Kinetics of Curing and Thermal Degradation of POSS Epoxy Resin/DDS System

Polyhedral oligomeric silsesquioxanes epoxy resin (POSSER) was prepared from 3-glycidypropyl-trimethoxysilane (GTMS) and tetramethylammonium hydroxide (TMAH) by hydrolytic condensation. POSSER was characterized using Fourier-transformed infrared spectroscopy (FTIR), ¹H-NMR, and liquid chromagraphy/mass spectrometry (LC/MS). The epoxy value of POSSER is 0.50 mol/100 g. The LC/MS analysis indicated that T₁₀ is the majority and contain some amount of T₈, besides, a trace T₉ also exists. The curing kinetics of POSSER with 4,4′-diaminodipheny sulfone (DDS) as a curing agent was investigated by means of differential scanning calorimetry (DSC). The curing reaction order n is 0.8841 and the activation energy Ea is 61.06 kJ/mol from dynamic DSC analysis. Thermal stability and kinetics of thermal degradation were also studied by thermal gravimetric analysis (TGA). TGA results indicated that the temperature of POSSE/DDS system 5% weight loss is approximately 377.0°C, which is higher by 12.6°C than that of pure POSSER, and the primary degradation reaction (300–465°C) followed first order kinetics; the activation energy of degradation reaction is 75.81 kJ/mol.     

松香基环氧树脂/马来海松酸酐固化反应动力学与热稳定性研究

松香与马来酸酐进行Diels-Alder反应合成马来海松酸酐(MPA),与环氧氯丙烷进一步反应生成松香基环氧树脂,以马来海松酸酐（MPA）做固化剂固化松香环氧树脂,利用差示扫描量热仪、动态力学谱仪、热重分析仪等分析手段,对该体系固化产物进行固化动力学和热降解动力学研究。结果表明,质量比为5∶5的环氧树脂/马来海松酸酐体系固化后玻璃化转变温度达53.2 ℃,平均固化反应活化能为52.29 kJ/mol;固化物在10 ℃/min时初始分解温度为211.9 ℃,最大分解温度为347.7 ℃,最终分解温度为639.0 ℃。     

Curing Behavior,Kinetics and Thermal Properties of o-Cresol Formaldehyde Epoxy Resin Modified by Liquid Crystalline Epoxy Resin

The curing kinetics of a bi-component system of o-cresol-formaldehyde epoxy resin (o-CFER) modified by liquid crystalline p-phenylene di[4-(2,3-epoxypropyl) benzoate] (p-PEPB), with 4,4-diamino-diphenyl ether (DDE) as a curing agent, was investigated by nonisothermal differential scanning calorimetry (DSC) method. The relationship between apparent activation energy, Ea, and the conversion α was obtained by the isoconversional method of Ozawa. A molecular reaction mechanism is proposed. The results show that the values of Ea in the initial stage are higher and tend to decrease slightly with the reaction progress. The primary amines have a higher Ea than secondary amines. The average curing Ea of o-CFER/p-PEPB/DDE system is 61.64 KJ/mol. These curing reactions can be described by a model proposed by ?esták and Berggren, which includes two parameters of m and n. Parameters such as reaction orders were evaluated using the ?esták-Berggren (S-B) equation and the following kinetic equation: dα/dt = Aexp(?Ea/RT)α ^m (1 ? a) ⁿ . The curing behavior of the system was studied by polarized optical microscopy (POM) and torsional braid analysis (TBA). The compatibility of the p-PEPB and o-CFER system is very good. Temperature of mechanical loss peak is higher by 63°C than the common o-CFER epoxy resin, when the weight ratio of p-PEPB with o-CFER is 4:100.     

Cure Kinetics and Thermal Property of Bisphenol-S Epoxy Resin and Phthalic Anhydride

Abstract

The cure kinetics of bisphenol-S epoxy resin (BPSER) and curing agent phthalic anhydride, with N,N-dimethyl phenzylamine as an accelerator, were studied by means of differential scanning calorimetry (DSC). Analysis of DSC data indicated that an autocatalytic behavior showed in the first stages of the cure. The autocatalytic behavior was well described by the model proposed by Kamal including two rate constants, k1 and k2, and two reaction orders, m and n. The overall reaction order, m + n, is in the range 2～3. The activation energies for k1 and k2 were 111.69 and 80.47 KJ/mol, respectively. Diffusion control was incorporated to describe the cure in the latter stages. The glass transition temperatures (T_gS) of the BPSER/anhydride samples isothermally cured partially were determined by means of torsional braid analysis (TBA). and the results showed that the reaction rate increased with increasing T_g in terms of the rate constant, but decreased with increasing conversion. The T_g of completely cured BPSER/anhydride system is about 40 K higher than that of BPAER. The thermal degradation kinetics of this system was investigated by thermogravimetric analysis (TGA). It illustrated that the thermal degradation of the BPSER/phthalic anhydride has n-order reaction kinetics.     

