Synthesis Process And Kinetics Of Novolac-type Phenolic Resins

Aiming at promoting production process level and product property of novolac-type phenolic resins, experiments of reaction kinetics have been operated and modelling has been studied. From the perspectives of process development and product structure optimization, rheological property of the reaction system and final product has been researched. Four parts were dedicated for this dissertation with the following information:Part Ⅰ:Basic concepts and applications of phenolic resis were expounded. Production processes of novolac-type phenolic resins were introduced, as well as process characteristics, to elaborate the development of continuous processes that mainly about the application of tube reactors. And the research status of reaction kinetics of novolac synthesis was concluded.Part Ⅱ:Experiments have been implemented to study the kinetics of synthesis process of novolac-type phenolic resins. With oxalic acid being the catalyst and the employment of titration, HPLC-MS,13C-NMR and GPC, the change rule of each component and microstructures in the reaction system, under the conditions of different temperatures (60 ℃,70 and 80℃) and raw material ratios (60℃,70℃ and 80℃), have been investigated. It was found that para-positon in the phenolic ring showed higher reactivity than ortho-position, which led to the quick generation and slow comsumption of 4,4’-Bisphenol F, as well as the high ratio of p-p methylene chain at the beginning of the reaction, and the high ratio of o-p methylene chain at the end of the reaction. Moreover, both o/p and molecular weight presented linear growth trend with branching degree.Part Ⅲ:Based on the reaction mechanism and experimental results, two kinds of kinetic models have been established. Model Ⅰ assumed that all the reaction sites had same reactivity, and Model Ⅱ investigated the chain struction in the reaction system that divided components with two chain length. Under the optimazation targets of minimum relative errors of all components, kinetic parameters, which was consistent with most of the components, have been fitted with experimantal data. Molecular weight and its distribution have been calculated with the parameters, and variation tendency of unknown components has been predicted.Part Ⅳ:On-line testing of rheological property in the reaction process has been operated, which found the reaction system could be regarded as Newtonian fluid. System viscosity rised as the reaction proceeded, as well as the linear increasing with o/p and molecular weight. A viscosity inflection point of transit decreasing in the reaction has been observed. For the viscosity of final product in five kinds of raw material ratios, correlations with o/p and molecular weight have been implemented. Testing results showed that final product viscosity increased with the increase of raw material ratio or the decrease of testing temperatures. Linear relationship between logarithmic viscosity and reciprocal of temperature has been established.