聚醚酰亚胺对共聚双马来酰亚胺树脂的增韧作用

采用二烯丙基双酚A、烯丙基酚醛改性4,4'-二氨基二苯甲烷双马来酰亚胺共聚制备了一类新型的双马来酰亚胺树脂(简称ABD)。以ABD为基体,选用热塑性树脂聚醚酰亚胺(PEI)为增韧剂,采用共混法制备了共聚双马来酰亚胺/聚醚酰亚胺(PEI)树脂体系。采用DSC和流变仪对ABD树脂的固化行为进行了研究,结果表明,该树脂粘度较低,室温下为液态,树脂的冲击强度为8.99 kJ/m2。通过DMA、TGA和扫描电镜对PEI加入量对树脂热性能和微观形貌的影响表明,添加质量分数为15%聚醚酰亚胺时,树脂冲击强度达到16.9 kJ/m2,比基体树脂提高了88%。     

Universal aspects of composite viscoelastic behavior

The viscoelastic behavior of a series of vinyl ester resins and E-glass fiber-reinforced composites is discussed. It is shown that the temperature shift factors for these systems, and others, suggests a universal behavior. A similar observation is made for the aging shift rate. On the other hand, the temperature dependence of compliance components per se appear to differ from system to system. Finally, it is shown that the retardation spectra for the vinyl ester resin and composites systems are the same to within a multiplicative constant in the glassy and in the short time transition regions. This shows that the presence of fibers has no influence on the distribution of retardation times in those regions.     

Environmental stress cracking of poly(butylene succinate)/cellulose triacetate blend films

Blend films of poly(butylene succinate) (PBS) with cellulose triacetate (CTA) were prepared using a solvent‐cast technique. The environmental stress cracking (ESC) behavior of commercial PBS films and that of as‐prepared PBS/CTA blend films were investigated in an aqueous NaOH solution. It was found that the fracture behavior of PBS films can be analyzed by linear fracture mechanics, that is, the stress‐intensity factor, K, is found to control the crack‐growth rate, da/dt, in PBS films. The enhancement of da/dt induced by increasing the normality of NaOH(aq) is more marked at a high value of K rather than at a low value of K. Furthermore, the ESC behavior of the PBS/CTA blends was studied in NaOH(aq). It was found that the behavior cannot be analyzed by linear fracture mechanics and that the addition of CTA into PBS increases the ESC resistance of the blends. Large‐scale yielding of the material around the crack tip seems to be responsible for the high ESC resistance of the blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 510–515, 2003     

聚醚酰亚胺/环氧树脂体系的固化及相分离行为研究

环氧树脂固化物本征的低韧性是限制其在复合材料应用的主要缺点之一。利用高性能热塑性树脂聚醚酰亚胺(PEI)与环氧树脂共混,系统研究了PEI在环氧树脂中的溶解行为、固化行为以及相分离行为。溶解试验表明:PEI与环氧齐聚物具有良好的相互溶解性;同时,PEI的加入降低了环氧树脂固化反应的活化能,但并没有改变其固化反应的机制。扫描电镜结果显示:随着PEI含量的增加,环氧/PEI浇铸体的相形貌从明显的分散颗粒相结构演变为双连续相结构和反转相结构。     

Reinforcing effect of organoclay in rubbery and glassy epoxy resins,part 1: Dispersion and properties

