Brief introduction of Vicat softening point
Vicat softening temperature (VST) is an engineering plastics, GE Plastics such as sample polymer in the liquid heat transfer medium in a certain load, constant temperature, 1mm2 indenting into 1mm depth temperature. There are professional instruments and testing standards.
The softening point of Vicat is suitable for controlling polymer quality and evaluating the thermal performance of new varieties. It is a method to evaluate the trend of high temperature deformation of thermoplastic, but it doesn't represent the service temperature of materials.
A method to improve the Vicat softening point
1, on the resin side, CPVC can be added by the chlorination of polyvinyl chloride (PVC) resin. It is a new type of engineering plastic. The product is a white or yellowish, odorless, odorless, non-toxic loose particle or powder. After the PVC resin was chlorinated, the irregularity of molecular bonds increased and the polarity increased. The solubility of the resin increased and the chemical stability increased. Thus the heat resistance, acid, alkali, salt and oxidant of the material increased. The mechanical properties of the numerical hot deformation temperature were increased. The chlorine content increased from 56.7% to 63-69%, and the softening temperature of Vicat increased from 72-82 PVC to 90-125 CPVC. The highest service temperature was up to 110 C, and the long-term usage temperature was 95 C. The shortcoming is that the processing is difficult, the formula should be adjusted accordingly. As for how much to add, it needs to be grasped by yourself. Of course, it is also important to choose the right PVC model
2, the dosage of lubricants, lubricants can reduce the Vicat softening point of PVC, so under the premise of ensuring normal production, the amount is reduced as much as possible. The use of external lubrication should be less better under the guarantee of non precipitation, and the amount of internal lubrication to ensure that the products are not brittle as far as possible. Minimize the use of low molecular weight lubrication and change it to high molecular weight lubricants, such as paraffin wax, PE wax, etc.
3, CPE is a toughening modifier, and the glass transition temperature is about -10 C, which can greatly reduce the PVC softening temperature, reduce the dosage, or mix with the core shell impact modifier, impact ACR and MBS, or add ABS modification.
4, reduce the use of plasticizers, or part of the solid powder plasticizer.
5, adding the PVC processing assistant ACR, whether it is the AS series or the acrylic acid ester series processing auxiliaries, can improve the Vicat softening point.
6, the use of packing. The filler (the choice of nano calcium carbonate) can be enhanced in a certain range, and can improve the softening point of Vicat. It is an undisputed fact that the performance of the products has a great influence on the performance of the products.
7, ensure good plasticizing degree, such as plasticizing degree about 70% of pipe material. Plasticization is not mechanical and other properties decrease, plasticizing, PVC will appear partial decomposition, performance will also be reduced, so the plasticity of the material should be grasped well.