关于艾叶的电化学指纹图谱研究

研究了艾叶-BrO-3-Mn2+-H+-丙酮组成的振荡反应体系在恒温条件下进行的振荡反应。测定了不同浓度、不同温度下艾叶的振荡反应行为,得到了不同温度、浓度下反应的诱导期,振荡周期及考察了参与物质组分浓度及转速对振荡反应的影响。结果表明:在固定其它反应物浓度、温度的条件下,艾叶的振荡浓度区间为10.27～38.18 mg/mL,艾叶振荡体系诱导期表观活化能为67.18 kJ/mol。     

硫离子对B-Z化学振荡反应的影响

文章研究了S2-对Ce4+-Br O3--CH2(COOH)2化学振荡反应的影响。结果表明随S2-的加入化学振荡反应的活化能、诱导期和振荡周期都有不同程度的增加,并且在0~2.5×10-3 mol·L-1范围内反应的对数周期对浓度(lgtz~c)呈现良好的线性关系。文章提供了一种S2-浓度的定量分析测试方法。     

槐米有效成分芦丁的提取及对经典BZ振荡反应的影响

采用酸析碱溶法对槐米中的有效成分芦丁进行了提取,然后在不同温度下,研究了提取物芦丁对经典BZ振荡反应体系的影响。实验结果表明,在298K温度条件下,芦丁浓度范围为0.1~0.5 g/L时,随着芦丁的浓度增大对振荡反应体系的影响不大。当温度在298~318K范围内,温度升高时振荡反应体系的诱导时间明显减小,但振荡周期变化不明显。将BZ振荡反应的诱导时间tin的倒数的对数对温度的倒数作图可得一直线,且线形关系良好,且可得到振荡反应的诱导期活化能随芦丁浓度的增加而减小,本文结果可能为芦丁的应用开发及定量分析提供依据。     

中药穿心莲的B-Z振荡反应研究

对于BrO-3-穿心莲-丙酮-Mn2+-H2SO4体系的化学振荡反应,测定了不同浓度,不同温度下,穿心莲的振荡反应行为,得到了不同温度、浓度下反应的诱导期,振荡周期,并由此计算出振荡∝c3.0786∝c2.7793反应的表观活化能及穿心莲的反应级数。并得到下列关系:100·exp-10405tinT;1tp,1∝c3.6650·exp-116900·exp-9847.1T。T;1tp,2     

金花黑茶-KBrO3-H2SO4的非催化振荡体系研究

在红茶的非催化振荡体系研究的基础上,对金花黑茶的非催化振荡反应进行了研究,包括各反应物(金花黑茶、KBrO_3、H_2SO_4)的浓度、反应温度对非催化振荡反应的影响,并分析了催化反应与非催化反应的不同,计算了金花黑茶非催化反应的活化能为90.43 kJ/mol。当[金花黑茶]=20.016 mg/mL,[H_2SO_4]=0.48 mol/L,[KBrO_3]=0.056 mol/L时,出现最佳振荡图谱,并且对非催化振荡反应的催化机理作了更进一步的探讨。     

溴化丁基橡胶液体抗氧剂的热分析研究

用热失重法(TG)和差示扫描量热法(DSC)分别测定了添加4种新型液体抗氧剂的溴化丁基橡胶(BIIR)的热失重温度、氧化诱导时间和氧化诱导温度,综合考察了4种抗氧剂的热稳定性和抗氧化性能,评选出性能最好的抗氧剂及其最佳添加量,并分别计算了BIIR的等温和非等温(动态)热氧化反应的活化能。结果表明,4种抗氧剂的热稳定性和抗氧化效果差异较大,但均能不同程度改善BIIR热氧化稳定性。等温热氧化动力学实验结果表明,BIIR热氧化反应符合阿伦尼乌斯方程,抗氧剂添加前后BIIR等温氧化反应活化能分别为131.14kJ/mol、150.25kJ/mol;动态热氧化动力学实验得到抗氧剂加入前后BIIR的非等温氧化反应活化能分别为86.23kJ/mol和108.49kJ/mol。     

