KINETIC MODELING OF ESTERIFICATION OF EPOXY RESIN IN THE PRESENCE OF TRIPHENYLPHOSPHINE FOR PRODUCING VINYL ESTER RESIN: MECHANISTIC RATE EQUATION

Due to its mechanical properties and ease of use, vinyl ester resin is enjoying increasing consideration. This resin normally is produced by reaction between epoxy resin and unsaturated carboxylic acid. In the present study, bis-phenol A based epoxy resin and methacrylic acid was used to produce vinyl ester resin. The reaction was conducted under both stoichiometric and non-stoichiometric conditions in the presence of triphenylphosphine as catalyst. The stoichiometric and non-stoichiometric experiments were conducted at 95, 100, 105 and 110℃ and at 90 and 95℃, respectively. The first order rate equation and mechanism based rate equation were examined. Parameters are evaluated by least square method. A comparison of mechanism based rate equation and experimental data show an excellent agreement. Finally, Arrhenius equation and activation energy were presented.

INFLUENCE OF MOLECULAR STRUCTURES OF SECONDARY AMINE TERMINATED POLY(ESTER-AMINE)S ON THE CURING PERFORMANCE WITH EPOXY RESIN

Five secondary amine terminated poly（ester-amine）s （defined as PEA） with controlled molecular structures were synthesized through reacting excessive piperazine with phthalicdiglycol diacrylate （PDDA） and 1,1,1-trimethylolpropane triacrylate （TMPTA） at a constant secondary amine/acrylate group ratio of 1.5/1 and at different PDDA/TMPTA molar ratios. Both IR and ^1H-NMR spectra indicated that all acrylate groups were consumed in the reaction, based on which the structural parameters were calculated from the ^1H-NMR spectra. With decreasing PDDA/TMPTA ratio, the content of secondary amine, degree of branching, molecular weight, Tg and Td increased accordingly. These polymers were further used as both crosslinkers and flexibilizers for a linear epoxy resin E51 to form cured films under ambient condition. The gel content, relative hardness and Tg of the resulting films increased as PEA molecules changed from linear to highly branching structures. Due to the flexibility of PEA molecules, all the films possessed excellent mechanical performance.

Study on the Novel Dicyanate Ester Resin Containing Naphthalene Unit

The novel dicyanate ester resin containing naphthalene unit (DNCY) was synthesized, and characterized by FT-IR, 1H-NMR, 13C-NMR and elemental analysis (EA). The thermal properties of DNCY resin was studied by thermal degradation analysis at a heating rate of 10 C /min-1 in N2 and air. The DNCY resin exhibited better thermal and thermal-oxidative stability than bisphenol A dicyanate (BACY) resin.

Curing mechanism of alkaline phenolic resin with organic ester

To study the curing mechanism of alkaline phenolic resin with organic ester, three esters were chosen to react with three systems — alkaline phenolic resin, potassium hydroxide aqueous solution containing phenol, and potassium hydroxide aqueous solution. The variations of pH, heat release and gel pH during the reactions were monitored and measured. Infrared spectroscopy(IR) and thermal gravity analysis(TG) techniques were used to characterize the curing reaction. It was found that organic ester is only partially hydrolyzed and resin can be cured through organic ester hydrolysis process as well as the reaction with redundant organic ester. The sequential curing mechanism of alkaline phenolic resin cured by organic ester was identified as follows: a portion of organic ester is firstly hydrolyzed owing to the effect of the strong alkaline; the gel is then formed after the pH decreases to about 10.8-10.88, meanwhile, the redundant organic ester(i.e. non-hydrolysis ester) starts the curing reaction with the resin. It has also been found that the curing rate depends on the hydrolysis velocity of organic ester. The faster the hydrolysis speed of the ester, the faster the curing rate of the resin.

