环氧化聚丁二烯/酸酐体系的热固化行为研究

使用差动热分析仪 ,以等速升温热固化和等温热固化方式研究了环氧化聚丁二烯及双酚A型环氧树脂在α 甲基 四氢苯酐、顺酐、酸酐 70 # 等固化剂作用下的热固化行为 ,确定了LEPB MBA体系固化反应的活化能在71.90～ 75 .0 3kJ·mol-1之间。实验证明 ,环氧化聚丁二烯和双酚A型环氧树脂在固化行为方面存在明显的差异     

碱性固化剂对环氧化聚丁二烯的固化行为研究

通过ＤＳＣ法研究了ＬＦＰＢ、双酚Ａ型环氧树３脂与咪唑类及胺类固化剂的热固化行为及反应活化能。结果发现,ＬＦＰＢ固化体系的活化能高于双酚Ａ型环氧树脂,且后者的放热集中。同时发现与酸酐固化剂相对照,本文中使用的ＬＦＰＢ－固化剂体系的活化能普遍高于ＬＥＰＢ酸酐体系的活化能。     

2,4,6-三(羟基苯甲基氨基)-均三嗪的合成及其与双酚A型环氧树脂的固化行为研究

合成了一种含三嗪环结构的环氧树脂固化剂2,4,6-三(羟基苯甲基氨基)-均三嗪(MFP).用动态DSC和原位红外光谱对MFP/DGEBA(双酚A型环氧树脂)体系的固化行为进行了研究.动态DSC研究表明,由于MFP分子结构中存在两种活泼氢(酚羟基氢和仲胺氢),固化反应存在明显的两个峰,相对应的表观活化能分别为70.5 kJ.mol-1和86.5 kJ.mol-1(Kissinger法),通过与另一相似化合物固化DGEBA的比较可知,在MFP固化DGEBA的过程中,酚羟基与环氧基反应相对较难.原位红外动力学结果很好地支持了上述结论.     

碳硼烷双酚二缩水甘油醚的合成与表征及耐高温性能研究

以o-(3)和m-碳硼烷双酚(4)为原料,经两步法合成了o-(1)和m-碳硼烷双酚二缩水甘油醚(2),FTIR、1H-NMR、GPC和环氧值测试都表明得到了预期结构的碳硼烷环氧树脂.固化反应动力学研究结果显示,1/DDS和2/DDS体系的反应活化能(Ea)分别为79.0和67.1 k J·mol-1,比E-51/DDS略高,说明碳硼烷结构的存在降低了环氧树脂的反应活性.以Ea结果为依据,确定了1(2)/DDS体系的固化工艺为180℃/2h+200℃/2h.热分析结果表明,以DDS为固化剂时,1和2的Tg分别为175.8和167.6℃,高于TDE-85的154.1℃.TGA结果表明,2/DDS固化物在空气气氛下700℃的残炭率高达78.7%,说明碳硼烷结构的存在极大提高了环氧树脂高温稳定性.碳硼烷环氧树脂空气气氛中的高温残炭率比氮气中高,原因是碳硼烷结构中的B-H键与空气中的氧气反应生成B—O—B结构,因而提高了残炭率,并在一定程度上延缓了体系的失重.     

含羧基硅氧烷的制备及其固化动力学研究

通过氯丙基甲基硅氧烷与过量的对苯二甲酸的缩合反应制备了一种新型的含羧基硅氧烷(CCS),CCS可以同双酚A型环氧树脂固化,根据Kissinger和Crane方程,用差热分析(DSC)对CCS和环氧树脂组合物的固化性能进行了分析。分析结果表明组合物固化反应的表观活化能为71.41 kJ.mol-1,反应级数为0.911;还给出了加热速度为10℃.min-1时的固化反应方程。     

酸酐固化环氧树脂/蒙脱土复合材料的等温固化动力学

用等温差示扫描量热法(DSC)研究了酸酐固化环氧树脂/蒙脱土复合材料的等温固化过程，考察了未处理的蒙脱土(MMT)和有机蒙脱土(OMMT)对环氧树脂固化动力学的影响. 实验表明， 环氧树脂的固化过程包含自催化机理，加入蒙脱土没有改变固化反应机理. 用Kamal方程对该体系的固化过程进行拟合，得到反应级数m、n，反应速率常数k1、k2，总反应级数(m + n)在2.4～3.0之间. MMT的加入使环氧树脂体系的k1、k2有所降低，而OMMT的加入对体系的k1、k2影响较为复杂，加入蒙脱土对环氧树脂固化体系的活化能影响较小.     

