改良的扭摆法在橡胶增韧环氧树脂的动态力学性能测定中的应用

对扭摆法进行改进后,测试了聚丙烯酸丁酯橡胶增韧环氧树脂固化的动态力学行为。研究了橡胶加入量和官能度对动态力学性能的影响,并对影响橡胶玻璃化转变温度移动的因素进行了讨论。     

丁腈羟增韧环氧树脂时间—温度—转变固化图

用扭辫分析的方法研究了端羟基液体丁二烯－丙烯腈共聚物增韧环氧树脂的固化行为，得到了增韧和未增韧环氧树脂的时间－温度－转变固化图并进行了比较。这些结果对理解增韧环氧树脂的形态和力学性能以及优化固化条件是很有用的。     

核壳颗粒增韧改性环氧树脂基体研究评述

环氧树脂(EP)具有优异的性能,被广泛应用在涂料、胶黏剂、复合材料等领域,但是其交联密度大,抗裂纹萌生和扩展能力差,因此,EP的增韧改性一直是国内外学者的研究重点。核壳颗粒(CSP)作为第二相加入EP中能达到良好的增韧效果,同时不会引起热力学性能的大幅损失,相较于传统增韧剂有较大的发展前景。本文在阐述EP的不同增韧机理的基础上,介绍了CSP增韧剂的增韧机理、主要类型及制备方法,评述了CSP材料、颗粒粒径、核壳比等因素对EP力学性能影响的研究结果,并分析了使用CSP增韧方法对作为复合材料基体的EP流变行为和固化动力学等工艺性能的影响。     

双马来酰亚胺树脂的增韧研究──橡胶的增韧

研究了无规端羧基丁腈橡胶对4,4＇-双马来酰亚胺基二苯甲烷/E-51环氧树脂/4,4＇-二氮基二苯砜体系的增韧作用,包括橡胶含量对固化树脂力学性能的影响,固化树脂两相结构的形成及其断裂形貌。在上述研究的基础上,分析了橡胶的增韧理论。     

环氧树脂/超支化聚酯/纳米SiO2复合材料的制备及性能

采用超支化聚酯与聚硅酸溶胶共混改性环氧树脂,制备了环氧树脂/超支化聚酯/纳米SiO2三元共混体系纳米复合材料。研究了超支化聚酯/聚硅酸溶胶增韧改性环氧树脂固化体系的力学性能及热性能,通过X射线衍射(WAXD)、差示扫描量热(DSC)、热重分析(TGA)及扫描电镜(SEM)等测试手段对材料的微观相态结构与性能进行了表征。结果表明,超支化聚酯/聚硅酸的加入使纳米复合材料的力学性能和热性能得到明显提高。当纳米SiO2的含量为1%(质量分数,下同)时冲击强度比纯环氧树脂提高了10.48kJ/m2,材料的起始热分解温度也提高了27℃。     

CE/EP/A复合体系的固化及膜性能

研究了环氧树脂/丁腈橡胶(EP/A)并用体系和二月桂酸二丁基锡(B)对氰酸酯树脂(CE)的固化以及CE/EP/A膜性能的影响.室温下停放30 d的CE/EP/A/B体系能有效固化.A用量从20%提高到24%,CE/EP/A/B(95-x/5/x/0.14)体系固化温度从163.9℃下降到152.2℃;B用量从0.14%...     

端羧基丁腈橡胶改性环氧树脂的结构与性能

用液体端羧基丁腈橡胶(CTBN)对固体环氧树脂(EP)进行改性,合成了CTBN-EP预聚物,研究了CTBN-EP/HTP-305体系的微观形貌、力学性能和热性能。研究结果表明,随着CTBN含量的增大,冲击强度及断裂伸长率显著提高,说明通过CTBN化学预聚改性的EP韧性提高,而体系的拉伸强度和热性能略有下降。动态热机械分析(DMA)测试体系的动态力学性能结果表明,体系出现了两相结构(Tg对应温度分别是-60℃和80℃～100℃)。扫描电镜(SEM)分析表明,固化过程中析出了橡胶相并均匀分散在环氧树脂基体中,形成了剪切空洞变形结构。     

