Nanostructures and thermomechanical properties of epoxy thermosets containing reactive diblock copolymer

Polystyrene‐block‐poly(glycidyl methacrylate) reactive diblock copolymer (PS‐b‐PGMA) was synthesized via atom transfer radical polymerization (ATRP). The diblock copolymer was characterized using nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The cured epoxy thermosets with 10–20 nm PS particles were prepared by blending the diblock copolymer with epoxy resin. The nanostructures were examined by means of transmission electronic microscopy (TEM) and small angle X‐ray scattering (SAXS). The formation of the nanostructures was caused by the reaction‐induced microphase separation mechanism. It is significant that the glass transition temperatures (T_gs) of these epoxy thermosets were increased by the addition of PS‐b‐PGMA reactive block copolymer as revealed by both differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Fibre reinforced composites of multifunctional epoxy resins

Glass and carbon fibre reinforced epoxy composites were fabricated for N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenyl methane (TGDDM) and its formulated systems with tri- and di-functional reactive epoxy diluents using 30% diaminodiphenyl sulphone (DDS) as a curing agent. The epoxy laminates were evaluated for their physical, chemical and mechanical properties [at room (26°C) and high (100°C) temperatures]. A marginal increase (<20%) in the mechanical properties of CFRP was found compared with GFRP laminates. Incorporation of epoxy diluents altered the mechanical properties of the composites significantly. The incorporation of triglycidyl-4-aminophenol diluent to TGDDM systems resulted in an improvement in mechanical properties of about 2–6%.     

Effect of the addition of aramid-CTBN block copolymer on adhesive properties of cured epoxy resins modified with CTBN

To improve the bond strength of carboxy-terminated butadiene acrylonitrile (CTBN)-modified epoxy resin, aramid-CTBN block copolymer was used as an additive to a bisphenol-A-type epoxy resin modified with CTBN. With the addition of aramid-CTBN block copolymer, the fracture energy values of the adhesive joints were more than twice that of the CTBN-modified system and about twelve times that of the unmodified system. Observations of the adhesive layers using an optical microscope revealed that the width of the damage zone near the crack-tip in the double cantilever specimen increased with the addition of the aramid-CTBN block copolymer. TEM micrographs showed that the diameter of the CTBN-dispersed phases decreased and a number of fine CTBN phases were dispersed in the epoxy matrix with the addition of the block copolymer. It is concluded that addition of the block copolymer leads to an increase in the dispersibility of the CTBN elastomer into the epoxy matrix and thus the bond strength of the block copolymer-added system is increased due to the increase in the area of the damage zone and the occurrence of shear deformation of the epoxy matrix.     

丁苯嵌段共聚物结构与性能研究

以苯乙烯（St）、丁二烯（Bd）为单体,正丁基锂为引发剂,通过阴离子聚合合成了丙烯腈-丁二烯-苯乙烯（ABS）改性用丁苯嵌段共聚物（LBS）。探讨了聚合温度、加料工艺对产品分子结构及性能的影响规律。详细分析了相对分子质量及其分布、结合St质量分数、分子结构参数、St序列分布与产品性能的关系,探讨了影响产品生胶门尼粘度（MV）的关键因素。合成出了可用于连续本体ABS改性的LBS新产品,并进行了连续本体ABS改性性能评价实验。     

Morphology and thermomechanical properties of epoxy thermosets modified with polysulfone‐block‐polydimethylsiloxane multiblock copolymer

Polysulfone‐block‐polydimethylsiloxane (PSF‐b‐PDMS) multiblock copolymer was synthesized via the Mannich polycondensation between phenolic hydroxyl‐terminated polysulfone and aminopropyl‐terminated polydimethylsiloxane in the presence of formaldehyde. The multiblock copolymer was characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC) and used as a modifier to improve the thermomechanical properties of epoxy thermosets. Transmission electron microscopy (TEM) showed that the epoxy thermosets containing PSF‐b‐PDMS multiblock copolymer possesses the microphase‐separated morphological structures. Depending on the content of the PSF‐b‐PDMS multiblock copolymer, the spherical particles with the size of 50–200 nm in diameter were dispersed into the continuous epoxy matrices. The measurement of static contact angles showed that with the inclusion of PSF‐b‐PDMS multiblock copolymer, the epoxy thermosets displayed the improved surface hydrophobicity. It is noted that the epoxy resin was significantly toughened in terms of the measurement of critical stress field intensity factor (K_1C). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