Application conditions for ester cured alkaline phenolic resin sand

Five organic esters with different curing speeds: propylene carbonate(i.e. high-speed ester A); 1, 4-butyrolactone; glycerol triacetate(i.e. medium-speed ester B); glycerol diacetate; dibasic ester(DBE)(i.e. lowspeed ester C), were chosen to react with alkaline phenolic resin to analyze the application conditions of ester cured alkaline phenolic resin. The relationships between the curing performances of the resin(including pH value, gel pH value, gel time of resin solution, heat release rate of the curing reaction and tensile strength of the resin sand) and the amount of added organic ester and curing temperature were investigated. The results indicated the following:(1) The optimal added amount of organic ester should be 25 wt.%-30 wt.% of alkaline phenolic resin and it must be above 20 wt.%-50 wt.% of the organic ester hydrolysis amount.(2) High-speed ester A(propylene carbonate) has a higher curing speed than 1, 4-butyrolactone, and they were both used as high-speed esters. Glycerol diacetate is not a high-speed ester in alkaline phenolic resin although it was used as a high-speed ester in ester cured sodium silicate sand; glycerol diacetate and glycerol triacetate can be used as medium-speed esters in alkaline phenolic resin.(3) High-speed ester A, medium-speed ester B(glycerol triacetate) and low-speed ester C(dibasic ester, i.e., DBE) should be used below 15 °C, 35 °C and 50 °C, respectively. High-speed ester A or lowspeed ester C should not be used alone but mixed with medium-speed ester B to improve the strength of the resin sand.(4) There should be a suitable solid content(generally 45 wt.%-65 wt.% of resin), alkali content(generally 10 wt.%-15 wt.% of resin) and viscosity of alkaline phenolic resin(generally 50-300 mPa·s) in the preparation of alkaline phenolic resin. Finally, the technique conditions of alkaline phenolic resin preparation and the application principles of organic ester were discussed.

Study on Polyurethane/(vinyl ester resin) IPN Damping Materials

Polyurethane/(vinyl ester resin) interpenetrating polymer network (PU/VER IPN) materials with broad temperatureranges and excellent damping properties from Iow temperature to room temperature were prepared. The influenceof comonomers and component ratios on the compatibility and damping properties of IPN materials was studied byDMA which indicates that such properties are improved by introducing acrylic esters instead of polystyrene (PSt)into VER comonomer system. The detected results of microstructure by AFM show that the phase ranges of thedual-phase continuous IPN materials obtained are both in nanometer scale. The results of mechanical propertiesshow that IPN materials show the regulation from elastic deformation to brittle deformation with the increase of VERproportion.

Synthesis and Application of a New Acrylic Ester Resin for Recycling SIPA from its Water Solution

A new acrylic ester polymer YWB-7 resin was prepared and characterized. The properties of YWB-7 resin were compared with those of the commercial Amberlite XAD-7, Diaion HP2MG and hypercrosslinked macroporous polymer NDA-150 resins. Both surface area and micropore area of YWB-7 resin were bigger than those of XAD-7 resin and HP2MG resin. The YWB-7 resin was successfully employed to recycle 5-sodiosulfoisophthalic acids （SIPA） from its solutions with and without methanol.

Effect of Strain Rate on Compression Behavior of Vinyl Ester Resin Casting

Quasi-static and high strain rate compressive experiments on vinyl ester casting were carried out by means of MTS (Material Test System) and Hopkinson bar. The behaviors of the compressed unstable and fracture of the resin casting at different strain rates were investigated.The results indicate that the response behavior of the resin casting is controlled by different mechanisms at different strain rate, and some mechanical properties of vinyl ester casting are rate-dependent: the casting are destroyed in toughness model under strain rate 3.3×10 -4～6.6×10 -3/s, while the casting are destroyed in brittleness model under strain rate 950～5800/s. The yield stress, yield strain energy density are all increased with the increasing strain rates at quasi-static as well as at high strain rates. What is interesting is that the yield strain decreased with the strain rates increasing at quasi-static while increased at high strain rates. It is considered that the casting occurred forcing high elastic deformation at high strain rates. The damage of the specimens is mainly controlled by axial stress before unstable deformation, while mainly controlled by shear stress after unstable deformation, and then developed to fracture finally. This progress is rate-dependent: the development of the cracks inside the castings increased with the strain rate increasing.

Investigation on Thermal and Dimensional Stability of Epoxy Resin In-Situ Modified by Cyanate Ester Resin and Polydimethylsiloxane

The thermal and dimensional stability of epoxy resin(EP)in-situ modified by cyanate ester(CE)and polydimethylsiloxane(PDMS)are investigated by means of experiments and numerical simulation.Thermal gravimetric analysis(TGA)and differential scanning calorimeter(DSC)are used to analyze the heat resistance of the modified EP.The dimensional stability is characterized by the volume shrinkage of the series PDMS/CE/EP obtained by the density method.The chemical structure of the PDMS/CE/EP is analyzed by Fourier transform infrared spectroscopy(FTIR).The results of TGA and DSC indicate that the thermal stability of PDMS/CE/EP decreases firstly and then increases with the increase in the amount of CE.The addition of PDMS shows a slight effect on the thermal stability.The 40%CE makes the blending system exhibit the lowest initial decomposition temperature,which reduces by 15.5%and 40.8%compared with pure EP and CE,respectively.The FTIR results suggested that the influence of CE on the thermal stability of the modified EP is mainly ascribed to the generation of oxazolidinone ring with low thermal stability and the increase in the triazine ring with high thermal stability.The volume shrinkage measurement results show that the introduction of CE and PDMS are both beneficial to the improvement of the dimensional stability of the blending systems.The in-situ addition of 80%CE shows the lowest volume shrinkage of6.11%.The thermal stress distribution of PDMS/CE/EP generated during the solidification process is simulated by the finite element analysis.The results suggested that the introduction of 80%CE into EP results in the lowest thermal stress in the blending system,which indicates that the system has the lowest volume shrinkage,which agrees well with the experimental results.

