Structure and adhesive properties of epoxy resins modified with acrylic particles

The morphology and physical properties of dicyandiamide (DICY)-cured epoxy resin modified with acrylic particles were studied. We used one homopolymer of methyl methacrylate (MMA) and three copolymers of MMA and glycidyl methacrylate (GMA) [P(MMA-GMA)] containing different amounts of GMA as the acrylic particles. When a mixture of the acrylic particles and the epoxy resin was heated, the particles were swollen with the epoxy resin and thus a soft gel with no fluidity was formed. Further heating to the reaction temperature of the DICY cured the soft gel. The structure of the acrylic particles strongly affected the physical properties of the soft gel and the cured epoxy resin. The cured system containing 5 mol% of GMA showed the best physical properties (impact strength and adhesive property), but there was a tendency for the physical properties to decline with a higher GMA content. We have determined that the GMA content of the acrylic particles affects the concentration of network chains in the system.     

硼改性酚醛树脂的合成与性能

利用半成品酚醛树脂粉与硼酸直接混合,然后固化得到硼含量不同的硼酚醛树脂,并用傅里叶红外光谱、热重分析和冲击试验等方法对其性能进行了分析。红外分析结果表明,硼酸与酚醛树脂中的酚羟基、苄羟基发生了反应,生成了新的交联键。热分析结果发现,在酚醛树脂中加入硼酸能提高树脂的耐热性,当硼酸加入量为10%时达到最高值。硼酚醛树脂的冲击强度先随硼酸加入量的增大而增加,在5%时达到最大值,然后下降。     

Optimizing the conditions of quantitative 13C-NMR spectroscopy analysis for phenol–formaldehyde resol resins

The experimental time of ¹³C-NMR quantitative analysis of phenol–formaldehyde resins was reduced so that quantitativeness was maintained. The quantitative spectra of 14 model resins were obtained using a gated decoupling technique suppressing the NOE. The paramagnetic additive, Cr(acac)₃, was used to shorten relaxation times of carbon atoms. The use of Cr(acac)₃ was optimized in two deuterated solvents, DMSO and acetone. To reach short relaxation times and further the measurement times, the concentration of relaxation reagent, the delay time, and the number of NMR scans were optimized. Quantitativeness was proved by analyzing the spectra of accurate mixture of model compounds, and the spectra of the condensed model resins. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1805–1812, 1998     

Phenol–formaldehyde–pyrolytic oil resins for wood preservation: A rheological study

The rheological properties of a phenol–formaldehyde resin containing various ratios of softwood pyrolytic oil as phenol substitute were investigated using the simple Bingham rheological model for viscoplastic fluids. Flow activation energy was determined for the various resin blends and the pyrolytic oil between room temperature and 50°C and correlations relating the flow activation energy to the weight fraction of pyrolytic oil in the resin are proposed. Apparent crosslinking activation energy with and without copper chloride used as an activator was also evaluated based on two gel time measurements between 75 and 105°C. A significant decrease in activation energy was observed for the phenol–formaldehyde resin cured with copper chloride, while the effect was less important for resins containing pyrolytic oil even when gel times were much shorter for PF‐resins. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Flame-retardant properties of phenol–formaldehyde-type resins and triphenyl phosphate in styrene–acrylonitrile copolymers

The thermal and flame-retardant properties of phenol–formaldehyde-type resins (crosslinked and noncrosslinked) in mixtures with triphenyl phosphate and styrene–acrylonitrile resins were evaluated. The mixtures show a synergistic effect between triphenyl phosphate and novolacs. Those containing phenol–formaldehyde novolac resins are found to be most flame retardant. There does not seem to be a relationship between the oxygen index (OI) and UL 94 tests. Scanning electron microscopy analysis show a surface structure with cavities and stratification, very similar to that of intumescent additives. Evidence was found indicating that this flame-retardant system works in both the gas and condensed phase. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1067–1076, 1998     

IR spectroscopy as a quantitative and predictive analysis method of phenol–formaldehyde resol resins

A set of resin samples was characterized by IR and ¹³C-NMR spectroscopy. The suitability of IR spectroscopy for the quantitative analysis of resins was evaluated by statistical methods using the NMR reference data as calibration. The values of interesting properties, for example, the amount of free phenol and the formaldehyde-to-phenol (F/P) molar ratio, of the resins being similar to the calibration resins were predicted from the IR spectra. Also, the predicted results were compared with the ones observed by ¹³C-NMR spectroscopy. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2175–2185, 1998     

Synthesis and thermal stability of novel anion exchange resins with spacer chains