熔融酯交换合成聚碳酸酯预聚体的动力学

研究了双酚A与碳酸二苯酯以氢氧化四丁基铵为催化剂的酯交换反应动力学。根据官能团模型推导出以苯酚浓度表示的积分型速率方程,得到了不同温度下的预聚合反应平衡常数,正、逆反应速率常数,活化能和反应热。酯交换反应的反应级数为二级,反应为放热反应,反应热为-17.45 kJ/mol,反应活化能为77.170 kJ/mol。探讨了不同反应温度、催化剂用量对反应速率的影响。实验数据与官能团模型符合良好,可以为后期的实验设计提供一定的理论指导。     

SC(NH2)2-H2O2-Cu2+-OH-封闭体系非线性动力学研究

利用微量量热仪测定体系热功率随时间的改变。对于SC(NH2)2-H2O2-Cu2 -OH-封闭体系,测定了不同浓度,不同温度下,体系的单峰振荡行为,得到了不同温度,不同浓度下的振荡周期,并由此计算出振荡反应的表观活化能和反应级数。并得到下列关系:1t∝c-0.3355     

多级连续搅拌反应器中丁二烯-苯乙烯负离子溶液聚合动力学

采用多级串联连续溶液聚合工艺,以n-BuLi为引发剂,四氢呋喃(THF)为结构调节剂,环己烷为溶剂,研究了不同平均停留时间、不同n-BuLi浓度以及聚合温度等反应条件对丁二烯(Bd)-苯乙烯(St)连续溶液共聚合反应动力学的影响。结果表明:在THF/[n-BuLi](摩尔比)为30、Bd/St(质量比)为7/3、聚合温度为80℃的条件下,多级串联连续溶液共聚合反应过程中Bd和St共聚合反应速率对[n-BuLi]呈近一次方关系,对单体浓度呈一次方关系;Bd的反应活化能为40.15kJ/mol,St的反应活化能为36.75kJ/mol。在上述同样的条件下而聚合温度为50~90℃时,Bd和St共聚合反应的竞聚率随温度的增加逐渐趋同。     

等温DSC法研究液态橡胶改性环氧树脂固化动力学

用等温差示扫描量热法(DSC)在三个不同的固化温度下研究了不同含量端羧基液态橡胶(CTBN)改性环氧树脂的等温固化过程,考察了不同CTBN含量对环氧树脂固化动力学的影响。通过Kamal方程对不同含量CTBN改性环氧树脂固化过程数据进行拟合,得到反应速率常数k1、k2及反应级数m、n,计算得到反应活化能的值,结果表明CTBN质量分数由0%到20%,k1、k2逐渐增大,反应前期活化能由67.34kJ/mol增加到80.31kJ/mol,增加了19.26%,反应后期活化能由94.19kJ/mol增加到180.07kJ/mol,增加了91.18%。     

十种草药的振荡指纹图谱

应用振荡技术,利用"BrO3--Mn2 -H -丙酮"振荡器,得到了杜仲、苦楝皮、板蓝根、厚朴、合欢皮、地骨皮、五加皮、穿心莲、秦皮、石菖蒲的振荡指纹图谱。考察了各个振荡体系的振荡范围、振荡诱导期、周期、振幅及振荡寿命。结果表明:这些振荡指纹图谱可用于辨识中草药。     

正交设计法优化黄柏涂膜剂成膜材料的制备工艺

采用L9(33)正交实验,以涂膜剂外观性状及成膜时间为考核指标,对黄柏涂膜剂成膜材料的制备工艺进行了优化.结果表明,在10％ PVA-124用量为10 mL、10％ PVA-1788用量为10 mL、甘油用量为1.5 mL的条件下得到的成膜材料成膜性好、易于涂展、韧性强,黄柏提取物在其中溶解均匀.     