氢化双酚A型环氧树脂的固化动力学

将氢化双酚A与环氧氯丙烷反应合成了氢化双酚A型环氧树脂(HBPA-EP),产物分别用多元胺类或酸酐类固化剂固化,利用差示扫描量热分析(DSC)对固化反应特性进行了研究,得到了相应的固化条件、固化反应活化能和固化反应动力学方程等.结果表明,当分别采用1,3-环己二甲胺、液态聚酰胺、顺式六氢苯酐、甲基六氢苯酐固化HBPA-EP(环氧值为0.45)时,其固化条件分别为100℃、2h,145℃、4h,90℃、2h,120℃、4h,130℃、2h,150℃、4h,140℃、2h和160℃、4h,用这4种固化剂进行固化反应的表观活化能分别为50.62、56.88、74.56 kJ/mol和68.36 kJ/mol,其反应级数分别为0.886、0.901、0.915和0.905.     

含苯并噁唑环氧树脂的合成、固化动力学及热性能

通过两步法制备了两种含苯并噁唑结构的环氧树脂双苯并二噁唑型环氧(DAROH-O)树脂与双酚A型苯并噁唑环氧(HOH-O)树脂,采用红外光谱和氢核磁共振波谱分析对树脂的结构进行了表征。结果表明:当以二氨基二苯基甲烷(DDM)为固化剂时,对于DAROH-O/DDM体系,采用Kissinger法和Ozawa法计算得到的表观反应活化能分别为176.92kJ/mol和175.36kJ/mol;对于HOH-O/DDM体系,采用Kissinger法和Ozawa法计算得到的表观反应活化能分别为198.45kJ/mol和196.15kJ/mol。热重分析结果表明这两种环氧树脂固化物的耐热性能均远高于普通双酚A环氧树脂/DDM固化物的耐热性能。固化物的失重过程包括两个阶段,第一阶段的分解出现在350～370℃,第二阶段的分解发生在600℃左右,属于苯并噁唑环的分解。     

树枝形大分子/环氧树脂体系固化反应动力学研究

用示差扫描量热仪(DSC)对树枝形大分子PAMAM/双酚-A型环氧树脂体系的固化反应动力学过程进行了分析。通过Kissinger法求得体系固化反应的表观活化能ΔE为59.78kJ/mol,通过Crane法求得体系的固化反应级数n=0.91,并计算出了反应速率常数k和不同升温速率下的频率因子A。根据动态DSC数据确定体系合适的固化反应温度为80~90℃,后固化温度为140℃。     

双酚A在环氧树脂和端羧丁腈增韧的环氧树脂中作用的研究

本文分别以六氢吡啶、三乙醇胺、70~#酸酐和三氟化硼单乙胺络合物为固化剂,研究了用双酚A改性的环氧树脂和端羧丁腈(简称CTBN)增韧的环氧树脂体系的热、机械性能、微观形貌和交联密度。研究结果表明只有在碱性催化型固化剂六氢吡啶或三乙醇胺下,双酚A的加入才会有突出的增韧效果。结果指出固化物冲击韧性的提高与网络交联密度有关,断裂韧性的提高是析出橡胶相体积分数增大和基体交联密度减小的协同作用所致。     

2－乙基－4－甲基咪唑固化环氧树脂的固化反应机理、动力学及其反应活性

本文应用ＤＳＣ和ＦＴＩＲ对２－乙基－４－甲基咪唑固化双酚Ａ二缩水甘油醚型环氧树脂体系的固化反应机理和２－乙基－４－甲基咪唑固化双酚Ａ二缩水甘油醚型、缩水甘油酯与脂环型环氧树脂体系的固化反应特征、动力学及其反应活性进行了研究．结果表明，双酚Ａ二缩水甘油醚型环氧树脂／咪唑体系的固化反应是分两步独立进行的，第一步是加成反应，第二步是催化聚合反应．缩水甘油酯与脂环型环氧树脂（ＴＤＥ－８５）／咪唑体系的固化反应过程也分两步进行，第一阶段反应主要是缩水甘油酯型环氧基进行的加成反应和催化聚合反应，第二阶段主要是脂环型环氧基进行的加成反应．各体系第一阶段的表现反应活化能均低于第二阶段活化能．当ＴＤＥ－８５型环氧树脂中引入缩水甘油醚型环氧树脂后，固化反应速率均较ＴＤＥ－８５环氧树脂单独固化时快．     