Spacer-modified anion exchange resins were prepared by suspension copolymerization of ω-bromoalkylstyrenes or ω-bromoalkyloxymethylstyrenes with 2–8 mol % of divinylbenzene, followed by quaternization with trimethylamine. The thermal stability of the spacer-modified anion exchangers of the OH form was examined by standing the resins in deionized water at 100–140°C for 30–90 days. The anion exchangers with alkylene chains such as butylene or heptylene groups between the benzene ring and the quaternary nitrogen exhibited higher thermal stability compared with commercial, strongly basic anion exchangers with benzylic ammonium groups. The thermal stability of the exchangers with butyleneoxymethylene or hexyleneoxymethylene spacers was also higher than that of the commercial exchangers. The exchanger with the propyleneoxymethylene spacer, however, had less stability than did the commercial ones. The decreased stability of this spacer-modified exchanger is due to the accelerated degradation of the spacer chain via Hofmann elimination. The excellent stability of the anion exchangers with alkylene or alkyleneoxymethylene spacers, except propyleneoxymethylene, results from the structure of the exchangers, where there are no reactive benzylic carbons, which are attached directly to the quaternary nitrogen. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1161–1167, 1997     

Phenol–furfural resins to elaborate composites reinforced with sisal fibers—Molecular analysis of resin and properties of composites

Resol type resins were prepared in alkaline conditions (potassium hydroxide or potassium carbonate) using furfural obtained by acid hydrolysis of abundant renewable resources from agricultural and forestry waste residues. The structures of the resins were fully determined by ¹H, ¹³C, and 2D NMR spectrometries with the help of four models compounds synthesized specially for this study. MALDI‐Tof mass spectrometry experiments indicated that a majority of linear oligomers and a minority of cyclic ones constituted them. Composites were prepared with furfural–phenol resins and sisal fibers. These fibers were chosen mainly because they came from natural lignocellulosic material and they presented excellent mechanical properties. Thermal analyses (dTG and DSC) and electron microscopy images indicated that the composites displayed excellent adhesion between resin and fibers. Impact strength measurement showed that mild conditions were more suitable to prepare thermosets. Nevertheless, mild conditions induced a high‐diffusion coefficient for water absorption by composites. Composites with good properties could be prepared using high proportion of materials obtained from biomass without formaldehyde. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of nanosized polypyrrole–polystyrene composite particles

Nanosized polypyrrole–polystyrene (PPy–PS) composite particles were synthesized by the polymerization of pyrrole on PS nanoparticles in the presence of FeCl₃. The PS nanoparticles were prepared from microemulsion polymerizations using the cationic nonpolymerizable surfactant cetyltrimethylammonium bromide (CTAB), the nonionic polymerizable surfactant ω‐methoxy[poly(ethylene oxide)₄₀]undecyl α‐methacrylate (PEO–R–MA‐40), or the cationic polymerizable surfactant ω‐acryloyloxyundecyltrimethylammonium bromide (AUTMAB). For the latexes stabilized by CTAB, the resulting PPy–PS composite particles exhibited relatively poor colloidal stability and the pressed pellets exhibited relatively low electrical conductivities (～10^?7–10^?3 S cm^?1). However, for the latexes stabilized by polymerizable surfactants, the resulting PPy–PS composite particles exhibited relatively good colloidal stability and relatively high conductivities (～10^?5–10^?1 S cm^?1). The effect of polymerizable surfactants on the colloidal stability of composite particles and the conducting mechanism of the composites are discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1360–1367, 2004     

Thermal properties and fire behaviour of materials produced from curing mixed epoxy and phenolic resins

Thermal stability and fire behaviour of materials obtained from curing mixed epoxy and phenolic resins have been studied, the decomposition processes being compared with those for the pure resins. Samples were cured by triethylenetetramine or p‐toluenesulphonic acid by isothermal pressing at 90^°C, and decompositions were carried out under nitrogen and air environment from 50 to 1000^°C. Only for mixtures with higher proportion of epoxy resin, the decomposition process goes through a unique step as for the pure resin. Results from fire tests indicated that mixtures are classified as M3 and F1. Copyright © 2008 John Wiley & Sons, Ltd.     

Variation of MUF and PMUF resins mass fractions during preparation

The variation of molecular mass distribution with the progress of the reaction was studied for the following: (i) sequential‐type melamine–urea–formaldehyde (MUF) resin formulations in which the sequence of addition of chemicals follows well‐defined species reactivity principles; (ii) a nonsequential MUF formulation in which simultaneous melamine and urea competition for formaldehyde yields a MF resin cocondensed with small amounts of urea. This resin became soaked with reacted and unreacted monomeric urea species. (iii) A PMUF resin, namely a MUF resin with a small proportion of phenol (7.8% by weight on melamine and urea) cocondensed with the main MUF fraction. All the formulations used were industrial resins formulations in current use. Development and variation of molecular mass fractions, from which performance and other useful resin parameters depend, have been found to depend on the type of resin formulation used for these type of aminoplastic resins. The two very different MUF resin formulations yielded different variations in molecular mass fractions during the progress of the reaction and during the so‐called ambient temperature “maturing” of the resin. The PMUF resin also showed both similar and different fractions present during manufacturing and during short term ageing at ambient temperature. While similarities in recurrent fractions and in trends are common to all the three different formulations, differences between them are also clearly observed. A major proportion of the reaction of some of the aminoplastic resins examined also occurs on ageing (i.e.“maturing” of the resin at ambient temperature), this appearing to be an essential phase of the resin preparation process. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4842–4855, 2006     

