聚离子液体修饰碳纳米管及其对环氧树脂力学性能的影响

为改善多壁碳纳米管(MWCNTs)在环氧树脂(EP)中的分散性和界面性质,以1-乙烯基-3-丁基咪唑六氟磷酸盐([VBIM]PF6)为单体合成聚离子液体(PIL),用于MWCNTs的表面改性.用热重分析(TG),拉曼光谱(Raman)和扫描电镜(SEM)对改性碳纳米管(PIL-CNTs)进行了表征.结果表明,PIL可吸附在MWCNTs表面且不改变MWCNTs的电子结构.与原始MWCNTs相比,PIL-CNTs在丙酮中的分散性更好.在EP中加入0.5 wt%的PIL-CNTs,以4,4'-二氨基二苯甲烷(DDM)为固化剂制备环氧树脂固化物.动态力学(DMA)研究表明,PIL-CNTs提高了EP的储能模量,玻璃化温度比纯EP和MWCNTs/EP分别提高了5.6℃和3.3℃;PILCNTs/EP的拉伸强度,弯曲强度和冲击强度较纯EP分别提高了35.2%,26.4%和45.0%.拉伸断面的SEM可看出PIL-CNTs在复合材料中的分散性和与环氧树脂基体的界面结合力均优于原始MWCNTs.     

有机硅改性双酚A型环氧树脂研究

采用二氯二甲基硅烷 (DMS) ,或DMS与α ,ω 二氯聚二甲基硅氧烷 (DPS)的混合物来改性双酚A型环氧树脂 ,通过对固化物的冲击强度、拉伸强度、断裂伸长率和玻璃化转变温度 (Tg)的测定 ,探讨了改性方法、有机硅组成与含量等对材料性能的影响 .结果表明 ,用 5 7phr的DMS改性时 ,树脂固化物的冲击强度达2 0 2kJ m2 ,拉伸强度达 6 7 0MPa ,断裂伸长率达 11 2 9% ,Tg 达 16 8 0℃ ;分别比未改性时提高了 9 4kJ m2 ,2 1 1MPa ,5 4 %以及 32 6℃ .而用 0 7phrDMS +10phrDPS共同改性时 ,除Tg 和拉伸强度略有上升外 ,冲击强度达到了 31 6kJ m2 ,断裂伸长率达到 81 6 % ,分别比纯环氧提高了 2 0 8kJ m2 和 75 7% .     

纳米纤维素晶须的表面改性及其在环氧树脂中的应用

以棉纤维素为原料,采用硫酸水解法制备了纳米纤维素晶须.以N,N-二甲基甲酰胺(DMF)为分散介质,二甲基氨基吡啶(DMAP)为催化剂,十二烯基琥珀酸酐为酯化剂对纳米纤维素晶须进行化学改性,得到了一系列取代程度不同的改性产物(记为DCNW).采用红外光谱(FTIR)、X射线衍射(XRD)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等手段对DCNW的结构和性能进行了分析和表征.选择表面取代度为0.3的改性产物作为复合材料的增强相.该改性产物能在丙酮中均匀分散和稳定悬浮,并且保持了改性前纳米纤维素晶须的棒状形态和高结晶度.将其分散于环氧单体中,通过浇铸法制备了纳米复合材料,考察了改性纳米纤维素晶须添加量对纳米复合材料拉伸性能、动态力学性能及耐湿热性的影响规律.结果表明,与空白环氧树脂相比,添加了改性纳米纤维素晶须的纳米复合材料的拉伸强度、杨氏模量和断裂伸长率都得到了提高.玻璃化转变温度、耐湿热性也得到了显著改善.其中,当改性纳米纤维素晶须的添加量为3.5%时,拉伸强度从纯环氧的39.85 MPa提高到72.33 MPa,增加了82%;杨氏模量增大了21%;断裂伸长率从纯环氧树脂的2.45%提高到7.29%,增加了198%;Tg值从纯环氧的103.4℃,提高到134.1℃;吸水率从1.9%下降到1.4%.     

