间-甲-白体系中粘合剂RS/A混炼工艺的研究

在间-甲-白直接粘合体系(粘合剂RS/粘合剂A/白炭黑)的配合中,对粘合剂RS/A的混炼工艺进行了试验研究。结果表明,混炼胶料采用密炼机二段混炼工艺,即:粘合剂RS在一段混炼中加入,粘合剂A在二段混炼中加入,采用密炼机不加压混炼。其胶料的焦烧时间长、加工安全性好,硫化速度较慢,树脂化反应延迟,胶料与浸胶帘线及未浸胶棕丝网布的粘合性能好。

Non-isothermal curing kinetics and thermal properties of benzoxazine-phenolic copolymers

Using novolac phenolic resin, aniline and formaldehyde as raw materials, benzoxazine-phenolic copolymers with different percentages of benzoxazine rings were prepared. FT-IR was adopted to characterize the molecular structure of the novolac-type phenolic resin and the benzoxazine-phenolic copolymer BP31. In order to understand the curing process of the copolymers, the curing behavior and curing kinetic characteristics were studied by differential scanning calorimetry （DSC）, and the catalytical effect of phenolic hydroxyl on the curing behavior of copolymers was investigated. To investigate the thermal properties of this resin, the thermal degradation behaviors of the cured samples were studied by thermal gravimetric （TG） method, and glass-transition temperatures （Tg） of the cured copolymers were also evaluated by DSC. The dynamic Ozawa method was adopted to determine the kinetic parameters of the curing process as well. The activation energy is 78.8 kJ/mol and the reaction rate constant is in the range from 40.0 to 5.2 （K/min）＂ according to reaction temperatures. The Ozawa exponent decreases from 2.4 to 0.7 with the increase of reaction temperature, and curing mechanism is expounded briefly according to the results. TG result shows that the highest char yield of copolymers is 50.3%. The highest Tg of copolymers is 489 K, which is much higher than that of pure benzoxazine resin.

Kinetics of Esterification of 2-Keto-L-Gulonic Acid with Methanol Catalyzed by Cation Exchange Resin

The kinetics of esterification of 2-keto-L-gulonic acid with methanol in the liquid phase catalyzed by cation exchange resin, D001, was studied. The experiments were carried out in a stirred batch reactor at 318, 323, 328, 333, 338, 341 K under atmospheric pressure. It is found that the speed of rotating rate has no effect on the esterification rate in the range of 300-500 r/min and the effect of internal mass transfer resistance is not obvious. The effects of temperature and catalyst loading on the reaction rate were researched under the condition of eliminating the effect of diffusion. The rate was found to increase with the increase of the temperature and catalyst loading. The experimental data were correlated with a kinetic model based on the pseudo-homogeneous catalysis. The kinetic equation for describing the reaction catalyzed by cation exchange resin was developed. The experimental data are in good agreement with the model.

Two-Stage Hydrogenation Modification of C_9 Petroleum Resin over NiWS/γ-Al_2O_3 and PdRu/γ-Al_2O_3 Catalysts in Series

Hydrogenation modification is one of the most important ways to produce high-quality petroleum resin. The col- orless C9 petroleum resin （CgPR） was obtained by two-stage catalytic hydrogenation over NiWS/？-A1203 catalyst and PdRu/ y-A1203 catalyst connected in series. Via the hydrogenation reaction, aromatic rings in C9PR were converted to alicyclic rings, and its color was reduced from Gardner color grade No. 11 to Gardner color grade No. 0. The optimum Ni/W atomic ratio was found to be close to 0.23, while the optimum Pd/Ru atomic ratio was close to 3.80. The TEM results showed that the morphology and size of sulfide or metal particles of the two kinds of catalysts remained almost unchanged after the reac- tion was carried our for 1 204 hours, attesting to their good catalytic stability.

Kinetic Modeling of Esterification Reaction of Free Fatty Acids Present in Macauba Oil Using a Cationic Resin as Catalyst

The cost of raw materials has the largest contribution to the final price of biodiesel produced by traditional routes, currently adopted in most industrial scale processes. That contribution comes from the need to use edible and noble oils, with low acidity, such as soybean oil. This work proposes＇the use of Macauba oil, a vegetable oil in focus in the State of Minas Gerais, Brazil, in which the current extractive yield generates a raw material with high acidity, therefore, not suitable to be used in biodiesel production. To make it technically feasible, a cationic exchange resin, the Purolite CT275DR, was used as a catalyst for esterification reaction with samples of Macauba oil, aiming to reduce its acidity. The resin can be reused, regenerated and easily removed from the reaction product, reducing costs with catalyst and purification stages. As a result of this work, in a sample of oil with an initial acidity of about 10% m/m were achieved acidity reductions up to 97% by using cationic resins as catalyst, demonstrating its potential use in the oil pretreatrnent step. Additionally, the data collected during all the analysis made it possible to define the chemical kinetic of the esterification reaction.

Chaos Analysis of Discharge Current Based on Tracking Test of Phenolic Resin

In tracking test, discharge is a complicated process and comparative tracking index (CTI) has wide varia-tion. To evaluate tracking resistance, the chaos analysis of discharge current is presented based on the tracking test of phenolic resin in accordance with IEC60112. According to the characteristics of statistical self-similarity and complexity of discharge current, the largest Lyapunov exponent is calculated, and the 2-dimensional attractor of discharge current is reconstructed. Moreover, the attractors of discharge current and recurrence plots of different discharge states are reconstructed. The results indicate that the chaos attractors have different characteristics in evo-lutionary tracks, the topological structure and grain direction of recurrence plots show significant differences. The chaos attractor can describe the tracking process, the recurrence plot can identify the tracking state clearly, while its arithmetic is simple.

ARX-NNPLS Model Based Optimization Strategy and Its Application in Polymer Grade Transition Process

Since it is often difficult to build differential algebraic equations (DAEs) for chemical processes, a new data-based modeling approach is proposed using ARX (AutoRegressive with eXogenous inputs) combined with neural network under partial least squares framework (ARX-NNPLS), in which less specific knowledge of the process is required but the input and output data. To represent the dynamic and nonlinear behavior of the process, the ARX combined with neural network is used in the partial least squares (PLS) inner model between input and output latent variables. In the proposed dynamic optimization strategy based on the ARX-NNPLS model, neither parameterization nor iterative solving process for DAEs is needed as the ARX-NNPLS model gives a proper representation for the dynamic behavior of the process, and the computing time is greatly reduced compared to conventional control vector parameterization method. To demonstrate the ARX-NNPLS model based optimization strategy, the polyethylene grade transition in gas phase fluidized-bed reactor is taken into account. The optimization results show that the final optimal trajectory of quality index determined by the new approach moves faster to the target values and the computing time is much less.

Statistical deduction and experimental verification on kinetic equations for the curing reactions of epoxy resins/amines

Based on three typical mechanisms (second-order, third-order and competitive mechanisms) for the curing reactions of the epoxy resins with amines, a pair of the kinetic equations (for primary and secondary aminations) was presented to explain the uniformity and relationship among the three different kinetic mechanisms of the reactions. The presented macro-equations were deduced from the kinetic micro-equations by the statistics method. And the constitutive equations were verified by experimental data at different reaction times and temperatures (95°C, 60°C and 39°C), taking diglycidyl ether of bisphenol A (DGEBA) /ethyleneamine (EA) as a model.