Synthesis,characterization, and metal adsorption properties of tannin–phenol–formaldehyde resins produced using tannin from dried fruit of Terminalia chebula (Aralu)

In this study, tannin extracted from Terminalia chebula (Aralu) was used to produce tannin–phenol–formaldehyde resins. They were produced to obtain resins with different tannin to phenol ratio in an attempt to optimize the ion exchange capacities of resins produced. The resins made were sulfonated to improve their properties further. Bivalent cations, such as Zn²⁺, Pb²⁺, Ca²⁺, Mg²⁺, and Cu²⁺, were used to estimate the adsorption properties of both unsulfonated and sulfonated resins. The glass transitions of representative resins were estimated using differential scanning calorimeter thermograms. Fourier transform infrared spectroscopic analysis was used to gauge changes on resins by sulfonation and adsorption of cations. The glass transition values of unsulfonated, sulfonated, and metal‐adsorbed sulfonated resins showed a similar increasing trend with the increase of phenol content in the resin. The glass transition temperature values reach a plateau beyond the tannin/phenol ratio of 1 : 0.5, indicating the formation of large molar masses facilitating entanglements beyond that ratio. The phenol ratio of 1 : 0.5 has shown the highest adsorption capacity for all the metal ions used. The highest adsorption capacity was shown for sulfonated tannin–phenol–formaldehyde resin with the tannin/phenol ratio of 1 : 0.5 for Pb²⁺, which is 0.610 meq/g. The adsorption equilibrium data obtained using the column technique were found fitting Freundlich isotherm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

新型液晶聚氨酯/环氧树脂复合材料的制备及性能

以联苯二酚,2,4-甲苯二异氰酸酯(2,4-TDI),乙二醇,N,N'-二(ω-羟乙基)均苯四甲酰二亚胺(BHDI)为单体,加成反应合成了1种同时含有联苯基和亚胺基的新型液晶聚氨酯(LCPBI),通过IR,DSC、偏光显微镜及X射线衍射仪对其结构和性能进行表征和分析。将该液晶聚氨酯与环氧树脂(E-51)共混制备了液晶聚氨酯/环氧树脂复合材料,通过力学性能测试,热重分析和电镜分析对其性能进行了研究并探讨了其增韧机理。结果表明,加入质量分数为3%的LCPBI,可使复合材料的冲击强度提高2.5倍,拉伸强度和弯曲强度也有不同程度的提高,热分解温度提高15～20℃。     

Structure and properties of epoxy resins modified with acrylic particles

The morphology and material properties of dicyandiamide (DICY)‐cured epoxy resins modified with acrylic particles consisting of a PBA (polybutyl acrylate) core and a PMMA (polymethyl methacrylate) shell and epoxy resins modified with acrylic rubber (PBA) particles alone were studied. It was found that the epoxy system modified with core/shell acrylic particles showed higher fracture toughness, indicating that the modification had a larger effect on improving the material properties of the epoxy resin. A characteristic shown by the core/shell acrylic particles is that they swell along with the epoxy resin under exposure to heat and gel before the latter cures. In this process, the epoxy resin penetrates the surface of the shell layer and a bond is formed between the epoxy matrix and the core/shell acrylic particles. This suggests that the epoxy matrix around the core/shell acrylic particles has the effect of increasing the level of energy absorption due to plastic deformation of the matrix. This is thought to explain why the epoxy resin modified with core/shell acrylic particles showed higher fracture toughness. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2955–2962, 1999     

环氧树脂改性超支化聚酯的合成及性能

以偏苯三酸酐、环氧氯丙烷及甲基丙烯酸缩水甘油酯为原料合成了超支化聚酯(HBP),再通过超支化聚合物的羧基与环氧树脂环氧基的反应得到环氧改性超支化聚合物;用GPC1、H-NMR、DSC、TGA表征了环氧改性超支化聚合物的结构和热性能;比较了不同环氧树脂用量改性前后树脂的光反应活性以及光固化涂层的耐擦洗性和硬度,测定了凝胶率-曝光时间曲线;以环氧改性超支化聚合物配制了光刻胶,在混合光源以及接触曝光的条件下,分辨率达到2~3μm,且图像十分清晰,断面整齐。环氧树脂用量为HBP羧基物质量的70%左右时,改性的超支化聚酯的光固化活性有明显提高,力学性能得到明显改进。     

