Heterocyclic‐based epoxy‐terminated structural adhesive. II. Curing,adhesive strength,and thermal stability

We studied the curing behavior of heterocyclic‐based epoxy‐terminated resins using diaminodiphenyl ether, diaminodiphenyl sulfone, benzophenone tetracarboxylicdianhydride, and the commercial hardener of Ciba‐Geigy's two‐pack Araldite as curing agents. The adhesive strength of the adhesives was measured by various ASTM methods such as lap‐shear, peel, and cohesive tests on metal–metal, wood–wood, and wood–metal interfaces. All of these results were compared with those of an epoxy resin prepared from bisphenol‐A and epichlorohydrin resin with an epoxy equivalent value of 0.519. The thermal stability of both the virgin resin and its cured form was also studied by thermogravimetric analysis. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3520–3526, 2002     

Syntheses of epoxy‐bridged polyorganosiloxanes and the effects of terminated alkoxysilanes on cured thermal properties

A series of epoxy‐bridged polyorganosiloxanes have been synthesized by reacting multifunctional aminoalkoxysilanes with diglycidyl ether of bisphenol A (DGEBA) epoxy resin. The reactions of trifunctional 3‐aminopropyltriethoxysilane (APTES), difunctional 3‐aminopropylmethyldiethoxysilane (APMDS), and monofunctional 3‐aminopropyldimethylethoxysilane (APDES) with DGEBA epoxy have been monitored and characterized by FTIR, ¹H NMR, and ²⁹Si NMR spectra in this study. The synthesized epoxy‐bridged polyorganosiloxanes precursors, with different terminated alkoxysilane groups, are thermally cured with or without the addition of curing catalysts. Organometallic dibutyltindilaurate, and alkaline tetrabutylammonium hydroxide have been used as curing catalysts to investigate the thermal curing behaviors and cured properties of epoxy‐bridged polyorganosiloxanes precursors. The maximum exothermal curing temperatures of epoxy‐bridged polyorganosiloxanes precursors are found to appear around the same region of 120°C in DSC analysis. The addition of catalysts to the epoxy/APTES precursor shows significant influence on the cured structure; however, the catalysts exhibit less influence on the cured structure of epoxy‐APMDS precursor and epoxy/APDES precursor. Curing catalysts also show significant enhancement in increasing the thermal decomposition temperature (T_d50s) of cured network of trifunctional epoxy‐bridged polyorganosiloxane (epoxy/APTES). High T_d50s of 518.8 and 613.6 in the cured hybrids of epoxy/APTES and epoxy/APMDS precursors are also observed, respectively. When trialkoxysilane‐terminated epoxy‐bridged polyorganosiloxanes precursor are cured, with or without the addition of catalyst, no obvious T_g transition can be found in the TMA analysis of cured network. The cured network of trialkoxysilane‐terminated epoxy‐bridged polyorganosiloxanes also exhibits the lowest coefficient of thermal expansion (CTE) among the three kinds of alkoxysilane‐terminated epoxy‐bridged polyorganosiloxanes investigated. The organic–inorganic hybrid, from epoxy‐bridged polyorganosiloxanes after the thermal curing process, shows better thermal stability than the cured resin network of pure epoxy‐diaminopropane. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3491–3499, 2006     

Curing and thermal behavior of diglycidyl ether of bisphenol A in the presence of a mixture of amines

