Abstract:

To evaluate the effect of poly（methyl）siloxane （PMSQ） on the mechanical and physicochemical properties of PHB/PCL films， 2 wt % PMSQ was added to the polyhydroxybutyrate （PHB）/polycaprolactone （PCL） blending systems with mass ratios of 25∶75， 50∶50， 75∶25 to prepare films by solution casting method. The results indicated that PMSQ exhibited an optimal enhancing effect on the tensile performance of the PHB25/PCL75 blends， resulting in an increase in elongation at break from 22.45 % to 70.83 %. FTIR spectra demonstrated the disappearance of the methyl （—CH₃） absorption peak of PMSQ along with an enhancement in the absorption peak intensity of the C=O bond in the PHB/PCL blending system. These results indicated that PHB and PCL were grafted onto PMSQ microspheres. SEM observation showed that the addition of PMSQ reduced the particle size of the PHB and PCL domains. The phase separation between the PHB and PCL phases was depressed due to an enhancement in their compatibility. DSC analysis suggested that the addition of PMSQ restricted the motion of PHB and PCL molecular chains and disrupted their spatial regularity， thus resulting in a decrease in crystallinity. In addition， TGA analysis indicated the addition of PMSQ increased the onset degradation temperature of the PHB/PCL blending systems and enhanced their thermal stability in accordance with the mass ratio of the two components.

Key words: polyhydroxybutyrate, polycaprolactone, polysiloxane, mechanical property, thermal stability