因子A=1.55×106s-1,反应级数n=0.89,该体系与链延长型双马来酰亚胺PPEK-BM I(DP=15)/DDS/E-51体系的固化反应动力学数据几乎相同,证明二者的固化反应过程相同。采用热失重分析仪(TGA)分析研究了上述2种固化体系的热分解动力学,前者的热分解活化能达215.04 kJ/mol,为后者的1.5倍以上,说明DHPZ-BM I/DDS/E-51是1种热稳定性能良好的耐高温环氧树脂体系。     

Preparation and properties of modified bismaleimide resins based on phthalide‐containing monomer

A series of bismaleimide resins based on phthalide‐containing monomer have been prepared by the copolymerization reaction of 3,3‐bis[4‐(4‐maleimidophenoxy)phenyl] ‐phthalide (PPBMI), 4, 4'‐dimaleimido diphenylmethane (MBMI) and 2, 2'‐diallyl bisphenol A (DABPA) in different feed ratios. The curing behavior, thermal, mechanical and physical properties and compatibility of all resultant resins were carefully characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), notched Izod impact test, water absorption test and scanning electron microscopy (SEM). DSC investigations showed that with an increase of the weight ratio of PPBMI, the dominating exothermic polymerization temperature (T_p) increased. The glass transitions were observed from DMA thermograms for the cured BMI resins in the temperature range from 277°C to 311°C and decreased with increasing PPBMI content. The TGA results indicated the thermal stability was improved as PPBMI content increased. The investigations of the mechanical properties showed a complicated trend with an increase in PPBMI content. In addition, the equilibrium water uptake of the modified resins was reduced as PPBMI content increased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1084‐1091, 2013     

Bulk properties of epoxy resin modified by epoxy–aminosilane copolymers

A linear epoxy–aminopropyltriethoxysilane addition polymer was used as a new epoxy modifier. In this paper, the thermal and mechanical properties have been determined by differential scanning calorimetry (DSC) and mechanical testing. The experimental results show that this copolymer modifier can effectively improve the toughness of resins without sacrificing their thermal resistance, stiffness and strength. As a comparison, the properties of epoxy resin blended with aminopropyltriethoxysilane (γ-APS) have been carried out simultaneously. © 1999 Society of Chemical Industry     

Synthesis and properties of chain‐extended bismaleimide resins containing phthalide cardo structure

Three novel bismaleimide (BMI) monomers containing phthalide groups in their structures, i.e. 3,3‐bis[4‐(4‐maleimidophenoxy)phenyl]phthalide, 3,3‐bis[4‐(4‐maleimidophenoxy)‐3‐methylphenyl]phthalide and 3,3‐bis[5‐isopropyl‐4‐(4‐maleimidophenoxy)‐2‐methylphenyl]phthalide, based on phenolphthalein, o‐cresolphthalein and thymolphthalein, respectively, were designed and synthesized. The chemical structures of the monomers were confirmed from ¹H NMR and ¹³C NMR spectroscopy and Fourier transform infrared spectroscopy. These monomers exhibit good solubility in common organic solvents, enabling easy solution processing. The thermal curing behavior of the monomers was investigated using differential scanning calorimetry, displaying broad exothermic peaks and large thermal processing windows. Thermogravimetric analysis and dynamic mechanical analysis were used to characterize the thermal stability and thermal mechanical properties of the resulting BMI resins. The results, in contrast to bisphenol A‐based BMI resin, indicate that the incorporation of the phthalide structure into the polybismaleimide network can effectively improve the thermal properties. Water absorption tests of the cured products demonstrate the chemical structure has an effect on moisture resistance. Copyright © 2010 Society of Chemical Industry     

Studies on mechanical,thermal, and morphology of diglycidylether‐terminated polydimethylsiloxane‐modified epoxy–bismaleimide matrices

An epoxy matrix system modified by diglycidylether‐terminated polydimethylsiloxane (DGETPDMS) and bismaleimide (BMI) was developed. Epoxy systems modified with 4, 8, and 12% (by wt) of DGETPDMS were made using epoxy resin and DGETPDMS, with diaminodiphenylmethane as the curing agent. The DGETPDMS‐toughened epoxy systems were further modified with 4, 8, and 12% (by wt) of BMI, namely (N,N′‐bismaleimido‐4,4′‐diphenylmethane). DGETPDMS/BMI/epoxy matrices were characterized using differential scanning calorimetry, thermogravimetric analysis, and heat deflection temperature analysis. The matrices, in the form of castings, were characterized for their mechanical properties, viz. tensile strength, flexural strength, and impact test, as per ASTM methods. Mechanical studies indicate that the introduction of DGETPDMS into epoxy resin improves the impact strength, with reduction in tensile strength, flexural strength, and glass transition temperature, whereas the incorporation of BMI into epoxy resin enhances the mechanical and thermal properties according to its percentage content. However, the introduction of both DGETPDMS and BMI enhances the values of thermomechanical properties according to their percentage content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 668–674, 2006     