The reinforcing effect of organoclay in two epoxy matrices, one rubbery and one glassy, was studied. The rubbery and glassy epoxy matrices were chosen to have a very similar chemistry to minimize its impact on the comparison of properties. The epoxy resin was EPON? 828, and the two hardeners were amine‐terminated polyoxypropylene diols, having different average molecular weights (MW) of 2000 and 230 g/mol, namely Jeffamine® D‐2000 and Jeffamine® D‐230, respectively. The nanocomposites were prepared with the organoclay Cloisite® 30B from Southern Clay Products. The quality of dispersion and intercalation/exfoliation was analyzed by means of X‐ray diffraction (XRD), field emission gun scanning electron microscopy (FEGSEM), and transmission electron microscopy (TEM). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to study the curing reactivity and the thermal stability of the epoxy resin systems, respectively. Tensile properties and hardness of epoxy resin and epoxy nanocomposites were measured according to ASTM standards D638‐02 and D2240‐00, respectively. Fracture surfaces were also analyzed by FEGSEM. These two epoxy systems as well as their nanocomposites display totally different physical and mechanical behavior. It is found that the quality of clay dispersion and intercalation/exfoliation, and the mechanical behavior of the glassy and rubbery epoxy nanocomposites are distinct. The results also indicate that the presence of the clay does not significantly affect the T_g of either the rubbery or the glassy epoxy; however, the fracture surface and mechanical properties were found to be influenced by the presence of nanoclay. Finally, several different reinforcing mechanisms are proposed and discussed for the rubbery and glassy epoxy nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Cure kinetics and physical properties of dicyanate/polyetherimide semi‐IPNs

The curing behavior and physical properties of dicyanate/polyetherimide (PEI) semi‐interpenetrating polymer network (IPN) systems were investigated. Differential scanning calorimetry (DSC) was used to study the curing behavior of the dicyanate/PEI semi‐IPN systems. The curing rate of the semi‐IPN system decreased as the PEI content increased. An autocatalytic reaction mechanism can describe well the curing kinetics of the semi‐IPN systems. The reaction kinetic parameters were determined by fitting DSC conversion data to the kinetic equation. The glass transition temperature of the semi‐IPNs decreased with increasing PEI content. Two glass transitions due to phase‐separated morphology were observed for the semi‐IPN containing over 15 phr (parts per hundred parts of dicyanate resin) PEI. The thermal stability and dynamic mechanical properties of the semi‐IPNs were measured by thermal analysis.     

聚醚酰亚胺对炭黑填充环氧树脂复合材料导电性能和吸波性能的影响

利用反应诱导方法设计制备了炭黑(CB)包覆环氧树脂(EP)微球/聚醚酰亚胺(PEI)(EP/PEI/CB)复合材料。研究了该复合材料的微观结构,测量了其导电性能及在Ka波段的吸波性能,并与CB填充EP(EP/CB)复合材料进行了对比。结果表明,在EP/PEI/CB中,CB选择性分布在PEI相中并形成较规则的立体网状连续相,EP为30μm左右大小的微球分散相,与EP/CB相比具有更低的体积电阻率。EP/PEI/CB属于一种谐振腔式吸波体,在33～40 GHz范围具有较好的吸波性能且优于EP/CB,最大吸收峰出现在35.61 GHz,峰值反射率(R)为–17.40 dB,吸收带宽3.22 GHz(R–10 dB).     

新型聚醚酰亚胺改性环氧树脂结构粘合剂

用新型聚醚酰亚胺 (PEI)改性四官能环氧树脂可以获得高强度、能长期耐温 2 0 0℃以上的结构粘合剂。基础研究表明 ,剪切强度除与加入的PEI量有关外 ,还与PEI分子质量、固化剂DDS用量等因素有关 ,其原因是不同的相结构所致     

Fracture Behaviour of Thermoplastic Modified Epoxy Resins

This work has shown that the addition of polyetherimide (PEI) can significantly increase the toughness of highly cross-linked epoxy resins, whilst retaining a high T_g and modulus. These combined properties indicate the potential of PEI modified epoxy resins for use as matrices for advanced composite materials. In terms of G_IC, addition of 20wt% PEI raised the toughness by a factor of eight. Evidence from SEM fracture surfaces suggests that the toughening mechanism operating in bulk PEI modified epoxy resin is ductile drawing of the PEI. Carbon fibre composites based on 30wt% PEI modified epoxy resin matrices show considerable improvement in toughness at low and high strain rates when compared with CFRP possessing unmodified or 20wt% modified PEI content epoxy resins.     