聚硫橡胶增韧环氧树脂/聚苯胺涂料的力学、耐热及防腐蚀性能

为了增强环氧涂料的力学、耐热和防腐蚀性能,以环氧树脂为基料、聚硫橡胶为增韧剂、聚苯胺(PANI)为防腐蚀成分,制备了聚硫橡胶增韧的环氧涂料。采用漆膜柔韧性、附着力、耐冲击性、硬度测试和电化学方法,研究了聚硫橡胶和聚苯胺用量对涂膜力学性能和防腐蚀性能的影响,并用热失重法和扫描电镜分析了最优配方涂膜的热稳定性和断裂特性。结果表明:当添加10%~15%聚硫橡胶(占环氧树脂的质量分数,下同)和5%PANI时涂膜的力学性能和防腐蚀性能较好;聚硫橡胶增韧对环氧树脂的热稳定性影响不大;聚硫橡胶增韧环氧树脂/聚苯胺涂层呈韧性断裂,防腐蚀性能明显强于清漆。     

增容作用和动态固化对聚丙烯/环氧树脂共混物形态结构的影响

研究了增容作用和动态固化对聚丙烯(PP)/环氧树脂(EP)共混物形态结构的影响。实验结果表明,PP/EP共混物是不相容共混体系,当环氧树脂含量小于50%时,共混物中环氧树脂以分散相存在,PP为连续相。反之,则共混物的相态发生相反转,即环氧树脂为连续相,PP为分散相。加入马来酸酐接枝聚丙烯(M AH-g-PP)促进环氧树脂与PP的相容性,使得分散相的颗粒明显变小。与PP/EP和PP/M AH-g-PP/EP共混物不同,当环氧树脂含量大于50%时,动态固化PP/EP和PP/M AH-g-PP/EP共混物仍是环氧树脂分散相和PP连续相结构,未出现相反转。对于相同含量环氧树脂的共混物,动态固化PP/M AH-g-PP/EP共混物中环氧树脂分散相尺寸明显小于动态固化PP/EP共混物中环氧树脂分散相尺寸。     

橡胶增韧环氧树脂的界面极化研究

研究了奇士橡胶增韧剂增韧的环氧树脂的介电性能与温度和频率变化的关系,并与未增韧的纯环氧树脂的情况作了对比分析,橡胶增韧环氧树脂介电性能的改变来自于环氧树脂固化过程中橡胶分散相的形成,进而导致界面松弛极化。在交变电场作用下,载流子在橡胶相的两端之间运动,其行为等效于偶极子,该过程可以MWS模型予以合理解释。     

CE改性及柔性膜性能

研究了催化剂、固化时间和温度对环氧树脂(EP)或丁腈橡胶(A)改性氰酸酯树脂(CE)固化反应的影响以及CE/A膜性能.不舍催化剂的CE/EP体系160℃不能有效固化,而含有二月桂酸二丁基锡(B)的CE/EP体系能有效固化,且固化反应速度随着B用量增加而提高.CE/A/B体系的固化程度随着固化时间延长和温度升高而提高.C...     

Curing behavior and kinetic analysis of epoxy resin/multi-walled carbon nanotubes composites

The effect of multi-walled carbon nanotubes (MWNTs), both amino-functionalized (f-MWNTs) and unfunctionalized (p-MWNTs) on the curing behavior of epoxy resin (EP) cured with triethanolamine (TEA), was investigated using differential scanning calorimetry (DSC). Because the triethylenetetramine (TETA) grafted on the f-MWNTs could act as curing agent and the produced tertiary amine as negative ionic catalysts of curing reaction of EP, so the activation energy of the EP/TEA system was decreased by the addition of f-MWNTs. Viscosity played a key role in the curing behavior of the EP/TEA/MWNTs system, for high viscosity of the EP/TEA/MWNTs system could hinder the motion of the functional groups. The curing heat in EP/TEA/f-MWNTs (weight ratio 1/0.1/0.01) system was higher than the neat EP/TEA (weight ratio 1/0.1) system, while the curing heat in EP/TEA/p-MWNTs (weight ratio 1/0.1/0.01) was lower than the neat system. When the content of f-MWNTs was increased to 2 phr (weight ratio of 1/0.1/0.02), the curing heat became lower than that of the neat EP/TEA system, which was the result of the higher viscosity of the EP/f-MWNTs/TEA system. Since the curing heat indicated the curing degree of the system generally, the addition of the f-MWNTs was thought to increase the curing degree of the epoxy matrix at a relatively low content.     