有机硅改性双酚F环氧树脂热性能研究

以TMA和TGA研究了含酚羟基的有机烷氧基硅烷及3,3′,3″-三羟基苯氧基硅烷三缩水甘油醚等多种自行设计、合成的有机硅改性剂改性双酚F环氧树脂的热性能。研究结果表明,有机硅可降低改性树脂的线胀系数,但端环氧基脂肪族聚硅氧烷及含酚羟基的二官能度有机硅的加入均使固化物玻璃化温度降低10℃以上;含环氧基的多官能度有机硅改性剂3,3′,3″-三羟基苯氧基硅烷三缩水甘油醚的加入可使线胀系数降低约20%,内应力指数降低约20%,抗开裂指数提高50%以上,固化物玻璃化温度基本不变,热分解温度有较大幅度的提高,是一种理想的环氧树脂增韧改性剂,可用于电子封装等行业用环氧树脂的改性。     

Mechanical and morphological properties of epoxy resins modified by poly(phthalazinone ether sulfone ketone)

A series of blends have been prepared by adding a novel thermoplastic poly(phthalazinone ether sulfone ketone) (PPESK) in varying proportions to diglycidyl ether of bisphenol A epoxy resin (DGEBA) cured with p‐diaminodiphenylsulfone (DDS). All the blends showed two‐phase structures characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Addition of the PPESK resulted in great enhancement of glass transition temperatures (T_g) both in the epoxy‐rich phase and in the PPESK‐rich phase by reason of the special structure of PPESK. There was moderate increase in the fracture toughness as estimated by impact strength. Fracture mechanisms such as crack deflection and branches, ductile microcracks, ductile tearing of the thermoplastic, and local plastic deformation of the matrix were responsible for the increase in the fracture toughness of the blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

耐热200℃双马改性环氧结构胶膜的研究

研制了一种双马改性环氧结构胶膜,探讨了主要组份对胶粘剂胶接性能的影响,考核了胶粘剂的耐热、耐老化等综合性能。该胶不但对金属之间具有良好的粘接强度,而且对双马树脂基复合材料具有良好的粘接性能。用扫描电镜(SEM)观测固化产物断裂面的微观形态为均相增韧结构;通过示差扫描量热法(DSC)测定该胶的热变形温度为211℃,用热重分析法(TG)测定该胶固化物明显热失重温度为378℃。热力学分析试验表明该胶可以在200℃下长期工作,提高了国内环氧类型膜状胶粘剂的耐温等级。     

Thermal and mechanical properties of epoxidized natural rubber modified epoxy matrices

Two sets (A and B) of bisphenol A–diglycidyl ether (DGEBA) based epoxy resin formulations were modified with epoxidized natural rubber (ENR 50) and its liquid version (LENR 50), and cured with amino propoxylate initiator/accelerator at ambient temperatures. The ENR 50 loading range was 1.6–5.9 wt%. Both sets could be loaded up to 12 wt% with LENR 50. Significant improvements in tensile toughness and impact toughness could only be observed for set A formulations. At the maximum LENR 50 loading achieved, the improvement in tensile toughness is 250% in comparison with that of the neat formulation; that for impact toughness is 125%. Differential scanning calorimetry reveals multiple transitions, characteristic of these systems. Scanning electron micrographs of fractured surfaces show uniform rubber dispersions in the submicrometre size range. At the loading levels used, LENR 50 particle dispersions fall within the range of 0.33–0.47 µm in size; those of ENR 50 are 0.48–0.67 µm in average size. Improvements in toughness are similar for both versions of epoxidized natural rubber. For both LENR 50 and ENR 50 modified epoxy systems, the extremes of 0.80 (set A) and 1.95 (set B) in glycidyl ether/reactive hydrogen molar ratios considered show distinct failure mechanisms, that of ductile failure with yielding in the former and brittle failure in the latter, irrespective of reactive diluent content. © 1999 Society of Chemical Industry     

Nanostructures and thermomechanical properties of epoxy thermosets containing reactive diblock copolymer

Polystyrene‐block‐poly(glycidyl methacrylate) reactive diblock copolymer (PS‐b‐PGMA) was synthesized via atom transfer radical polymerization (ATRP). The diblock copolymer was characterized using nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The cured epoxy thermosets with 10–20 nm PS particles were prepared by blending the diblock copolymer with epoxy resin. The nanostructures were examined by means of transmission electronic microscopy (TEM) and small angle X‐ray scattering (SAXS). The formation of the nanostructures was caused by the reaction‐induced microphase separation mechanism. It is significant that the glass transition temperatures (T_gs) of these epoxy thermosets were increased by the addition of PS‐b‐PGMA reactive block copolymer as revealed by both differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of halogen‐free flame‐retarded phthalonitrile–epoxy blends

Halogen‐free flame‐retarded blends composed of 2,2‐bis[4‐(3,4‐dicyanophenoxy) phenyl] propane (BAPh) and epoxy resin E‐44 (EP) were successfully prepared with 4,4′‐diaminodiphenyl sulfone as a curing additive. The structure of the copolymers was characterized by Fourier transform infrared spectroscopy, which showed that epoxy groups, a phthalocyanine ring, and a triazine ring existed. The limiting oxygen index values were over 30, and the UL‐94 rating reached V‐0 for the 20 : 80 (w/w) BAPh/EP copolymers. Differential scanning calorimetry and dynamic rheological analysis were employed to study the curing reaction behaviors of the phthalonitrile/epoxy blends. Also, the gelation time was shortened to 3 min when the prepolymerization temperature was 190°C. Thermogravimetric analysis showed that the thermal decomposition of the phthalonitrile/epoxy copolymers significantly improved with increasing BAPh content. The flexible strength of the 20:80 copolymers reached 149.5 MPa, which enhanced by 40 MPa compared to pure EP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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