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.     

Synthesis and characterization of novel epoxy resin bearing naphthyl and limonene moieties, and its cured polymer

The synthesis of novel epoxy resin containing both naphthalene moiety and cycloaliphatic group by chemical bonding in the same molecule has been conducted starting from naphthol and limonene. Its chemical structure was characterized with FTIR spectroscopy, NMR, and GPC analyses. Dynamic cure behaviors with different curing agents were investigated using differential scanning calorimetry. The physical properties of the resulting polymers were evaluated with dynamic thermal mechanical spectroscopy, thermogravimetric and thermal mechanical analysis, and X-ray diffraction. Compared to that of diglycidyl ether of bisphenol A, cured polymer of the novel epoxy resin showed remarkably higher glass transition temperature (T_g), lower coefficient of thermal expansion, higher thermal stability, better moisture resistance and dielectric property.     

Synthesis and characterization of a novel epoxy resin containing naphthyl/dicyclopentadiene moieties and its cured polymer

A new epoxy resin containing both naphthalene and dicyclopentadiene (DCPD) groups was synthesized to produce a highly heat-resistant network, and the curing behavior was investigated using diaminodiphenylsulfone (DDS) as curing agent. The chemical structures were characterized with FTIR spectroscopy, NMR, MS, and GPC analyses. Dynamic curing behavior was investigated using differential scanning calorimetry (DSC). The physical properties of the resulting polymers were evaluated with dynamic thermal mechanical analyses (DMTA) and thermogravimetric analyses (TGA). The cured polymer showed great improvement in heat-resistant property including remarkably higher glass transition temperature (T_g) and thermal stability. Such properties make this new epoxy resin highly promising for heat-resistant applications.     

Characteristics of epoxy resin cured with in situ polymerized curing agent

In order to improve the heat resistance of a cured epoxy resin together with reducing the viscosity of the resin composition, an epoxy resin was cured with a curing agent formed from the radical copolymerization of vinyl monomers during the cure process of the epoxy resin. N-phenylmaleimide and p-acetoxystyrene were used as vinyl monomers of the curing agent. The epoxy resin was cured by the insertion reaction of the ester group of the in situ polymerized curing agent and the epoxy group of the epoxy resin. In the cure system of the epoxy and the phenol resins, reduction of the viscosity of the resin composition was achieved by replacing some or all of the phenol resin with these monomers. When all phenol resins were replaced by these monomers, the viscosity of resin composition (0.01 Pa s at 70 °C) decreased by about 1/2000 compared with that of the system with only phenol resin (21 Pa s at 70 °C). The glass transition temperature (T_g) of the cured resin with no phenols was 174 °C, an improvement of 17 °C compared with that of the system cured with only phenol resin. The flexural strength of the new resins remained unchanged.     

An approach to chemical recycling of epoxy resin cured with amine using nitric acid

An approach to chemical recycling of epoxy resin was pursued. Bisphenol F type epoxy resin cured with 1,8-p-menthanediamine could be completely decomposed in nitric acid solution resulting from low corrosion resistance to nitric acid. Organic decomposed products of the resin with the highest yield were extracted from neutralized solution. The extract was repolymerized to prepare recycled resin, mixed with bisphenol F type epoxy resin and curing agent of phthalic anhydride. The mechanical properties of virgin resin and recycled resins were compared. It was surprising that the recycled resins were far superior to the virgin resin in strength. The results obtained from differential scanning calorimeter (DSC) showed that the glass transition temperature (T_g) of recycled resins was higher than that of virgin resin. The reason that they formed the better network structure was discussed.     

Dynamically cured PP/MAH-g-SEBS/epoxy blends

Abstract

A new method concerning the simultaneous reinforcing and toughening of polypropylene (PP) is reported. Dynamic cure of the epoxy resin with 2-ethylene-4-methane-imidazole was successfully applied in the PP/maleic anhydride grafted styrene–ethylene–butylene–styrene (MAH-g-SEBS) triblock co-polymer, and the obtained blends were named as dynamically cured PP/MAH-g-SEBS/epoxy blends. The stiffness and toughness of the blends are in a good balance, and the smaller size of the epoxy particle in the PP/MAH-g-SEBS/epoxy blends shows that MAH-g-SEBS was also used as a compatibiliser. The structure of the dynamically cured PP/MAH-g-SEBS/epoxy blends is the embedding of the epoxy particles by MAH-g-SEBS. The cured epoxy particles as organic filler increase the stiffness of the PP/MAH-g-SEBS blends, and the improvement in the toughness is attributed to the embedded structure. The tensile strength and flexural modulus of the blends increase with increasing epoxy resin content, and the impact strength reaches a maximum of 342 J m^?1 at the epoxy resin content of 10wt-%. Differential scanning calorimetry analysis shows that the epoxy particles in the dynamically cured PP/MAH-g-SEBS/epoxy blends could have contained embedded MAH-g-SEBS, decreasing the nucleating effect of the epoxy resin. Wide angle X-ray diffraction analysis shows that the dynamical cure and compatibilisation do not disturb the crystalline structure of PP in the blends.     

