Factors impacting the resilience of PU foam encompass various dimensions:
1. Cell Opening Rate:
Elevated open-cell rates result in a uniform distribution of polymers in the naturally open-celled foam network, fostering heightened resilience. Conversely, reduced open-cell rates correlate with diminished resilience. To address this, one may contemplate increasing the foaming agent quantity, adjusting the cell wall’s surface tension for a moderate cell wall rupture, thereby augmenting the open-cell rate of polyurethane foam plastic.
2.Cell Shape:
Increased regularity in cell shape corresponds to enhanced resilience in polyurethane foam plastic. Spherical cell structures demonstrate superior resilience, whereas needle-shaped structures are prone to collapse. Mitigating cell collapse can be achieved by lowering the foaming temperature, preventing excessive expansion and mutual compression deformation.
3.Cell Pore Size and Distribution:
Within the same system, foaming bodies with a higher proportion of small cells exhibit a superior rebound rate. However, there exists an optimum cell pore size, and the rebound rate rises with increased cell density. Optimizing cell density can be achieved by appropriately increasing the pore stabilizer.
4.Polyether Polyol:
Within a specific range, a higher relative molecular weight in polyether polyol enhances the flexibility of the molecular chain, leading to improved resilience. When utilizing polyether polyols with a substantial relative molecular weight, precautions are necessary to mitigate degradation. This includes incorporating an adequate amount of antioxidant before the polymerization reaction.
5.Isocyanate:
Managing the isocyanate index, or TDI index, is crucial. The foam hardness can be effectively and safely controlled within the TDI index range of 105~115. A proportional increase in the TDI index within a defined range results in heightened foam hardness and resilience. Hence, adjusting the TDI index can be a suitable approach.
6.Other Factors:
The resilience of foam plastic exhibits an initial increase followed by a decrease with an upsurge in the mass ratio of water to polyol. Maintaining higher resilience involves adjusting the water addition amount. Additionally, as the mass ratio of chain extender to polyol increases, product tensile strength rises while resilience decreases. Hence, contemplating a reduction in the chain extender quantity is a viable consideration.