Melt reaction of polymer blends comprising poly (s-CAPROLACTONE) and epoxidized natural rubber / Jurita Che Mat

Poly(s-caprolactone) (PCL) is a semicrystalline polymer and epoxidized natural rubber with 25 mole % epoxidation level (ENR-25) is an amorphous polymer. Blends of PCL with ENR-25 were prepared using solvent casting method. Terminal hydroxyl group of PCL may trigger reaction between the constituents at relatively high temperature since the epoxy group from ENR-25 provides reactive site. Glass transition temperature (Tg) for neat PCL and neat ENR-25 are -65.5 °C and -42.7 °C, respectively. Two Tgs are observed over the entire composition range. This reveals immiscibility between PCL and ENR-25. DSC traces display an exothermic peak when PCL/ENR-25 blends were annealed at temperature ranging from 324 up to 330 °C. It turns out that rate of melt reaction of PCL/ENR-25 blends stays approximately constant for respective blends with increasing Tas. FTIR studies indicate the ring opening of epoxy group in ENR-25 after melt reaction of PCL/ENR-25 blends. Two phases morphologies formed in the blends as observed under polarizing optical microscope (POM) at Tc = 35 °C before melt reaction.