添加剂对镍系催化苯乙烯-丁二烯-苯乙烯嵌段共聚物加氢的影响

考察了镍系催化剂用于苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)加氢时添加剂对加氢反应的影响。结果表明,六甲基磷酰三胺(HMPA)是一种较好的添加剂。催化剂的最佳陈化方式为：于50℃将HMPA加入到环烷酸镍(简称Ni)中,使其充分络合,然后加入三异丁基铝(简称Al)。在65℃。1．96MPa的条件下,当Ni用量为0．001g/g,HMPA/Ni(摩尔比)为1．0,Al/Ni(摩尔比)为6～8时。可制得氢化度大于98％的氢化SBS。     

氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物研究进展

概述了氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物(SEBS)国内外生产状况,介绍了SEBS生产工艺技术及其加氢催化剂的开发进展,提出应加强SEBS的改性及应用技术开发,在国内尽快实现SEBS的规模化工业生产。     

Nanostructured thermosets from self‐assembled amphiphilic block copolymer/epoxy resin mixtures: effect of copolymer content on nanostructures

Nanostructure formation in thermosets can allow the design of materials with interesting properties. The aim of this work was to obtain a nanostructured epoxy system by self‐assembly of an amphiphilic diblock copolymer in an unreacted epoxy/amine mixture followed by curing of the matrix. The copolymer employed was polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA). The thermoset system, formed by a diglycidyl ether of bisphenol A‐type epoxy resin and diaminodiphenylmethane hardener, was chosen to ensure the miscibility of most of the PMMA block until matrix gelation. Transparent materials with microphase‐separated domains were obtained for copolymer contents lower than 40 wt%. In systems containing 20 and 30 wt% block copolymer, the PS block formed spherical micelles or worm‐like structures before curing, which were stabilized through curing by the more compatible PMMA block phase. Nanostructured thermoset systems were successfully synthesized for self‐assembled amphiphilic block copolymer–epoxy/amine mixtures for copolymer contents lower than 40 wt%. Copyright © 2009 Society of Chemical Industry     

交联型竹粉/苯乙烯-异戊二烯嵌段共聚物/溴化丁基橡胶吸振复合材料

将竹加工的边角料粉碎并用乙烯基三(β-甲氧基乙氧基)硅烷偶联剂处理,再与苯乙烯-异戊二烯嵌段共聚物和溴化丁基橡胶的共混物进行复合,在过氧化二异丙苯(DCP)引发剂的作用下制得交联型橡胶吸振复合材料.用硫化仪考察了不同温度下材料转矩随时间的变化情况,并对材料的动态力学性能进行了分析.结果表明,最佳混炼温度是125～155℃(控制物料的实际温度不超过145℃);在170 ℃下用DCP引发交联可得到外观平整光滑的具有类似竹材加工性的复合材料;当竹粉和DCP用量分别为45份(质量,下同)和0.8份时,复合材料具有较好的力学性能、较宽的玻璃化转变温度范围和较大的损耗因子,吸振减震性能较好,但上限使用温度应不超过150℃.     

嵌段共聚物PEO—PPO—PEO增韧环氧树脂的研究

采用嵌段共聚物PEO—PPO-PEO对环氧树脂进行增韧改性。结果表明,PEO—PPO—PEO对环氧树脂具有较好的增韧改性作用,PEO—PPO—PEO／EP／MeTHPA体系的冲击强度随着嵌段共聚物含量的增加而增大,而对拉伸强度影响较小。当F38质量分数为20％时,固化物的冲击强度能提高190％,而拉伸强度仅下降6．2％。TG测试结果表明,PEO—PPO—PEO的加入对环氧固化物的热性能影响不大。     