The curing behavior of diglycidyl ether of bisphenol A (DGEBA) was investigated by differential scanning calorimetry with mixtures of silicon‐containing amide–amines and diaminodiphenyl sulfone (DDS). Silicon‐containing amide–amines were prepared by the reaction of 2.5 mol of 4,4′‐diaminodiphenyl ether (E), 4,4′‐diaminodiphenyl methane (M), 3,3′‐diaminodiphenyl sulfone (mS), 4,4′‐diaminodiphenyl sulfone (pS), bis(3‐aminophenyl) methyl phosphine oxide (B), or tris(3‐aminophenyl) phosphine oxide (T) with 1 mol of bis(4‐chlorobenzoyl) dimethyl silane. Mixtures of the amide–amines and DDS at ratios of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25, and 1:0 were used to investigate the curing behavior of DGEBA. A single exotherm was observed on curing with a mixture of amide–amine and DDS. This clearly shows that the mixture participated in the cocuring reaction. The peak exotherm temperature depended on the structure and the molar ratio of amide–amines. With all of the amide–amines and DDS, a significant decrease in the kick‐off temperature of the curing exotherm was observed on the incorporation of a 0.25 molar fraction of amide–amines. Thus, with the mixture, the curing temperatures were reduced and were lowest for ether‐containing amide‐amines and highest for methylene‐containing amide–amines. The char yield was almost similar in the samples cured with amide–amines (E, pS, or mS) or DDS. The char yield was higher than for either of the constituents when a mixture was used. A synergistic behavior was observed when a mixture of E, M, mS, or pS and DDS was used, whereas mixture of B or T and DDS showed antigonism in the char yield. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1739–1747, 2003     

Use of allyl‐functional benzoxazine monomers as replacement for styrene in vinyl ester resins

New vinyl ester systems are prepared using allyl‐functional benzoxazine monomers, 3‐allyl‐6‐methyl‐3,4‐dihydro‐2H‐benzo[e][1,3]oxazine (pC‐ala) or bis(3‐allyl‐3,4‐dihydro‐2H‐benzo[e][1,3]oxazin‐6‐yl)methane (BF‐ala), as reactive diluents for vinyl ester resins derived from an epoxy resin, diglycidyl ether of bisphenol A, instead of using styrene. Different initiators are used to investigate the copolymerization of allyl function from pC‐ala with vinyl function from vinyl ester resin prepolymer. The temperature dependence of viscosity is studied to demonstrate the retention of processability of the new vinyl ester resins. Dynamic mechanical and thermogravimetric analyses are used to investigate the dynamic mechanical properties and thermal stability of the new resins. Copyright © 2012 Society of Chemical Industry     

Vinyl ester resin: Rheological behaviors,curing kinetics,thermomechanical, and tensile properties

The effects of isothermal temperature on the curing extent, gel time, dynamic rheological behaviors, and mechanical properties of vinyl ester resins (VERs) were systematically studied. Although, the curing extent was observed increase with increasing the operating temperature, the study of residual heat of cured VERs indicated that the final curing extent depended on the postcuring process. The values of shear storage and loss modulii at gel point were observed to decrease with increasing both the isothermal temperature and heating rate, which were associated with the formation of microgels during the gelation process. With increasing isothermal temperature and heating rate, the microgel did not have enough time to grow well, causing a reduced shear storage and loss modulii at the gel time. The storage and loss modulii of the cured VERs were also studied and shown that with temperature increased to the glass transition, both modulii were first decreased and then increased. © 2013 American Institute of Chemical Engineers AIChE J, 60: 266–274, 2014     

MFE环氧乙烯基酯树脂固化性能的研究

本文对MFE环氧乙烯基酯(含MFE型和AFE型二种型号)树脂的固化性能(凝胶时间、放热峰和固化收缩率)作了报道并进行讨论。     

Synthesis,characterization, thermal,and viscoelastic properties of an unsaturated epoxy polyester cured with different hardeners

The chemical modification of the structure of the unsaturated polyester obtained in poly condensation process of 1,2,3,6‐tetrahydrophthalic anhydride, maleic anhydride, and ethylene glycol by well known conventional method of epoxidation with peracetic acid in mild conditions has been presented. The new material containing both epoxy groups and unsaturated double bonds in polyester chain was characterized by FTIR and ¹H NMR spectra. The prepared unsaturated epoxy polyester was suitable material for further chemical modification. Both epoxy groups and unsaturated double bonds can be used as cross‐linking sites. Curing behavior, thermal, and visco‐elastic properties of the unsaturated epoxy polyester cured with different hardeners: 1,2,3,6‐tetrahydrophthalic anhydride (THPA), hexahydrophthalic anhydride (HHPA), and/or with vinyl monomer (styrene) using radical initiator—benzoyl peroxide (BPO) were studied by differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), and dynamic mechanical analysis (DMA). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