Studies on interacting Blends of Acrylated Epoxy resin based Poly(Ester-Amide)s and Vinyl EsterResin

Epoxy resin based Unsaturated poly(ester-amide) resins (UPEAs) can be prepared by many methods but here these were prepared by reported method [1]. These UPEAs were then treated with acrylotl chloride to afford acrylated UPEAs resin (i.e. AUPEAs). Interacting blends of equal proportional AUPEAs and vinyl ester epoxy (VE) resin were prepared. APEAs and AUPEAs were characterized by elemental analysis, molecular weight determined by vapour pressure osmometer and by IR spectral study and by thermogravimetry. The curing of interacting blends was monitored on differential scanning calorimeter (DSC). Based on DSC data in situ glass reinforced composites of the resultant blends have been prepared and characterized for mechanical, electrical and chemical properties. Unreinforced blends were characterized by thermogravimetry (TGA).

SPECTROSCOPIC DETERMINATION OF THE AVERAGE NUMBER OF COAGGREGATES (Nco) OF CHOLESTERYL ESTERS AND THE FLUORESCENCE PROBE

Average aggregate number of coaggregates(N_co)of CE-n or BL-n and the fluoresc- ence probe(Np-16)have been determined by using time-resolved fluorescence spectroscopy. Chain-length,hydroxy-group and chain-foldability effects on the N_co have been discussed.

Mechanical Properties of Submicron Glass Fiber Reinforced Vinyl Ester Composite

Vinyl ester (VE) resin inherently has intrinsic brittleness due to its high cross-link density. To improve mechanical performance, micro/nano fillers are widely used to modify this matrix. In present study, glass fiber in submicron scale at low contents was added into VE to prepare submicron composite (sMC). The impact resistance of un-notched sMC degraded with the increase of sGF content while that of notched-sMC remained the unchanged. Flexural properties of sMCs also were the same with that of neat resin. The results of Dynamic mechanical analysis (DMA) test showed the slight increase of storage modulus and the decrease of tan delta value in the case of sMC compared to those of un-filled matrix. However, the Mode I fracture toughness of sMC improved up to 26% and 61% corresponding to 0.3 and 0.6 wt% glass fiber used. The compact tension sample test suggests that there is the delay of crack propagation under tensile cyclic load in resin reinforced by submicron glass fiber. The number of failure cycle enlarged proportionally with the increment of sGF content in matrix.

Investigation on the Structure and Curing Performances of Secondary Amine Terminated Hyperbranched Poly(ester-amine)s

Three secondary amine terminated hyperbranched poly（ester-amine）s （defined as HPEA1, HPEA2 and HPEA3） were synthesized from piperazine （A2） and trimethylolpropane triacrylate （TMPTA, B3） at their molar ratios of 2.5：1, 2.25：1 and 2.0：1, respectively. The polymers were analyzed by 1H NMR, GPC, DSC and TGA. The results indicated that the ratio of secondary amine to tertiary amine and the content of secondary amine decreased, while the molecular weight, molecular weight distribution and glass transition temperature （Tg） increased from HPEA1 to HPEA3. Due to their reactive terminal groups and flexible chains, these polymers further reacted with an epoxy resin （E51） to form cured films under ambient conditions. With increasing the ratio between secondary amine groups and epoxy groups from 1：2 to 2：1, the gel content, film hardness and onset decomposing temperature of the cured samples increased. The good film performances should make the polymers as the components of non-solvent coating materials.

Synthesis and Characterization of Modified Epoxy Resins by Silicic Acid Tetraethyl Ester and Nano-SiO_2

A kind of modified epoxy resins was obtained by condensation of epoxy resin with silicic acid tetraethyl ester（TEOS） and nano-SiO2. The reactions were performed with hydrochloric acid as a catalyst at 63 ℃. The structure, thermal stability and morphological characteristics of the modified epoxy resins were studied through infrared spectra（FT-IR） analysis, thermogravimetric（TG） analysis and scanning electron microscopy respectively. It has been found from the IR and TG study that modified epoxy resins have greater thermal stability than epoxy resins, and its thermal stability has been improved by the formation of inter-crosslinked network structure. The modified epoxy resins exhibit heterogeneous morphology and heterogeneity increases with more TEOS feeding, which in turn confirms the formation of inter-crosslinked network structure in modified epoxy resins.

