PVC heat stabilizers Congo test method

PVC used for the final products of different industries. Different performance, PVC heat stabilizers evaluation and testing will need a different approach. Here to introduce a Congo red paper test method.
According to GB GB2917.1-2002, Congo red test method for testing PVC heat stabilizer, a major test method, the  one pack stabilizer experimental apparatus shown in Figure 1.
Using an oil bath pot, built glycerin, will be tested PVC heat stabilizers mixed with the material after being loaded into a small test tube, so that the material becomes a slight concussion and firm, and then placed in an oil bath pot among glycerol oil bath pot set in advance a temperature of approximately 170 ℃, PVC material within the small tube and the Stearate zinc  upper surface of the upper surface level of glycerin, small tube top, with a thin tube inserted into the plug, the upper and lower transparent glass, the glass tube Congo red paper hit the bottom of the roll inserted so Congo red paper with the lower edge of the upper edge of the PVC material is located about 2 cm. After the start of the experiment, record the test tube to the test tube from Congo red paper turns blue start time is the thermal stabilization time. The basic theory of this experiment is that when the PVC at a temperature of about 170 ℃ when rapid decomposition, but with the addition of a heat stabilizer, suppresses the decomposition, with time, the heat stabilizer consumption occurs when the consumption is completed , PVC dramatically HCl gas decomposition in magnesium hydroxide  this case, the test tube as Congo Red reagent reacts easily with HCl and discoloration, will be immediately apparent, a note of the time determined by the length of time to heat stabilizer the effect of pros and cons.