MOCA/环氧树脂体系的固化行为

采用FT-IR、DSC等方法研究了亚甲基双邻氯苯胺(MOCA)/环氧树脂体系的固化行为,并对其固化动力学行为进行了研究。结果表明,体系固化行为与固化温度、固化时间及固化剂的用量有密切关系。其中固化剂的用量以MOCA质量分数在26%~33%为宜。当MOCA含量在28.6%时,最佳固化条件为:由最佳起始固化温度165℃左右缓慢升温到208℃左右恒温固化,最后在258℃左右恒温一段时间使树脂充分固化。其固化反应方程为:-dα/dt=k(1-α)1.15。     

Effects of modified hyperbranched polyester as a curing agent on the morphology and properties of dynamically cured polypropylene/polyurethane blends

The dynamic vulcanization process, usually used for the preparation of thermoplastic elastomers, has been applied to prepare polypropylene (PP)/polyurethane (PU) blends. Boltorn^TM H20 (H20) hyperbranched polyester containing 16 hydroxyl end gropus and pentaerythritol are used as curing agents, respectively, for curing PU oligomer during blending with molten PP. To improve the compatibility of cured PU particles with PP matrix, H20 is partly functionalized with stearic acid. The morphology, mechanical properties, thermal properties and melt flow index (MFI) of the PP/PU blends with different curing agent are investigated. Compared with pentaerythritol, SEM photographs show that H20 partly functionalized with stearic acid effectively reduces the size and size distribution of cured PU particles in PP/PU blends which also is proved by MFI measurement. Consequently, the dynamically cured PP/PU blends with modified H20 have better mechanical properties than those cured with pentaerythritol. The shifts of crystallization peaks to higher temperatures for all PP/PU blends indicate that PU particles in the blends can act as effective nucleating agents. Moreover, due to the smaller size of PU particles PP/PU blends cured with modified H20 have higher crystallization temperatures than those blends cured with pentaerythritol at the same PU content.     

Thermal and dynamic mechanical properties of IPNS formed from unsaturated polyester resin and epoxy polyester

The interpenetrating polymer networks (IPNs) were formed by unsaturated polyester resin (UPR) polymerized by free radical initiators: benzoyl peroxide (BPO) or cumene hydroperoxide (CHP) and epoxy polyester (EP), cured with acid anhydrides: tetrahydrophthalic anhydride (THPA) or maleic anhydride (MA). IPNs consisting 10, 30, 50, 70, 90 wt% of EP were prepared. The effect of the EP component in the IPNs and the type of curing agent on the cure behavior, thermal, and viscoelastic properties have been investigated. The results showed that both EP content and used curing system influenced on studied properties. As the EP content increased, the glass transition temperatures (T _g) also increased. Moreover, higher values of tanδ_max and lower values of cross-linking density in a rubbery state (ν_e) of IPNs containing higher EP content, probably due to plasticization effect of EP component were observed. Additionally, more heterogeneous network structure (higher values of the full-width at half-maximum (FWHM) as the EP content decreased was prepared. The thermal and viscoelastic properties of the blends cured with BPO/MA or CHP/MA system were considerably better than those cured with BPO/THPA or CHP/THPA. The higher stiffness, ν_e, T _g and lower tanδ_max values were obtained. It was probably connected with the interactions of carbon–carbon double bonds of MA with vinyl monomer (styrene), UPR and radical initiators causing to obtain more cross-linked polymer network structure. This supposition was confirmed on basis of the cure reaction monitored by DSC. The chemical interactions between two components of the blends and epoxy hardener caused that the BPO/MA or CHP/MA cure systems influenced on the cure behavior of UPR and EP components in the IPNs. The exotherm peak temperature (T _max1) shifted to lower values compared to these in the neat UPR whilst T _max2 shifted to higher values than in the neat EP. However, the cure behavior of the UPR was not greatly affected by the presence of EP component when BPO/THPA or CHP/THPA cure systems were used due to the lack of chemical interactions between the components and their curatives.     