由苧烯合成脂环族双环氧化合物及固化物热性能

以天然产物(R)-(+)-苧烯为原料,通过烯烃加氢烷基化、酯化和有机过氧化物环氧化反应合成得到含有苧烯结构单元的新型双官能团脂环族环氧化合物。利用核磁共振波谱(1HNMR和13CNMR)、质谱和红外光谱(FTIR)来表征反应中间体和脂环族环氧化合物结构。以2-乙基-4-甲基咪唑为促进剂、酸酐为固化剂,采用示差扫描量热(DSC)和热重分析(TGA)方法研究该脂环族环氧固化物的热性能。环氧化合物与甲基六氢邻苯二甲酸酐、4-环己烯-1,2-二甲酸酐和内亚甲基邻苯二甲酸酐固化产物的Tg分别为158、137、150℃。结果表明,脂环族环氧化合物与酸酐固化剂热固化后得到的交联聚合物具有良好的热性能。     

Copolymerization modification: improving the processability and thermal properties of phthalonitrile resins with novel comonomers

Two novel tetrahydrophthalic anhydride end‐capped imide compounds (THAN and THBN) with high thermal stability were synthesized to promote the curing reaction of 1,3‐bis(3,4‐dicyanophenoxy)benzene (3BOCN), and to study the effects of comonomer structure on the curing behavior and thermal performance of phthalonitrile resins. The curing behaviors of THAN/3BOCN and THBN/3BOCN blends with various molar ratios were investigated using rheological analysis and differential scanning calorimetry, suggesting a wide processing window. Dynamic mechanical analysis and thermogravimetric analysis showed that the cured resins possessed high glass transition temperatures (> 500 °C), and superior thermal and long‐term thermo‐oxidative stabilities with weight retention of 95% ranging from about 544 to 558 °C in both nitrogen and air. All these results indicated that the processability and thermal properties of phthalonitrile resins could be improved further by modifying the structure of comonomer in this kind of curing system. © 2018 Society of Chemical Industry     

紫外光固化丙烯酸环氧树脂的合成及表征

丙烯酸环氧树脂是近年来发展的一种新型光固化涂料,由于其对环境污染少、能耗低、效率高、收缩性小、化学稳定性好等优点,而被广泛地应用.以丙烯酸或甲基丙烯酸及环氧树脂E-51为原料,合成了丙烯酸环氧树脂,并对其合成的各种影响因素进行了试验探索.适宜条件为:催化剂四甲基氯化铵用量0.6%,反应温度85～100℃,反应时间3.5～4h,投料时丙烯酸物质的量/环氧树脂物质的量比为2.08:1～2.17:1.     

Effects of butyl acrylate modified polypropylene on structural and thermal properties of foamed polypropylene

In this work, the melt strength of PP matrix was reinforced by crosslinking‐modified PP (CM‐PP) which was yielded by peroxide‐initiated crosslinking of linear PP with butyl acrylate (BA). The nano‐silica aerogel (nano‐SiO₂) worked as a nucleating agent for foaming. The effects of CM‐PP with the various contents of BA on the foaming behavior and thermal property of PP were studied by measurements of density, thermal conductivity, Vicat softening temperature and SEM. The results showed that the foamed PP got the best properties when the crosslinking PP modified with the weight ratio of butyl acrylate was 10 wt %. The density of the obtained foamed PP with uniform closed cells was as low as 0.23 g/cm³, the thermal conductivity was 0.044 W/(m K), and the Vicat softening temperature was 120 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44340.     

