In this particular case, samples from melt mixing were used for investigation. The results are shown in Fig. 2. On the first heating scan, the cold-crystallistion exothermic peak was observed in both PLA/NR and PLA/ENR blends.
These results suggest that the incorporation of NR and ENR would enhance the crystallization PLA. In general, crystallization behaviour of a crystallisable matrix in immiscible blends can be affected by two major phenomena which are the migration of impurities during melt-mixing and the nucleating activity at the interface between these two polymers. The small molecules, which migrated from the rubbers could act as nuclei for PLA [2, 12-13].
Increasing the rubber content can lead more migration of small molecules and the nuclei density in crystallisable phase increased.
It is also observed that increasing rubber content could result in the formation of larger droplets and cause a lower interfacial contact area.
The crystallinity was therefore decreased