PVA改性PAMPS-PAM超高力学性能双网络水凝胶的制备

采用紫外光引发聚合制备了聚乙烯醇(PVA)改性的聚(2-丙烯酰胺基-2-甲基丙磺酸)-聚丙烯酰胺(PAMPS-PAM)双网络(DN)水凝胶.测定并比较了PVA改性前后PAMPS-PAM双网络水凝胶的溶胀动力学;通过扫描电子显微镜(SEM)观察了单网络水凝胶的结构;测定PVA改性前后PAMPS-PAM双网络水凝胶的压缩及拉伸性能.结果表明,经PVA改性后的PAMPS-PAM双网络水凝胶有较高的溶胀比;0.82%PVA用量的PAMPS-PAM双网络水凝胶在90%压缩形变率下仍保持完整、最大拉伸应力达到0.5 MPa,大幅提高PAMPS-PAM双网络水凝胶的力学性能.     

环氧改性水性聚氨酯乳液的制备及其膜性能

以聚己内酯二元醇(CAPA)为软段,异佛尔酮二异氰酸酯(IPDI)和六亚甲基二异氰酸酯(HDI)为硬段,环氧树脂E-44为大分子交联剂,经相转化法合成了一系列环氧树脂改性负离子水性聚氨酯(EPPU)自乳化乳液,并制备了改性水性聚氨酯的固化膜.通过FTIR、TGA及接触角、力学性能测试对聚合物结构及其膜性能进行了研究.通过原子力显微镜(AFM)观察膜表面形态和表面粗糙度.乳液粒径及粒径分布通过动态激光光散射法(DLLS)测定.FTIR分析表明环氧树脂的羟基和环氧基都参与了发应.TGA表明,环氧树脂的加入可以提高聚氨酯的热稳定性.随着w(E-44)增大,改性聚氨酯膜的拉伸强度得到改善,断裂伸长率减小.随着w(E-44)增大,乳液粒径增大,薄膜的接触角增大,改性后的PU膜表面光滑度下降,拒水性增强.     

咪唑基离子液体Br[C_(14)im](CH_2)_4[C_(14)im]Br对PP结构与性能的影响

应用Gemini型咪唑基离子液体和聚丙烯(PP)熔融共混,制备出Gemini型咪唑基离子液体改性PP,并对改性PP的结构与性能进行了表征与测试.研究结果表明,Br[C14im](CH2)4[C14im]Br添加到PP中后,起到了异相成核的作用,同时使PP晶体结晶度减小;添加离子液体的样品熔融峰温,结晶峰温与纯样相近,同时离子液体也诱导了PP中α晶的生成;Gemini型咪唑基离子液体可以提高PP的抗静电性能,加入量为3 phr时,表面电阻率为8.97×109Ωcm,抗静电性能优良;此外,添加离子液体后样品拉伸强度有所降低,冲击强度有所提高,断裂伸长率有所下降,降低了PP的玻璃化温度,说明离子液体对PP有增塑作用.     

聚苯氧基磷酸联苯二酚酯/聚磷酸铵膨胀阻燃剂对环氧树脂阻燃性能影响研究

以聚苯氧基磷酸联苯二酚酯(PBPP)与聚磷酸铵(APP)组成复合阻燃剂,对环氧树脂(EP)进行阻燃改性.通过氧指数(LOI)、垂直燃烧(UL-94)、热失重(TGA)、锥形量热(CONE)和扫描电镜(SEM)等方法研究改性环氧树脂的阻燃性能和阻燃机理.结果表明,PBPP/APP体系对EP具有较好的阻燃性能,阻燃剂添加量为10%时能使环氧树脂的氧指数提高到29.6%,垂直燃烧等级达到UL94 V-0级,残炭量大大增加;平均热释放速率下降45.7%,热释放速率峰值下降51.0%,有效燃烧热平均值下降21.1%;TGA、CONE、SEM等综合分析显示了PBPP/APP改性后的环氧树脂比纯环氧树脂具有更高的热稳定性,燃烧后能够形成连续、致密、封闭、坚硬的焦化炭层,在聚合物表面产生有效覆盖、隔绝了氧气,改善了环氧树脂的燃烧性能.     

双酚A型环氧改性R-122环氧树脂的研究

用双酚A环氧树脂(E-44)改性脂环类环氧树脂(R-122),通过对改性R-122环氧树脂力学性能和热性能的测定,探讨了固化工艺,固化荆体系对改性R-122环氧树脂韧性的影响。结果表明：改性R-122环氧树脂冲击强度提高40％,弯曲强度提高75％,断裂能提高81％,而热变形温度和玻璃化转变温度基本不变。R-122树脂基复合材料随E-44的加入冲击强度和弯曲强度分别提高12％和18％。     