Curing Kinetics and Thermal Properties Characterization of o-Cresol-formaldehyde Epoxy Resin and MeTHPA System

The kinetics of the cure reaction for a system of o-cresol-formaldehyde epoxy resin (o-CFER) with 3-methyl-tetrahydrophthalic anhydride (MeTHPA) as a curing agent and N,N-dimethyl-benzylamine as an accelerator was investigated by means of differential scanning calorimetry (DSC). Analysis of DSC data indicated that an autocatalytic behavior showed in the first stages of the cure for the system, which could be well described by the model proposed by Kamal, which includes two rate constants, k₁ and k₂, and two reaction orders, m and n. The activation energy E₁ and E₂ are 195.84 and 116.54 kJmol^?1, respectively. In the later stages, the reaction is mainly controlled by diffusion, and a diffusion, factor, f(α), was introduced into Kamal's equation. In this way, the curing kinetics were predicted well over the entire range of conversion. Molecular mechanism for the curing reaction was discussed. The glass transition temperature T_g was determined by means of torsional braid analysis (TBA). The results showed that T_gs increased with curing temperature and conversion up to a constant value about 367.1 K. The thermal degradation kinetics of the system was investigated by thermogravimetric analysis (TGA), which revealed two decomposition steps.     

新型酚醛树脂固化反应动力学及固化机理研究

采用DSC热分析对S酚醛树脂的固化过程进行了动力学研究,得出了该树脂的固化工艺温度及固化动力学参数,其凝胶化温度、固化温度和后处理温度分别为360.7K、421.6K和463.4K;反应级数n=0.912、表观活化能E=76.14kJ·mol^-1,反应频率因子A=4.704×10^8min^-1。采用红外光谱分析初步探讨了该树脂的固化机理,结果表明其固化反应主要是苄羟基与苯环邻位上活泼氢产生交联缩合反应,少量为苄羟基之间的缩合反应。     

聚碳酸酯改性环氧树脂的固化动力学与热性能研究

用动态DSC法研究了聚碳酸酯(PC)改性环氧树脂(EP)体系的固化行为,采用Flynn-Wall-Ozawa法分析了EP/PC体系固化活化能与转化率的关系,利用Kissinger和Crane方程研究了EP/PC体系固化动力学参数,并用TG和DSC研究了复合体系的热性能。结果表明:PC的加入没有改变EP的固化机理,反应级数基本不变,但是降低了EP固化物的热分解温度和玻璃化转变温度。     

环氧树脂/稻壳SiO2纳米复合材料的热性能及拉伸性能研究

将稻壳用酸处理后在600 ℃焚烧得到纯度为99.3%、比表面积为212 m2/g的SiO2。经硅烷偶联剂γ-氨丙基三乙氧基硅烷（KH550）改性后的SiO2为无定形态,尺寸在30~50 nm之间。将改性后的稻壳SiO2与环氧树脂复合,利用热分析方法考察了纳米复合材料在N2气氛中的热性能,并采用万能材料试验机测试其拉伸性能。结果表明：稻壳SiO2的加入能有效增加环氧树脂/稻壳SiO2纳米复合材料的热稳定性,复合材料的起始分解温度（Ti）、分解速率最大时的温度（Tmax）以及失重50 %的分解温度（T50 %）均高于纯环氧树脂,并随稻壳SiO2含量的增加而增加。当环氧树脂/稻壳SiO2纳米复合材料的组成相同时,KH550改性的复合材料的Ti、Tmax和T50 %均比未经过KH550改性的高。随KH550用量增加,复合材料T50 %向高温方向移动。此外,复合材料的拉伸强度、断裂伸长率和模量也高于纯环氧树脂。     

聚酰亚胺-环氧树脂胶黏剂的固化动力学研究

以2,2-双[4-(4-氨基苯氧基)苯基1丙烷(BAPOPP)和2,2-双[4-(3,4-二羧基苯氧基)苯基]丙烷二酐(BPADA)为原料在室温下于DMAe溶剂中合成了一种新型聚酰亚胺,并用其改性环氧树脂体系获得聚酰亚胺-环氧体系胶黏剂.利用差示扫描量热计(DSC),以不同的升温速率对聚酰亚胺-环氧树脂胶黏剂进行DSC...     

