There has been speculation that the macroscopic properties of foams, such as air
flow, are directly related to foam compression set. However, it has since been recognized
that the molecular structure is the relevant size scale for understanding the compression
sets, which are simply symptomatic of the underlying polymer structure resulting from
the polymerization reactions that occur during foaming (Sonnenschein et al. 2007).
Researchers have empirically determined that formulation modifications can result in
large differences in compression set values (Van der Schuur et al. 2004).
The compression set is a measure of the elastic behavior of the material. Figure 1
shows that the control NRLF (with 0 phr RHP) had the lowest compression set. Low
compression sets indicate a high elasticity. NRLFs with higher RHP filler loadings had
higher compression sets. Figure 2 reveals that the control NRLF (with 0 phr RHP) had
the highest and fastest recovery percentage. The recovery percentage of RHPincorporated
NRLF decreased with increased RHP loading. Non-elastic deformation was
mainly due to the deformation of the hard phase (Van der Schuur et al. 2004). This is
probably due to the increased presence of RHP. Upon aging and compression force at
70 ºC, RHP filler starts to decompose hence affecting the surrounding NRL matrix and
contributing to poor adhesion properties. This non-elastic deformation due to aging of