Fluorescence labels to monitor water absorption in epoxy resins

Water uptake phenomena was studied in a group of commercial epoxy based thermosets using gravimetric and fluorimetric analysis. The different epoxy formulations were labeled with two dansyl derivatives differing in the spacer length between the chain and the fluorophore moiety. The fluorimetric method consisted of monitoring the changes in the first moment of the dansyl emission band as a function of water immersion time. Using the fluorescence, it was possible to obtain the parameters that govern the water diffusion process and there was a good concordance with gravimetric results. Furthermore, the fluorescence response of the dansyl moieties was used to study the effect of the molecular structure of the polymers in the water absorption process.     

Preparation of cured epoxy resin particles having one hollow by polyaddition reaction

In 1996, the authors proposed a novel method to prepare micron-sized, hollow cross-linked polymer particles. This method is based on the self-assembling of phase separated polymer at interface with water, which was named SaPSeP method, formed by suspension polymerization of divinyl monomer in toluene droplet dissolving previously polystyrene. The SaPSeP method was developed to be applicable to polyaddition reaction system of epoxy resin with diamine. The presence of PS dissolving in epoxy/diamine/toluene droplets promotes the phase separation of the epoxy resin reacted with the diamine. The epoxy resin molecules tend to adsorb at the interface of the droplets. These points were accord with the required conditions for the preparation of hollow particle by the SaPSeP method. Cured epoxy resin particles having one hollow were successfully prepared by the polyaddition reaction in the dispersed system of Epikote 806/630/604, of which equivalent ratio was 5/4/1.     

高折射率含硫环氧树脂的合成与表征

通过2，2‘-二巯基二乙硫醚（MES）与环氧氯丙烷反应，合成了一种新型高折射率，低色散的2，2‘－二巯基二乙硫醚缩水甘油醚型光学环氧树脂（DGEMES），采用红外光谱和核磁共振谱图表征了该树脂的结构，并详细讨论了直接法和间接法合成DGEMES的各种反应条件对产率的影响，得出直接法制取DGEMES的最佳原料配比为：n(MES):n(环氧氯丙烷）：n(NaOH)=1:5:1.9，产率为981％，折射率为1．5450，间接法制取DGEMES中的最佳原料配比为：n(MES):n(环氧氯丙烷）:n(NaOH)=1:2.4:6，产率为99．32％，折射率为1．5661。     

Polymerization induced phase separation in poly(ether imide)-modified epoxy resin cured with imidazole

This paper studies the phase separation in poly(ether imide) (PEI) modified epoxy resin using imidazole (C₁₁Z-CNS) as epoxy hardener to control its morphology. The sponge-like phase structures were founded at higher PEI concentration (10-25 phr), while homogeneous structures are formed at low PEI concentration (5 phr). The effects of PEI concentration on curing kinetics and phase structures were studied by differential scanning calorimeters (DSC) and scanning electron microscopy (SEM). It is shown that although the addition of PEI does not change the curing mechanism, the separated morphology becomes finer at high PEI concentration. The curing rate and conversion decrease with the increase of the content of PEI. The chain growth polymerization of these systems caused an early gelation (conversion <10%) and early freezing of morphologies. The evolution of phase separation in the early stage was monitored by synchrotron radiation small angle X-ray scattering (SR-SAXS) and transmission electronic microscopy (TEM). It is suggested that the formation of sponge-like phase structure could be attributed to the strong viscoelastic effects in the early stage of phase separation.     

Mechanical properties of epoxy networks based on DGEBA and aliphatic amines

The mechanical properties of epoxy networks based on diglycidyl ether of bisphenol A epoxy resin cured with various linear aliphatic amines, such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and cyclic amines such as 1‐(2‐aminoethyl)piperazine and isophorone diamine, were studied. General characteristics such as T_g, density, and packing density, were determined and related to the structure and funcionality of the curing agent. Dynamic mechanical spectra were used to study both the α and β relaxations. Tensile and the flexural tests were used to determine the Young's and flexural modulus, and fracture strength all in the glassy state. Furthermore, linear elastic fracture mechanics was used to determine K_IC. As a rule, isophorone diamine network presented the higher tensile and flexure modulus while 1‐(2‐aminoethyl)piperazine gave the highest toughness properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Tetrafunctional aliphatic epoxy I. Synthesis and characterization

A low viscosity tetrafunctional epoxy resin was synthesized by reacting amino-terminated polydimethylsiloxane with epichlorohydrin followed by dehydrohalogenation. The synthesized tetrafunctional aliphatic epoxy resin had an epoxy equivalent weight of 382, M_n of 1492, M_w of 2296, and a viscosity of 4.2 poise at 25°C. The chemical structure of the tetrafunctional aliphatic epoxy resin was studied by gel permeation chromatography (GPC), Fourier transform infrared spectra (FTIR), and ¹H-NMR spectra. Results showed the tetrafunctional aliphatic epoxy-blended aromatic epoxy resin possessed high impact strength and flexural strength. SEM photographs were investigated to study the compatibility of the blended epoxy system. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 51–58, 1998     