聚酯型扩链脲改性环氧树脂E-51/DDS体系反应活性研究

提高二氨基二苯砜(DDS)固化环氧树脂体系的反应活性,降低反应温度、提高反应速率,具有重要的研究意义和实用价值.本研究以聚酯(PEGA1000,2000,PNGA1000,2000)、甲苯-2,4-二异氰酸酯(TDI)、二甲胺为原料合成了含有聚酯型柔性间隔基的扩链脲U-PEGA1000,2000,U-PNGA1000,2000,用其改性环氧树脂E-51/DDS体系,采用DSC系统考察了改性体系的固化反应活性.结果表明,改性体系固化反应活性明显提高,固化反应表现活化能降低,固化反应峰顶温度从230℃降至170℃,固化反应的表观活化能由67.74kJ/mol降至47.80kJ/mol.     

Kinetic investigations of the process of encapsulation of small hydrocarbons into a cavitand-porphyrin

Exchange of guest molecules into capsule shaped host molecules is the most fundamental process in host-guest chemistry. Several examples of quantitative measurements of guest exchange rates have been reported. However, there have been no reports on the activation energies of these processes. A molecule known as cavitand-porphyrin (H2CP) has been reported to have a flexible host structure capable of facilitating moderate guest exchange rates suitable for kinetic measurements of the guest exchange process with 1H NMR. In this article, various kinetic and thermodynamic parameters related to the process of encapsulation of small hydrocarbons into H2CP in CDCl3 solution were determined by 2D exchange spectroscopy (EXSY): association and dissociation rate constants (k(ass) = 320 M-1 s-1, k(diss) = 1.4 s-1 for methane at 25 degrees C), the corresponding activation energies (E(a,ass) = 27 kJ.mol-1, E(a,diss) = 58 kJ.mol-1), and thermodynamic parameters for each process (DeltaG++(ass) = 59 kJ.mol-1, DeltaG++(diss) = 72 kJ.mol-1, DeltaH++(ass) = 25 kJ.mol-1, DeltaH++(diss) = 55 kJ.mol-1, DeltaS++(ass) = -113 J.K-1.mol-1, and DeltaH++(diss) = 58 J.K-1.mol-1 for methane). The thermodynamic parameters (DeltaG degrees = -13 kJ.mol-1, DeltaH degrees = -31 kJ.mol-1, DeltaS degrees = -60 J.K-1.mol-1 for methane) for this encapsulation equilibrium determined by EXSY were comparable to those for methane determined by 1D 1H NMR titration (DeltaG degrees = -11 kJ.mol-1, DeltaH degrees = -33 kJ.mol-1, DeltaS degrees = -75 J.K-1.mol-1 for methane). In addition, the structure of the methane encapsulation process was revealed by ab initio MO calculations. The activation energies for methane association/dissociation were estimated from MP2 calculations (E(a,ass) = 58.3 kJ.mol-1, E(a,diss) = 89.1 kJ.mol-1, and DeltaH degrees = -30.8 kJ.mol-1). These values are in accord with the experimentally determined values. The observed guest exchange rates and energies are compared with the corresponding values of various reported capsule-shaped hosts.     