气相生长碳纤维/形状记忆聚氨酯复合薄膜的力学及形状记忆性能研究

采用溶液混合法制备了不同含量的气相生长碳纤维(VGCF)增强形状记忆聚氨酯(SMPU)的复合材料薄膜,测试分析了纯SMPU及VGCF/SMPU复合材料薄膜的力学性能及形状记忆性能.结果表明,制得的复合材料薄膜在VGCF含量达到9 wt%时,VGCF在SMPU基体中仍具有较好的分散性;SMPU与VGCF复合后,得到的复合材料薄膜的拉伸强度和刚度有较大程度的提高,含量达到9 wt%时复合材料薄膜的拉伸强度比纯SMPU提高66%,弹性模量提高300%,储能模量也有较大程度提高;SMPU与VGCF复合后,形状记忆性能有一定的下降,但经过适当预处理后,其形状记忆性能可以基本接近纯SMPU.     

两种不同化学组成的超支化聚氨酯改性环氧树脂

利用芳香族二元异氰酸酯和脂肪族二元异氰酸酯分别与二乙醇胺反应,设计合成了不同化学组成的超支化聚氨酯,考察了其对环氧树脂的改性作用.运用核磁共振、傅里叶红外光谱(FTIR)、扫描电子显微镜(SEM)、弯曲、拉伸、冲击强度、储能模量、示差扫描量热法(DSC)以及热失重(TGA)等对超支化聚氨酯的结构及其性能进行了证实和表征,并发现基于芳香族超支化聚氨酯改性的环氧树脂共混体系表现出均相结构,而脂肪族超支化聚氨酯和环氧树脂共混后却形成了非均相体系.均相的共混体系证明超支化聚合物自身能够有效地改善环氧树脂的力学性能和热学性能.     

Pyrolysis and fire behaviour of epoxy resin composites based on a phosphorus-containing polyhedral oligomeric silsesquioxane (DOPO-POSS)

The pyrolysis and fire behaviour of epoxy resin (EP) composites based on a novel polyhedral oligomeric silsesquioxane containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-POSS) and diglycidyl ether of bisphenol A (DGEBA) have been investigated. The pre-reaction between the hydroxyl groups of DOPO-POSS and the epoxy groups of DGEBA at 140 °C is confirmed by FTIR, which means that DOPO-POSS molecules of hydroxyl group could easily disperse into the epoxy resin at the molecular level. The EP composites with the DOPO-POSS were prepared through a curing agent, m-phenylenediamine (m-PDA). The morphologies of the EP composites observed by SEM indicate that DOPO-POSS disperses with nano-scale particles in the EP networks, which implies good compatibility between them. The thermal properties and pyrolysis of the EP composites were analyzed by DSC and TGA, TGA-FTIR, and TGA-MS. The analysis indicates that the DOPO-POSS change the decomposition pathways of the epoxy resin and increase its residue at high temperature; moreover, the release of phosphorous products in the gas phase and the existence of Si-O and P-O structures in the residue Is noted. The fire behaviour of the EP composites was evaluated by cone calorimeter (CONE). The CONE tests show that incorporation of DOPO-POSS into epoxy resin can significantly improve the flame retardancy of EP composites. SEM and XPS were used to explore micro-structures and chemical components of the char from CONE tests of the EP composites, they support the view that DOPO-POSS makes the char strong with the involvement of Si-O and P-O structures.     

Organic/inorganic hybrid epoxy nanocomposites based on octa(aminophenyl)silsesquioxane

Octa(aminophenyl)silsesquioxane (OAPS) was used as the curing agent of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin. A study on comparison of DGEBA/OAPS with DGEBA/4,4′-diaminodiphenyl sulfone (DDS) epoxy resins was achieved. Differential scanning calorimetry was used to investigate the curing reaction and its kinetics, and the glass transition of DGEBA/OAPS. Thermogravimetric analysis was used to investigate thermal decomposition of the two kinds of epoxy resins. The reactions between amino groups and epoxy groups were investigated using Fourier transform infrared spectroscopy. Scanning electron microscopy was used to observe morphology of the two epoxy resins. The results indicated that OAPS had very good compatibility with DGEBA in molecular level, and could form a transparent DGEBA/OAPS resin. The curing reaction of the DGEBA/OAPS prepolymer could occur under low temperatures compared with DGEBA/DDS. The DGEBA/OAPS resin didn’t exhibit glass transition, but the DGEBA/DDS did, which meant that the large cage structure of OAPS limited the motion of chains between the cross-linking points. Measurements of the contact angle indicated that the DGEBA/OAPS showed larger angles with water than the DGEBA/DDS resin. Thermogravimetric analysis indicated that the incorporation of OAPS into epoxy system resulted in low mass loss rate and high char yield, but its initial decomposition temperature seemed to be lowered.     