环氧磷酸的合成及对环氧树脂固化物的阻燃耐热性研究

将环氧树脂和磷酸直接反应,制得了含磷11%、与环氧树脂相容性较好的新型含磷阻燃剂(EPH),用氧指数测定、热重法等方法研究了其对环氧树脂二乙烯三胺固化物阻燃耐热性的影响。实验结果表明该阻燃剂对环氧树脂固化物有较好的阻燃作用,能明显提高树脂固化物的残炭量,主要发挥凝聚相阻燃作用。     

Epoxy resins possessing flame retardant elements from silicon incorporated epoxy compounds cured with phosphorus or nitrogen containing curing agents

New silicon-containing epoxy compounds were obtained by reacting a bisphenol-A type epoxy and an o-cresol-formaldehyde novolac type epoxy with diphenylsilandiol and triphenylsilanol, respectively. The reactions were performed with tin(II) chloride as a catalyst at 140-170 °C. With various feeding ratios of reactants, the epoxy compounds contained various silicon contents. The thermal stability and the flame retardant property of the cured epoxy resins were improved with this incorporation of silicon. Synergistic effects of phosphorus/silicon and nitrogen/silicon on enhancing limited oxygen index values were also observed for the epoxy resins from the silicon-containing epoxy compounds cured with phosphorus- and melamine-containing agents.     

新型潜伏性环氧树脂固化剂的研制

采用乙二胺与丙烯酸甲酯在乙醇中反应合成了一种具有潜伏性的环氧树脂固化剂。利用红外光谱和元素分析确定产物的化学结构 ,热失重分析结果表明产物基本达到了作为潜伏性固化剂的要求     

液晶环氧树脂改性普通环氧树脂的研究

合成了一种液晶环氧树脂,并使之与普通环氧树脂共混固化,共混固化物的力学性能和热稳定性比普通环氧树脂固化物有明显的提高。     

Cure kinetics and morphology of blends of epoxy resin with poly (ether ether ketone) containing pendant tertiary butyl groups

The cure kinetics and morphology of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin modified with a poly (ether ether ketone) based on tertiary butyl hydroquinone (PEEK-T) cured with diamino diphenyl sulphone (DDS) were investigated using differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and dynamic mechanical thermal analysis (DMTA). The results obtained from DSC were applied to autocatalytic and diffusion controlled kinetic models. The reaction mechanism broadly showed autocatalytic behaviour regardless of the presence of PEEK-T. At higher PEEK-T concentration, more diffusion controlled mechanism was observed. The rate of curing reaction decreased with increase in thermoplastic content and also with the lowering of curing temperature. The activation energies of the blends are higher than that of the neat resin. The blends showed a phase separated morphology. The dispersed phase showed a homogeneous particle size distribution. The T_g of the neat resin decreased with the decrease in cure temperature. Two T_g's corresponding to the epoxy rich and thermoplastic rich phases were observed in the dynamic mechanical spectrum. The storage modulus of 10 and 20 phr PEEK-T blends are found to be greater than the neat resin.     

Characterization and modeling of diglycidyl ether of bisphenol‐a epoxy cured with aliphatic liquid amines

The characterization by DMA and compressive stress‐strain behavior of an epoxy resin cured with a number of liquid amines is studied in this work along with predictions of the associated properties using Group Interaction Modeling (GIM). A number of different methods are used to assign two of the input parameters for GIM, and the effect on the predictions is investigated. Excellent predictions are made for the glass transition temperature, along with good predictions for the beta transition temperature and modulus for the majority of resins tested. Predictions for the compressive yield stress and strain are less accurate, due to a number of factors, but still show reasonable correlation with the experimental data. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3130–3141, 2013     

环氧多聚磷酸铵的合成及其对环氧树脂固化物性能的影响

将环氧树脂和多聚磷酸直接反应后用氨水中和,制得了含磷18.5%且与环氧树脂相容性较好的新型环氧多聚磷酸铵(EPPA)阻燃剂。用极限氧指数、冲击强度、硬度、热失重等测试方法研究了EPPA对环氧树脂二乙烯三胺固化物阻燃性以及其它各种性能的影响。实验结果表明该阻燃剂对环氧树脂固化物有较好的阻燃作用,适量添加EPPA可大幅提高固化物的韧性,并且对固化物的硬度以及热稳定性影响不大。     

新型环氧树脂添加剂—环氧醚的研制

本文以双酚A型环氧树脂和二乙二醇醚为主要原料,合成了新型环氧树脂添加剂－环氧醚。实验表明,催化剂用量、反应温度和环氧树脂的种类对氧醚的性能有较大的影响。