New porous carbon materials,Woodceramics: Development and fundamental properties

Woodceramics are new porous carbon materials obtained by carbonizing wood or woody material impregnated with thermosetting resin such as phenol resin in a vacuum furnace. During the carbonizing process, thermosetting resin changes into glassy carbon, which has superior corrosion resistance and mechanical strength, reinforces the material and suppresses the fissures and warps (caused by the porous structure specific to wood) that develop during thermoforming. The dimension, weight decrease rate, and electrical characteristics depend on the thermoforming temperature. The manufacturing method of Woodceramics is introduced in this paper and various industrial uses, such as electromagnetic shields, are discussed.     

聚醚酰亚胺对共聚双马树脂的增韧作用

采用聚醚酰亚胺(PEI)来提高共聚双马树脂的断裂韧性。实验结果表明,PEI是共聚双马树脂的有效增韧剂;分别加入10份和12.5份的PEI,可使共聚双马树脂的断裂韧性(GIC)分别提高到650J/m2和805J/m2,弯曲模量变化不大,弯曲强度则小幅度下降。用扫描电子显微镜(SEM)和动态力学分析(DMA)研究了改性树脂体系的微观结构,发现其断裂韧性主要与相态结构有关。     

PEI及其改性物增韧环氧树脂研究

综述了Polyetherimide (PEI)及其改性物对环氧树脂的增韧研究进展。由于体系的相态结构是决定材料力学性能的重要因素 ,通过对PEI增韧TGDDM/DDS、Epikote82 8/DEAPA、TGAP/DAP、MY0 510 /DDS及HPT10 71/HPT10 61M等环氧树脂材料改性前后的相态结构和力学性能进行了分析比较 ,认为PEI对环氧树脂体系的增韧改性是成功的。     

Poly(ether imide)‐modified benzoxazine blends: Influences of phase separation and hydrogen bonding interactions on the curing reaction

Polymer blends of polybenzoxazine (PBZ)/poly(ether imide) (PEI) were prepared by the in situ curing reaction of benzoxazine (BZ) resin in the presence of PEI. Phase separation induced by the polymerization of BZ resin was observed. The rheological behaviors, morphologies, and their evolution process of BZ/PEI blends were investigated by rheometer and scanning electron microscope. Phase separation that took place at the early stage of the curing reaction effectively reduced the dilution effect of PEI. Fourier transform infrared (FTIR) results suggested that hydrogen bonds between PBZ and PEI existed during the whole curing process, although weakened with phase separation. The decrease of isoconversion activation energy indicated that the polymerization of BZ resin was facilitated in the presence of such kind of hydrogen‐bonding interactions. By changing the weight fraction of PEI, extensive phase separation was obtained in PBZ blends with 5 and 20 wt % of PEI, in which systems, the crosslinking density and glass transition temperature (T_g) of PBZ‐rich phase were greatly improved compared to this single PBZ system. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Combination of lignin polyol–tannin adhesives and polyethylenimine for the preparation of green water‐resistant adhesives

In this study, a green adhesive from renewable lignin and tannin was developed with polyethylenimine (PEI) with a method to improve the water resistance of the lignin/tannin adhesive. Lignin polyols were prepared through the liquefaction of oil‐palm empty fruit bunches. The characteristics of the adhesive samples were compared with those of a commercial phenol–formaldehyde resin. Three plywood specimens bonded with the new adhesive showed a very high tensile strength (63.04 MPa) and were very water resistant. The effect of the solid content of the adhesives on the tensile strength and gel time and various weight ratios of PEI on the tensile strength and water resistance of the plywood specimens were evaluated. Thermal stability tests revealed that the lignin polyol–tannin/PEI adhesives had a high heat resistance (360 °C). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43437.     