碳纳米管改性环氧树脂的导热和阻燃性能

以双酚A二缩水甘油醚(DGEBA)环氧树脂(Epoxy Resin,EP)为基体、甲基六氢苯酐(MHHPA)为固化剂、以多壁碳纳米管(MWCNTs)为添加剂制备了环氧树脂/碳纳米管纳米复合材料。通过对微观结构、玻璃化转变温度(Tg)、热失重、热导率和锥形量热测试结果分析,研究了质量分数少于1.5%的MWCNTs对环氧树脂的导热和阻燃性能影响,结果表明,MWCNTs质量分数为1.5%时,复合材料发生团聚;纳米复合材料随着MWCNTs质量分数的增加Tg值先增加后降低;失重5%时,对应的温度先增加后降低,残炭量增加;样品的热导率呈现先升高后降低的趋势,当MWCNTs质量分数为1%时,复合材料的热导率最大;MWCNTs加入后环氧树脂的总释热量减少,释烟量增加,阻燃性得到一定程度的提高。     

Improving Thermal and Flame Retardant Properties of Epoxy Resin with Organic NiFe‐Layered Double Hydroxide‐Carbon Nanotubes Hybrids

To improve the dispersion of carbon nanotubes (CNTs) and flame retardancy of layered double hydroxide (LDH) in epoxy resin (EP), organic nickel‐iron layered double hydroxide (ONiFe‐LDH‐CNTs) hybrids were assembled through co‐precipitation. These hybrids were further used as reinforcing filler in EP. EP/ONiFe‐LDH‐CNTs nanocomposites containing 4 wt% of ONiFe‐LDH‐CNTs with different ratios of ONiFe‐LDH and CNTs were prepared by ultrasonic dispersion and program temperature curing. The structure and morphology of the obtained hybrids were characterized by different techniques. The dispersion of nanofillers in the EP matrix was observed by transmission electron microscopy (TEM). The results revealed a coexistence of exfoliated and intercalated ONiFe‐LDH‐ CNTs in polymer matrix. Strong combination of the above nanofillers with the EP matrix provided an efficient thermal and flame retardant improvement for the nanocomposites. It showed that EP/ONiFe‐LDH‐CNTs nanocomposites exhibited superior flame retardant and thermal properties compared with EP. Such improved thermal properties could be attributed to the better homogeneous dispersion, stronger interfacial interaction, excellent charring performance of ONiFe‐LDH and synergistic effect between ONiFe‐LDH and CNTs.     

Reinforcing epoxy resin through covalent integration of functionalized graphene nanosheets

A chemically converted graphene/epoxy (EP) resin nanocomposite has been developed through the use of the functionalized graphene nanosheets (FGNs). The FGNs were prepared via the reaction of amines with alkylcarboxyl groups attached to the graphite oxides in the course of a dicarboxylic acid acyl peroxide treatment. FGNs/EP composites were prepared by dissolving the FGNs in organic solvent followed by mixing with EP and curing agent. In this composite, the FGNs were able to create molecular entanglement with EP matrix by taking advantage of the reactions between amine groups of FGNs and EP groups of EP, thus the FGNs could be covalently integrated into the EP matrix and became part of the cross‐linked network structure rather than just a separated component. Great enhancement in the mechanical properties of the epoxy composite, such as the ultimate tensile strength and toughness, had been achieved with small loading (0.1 wt%) of FGNs by 17.0% and 262.2%, respectively. However, the FGNs reinforced EP composites showed a slight decrease in glass transition temperature (Tg). Copyright © 2014 John Wiley & Sons, Ltd.     

Toughness Behaviour of Vinylester/Epoxy Thermosets with Interpenetrating Network Structure

Vinylester/epoxy-based (VE/EP) thermosets of interpenetrating network (IPN) structure were produced by using a VE resin (bismethacryloxy derivative of a bisphenol-A type EP resin) and EP resins of aliphatic (Al-EP) and cycloaliphatic (Cal-EP) nature. Curing of the EP resins occurred either by an aliphatic (Al-Am) or a cycloaliphatic (Cal-Am) diamine compound. Dynamic mechanical thermal analysis (DMTA) and atomic force microscopy (AFM) suggested the presence of an interpenetrating network (IPN) in the resulting thermosets. AFM scans taken on the ion-etched surface of EP showed a featureless homogeneous structure. On the other hand, VE exhibited a two-phase microgel, whereas VE/EP a two-phase interpenetrating network (IPN) structure. Toughness was characterised by parameters of the linear elastic fracture mechanics, viz. fracture toughness (K_c) and fracture energy (G_c). Unexpected high K_c and G_c data were found for the systems containing cyclohexylene units in the EP network. This was attributed to beneficial effects of the conformational changes along the cyclohexylene linkages (chair/boat). The failure mode of the VE/EP thermoset combinations was studied by scanning electron microscopy (SEM) and discussed.     

