Studies on the Effect of the Plasticizer and Plasma Treatment on Mechanical Properties of Biodegradable Polycaprolactone(PCL)/Starch Blends

• Main Authors: Jing-Yi Wu, 吳靜宜
• Other Authors: Chi-Yuan Huang
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/06479798528176965695

博士 === 大同大學 === 材料工程學系(所) === 101 === In this study, The author used the biodegradable polymer Polycaprolactone, starch, and plasticizer to prepared the biodegradable blends in Brabender. The influence of plasticizer on the molecular structure, crystalline structure, tensile properties, and fracture property of blends were studied. In addition, the effect of molecular structure of the biodegradable composites was analysis by Fourier transform infrared spectroscopy (FT-IR), dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The tensile properties, and fracture property of composites were analysis by tensile test and scanning electron microscopy (SEM). The last, the crystalline structure of composites was analysis by X-ray Diffraction analysis. From above analysis, it show that glycerol was reacted with starch to form intra-molecular hydrogen bond to destroyed the crystalline of starch to impress the wavenumber in FT-IR spectrum of the OH group on starch at 3240, 3472, and 3595cm-1 shifted to lower position approximately 3184, 3436, and 3568 cm-1. And the wavenumber in FT-IR spectrum of the OH group on GA was also affect to shift from 3228 cm-1 to higher position at 3286 cm-1. This indicated that the phase separation between GA and starch also confirmed by DMA. Although, GA was separated with starch, but also disturbed the crystalline of starch during blending to form VH type structure in PCL/ST/GA composite. From tensile test and SEM analysis, the poor mechanical properties (max stress at 6.5MPa and elongation at breaking at 10%) of PCL/ST/GA blend causing by lacing adhesive between PCL and starch/GA. In other hand, from FT-IR analysis, it shows the new wavenumber at 1733 and 1731 cm-1 in FT-IR spectrum of PEG400 and PEG 3350(PEGs), which were molecular weight as 400 and 3350, as plasticizer in PCL/ST blends causing by that PEG were reacted with PCL to generated intra-molecular force (hydrogen bond). In DMA analysis and SEM analysis, it shows that the phase separated of PCL and starch was improved by adding PEGs in the PCL/ST blends. Besides, PEG molecular weight which was 3350 was high enough to make the PCL recrystallized. The yield-stress of PCL/ST/PEG 3350 was 4.5MPa and the stress at breaking of PCL/ST/PEG 3350 was increased from 4.5 MPa to 9.0 MPa. Also the elongation at breaking of PCL/ST/GA blend was increased from 300% to 600%. In DSC analysis, it shows that crystalline of PCL increased from 24.4% to 36.8% by PEG 3350 as plasticizer adding in PCL/ST blend and the melting point of blend was increased from 54.4℃ to 59.5℃. In XRD analysis, it shows that the new peak greened at 21.1o was resulted from PCL recrystallized by adding PEG3350 in blend. The fracture behavior analysis was showed that the buck structure which was form by PEG3350 reacted with PCL and starch in blend were postponed until they could initiate immediate dilatational shear yielding. And the same time the starch grains without reacted with PEG 3350 were strengthened the mechanical properties to from polymeric materials exhibited shear-yield deformation. In paper two, the author used the plasma to treated PCL to improve the mechanical properties of blends. The results show that the optimum condition of plasma to treat PCL was at 20W for 5 minutes in tensile test and free radical analysis. In this condition, the maximum stress of blends was 9MPa and the yield stress also achieved 6.5MPa. And the elongation at break of blends also increased from 600% to 650%. Plasma treatment was an effective method to improve the mechanical properties of PCL/ST/PEG3350 composite.