对称型双端过渡态丁二烯/苯乙烯嵌段共聚物的性能研究

采用以双卤代烷烃取代型双锂齐聚物为引发剂、环己烷为溶剂、丁二烯 (B)、苯乙烯 (S)单体一次加入的方法 ,合成了对称型双端过渡态丁二烯 /苯乙烯嵌段共聚物S— (S/B)—B— (B/S)—S ,并对其性能进行了研究。结果表明 ,对称型双端过渡态丁二烯 /苯乙烯嵌段共聚物具有明显的海岛两相结构 ,嵌段共聚物存在两个玻璃化温度 ;随着单体配比 (质量比 )S/B的增大 ,嵌段共聚物的各项物理性能变化趋势不明显。     

Impact resistance of fibrous glass reinforced plastics using polycarbonate‐polydimethylsiloxane block copolymer

By using reactive polydimethylsiloxanes that have phenolic hydroxyl groups at the ends of the chain, a polycarbonate‐polydimethylsiloxane (PC‐PDMS) block copolymer was prepared, and the properties of fibrous glass reinforced plastics (GF‐PC) using this copolymer were examined. The Izod impact value of the PC‐PDMS/GF composite increases with an increase in the degree of polymerization of reactive PDMS (n) between 40 and 160. When n is 40, the Izod impact value of the PC‐PDMS/GF composite is equal to that of the PC/GF composite. The Izod impact value is independent of the PDMS content of the copolymer when it is between 2 and 4 wt %. The PC‐PDMS/GF composite is superior, in the balance between fluidity and impact resistance, to the PC/GF composite. From the results of SEM, adhesion between the polymer and GF of the PC‐PDMS/GF composite is superior to that of the PC/GF composite. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1123–1127, 2002     

Theoretical study on morphology of ABCD 4-miktoarm star block copolymer

A real-space implementation of the self-consistent field theory (SCFT) has been used to study the morphologies of ABCD 4-miktoarm star block copolymers. For the sake of numerical tractability, the morphologies and the phase diagrams of ABCD 4-miktoarm star block copolymers are investigated in two dimensions (2D) by varying the volume fractions of the blocks and the interaction parameters. Many interesting and complex morphologies occur and compared with ABCD linear block copolymers; ABCD 4-miktoarm star block copolymers have more regular disciplines. We found that systems with similar components have similar morphologies and at the weaker segregation, the minority components always cannot separate from the other blocks and they easily dissolve to form one phase with other block(s), but with the increase of the segregation degree (large ), the ordered phases can be well separated. With the help of our computational prediction, experimental researchers can work more purposefully and efficiently.     

苯乙烯-异戊二烯-苯乙烯(SIS)嵌段共聚物的镍系催化加氢

Ni(naph) 2 /Al(i-Bu) 3 常温、常压催化SIS加氢的研究结果表明 ,反应只发生在PIp中的不饱和双键上 ,苯环不参与加氢反应 ;实验条件下 ,PIp中的 3,4-链节、1,4-链节具有相同的加氢活性 ;在 5 0℃、0 .1MPa氢压、1.90× 10 -4 mol/g·SIS的Ni用量、Al与Ni的摩尔比为 5时 ,SIS的加氢度可达92 .6 %;陈化后的催化剂显示出较高的加氢活性。     

Mechanical properties–morphology relationships in nano‐/microstructured epoxy matrices modified with PEO–PPO–PEO block copolymers

Epoxy‐based blends containing poly(ethylene oxide)‐co‐poly(propylene oxide)‐co‐poly(ethylene oxide) (PEO–PPO–PEO) block copolymers with different PEO/PPO molar ratios have been investigated in order to analyze the effect of the generated morphologies and interactions between components on the mechanical properties of the blends. Mechanical, morphological and dynamic mechanical analyses indicate that the observed increase of flexural modulus can be related to the decrease of free volume. In modified systems that remain miscible, an increase of flexural modulus, strength and fracture toughness can be observed. Also, macrophase‐ and microphase‐separated systems show an increase of fracture toughness but not of flexural modulus and strength at low contents of block copolymers. Copyright © 2007 Society of Chemical Industry     

