3. Results and discussion
3.1. DSC endotherms of the films
Table 2reports the thermal characteristics of the pure components and the films. Pure Gellan has a glass transition much below room temperature (−12.2 °C), while the blends show a shift in glass transition to higher temperatures. Fig. 1shows the DSC melt thermograms for pure Gellan, pure PVA and the Gellan and PVA blends. The thermal analysis of Gellan/PVA blends by DSC showed that the melting temperatures (Tm) shift due to the interaction of the two polymers. In the case of immiscible blends such as poly(hydroxybutyrate–cohydroxyvalerate) and poly(ε-caprolactone) two distinct melting temperatures have been reported ( Chun & Kim, 2000). The Gellan+PVA blends exhibit a single melt temperature that is shifted to higher temperature with increasing amount of PVA. The melt peak temperature (Tm) of pure Gellan is 115.5 °C, Gellan and PVA blends increased from 124.7 to 168.1 °C with increased amounts of PVA, while pure PVA has a melt peak temperature (Tm) of 202.7 °C. The temperature difference between the temperature of the onset of melt (To) and the completion of melt (Tc), the melt range, is around 120–130 °C for the blends while for pure Gellan and PVA a sharp melt range 40–50 °C was observed. In the case of PVA and chitin blends, Young et al. (1996) have reported that the melt peak of PVA decreased with increasing amount of chitin due to molecular interaction. The DSC thermograms of poly(ethylene glycol)-block-poly(l-lactide) poly[(R)-3-hydroxybutyrate]/poly(l-lactide) blends were shown to be compatible, showing single glass transition and single melt peak ( Yoon et al., 2000). The shift in Tg values and the peak melt temperatures of the thermograms of the PVA, Gellan blends indicate an interaction between the two polymers.
3. ผลลัพธ์ และสนทนา3.1. DSC endotherms ของภาพยนตร์Table 2reports the thermal characteristics of the pure components and the films. Pure Gellan has a glass transition much below room temperature (−12.2 °C), while the blends show a shift in glass transition to higher temperatures. Fig. 1shows the DSC melt thermograms for pure Gellan, pure PVA and the Gellan and PVA blends. The thermal analysis of Gellan/PVA blends by DSC showed that the melting temperatures (Tm) shift due to the interaction of the two polymers. In the case of immiscible blends such as poly(hydroxybutyrate–cohydroxyvalerate) and poly(ε-caprolactone) two distinct melting temperatures have been reported ( Chun & Kim, 2000). The Gellan+PVA blends exhibit a single melt temperature that is shifted to higher temperature with increasing amount of PVA. The melt peak temperature (Tm) of pure Gellan is 115.5 °C, Gellan and PVA blends increased from 124.7 to 168.1 °C with increased amounts of PVA, while pure PVA has a melt peak temperature (Tm) of 202.7 °C. The temperature difference between the temperature of the onset of melt (To) and the completion of melt (Tc), the melt range, is around 120–130 °C for the blends while for pure Gellan and PVA a sharp melt range 40–50 °C was observed. In the case of PVA and chitin blends, Young et al. (1996) have reported that the melt peak of PVA decreased with increasing amount of chitin due to molecular interaction. The DSC thermograms of poly(ethylene glycol)-block-poly(l-lactide) poly[(R)-3-hydroxybutyrate]/poly(l-lactide) blends were shown to be compatible, showing single glass transition and single melt peak ( Yoon et al., 2000). The shift in Tg values and the peak melt temperatures of the thermograms of the PVA, Gellan blends indicate an interaction between the two polymers.
การแปล กรุณารอสักครู่..