炭黑对EPDM硫化动力学影响研究

炭黑是三元乙丙橡胶(EPDM)主要填充剂,对其硫化动力学有重要的影响。探讨了炭黑的比表面积、填充量及结构与硫化反应级数、硫化反应表观速度常数、诱导时间、硫化反应表观活化能之间的关系。结果表明,快压出炭黑550对硫化反应表观反应级数基本上没有影响,对诱导时间及反应速度常数有不同程度的影响,填充量对表现活化能有较大影响。     

Kinetic Processes Involved in the Sintering and Crystallization of Glass Powders

Viscometry, crystal growth kinetics, and glass powder sintering were used to determine the activation energies of viscous flow, crystal growth, and sintering behavior of a standard NBS 710 glass and two crystallizable glass powders in the calciaaluminosilicate system. In a system which sintered successfully to zero porosity, the activation energy for sintering was comparable to the activation energy of viscous flow. When the apparent activation energy for the sintering process was lower than that of viscous flow, sintering was found to proceed at a slower rate because the precipitated crystalline phase retarded viscous flow and the shrinkage of the pores. Initial crystallization appeared to occur on the surfaces of coalesced particles. A chemical treatment was partially successful in suppressing the onset of surface nucleation of the precursor powder.     

Kinetics of Carbothermal Reduction of Quartz Under Vacuum

The kinetics of reduction of 0.2 mol of –70?mesh quartz particles by 0.2 mol of graphite were determined in a batch reactor between 0.25 and 10⁻⁰ torr. The effects of temperature, CO partial pressure, SiO₂ phase transformation, and alkali and alkaline-earth oxide additives on the rate of reaction were studied. Increasing CO overpressure retarded carbothermal reduction. At 1400−C, addition of 5 wt% alkali oxide inhibited the reaction, whereas the same amount of alkaline-earth oxide decreased the induction time; CaO was the best promoter. The initial reaction rate obeyed the cubic power law of nucleation growth at weight losses <15%, with an apparent activation energy of 77 kcal/mol. At higher weight losses, the Austin-Rickett equation with an exponent near 2 was more applicable. The results are consistent with a model based on a transitory phase intermediate.     

Curing Kinetics of Liquid Crystalline Epoxy Resins Based on Bisphenol-S Mesogen with DDE by Nonisothermal DSC Data

The curing kinetics for a system of Sulfonyl bis(4,1-phenylene)bis[4-(2,3-epoxypro pyloxy)benzoate] (p-SBPEPB) with 4,4′-diaminodiphenyl ether (DDE) were investigated by nonisothermal differential scanning calorimetry (DSC). The dependencies of the apparent activation energy Ea and the conversion α during overall curing reaction were revealed by Ozawa's method. The results shown the Ea decreased drastially from 107 to 75 KJ/mol with α in the initial stages (α = 0–20%), the average apparent activation energy Ea of p-SBPEPB/DDE is 82.81 KJ/mol and was relatively constant in the 0.5 to 0.9 conversion interval. Some parameters were evaluated using the two kinetic models of ?esták–Berggren (S-B) equation and JMA model. The liquid crystalline (LC) phase had formed and was fixed in the system during the curing process.     

星形PLA-HTPB聚氨酯共聚物的合成与表征

采用自制的星形聚乳酸(PLA)和端羟基聚丁二烯(HTPB)为主要原料,甲苯-2,4-二异氰酸酯为扩链剂合成了星形PLA-HTPB聚氨酯共聚物,通过FT-IR、DSC、TG等测试手段对此共聚物的结构与性能进行表征。结果表明,星形PLA-HTPB聚氨酯共聚物两相具有各自的玻璃化转变温度,两相之间存在相分离现象;其热分解过程为2步,乳酸链段的起始热分解温度为229℃,表观活化能为83.11kJ/mol,反应为一级反应;丁二烯链段的起始热分解温度为414℃,表观活化能为192.83kJ/mol,反应为非一级反应。     

A study on the properties of epoxy resin toughened by a liquid crystal‐type oligomer

A series of novel reactive toughening agents (LCEU_PPG) containing both a flexible spacer and rigid liquid crystalline unit were synthesized to modify the bisphenol epoxy resin/dicyandiamide curing system. The curing reactivity, apparent activation energy, curing mechanism, dynamic mechanical behavior, and impact strength of the modified system were systematically studied. Compared with the unmodified system, the results indicate that LCEU_PPG have greatly accelerated the curing reaction between epoxy resin and dicyandiamide, reduced the apparent activation energy of the curing reaction, enhanced the impact strength 3–7 times, and maintained high dynamic modulus and good thermal properties. In addition, SEM observation of the fracture surfaces showed a two‐phase microstructure in the modified systems. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 177–184, 1999