荧光环氧琥珀酸共聚物的合成及性能研究

以2-氨基噻唑和自制的环氧琥珀酸盐（ESA）为原料合成了含荧光标记的环氧琥珀酸共聚物,研究了产物的荧光性能和阻垢、缓蚀性能。实验表明,该荧光标记聚合物的荧光强度与其浓度呈一定的线性关系;在浓度为20 mg/L的条件下,该聚合物的阻垢率达到85%,缓蚀率为56.18%。     

Microstructure and performance of block copolymer modified epoxy coatings

The effects of two diblock copolymers, poly(ethylene-alt-propylene)-b-poly(ethylene oxide) (PEP–PEO) and poly(1,2-butadiene)-b-poly(2-vinyl pyridine) (PB–P2VP) on the mechanical properties of epoxy coatings were studied. Both modifiers self-assembled into spherical micelles of 10–20 nm diameter in cured bulk epoxy. This morphology was preserved in 15 μm thick coatings; however, micelle segregation to the coating/substrate interface was also observed. The critical strain energy release rate, G_1c, of bulk thermosets was enhanced by up to fivefold with the addition of block copolymers. Likewise, the abrasive wear resistance of thin coatings increased with modifier inclusion. The results showed that at 5 wt.% of loading, block copolymers were able to impart a 40% increase in abrasive wear resistance to modified coatings over neat ones. Block copolymer modifiers did not sacrifice the modulus and glass transition temperature of bulk thermosets and coatings, or the hardness and transparency of coatings.     

Cooling rate and dilution affect the nanostructure and microstructure differently in model fats

The effects of cooling rate and solid mass fraction on the polymorphism, nano and microstructure, thermal and rheological properties of binary mixtures of fully hydrogenated canola oil and canola oil at 20°C have been studied. The β‐polymorph was observed in fully hydrogenated canola oil (FHCO) when crystallized at slow cooling rates (0.1C°/min), however crystallization at higher cooling rates (0.7 and 10°C/min) resulted in the formation of the α form. The β‐polymorph was detected in all the binary mixtures of FHCO/canola oil and was not affected by crystallization at different cooling rates. Melting thermograms obtained from 100% FHCO displayed three melting peaks, associated with the development of the β‐polymorph via α→ β′→ β‐polymorphic transition in the DSC pan. Some solubilization of solid FHCO into canola oil was observed and the solubility was proportionally higher with increasing liquid oil fraction. The strong influence of the matrix concentration on micro/nanoscale structure was demonstrated by characterization of crystal size using cryogenic transmission electron (Cryo‐TEM) and polarized light microscopy (PLM). Crystallization under higher cooling rates lead to formation of smaller nano and meso‐structural elements. Furthermore, oscillatory rheology showed the influence of structural elements' size and polymorphism on material strength. The shear storage modulus (G′) of the mixtures was higher when crystallized at fast cooling rates (10°C/min). In contrast, for pure FHCO, G′ increased by lowering the cooling rate and the highest storage modulus was observed after crystallization at 0.1°C/min.     

Asphaltenes as a tackifier for hot-melt adhesives based on the styrene-isoprene-styrene block copolymer

The use of heavy crude oil asphaltenes and resins (termed asphaltenes) as the components of hot-melt adhesives based on the styrene-isoprene triblock copolymer was considered. The rheological, thermophysical, strength, and adhesive characteristics of the mixtures containing from 10 to 40 wt% of asphaltenes were studied. The addition of 10 to 20 wt% of asphaltenes enhanced the strength and adhesive properties of the mixtures and only slightly changed their rheology. The higher concentrations of asphaltenes reduced the viscosity of the mixtures but did not lead to improved characteristics of the adhesives. The ambiguous effect of asphaltenes is probably due to their uneven distribution between the microphases of the block copolymer as well as their ability to act both plasticizers and reinforcing particles depending on temperature. A comparison of asphaltenes and conventional tackifiers based on hydrocarbon resins revealed their comparable effect on the properties of the block copolymer.