酚醛树脂/蒙脱土纳米复合材料的制备及固化反应动力学研究

利用自制的有机蒙脱土 ,采用浇模固化成型法制备酚醛树脂 /六次甲基四胺 /蒙脱土纳米复合材料 ,并用XRD观察有机蒙脱土分别在热塑性和热固性酚醛树脂中复合行为 .研究发现 ,由于两种树脂的固化反应机理不同 ,热固性酚醛树脂与蒙脱土复合 ,可得插层型纳米复合材料 ;而采用热塑性酚醛树脂进行固化 ,则得到部分剥离的纳米复合材料 .通过DSC进一步研究热塑性酚醛树脂 /蒙脱土复合体系的固化反应动力学 .运用Kissinger ,Flynn Wall Ozawa ,Crane方法求出活化能和反应级数等动力学参数 .结果发现 ,加入蒙脱土使固化反应活化能下降 ,反应级数减小 ,从而有利于固化工艺的实现 ,便于纳米复合材料实际应用 .     

Effect of three boron flame retardants on thermal curing behavior of urea formaldehyde resin

The purpose of the study was to investigate the effects of three kinds of flame retardant (FR), boric acid, zinc borate, and borax on the thermal curing behavior of urea–formaldehyde (UF) resin. Both pH value and gel time were measured to study the curing characters of the UF resin with different loading levels of FR. In addition, differential thermal analysis was also used to obtain kinetic analyses parameter. The results showed that boric acid decreased pH value of UF resin, and reduced gel time of the UF resin. There are no significant changes of the UF resin curing characters with different loading levels of FR. The activation energies for curing reaction of UF resins in the presence of boric acid, zinc borate, and borax, were 84.37, 84.41, and 118.4 kJ/mol, respectively, higher than that of the control one (75.38 kJ/mol). All FRs showed adverse effect on the curing behavior of the UF resin.     

Chemorheological analysis of a gelled resol resin curing under non-isothermal conditions by shear strain

The chemorheological behavior of curing of a resol resin was analyzed under non-isothermal conditions beyond the gelation point. Two heating ramps (0.5 and 1 °C/min) from 0 to 100 °C were performed. The rheological measurements of the resin were performed using oscillatory shear strain. The obtained profiles for the resin’s complex viscosity were applied, after treatment by two calculation methods, to the four- and six-parameter Arrhenius models. These models allow one to establish the viscous flow region of the resin and the kinetic parameters of the material’s curing process. The six-parameter Arrhenius model was selected as the best method for modeling of the resin’s rheological behavior during its curing process. The viscous-flow activation energies determined for the gelled resol resin curing were 67.1 and 58.3 kJ/mol for the 0.5 and 1 °C/min heating rates, respectively. The activation energies of the resin curing process were 41.7 and 67.0 kJ/mol for each temperature ramp.     

Studies on the kinetics of curing and thermal stability of a novel tetrafunctional epoxy resin, N,N,N'',N−tetraglycidyl-2, 2-Bis-[4-(p-aminophenoxy)- phenyl]propane, using various amine curing-agents with or without fortifier

A novel tetrafunctional epoxy resin, N,N,N,Nt'-tetraglycidyl-2,2-bis[4-(p-aminophen-oxy)phenyl]propane, has been synthesised. The curing kinetics and thermal stability of the cured product have been investigated using various amine curing-agents. The overall activation energy for the curing reaction is observed to be in the range 30.3–126.2 kJ mol⁻¹. The cured products have good thermal stability.     

双烯类聚合物的热分析——Ⅲ.铁与其它催化体系聚1,2-丁二烯及其衍生物的热分析

<正> 由不同催化体系制得的聚1,2-丁二烯,由于其立体规整性(如等规、间规和无规)不同,其形态、热学性质也会有所不同。关于它们的热学性质文献报道不多。我们曾报道,由三乙酰基丙酮钴-三异丁基铝-二硫化碳催化体系制备的间规聚1,2-丁二烯是晶态的;而由正丁基锂和MoCl_4OR-(i-Bu),AlOR′制得的是无规聚1,2-丁二烯;是非晶态     

Indirect Catalysis, Caused by Hydrogen Spillover Through the Gas Phase. Activation by Hydrogen Oxygen Reaction

Earlier investigations revealed that glass surfaces may get catalytic properties by hydrogen spillover. Occasional activations by oxyhydrogen reaction, observed there, were executed systematically now and revealed high and stable degrees of activity of glass activated in this way. The activation energies for the hydrogenation of cyclohexene on the glass 'catalyst' are18.1 kJ mol-1 (T > 367 K)33.6 kJ mol-1 (T > 367 K)