What is the impact of PVC material on the flexibility of the water stop belt?

Molecular structure

• PVC (Polyvinyl Chloride) is made from the polymerization of vinyl chloride monomers. Its molecular chain has lots of chlorine atoms. The chlorine atoms make the force between molecular chains stronger. This limits the free movement of molecular chains and makes the waterstop less flexible.
• If the degree of polymerization of the PVC molecular chain is high, the molecular chain is long. Then the entanglement between molecules will also increase. So the waterstop becomes more rigid and less flexible. When the degree of polymerization is low, the molecular chain is short. The force between molecules is relatively weak. So the waterstop may be more flexible, but its strength and other properties may be affected.

Plasticizer addition

• Plasticizers are important for the flexibility of PVC waterstops. When making PVC waterstops, people usually add some plasticizers like phthalate esters. Plasticizer molecules can get between PVC molecular chains. They weaken the force between molecular chains. So the molecular chains can slide more easily. This makes the waterstop more flexible.
• The amount of plasticizer added is very important. If too little plasticizer is added, the waterstop may not be flexible enough. If too much is added, the waterstop will be more flexible. But its strength, heat resistance and other properties will get worse. Also, there may be problems like plasticizer migration. This will affect the long - term performance of the waterstop.

Other additives

• Adding stabilizers can improve the heat and light stability of PVC. It can stop PVC from degrading during processing and use. This helps keep the flexibility of the waterstop. If PVC degrades and the molecular chain breaks, the waterstop's performance will become bad. And its flexibility will be affected too.
• The type and amount of fillers also affect the flexibility. Adding too much of some inert fillers like calcium carbonate will make the PVC waterstop more rigid and less flexible. But some special fillers like nanoscale toughening agents may improve the flexibility and other properties of the waterstop.

Processing technology

• The processing temperature has a big effect on the flexibility of PVC waterstops. If the temperature is too high, the PVC molecular chains will move too much. This can cause the molecular chains to degrade or cross - link. Then the waterstop will be less flexible. If the temperature is too low, the molecular chains can't move well. It's hard to process and shape the waterstop. This may also affect its final flexibility.
• Processing parameters like stretching and extrusion can change how the PVC molecular chains are arranged. Stretching properly can make the molecular chains line up. This can improve the strength and flexibility of the waterstop. But stretching too much can break the molecular chains or cause internal stress. Then the flexibility will get worse.