EFFECT OF CATALYST ON THE REACTION BETWEEN ACTIVE ESTER AND EPOXY RESIN

In this study the third amine and phosphine were selected as the catalysts of epoxy resin, the influence of these catalysts on curing reaction was observed in comparison with the former selected quadrupole onium salt and the influence of them on physical properties of solidified matter was also studied. (Author abstract) 10 Refs.

丙烯酸硅烷酯柔性自抛光防污涂料制备及性能

以甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸异辛酯、丙烯酸甲氧基乙酯、丙烯酸三异丙基硅酯为单体,制备了丙烯酸硅烷酯基体树脂,将其与韧性树脂(液态聚丁二烯)共同作为成膜共混树脂,并以Cu_(2)O作为主要防污剂组分、吡啶硫酮铜(CuPT)和代森锌(Zineb)为辅助有机防污剂组分,配制了柔性自抛光防污涂料。对丙烯酸硅烷酯基体树脂进行了FTIR表征和玻璃化转变温度(Tg)测定,对成膜共混树脂进行了SEM测试,对柔性自抛光防污涂料进行了柔韧性、附着力、吸水率和防污性能测试。结果表明,丙烯酸硅烷酯基体树脂的Tg=–20.54℃时,具有较好的物理机械性能;韧性树脂可以作为外增塑手段增加丙烯酸硅烷酯基体树脂的柔韧性,当m(丙烯酸硅烷酯基体树脂)∶m(韧性树脂)=7∶3时,成膜共混树脂的相容性最好;柔性自抛光防污涂料柔韧性为1级,在弹性体基材表面附着力达到4.0 MPa;经过60 d测试,吸水率为1.1%~1.2%;浅海浸泡挂板36个月显示出明显的防污效果。

含磷POSS阻燃乙烯基酯树脂性能研究

将含磷POSS(DMPOSS)以5wt%、10wt%和15wt%的添加量添加到乙烯基酯树脂中,通过差示扫描量热仪(DSC)、热重分析(TG)、极限氧指数(LOI)、锥形量热仪和扫描电镜(SEM)测试研究了DMPOSS对乙烯基酯树脂玻璃化转变温度、热稳定性和燃烧性能的影响。DSC测试结果表明:DMPOSS的加入能够明显提升乙烯基酯树脂的玻璃化转变温度。LOI测试结果表明:添加DMPOSS改性的乙烯基酯树脂的氧指数随DMPOSS含量的增加而逐渐升高。当添加15wt%DMPOSS时,乙烯基酯树脂的氧指数达到23.8%。锥形量热仪测试结果表明:DMPOSS的加入能够有效降低乙烯基酯树脂的热释放。当添加15wt%DMPOSS时,乙烯基酯树脂的热释放速率峰值降低了44.9%,总的热释放降低了30.4%。

CE/nano-SiO_2复合材料的RTM工艺条件

以CE(氰酸酯)树脂为基体,以硅烷偶联剂(KH-560)表面处理过的纳米二氧化硅(nano-SiO2)为改性剂,采用高速均质剪切法制备CE/nano-SiO2复合材料;然后以该复合材料体系的黏度、凝胶化时间、弯曲强度和玻璃化转变温度(Tg)为考核指标,采用单因素试验法优选出满足树脂传递模塑(RTM)工艺用复合材料体系的最佳工艺条件。结果表明:当w(nano-SiO2)=3%、工作温度为(90±10)℃、工作时间≤10 h、固化温度为110～200℃和后处理工艺条件为220℃/4 h时,复合材料在低温时具有良好的稳定性,在高温时具有良好的反应性,完全满足RTM工艺的基本要求。

氨基膦酸型螯合树脂吸附Ce(Ⅳ)的性能及机理研究

测定了氨基膦酸型螯合树脂 (D4 12 )对 Ce( )的吸附容量 ,讨论了溶液 p H、粒径、时间、温度等因素对其吸附性能的影响。测得了不同粒径的树脂的吸附速率常数 ,判断其吸附控制类型为孔隙扩散限制。并采用红外及化学分析方法 ,推测出 D4 12螯合树脂对 Ce( )的吸附机理。

PC/YAG∶Ce荧光树脂的制备及光谱分析

采用熔融共混法和高温压模法制备出PC/YAG∶Ce荧光树脂片,样品经减薄和抛光处理后,通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、光致发光(PL)、透射光谱等测试手段进行分析。厚度为0.87 mm的样品在500~800 nm范围内的透过率约为65%。样品主相为Y3Al5O12,在342 nm和448 nm有两个激发峰。样品的发射光谱在532 nm有一宽峰,属于Ce3+的5d→4f特征跃迁发射。荧光树脂片中荧光粉含量越高,样品发射强度越大,是一种适合用于白光LED封装的新型荧光材料。