Research On Rubber Temperature Fields During Microwave Curing Process

Vulcanization is the last procedure in the process of rubber processing, which is also the most important working procedure, aiming at making the physical and mechanical properties of rubber in different parts achieve the best. Traditional vulcanization ways are mainly ways of external heating, transferring heat from outside to inside by heat conduction, with a feature of long curing time, uneven curing effect and severe waste of energy; while microwave heating is a kind of body heating method,internal and external molecules move simultaneously under the action of electromagnetic waves, to convert mechanical energy into heat energy, shorten the curing time, along with the vulcanization effect more even, and more energy saved.However, rubber vulcanization process is relatively complicated, the research with respect to the rubber microwave vulcanization has not applied in the whole curing process. Meanwhile, it is of significant importance to study the temperature field in microwave heating process of rubber, as temperature is one of three vulcanization elements in curing process, when heated with an inappropriate temperature, the phenomenon of under cure or over cure would appear, resulting in poor performance of rubber.Based on the theory of electromagnetic field, by placing HNCD rubber in different positions of the microwave heating cavity, the temperature heating process was studied, and the temperature field at each place point, in each layer and inner the whole cavity can be got; put different kinds of rubber in the microwave cavity to study the rule of temperature rise and the influence of different dielectric parameters on the temperature field of rubber films; combined with vulcanization theory of rubber, the microwave vulcanizates were obtained with the method of power time combination,and whose specific heat characteristics and degree of cure were also studied, using degree of cure to characterize the curing effect of microwave vulcanizates, conclusions can be got as follows:(1) The temperature rise of rubber film shows a non-linear trend when heated in microwave cavity, the temperature in the central regions of most rubber films is more higher than that in the edge area, the closer to the waveguide position, the higher the whole temperature of rubber and the electromagnetic field in cavity are;(2) During the process of heating rubber film for 20 minutes at 200 W power, the temperature rise rule of rubber film can be expressed by an univariate cubic function;(3) The rate of temperature rise was accelerated due to the curing reaction heat in microwave curing process, the distribution of rubber is even after being heated, in which the area of temperature between 130 ? and 140 ? can reach above 80%;(4) The higher the dielectric constants of rubber is, the higher maximum temperature that it can reach after microwave heating;(5) Adopting the method of power and time combination to heat rubber using microwave, and completed the heat preservation process by continuously conversion of high and low power, the degree of cure of microwave vulcanizates of tread rubber,seam allowance wear-resisting rubber, inside liner rubber, and sidewall soft rubber can all reach more than 90%, which is in accordance with that of plate vulcanizing rubber.