Thermal characterization of diglycidyl ether of bisphenol‐A/phosphorus containing amines

In order to improve the thermal resistance of diglycidyl ether of bisphenol‐A (DGEBA), phosphorus‐containing di‐ and tri‐amines, i.e., bis (3‐aminophenyl) methyl phosphine oxide (B) and tris (3‐aminophenyl) phosphine oxide (T), were used as curing agents. The effect of phosphorus content on the curing characteristics and char residue of cured resins in nitrogen atmosphere was evaluated by using different molar ratios of conventional curing agent, i.e. 4, 4′‐diaminodiphenyl sulfone (D) and amine B or T. Activation energy of curing, as evaluated by using the multiple heating rate method, was lowest when triamine T (61.0 kJmol^?1) was used as hardener and was highest when D (68.7 kJmol^?1) was used. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 390–395, 2001     

Preparation,cure kinetics,and thermal properties of novel acetylene terminated silazanes

A new kind of acetylene terminated silazanes, N‐(3‐acetylenephenyl)‐diorganosilazanes (abbreviated as APSZs) with three kind of substituents, were synthesized by the aminolysis of dichlorosilane with 3‐aminophenylacetylene (3‐APA). Structure of APSZs was confirmed by Fourier transform infrared spectroscopy (FT‐IR) and nuclear magnetic resonance (NMR). Thermal behavior of the cured silazanes was determined by thermogravimetry analysis (TGA), revealing that cured silazanes exhibited high temperature resistance. The ceramic yields of APSZ‐Me₂, APSZ‐MeVi, and APSZ‐Ph₂ at 1000°C under nitrogen were 77.6, 81.9, and 68.7%, respectively. The peak separation of derivative thermogravimetric data was employed to evaluate the three major regions of the thermolysis, and the kinetic parameters of thermolysis were calculated by the method of Kissinger from dynamic thermogravimetric measurement in nitrogen atmosphere at several different heating rates. Influence of substituents on the thermal behavior of cured silazanes in each separated region was discussed. The results showed that the vinyl derivative exhibit higher thermal stability than methyl and phenyl derivatives due to the high decomposition activation energy and small pendant group. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis, characterization, thermal and flame retardant properties of novel aryl phosphinate diglycidyl ether cured with anhydride

A novel aryl phosphinate diglycidyl ether, 10-(2′,5′-diglycidyl ether phenyl)-9,10-dihydro-9-oxa-l0-phosphaphenanthrene-10-oxide (DHQEP), was synthesized. The structure of the diglycidyl ether was characterized by elemental analysis, mass, FTIR, ¹H, ¹³C, ³¹P NMR spectroscopies and X-ray single crystal analysis. In addition, compositions of the diglycidyl ether with three curing agents, e.g. phthalic anhydride (PA), hexahydrophthalic anhydride (HHPA), and aryl phosphinate anhydride (DMSA), were used for making a comparison of its heat and flame retardancy with that of DER331 and DEN438. The resulting aryl phosphinate epoxy-resin composites demonstrated a higher limiting oxygen index (LOT) value as well as a higher char yield, confirming the effectiveness of aryl phosphinate epoxide as a flame retardant for epoxy resins.     

硅丙树脂的制备及性能表征

以乙烯基三乙氧基硅烷(VTES)、甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)为单体,过氧化二苯甲酰(BPO)为引发剂,利用溶液聚合法合成含硅氧烷丙烯酸树脂P(MMA-BA-VTES)(PMBV),适宜的聚合条件为:nBA∶nMMA∶nVTES=2∶2∶1,BPO用量为单体总量3％,温度110℃.在该条件下,聚合反应转...     