用DSC技术研究环氧树脂体系的固化反应

本文用差示扫描量热法(DSC)研究了九种环氧树脂与六种固化剂的反应性。分析了环氧树脂的结构和固化剂的结构对各环氧树脂体系的固化反应的影响,并结合热失重分析(TG)研究了间苯二胺(m-PDA)和二氨基二苯基砜(DDS)与各种环氧树脂固化物的分解温度。      

The preparation and performance of a novel room-temperature-cured heat-resistant adhesive for ceramic bonding

A novel adhesive for joining ceramic materials was made using silicon-epoxy interpenetrating polymer networks (IPNs) as matrix (based on silicon resin (SR) and diglycidyl ether of bisphenol A (DGEBA) epoxy resin (EP)), γ-glycidoxypropyltrimethoxysilane (γ-GPS) as cross-linking agent, dibutyltin dilaurate (DBTDL) as catalyst, Al, low melting point glass (GP) and B₄C powders as inorganic fillers, low molecular polyamide (LMPA 650) as curing agent. The character and heat-resistance property of the IPNs and adhesive were tested by FT-IR, DSC and TG. The compressive shear strength of ceramic joints was investigated at different temperatures in atmosphere surroundings. The modification mechanism of inorganic fillers was studied using XRD. Results showed that the IPNs were a homogeneous morphology of inter-crosslinked network structure with single T_g. The adhesive could be cured at room temperature with good heat-resistance property due to the chemical bond of epoxy group and Si-O-Si. The optimum compressive shear strength (9.44 MPa at 1000 °C) occurred at SR/EP ratio: 9/1, content of KH560: 2%, Al/GP/B₄C ratio: 3.2/4/3, fillers/IPNs ratio: 6/4. The adhesive had good heat-resistance property with 10% weight loss at 435 °C. Failure mode of joint was mixing failure due to the high chemical bonding force.     

环氧树脂改性双环戊二烯型氰酸酯树脂固化反应性

采用凝胶试验、 FTIR和DSC等手段研究了环氧E-51与双环戊二烯型氰酸酯(DCPDCE)共聚体系的固化反应性以及阶梯固化过程中—OCN基、 三嗪环、 唑啉、 噁唑啉酮的变化情况。结果表明, 环氧树脂既能够催化氰酸酯本身三聚成环反应, 又对氰酸酯三聚成环反应有稀释作用。当环氧树脂含量(环氧占混合物总量的质量百分比)大于5wt％时, 催化效果增加不明显, 稀释作用加强; 当环氧树脂含量约为25wt%时, 以上两种作用效果基本平衡, 改性体系的固化反应活性和纯DCPDCE相当。阶梯固化时, 低温阶段(160~180℃)主要发生生成三嗪环和唑啉的反应, 高温阶段(200~220℃)主要发生三嗪环和唑啉向噁唑啉酮的转化反应。另外, —OCN基的低温转化率随着环氧树脂含量的增大而提高, 固化树脂的最终结构组成和环氧树脂的含量有关。      

The effect of temperature on the geopolymerization process of a metakaolin-based geopolymer

This paper describes the effect of different curing temperatures on the geopolymerization process, physical, mechanical and optical properties of a metakaolin-based geopolymer activated by alkali. The influence of different curing temperatures (within the range 30 to 90 °C) was studied systematically by means of differential scanning calorimetry (DSC), SEM, UV/Vis Spectrophotometry, Leaching analysis and Brunauer-Emmet-Teller method (BET). The results showed the existence of an optimum temperature at which the geopolymer presents the best physical and mechanical properties. The geopolymers cured at 30 and 90 °C presented high porosity, and were translucent to the Visible light, which makes possible to tailor this inorganic polymers for optical and photocatalytic applications.