The indentation hardness measurement indicated that the addition of PUD into NRL softens the latex foam. The texture of these blend foam materials is relatively soft, compared to the NRL foam of similar density (Figure 5). However, the hardness of the blend foam may be further modified with fillers9.
The compression set value of the blend foam shows a substantial increase compared to the NRL foam. The blend foam indicated a lower ability to recover from deformation as shown in Figure 6. This may be attributed to the overall structure of the foam which can be observed in the SEM micrograph.
Figure 7 shows the age hardening percentage of NRL and blend foam. The blend foam indicated a higher percentage of age hardening compared to the NRL foam, which suggested that the NRL foam’s property performed better under humid conditions