Novel urethane/epoxy resin hybrid materials using a moisture‐curing system

Novel curing systems of a urethane/epoxy resin [diglycidyl ether of bisphenol A (DGEBA)] alloy using the moisture‐latent hardener ketimine (K‐systems) were investigated on the DGEBA‐rich side and were compared with aromatic diamine curing systems (A‐systems). Almost all the added DGEBA was separated from the polyurethane matrix and dispersed as 2–10‐μm‐diameter particles after curing in the A‐systems. Therefore, DGEBA did not act as a reinforcing agent for the polyurethane matrix. However, 50% of the added DGEBA was dispersed as particles with a diameter of 1–4 μm, and the other 50% was incorporated into the polyurethane matrix in the novel K‐systems. Therefore, the polyurethane matrix in the K‐systems should be reinforced effectively by both incorporated and finely dispersed DGEBA and should result in significant improvements in the stress–strain properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1137–1144, 2004     

聚吡咯改性层状黏土/聚己内酯抗菌纳米复合材料的制备与性能

利用Fe³⁺引发吡咯（Py）在层状双羟基金属氧化物（LDHs）表面发生氧化反应,形成聚吡咯（PPy）包覆LDHs（LDHs@PPy）;以LDHs@PPy和聚己内酯（PCL）为原料,采用溶液浇筑方法制备LDHs@PPy/PCL纳米复合薄膜.研究结果表明,LDHs@PPy对大肠杆菌和金黄色葡萄球菌的抗菌率均达到99.7%,其与基材PCL界面相容性良好,而且在基材中还具有异相成核作用.当LDHs@PPy的质量分数仅为1%时,LDHs@PPy/PCL纳米复合材料的拉伸强度和断裂伸长率分别增加35%和23%,氧气渗透性降低幅度达到56%,对大肠杆菌和金黄色葡萄球菌的抗菌率均超过99.99%,表现出良好的抗菌活性,拓展了层状黏土/生物基高分子复合材料在活性包装领域的应用.     

Free volume hole size of Cyanate ester resin/Epoxy resin interpenetrating networks and its correlations with physical properties

Cyanate ester (CE) resin was blended with epoxy resin (EP) at different mass ratios (CE/EP: 100/0, 90/10, 70/30, 50/50, 30/70, 10/90, and 0/100). The curing process of the blend system was characterized by Fourier transform infrared spectrometry (FTIR) and differential scanning calorimetry (DSC). Examination of the mechanical properties, thermal stability, and morphology of the blend systems showed that addition of epoxy resin resulted in improved toughness but a little sacrifice in thermal stability when compared with neat CE. The free volume size of the blend system determined by positron annihilation lifetime spectroscopy (PALS) decreased with the epoxy resin content, which is consistent with the chemical structure changes for the copolymerization between CE and EP. The crosslinking units of curing products (oxazoline, oxazolidinone, and polyether network) of the blends are all smaller in size than those of triazine ring structure from neat CE. Therefore, the free volume size of the blends decreases with increase of EP content. The correlations between the free volume properties and other physical properties (thermal stability and mechanical properties) have also been discussed.     

Improving the dispersion and flexural strength of multiwalled carbon nanotubes-stiff epoxy composites through β-hydroxyester surface functionalization coupled with the anionic homopolymerization of the epoxy matrix

Multiwalled carbon nanotubes (MWNTs) were functionalized in a two-step acid-epoxy functionalization process, in which suitable surface condition and reactivity compatible with the DGEBA epoxy resin was introduced. The use of (4-dimethylamino)-pyridine as an initiator for DGEBA homopolymerization produced covalent bonds between the functionalized MWNTs and the epoxy matrix through chain transfer reactions involving the secondary hydroxyls. This process yielded uniform MWNTs-stiff epoxy composites with significant enhancement in flexural strength without sacrificing the elastic modulus when compared to the neat resin.