Properties of bismaleimide resin modified with polyrotaxane as a stress relaxation material

In this study, 4,4′‐diphenylmethane bismaleimide (BMI)/2,2′‐diallylbisphenol A (DABPA) resin was modified with polyrotaxane (PR) as a stress relaxation material. Based on a dynamic mechanical analysis and various properties of the cured resin, the influence of the motion of PR on the cured properties of BMI/DABPA/PR alloy is discussed. The cyclic molecule α‐cyclodextrin (α‐CD) that is threaded onto the PR axis contains a methacryl group in its side chain that reacts with the allyl group of BMI/DABPA resin. The methacryl group of PR reacted with the allyl group of BMI/DABPA matrix resin to form a transparent and dense network structure, so that the glass transition temperature was increased with increasing PR concentration. In addition, the toughness, impact resistance and adhesiveness of BMI/DABPA resin were improved by modification with PR. These results indicate that the poly(ethylene glycol) chain, which is the axial polymer of the PR, moves in the space formed by the cavities of the threaded α‐CD and the surrounding BMI/DABPA resin matrix in the glassy state, thereby relaxing the internal stress applied to BMI/DABPA/PR resin. The range of applications of BMI/DABPA resin modified with PR may expand into fields requiring high heat resistance in addition to excellent toughness and adhesiveness. © 2018 Society of Chemical Industry     

Reversible Photochromic Nanofiber Membrane Containing Comb‐Like Poly(octadecyl acrylate) Nanoparticles Used for Ultraviolet Intensity Indicator

A novel reversible photo‐responsive polyvinyl alcohol (PVA)/polyethylenimine (PEI) electrospinning nanofiber membrane (NFM), assembled with photochromic nanoparticles containing spiropyran, is herein presented and the water resistance, mechanical properties as well as photochromic properties are investigated systematically. Here, glutaraldehyde, which can undergo a cross‐linking reaction with PVA/PEI, is selected as a cross‐linker to enhance water resistance and mechanical behavior of the NFM. Photochromic polymer nanoparticles are prepared using octadecyl acrylate as polymer matrix monomer through miniemulsion polymerization. Effect factors of the whole preparation process such as the PVA/PEI mass ratio, the amount of emulsifier, and the amount of photochromic nanoparticles added are regulated to obtain the optimal experimental parameters. The surface morphology and microstructure, water resistance, and mechanical properties of NFMs are studied by thermal field emission scanning electron microscopy, static water contact angle tester, and tensile universal testing machine, respectively. Furthermore, UV–vis spectrophotometer is employed to investigate the photochromic performance and fatigue resistance of NFMs. Overall, analyses reveal that the reversible photo‐responsive electrospinning NFM exhibit excellent photoresponsivity, photoreversibility, and fatigue resistance upon UV irradiation, thus showing promising application in the field of ultraviolet intensity indicator.     

Acrylic resin reinforcement of reconstituted collagen films

The protein collagen is a major constituent of mammalian tissue. Treatment of calfskin with an enzyme under acid conditions simultaneously solubilizes much of the collagen and removes non-helical telopeptides which are believed to contribute to immune response. Then, the solid collagen can be reconstituted by precipitating the solubilized material with weak alkali. Films from the enzyme-treated, acid-soluble collagen are strengthened by cross-linking with glutaraldehyde. Composite films are made by coprecipitating collagen (from a solution) with an acrylic resin (from a latex). In one example, an acrylic resin to collagen ratio of 1:3 gives a wet-tensile strength about 30 percent higher than that for collagen alone. The tensile strength range of these wetted films (20 to 30 megapascals) is typical of the upper range for such limp films as polyethylene. On the other hand, ‘bone-dry’ collagen has a higher strength similar to that of glassy polymers such as polystyrene.     

单层流延膜专用树脂结构及性能研究

以利用Unipol气相聚乙烯中试装置自主研发的熔体流动速率为3.5 g/10 min的单层流延膜专用树脂为目标产品,同时收集市场上典型的同类进口产品,对2种产品的分子链结构进行了对比剖析,研究了分子链结构对产品性能的影响。结果表明,自主研发产品与进口产品的相对分子质量及其分布相当,序列结构分布相似,共聚单体在聚合物分子链中独立存在,并且分布均匀,但自主研发产品的级分分布与进口产品不同,结晶行为存在差异,这种差异使得自主研发产品的冲击、撕裂性能优于进口产品,而拉伸及光学性能相对略差。