Studies on Dielectric and UV Shielding Properties of Epoxy Functionalized Alumina/Silane-Modified Amine Epoxy Nanocomposites

In the present work, 3-glycidyloxypropyltrimethoxysilane functionalized alumina (F-Al₂O₃) was prepared and the formation of chemical bonding was confirmed with FTIR spectroscopy. Varying weight percentages of (5, 10, 15 and 20 wt%) glycidyl F-Al₂O₃ were reinforced with blend of diaminophenoxydimethylsilane and epoxy resin and then cured with diamonodiphenylmethane. The surface morphology of samples was analyzed before and after UV exposure for 168 h using SEM. The 20 wt% F-Al₂O₃ reinforced epoxy nanocomposite sample possesses higher thermal stability, higher dielectric constant and better UV radiation resistant properties than that of other weight percentages of F-Al₂O₃ reinforced epoxy nanocomposites.     

有机硅/聚醚胺复合固化剂改性环氧树脂及其性能研究

以二甲基二乙氧基硅烷、γ-氨丙基三乙氧基硅烷、二苯基二甲氧基硅烷为单体,通过水解、缩聚制备了含有氨基活性功能基团的有机硅低聚物（PS）,然后以PS与聚醚胺与环氧树脂进行固化交联得到机硅改性环氧树脂,研究探讨了PS含量对改环氧树脂耐热性、力学性能及吸水性能的影响。结果表明：当PS添加量为基体树脂的30%时,改性树脂的耐热性能有明显提高,800oC残留量为26.45%,拉伸强度为68.27MPa,弯曲强度为81.68MPa,与水表面接触角为109.3°,吸水率为2.59%,比未改性树脂分别提高了17.24% ,6.6%,17.3%,21.3%和降低了0.12%。     

硅烷单体改性环氧树脂的固化及性能

分别用苯基三甲氧基硅烷(PTMS)和3-缩水甘油醚氧丙基三甲氧基硅烷(KH560)单体对环氧树脂进行了化学改性,通过红外(FT-IR)、核磁(1H NMR)对其化学结构进行了表征。以聚酰胺650为固化剂,用差示扫描量热仪(DSC)研究了固化物的固化动力学。此外还研究了涂膜的热失质量(TGA)、吸水率、附着力等性能。结果表明:苯基三甲氧基硅烷和3-缩水甘油醚氧丙基三甲氧基硅烷接枝上环氧树脂,与纯环氧树脂相比,改性后的树脂具有更好的热稳定性和更低的吸水率。改性环氧树脂固化后形成两面性质不同的涂层,与底材接触的涂层底面保留了环氧树脂原有的附着力,而涂层表面则具有高憎水性,起到防腐等作用。     

腰果酚基环氧树脂的合成及其性能研究

设计合成了一种腰果酚基环氧树脂。首先,以羟乙基腰果酚醚(HCE)和三氯氧磷(POCl3)为原料,利用亲核取代反应合成了一种具有三臂结构的预聚体(PT-HCE)。采用双氧水/甲酸的均相催化法对PT-HCE进行了环氧化,合成了磷酸三羟乙基腰果酚醚环氧树脂(EPT-HCE),同时探究了甲酸的投料比对环氧值的影响。结果表明:当双键与甲酸的物质的量比为1∶0.4时,环氧值能达到最高值0.18 mol/(100 g)。通过傅里叶变换红外光谱仪(FT-IR)、核磁共振波谱仪(NMR)对PT-HCE和EPT-HCE的结构进行了表征,证明了环氧树脂被成功合成。此后,利用所合成的树脂制备了热固化涂料,研究了酸酐含量等对涂层附着力、铅笔硬度和耐冲击性等性能的影响,还将EPT-HCE与双酚A型环氧树脂E51进行了复配。结果表明:相比于纯E51环氧树脂制备的涂层,加入EPT-HCE树脂后的涂层柔韧性得到了提高。     

