Many manufacturers of PVC foamed boards often encounter a problem: even though they've added enough foaming agent, why doesn't the board expand? Or, even if it expands, the core layer is full of broken bubbles and breaks easily.

Actually, foaming is like blowing up a balloon.

The foaming agent is the "mouth" that produces the gas, and the melt is the "balloon skin" that encloses the gas. If the "balloon skin" is too thin and brittle (low melt strength), it will burst when the air is blown in. The foaming regulator is used to thicken and reinforce this "balloon skin."

The foaming regulator is a high molecular weight acrylate copolymer (ACR). Unlike processing aids (primarily promoting plasticization), the foaming regulator has a higher molecular weight and its main function is to enhance the elasticity and ductility of the melt.

It can enhance melt strength (its core function), improve surface smoothness, and increase filler load-bearing capacity:

In the foaming region, the melt temperature is high and the viscosity decreases. Foaming modifiers' long-chain molecules can entangle together, "calcifying" the melt and making it less prone to breakage during stretching. This allows bubbles to grow stably, forming perfectly round closed cells.

If the melt pressure is unstable at the die exit, "melt fracture" can easily occur, resulting in a rough surface. Adding a foaming modifier makes the melt flow more uniform, significantly improving the surface smoothness of the board.

With high-filler formulations, melt strength drops sharply. Foaming modifiers can compensate for this loss, allowing for the addition of more calcium carbonate without sacrificing mechanical properties, helping to reduce formulation costs.

If you want your foamed boards to be lighter, stronger, and have a smoother surface, choosing a suitable foaming modifier is more effective than simply adjusting the amount of foaming agent!