Study of poly(vinyl chloride)/acrylonitrile–styrene–acrylate blends for compatibility,toughness, thermal stability and UV irradiation resistance

A novel rigid poly(vinyl chloride) (PVC)/acrylonitrile–styrene–acrylate (ASA) copolymer blend with good ultraviolet (UV) irradiation resistance and toughness was reported. ASA with good weatherability and toughness was mixed with PVC by conical twin‐screw extruder to improve the UV irradiation resistance and toughness of PVC. The blends were characterized using Fourier‐transform infrared spectra, dynamic mechanical analysis, and scanning electron microscope. Notch Charpy impact test was used to characterize the UV radiation induced changes in toughness. The results showed that ASA was able to toughen PVC with simultaneously improving heat resistance, thermal stabilization, and protecting PVC from irradiation photochemical degradation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2143–2151, 2013     

Addition‐curable propargyl‐containing novolac‐type phenolic resin: Its synthesis,characterization, cure,and thermal properties

In this article, propargyl functionalized novolac resins (PN resins), with varying propargyl contents and varying molecular weights, were synthesized conveniently. The structural characteristics were determined by ¹HNMR and FTIR methods. Thermal cure studies revealed that the uncatalyzed thermal cure was remarkably affected by propargyl extent, while it was hardly affected by molecular weight. The processability of the as‐prepared PN resins was excellent as matrix of composite materials. The cure mechanism was complicated; postcure at high temperature was required to achieve entire crosslink formation. Both dynamic mechanical analysis and thermogravimetric analysis showed that the cured PN resins had substantially improved thermal mechanical properties and thermal stability in comparison to conventional cured phenolics. High propargyl extent was preferred for high thermal stability. The results show that PN resin is one of the ideal candidates for advanced composites matrices in thermostructural and ablative applications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1010–1017, 2006     

Sb‐intercalated layered double hydroxides–poly(vinyl chloride) nanocomposites: Preparation,characterization, and thermal stability

In this study, a novel ‐intercalated layered double hydroxide (Sb‐LDH) was prepared by simultaneous recovering of LDH structures and intercalation of into LDH layers. The prepared Sb‐LDH composites remain the hydrotalcite structure with layered geometry and show higher thermal property than that of LDH. When applied to poly(vinyl chloride) (PVC) composites, Sb‐LDH showed limited thermal stability for PVC at the early stage of thermal and thermooxidative degradation processes. However, Sb‐LDH could retard the thermal cracking of the carbonaceous conjugated polyene of PVC which may hinder further degradation, and the moderate amount of Sb‐LDH (1, 2, and 5 wt %) in PVC resin can retard the process of decarbonation and enhance char formation. Sb‐LDH also promoted the transparency of PVC but darkened the color. With the advantages of transparency promotion, high temperature resistance, and long‐term stability, the prepared Sb‐LDH is a potential thermal stabilizer for PVC resins. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42524.     

新型含磷酚醛树脂的合成与性能

通过亚膦酸酯与碳碳双键之间的亲电加成反应,合成了一种新型的含磷马来酰亚胺酚醛树脂。采用红外光谱(FTIR)和元素分析法对聚合物的结构进行了表征。并用此含磷酚醛树脂作为环氧树脂的固化剂制得了一含磷氮的环氧固化物。采用热分析法、极限氧指数法对相应环氧固化物的耐热性能和阻燃性能进行了表征。研究结果表明:以该含磷聚合物作为环氧树脂的固化剂,对稳定固化物骨架碳的结构和交联成炭能力的提高起到了增强作用;环氧固化物具有较高的玻璃化转变温度(145.4℃)和较高的热稳定性(T508℃),极限氧指数显示其具有较好的阻燃性能。     

含乙烯基有机硅树脂的电子束固化行为研究

以八甲基环四硅氧烷、四甲基四乙烯基环四硅氧烷为单体,六甲基二硅氧烷为封端剂,碱胶为催化剂,合成了含乙烯基有机硅树脂;并研究了电子束辐射剂量对其固化行为的影响和固化涂层的热性能。红外谱图及凝胶率测试结果表明,有机硅树脂中的碳碳双键吸收峰强度随辐射剂量的增加而减弱,辐射诱导交联网络结构的形成导致固化涂层的凝胶率随剂量的增加而显著增加;辐射剂量为30 kGy时,凝胶率为46.2%;辐射剂量增加至60 kGy时为70.1%和100 kGy时为85.9%。差示扫描量热分析和热质分析结果表明,固化涂层具有优良的耐低温性和热稳定性。