双环戊二烯型氰酸酯树脂／环氧树脂固化物热降解反应动力学及其机理研究

采用环氧树脂对双环戊二烯型氰酸酯（DCPDCE）进行共聚改性，分析了不同比例共聚产物在不同升温速率下的热失重曲线，对共聚产物的热降解反应动力学进行了研究。分别利用Ozawa和Coats-Redfern方法计算体系的活化能数据，采用Ozawa方法计算得到DCPDCE和DPCDCE／环氧树脂（85／15）体系的活化能分别为163．93kJ／mol和159．94kJ／mol，得到的结果与Coats-Redfern方法计算得到的结果进行了对比，并分析了固化产物的热降解反应机理。     

环氧树脂固化动力学的非等温DSC研究

用非等温DSC对环氧树脂在动态升温过程中的固化动力学进行了研究,采用Kissinger方程对固化动力学模型参数中固化反应活化能、反应级数和指前因子进行了计算,并用Ozawa法对固化反应活化能进行了验证,计算结果表明,EP/DDS固化反应符合n阶固化动力学模型,结合不同升温速率下的特征温度,对环氧树脂的固化条件进行了优化。     

Bio-based Sulfonated Epoxy/Hyperbranched Polyurea-modified MMT Nanocomposites

Hyperbranched polyurea modified nanoclay was used for the preparation of vegetable oil modified sulfone epoxy nanocomposites at different loadings (1–5 wt%) for the first time. The bio-based nanocomposites were characterized by XRD, SEM, TEM, and FTIR techniques. These nanocomposites showed an enhancement of thermal stability up to 48°C as revealed by thermo-gravimetric analysis. The nanocomposites with 5 wt% of nanoclay exhibited more than 300 percent improvement in tensile strength, though the elongation at break decreases with the increase of nanoclay loading. Thus the studied nanocomposites possess better performance over the pristine system.     

聚酰胺6/环氧树脂改性蒙脱土纳米复合材料的制备与性能

采用环氧树脂改性蒙脱土（MMT）得到有机化蒙脱土（OMMT）,再用熔融插层法制备了聚酰胺6 （PA6）/ OMMT纳米复合材料。采用X射线衍射仪、透射电子显微镜、万能材料试验机、热重分析仪等研究了PA6/OMMT复合材料的形态结构、力学性能和热稳定性。结果表明,经环氧树脂改性得到的OMMT的层间距明显增加,从未改性的1.22 nm增加到5.13 nm,并以纳米尺度分散于PA6基体中;随着OMMT含量的增加,PA6/ OMMT复合材料的强度和模量增加,热变形温度提高,其拉伸强度可达76 MPa,弯曲模量达到3.462 GPa,热变形温度为134 ℃;PA6/ OMMT复合材料失重10 %时的温度为422 ℃,比纯PA6的406 ℃提高了16 ℃,改善了PA6的热稳定性。     

多面体低聚倍半硅氧烷对环氧树脂热性能影响分析

选用有机-无机纳米杂化材料乙烯环氧基多面体低聚倍半硅氧烷(EOVS)和环氧醚基多面体低聚倍半硅氧烷(GPOSS)为改性剂,与4,4′-二氨基二苯甲烷环氧树脂共混制得不同改性剂质量分数(树脂与改性剂总质量的百分数)的EOVS或GPOSS改性环氧树脂,考察了改性树脂的固化反应程度、玻璃化转变温度(Tg)和热稳定性.结果表明...     

有机累托石/环氧树脂(OREC/EP)复合材料的制备和性能研究

用单体原位插层技术制备了有机累托石/环氧树脂(OREC/EP)复合材料,考察了OREC的加入及其含量对复合材料OREC/EP体系的力学性能、耐介质性能和耐紫外线性能的影响。研究发现:OREC是一种良好的环氧树脂增韧改性剂,OREC的加入可改善复合材料的综合性能。当OREC质量分数为3%时,冲击强度和弯曲强度提高幅度最大,分别为6.25%和8.39%,耐海水性能效果最好;在添加质量分数为1%~7%时,复合材料体系的耐酸(碱)和耐紫外线性能均随OREC含量的增加而上升。