Rubber foaming principle and influencing factors
The amount of gas generated by a blowing agent is defined as the volume of gas released per unit mass of the blowing agent in the standard state, expressed in mL / g. The decomposition rate of the blowing agent refers to the amount of gas released by the decomposition of a certain mass of blowing agent per unit time at a certain temperature. Since the polymer itself does not alter the decomposition mechanism of the blowing agent, it is not possible to measure the gas evolution of the blowing agent in the polymer. The volume of gas drawn (converted to standard volume) is plotted as a function of the heating time, usually by heating the blowing agent over a period of time in an inert dispersant such as DOP or mineral oil. (Figure 6-1), from the slope of the curve can be obtained at the temperature of the decomposition rate of the blowing agent, the total decomposition of the total volume of gas divided by the quality of the agent to obtain the amount of blowing agent gas. Different types of foaming agent, particle size of different 'different temperature' of its decomposition rate is different. In general, the low decomposition temperature of the blowing agent, the decomposition rate; for the same blowing agent, small particle size, high temperature, the decomposition rate. The gas evolution rate and the decomposition rate of the foaming agent affect the size and structure of the cell, the gas evolution is large, the decomposition speed is fast, the formation of the cell is large and the probability of the opening is large.