不同固化剂下低摩尔比脲醛树脂热行为及胶接胶合板性能

通过对3种固化剂下5种低摩尔比脲醛树脂进行热分析和胶合板制造实验,研究了摩尔比、游离甲醛含量、固化剂种类等对低摩尔比脲醛树脂胶粘剂固化反应起始温度、峰顶温度、终止温度和胶合板胶合强度及其甲醛释放量的影响。实验结果表明:1)与传统的氯化铵固化剂相比,过硫酸铵催化的脲醛树脂的热分析曲线的起始温度和峰顶温度都很低,显示出良好的固化促进作用;2)以过硫酸盐作固化剂时,低摩尔比脲醛树脂固化过程中起始温度和峰顶温度受摩尔比的影响较小;3)摩尔比为1．0的脲醛树脂胶接胶合板的胶合强度也能够满足GB／T 9846．3-2004Ⅱ类胶合板的要求;4)用过硫酸盐作固化剂制备的胶合板的甲醛释放量较低。     

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。     

Lignocellulosic substrates influence on TTT and CHT curing diagrams of polycondensation resins

Lignocellulosic substrates such as wood were found to have a marked modifying influence on a well‐defined region of CHT diagrams during hardening of phenol–formaldehyde (PF) and urea–formaldehyde (UF) polycondensates. This was ascribed to more complex resin phase transitions due to resin/substrate interactions peculiar to these substrates. The chemical and physical mechanisms of the interactions of the resin and substrate causing such CHT diagram modifications are presented and discussed. The Di Benedetto equation describing the glass transition temperature T_g of the system as a function of the resin degree of conversion p has been slightly modified to take into account the modified CHT diagram. The modified CHT diagram can be used to good effect to describe the behavior of polycondensation resins when used as wood adhesives during their curing directly into the wood joint. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 915–925, 1999     

Separation of gold(III) ions from copper(II) and zinc(II) ions using thiourea–formaldehyde or urea–formaldehyde chelating resins

Thiourea–formaldehyde (TF) and urea–formaldehyde (UF) chelating resins were synthesized and these resins were used in the separation of gold(III) ions from copper(II) and zinc(II) base metal ions. In the experimental studies, the effect of acidity on gold(III) uptake and gold(III) adsorption capacities by batch method, and loading and elution profiles of gold(III) ions, gold(III), copper(II), and zinc(II), dynamic adsorption capacities and the stability tests of TF and UF resins by column method were examined. By batch method, the optimum acidities were found as pH 2 and 0.5M HCl, and gold(III) adsorption capacities in the solutions including copper(II) and zinc(II) ions were obtained as 0.088 and 0.151 meq Au(III)/g for UF and TF resins, respectively. On the other hand, by column method, the dynamic adsorption capacities were calculated as 0.109 meq Au(III)/g with TF, 0.023 meq Au(III)/g with UF, 0.015 meq Cu(II)/g with TF, 0.0057 meq Cu(II)/g with UF, and under 6.1 × 10^?5 meq Zn(II)/g with TF or UF. TF resin was more effective in the separation and the concentration of gold(III) ions from copper(II) and zinc(II) ions than UF resin. It was seen that sulfur atoms contributed the gold(III) adsorption comparing with oxygen atoms. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

新型含硼苯并噁嗪的合成及其与环氧树脂共混热性能

以乙醇胺、硼酸为原料合成硼酸乙醇胺酯（BAE）,再用所得硼酸乙醇胺酯与多聚甲醛、苯酚反应,合成含硼苯并噁嗪（BAE-BOZ）。将所得BAE-BOZ高温固化,BAE-BOZ和环氧树脂E-51按照不同的质量比进行熔融共混,并经高温固化。采用FT-IR,¹H NMR 和¹³C NMR等分析了BAE-BOZ的化学结构,证明了产物为目标产物;采用DSC对BAE-BOZ的固化特性进行研究;采用TG 分析了含硼乙醇胺型苯并噁嗪poly（BAE-BOZ）和BAE-BOZ/E-51共聚物的热稳定性。结果表明：BAE-BOZ在218℃出现了固化峰;BAE-BOZ的硼含量达到8.67%,在N₂条件下,poly（BAE-BOZ）的热分解温度为302℃,在426℃时热分解速率最快,800℃的残炭率为58.08%,与未经硼改性的乙醇胺型苯并噁嗪（E-BOZ）相比,热分解温度提高40℃,残炭率提高了16.28%;BAE-BOZ/E-51共聚物的热分解温度达到343℃,热性能得到进一步提高。