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Silk fibroin powder and biodegradable polybutylene adipate terephthalate (PBAT)/poly lactide (PLA) blends were melt-mixed together to fabricate natural and synthetic polymers as possible new sources of biomaterials. Morphological observations conducted through scanning electron microscopy indicated poor dispersion of the silk powder agglomerates, which resulted from strong hydrogen interactions between silk powder chains in the PBAT/PLA matrix. Although the silk powder agglomerates decreased the mechanical properties, as silk powder fractions increased, the ternary blend with 10 wt % silk powder still displayed high impact strength of 108 J/m and tensile modulus of 1.2 GPa. On the basis of mechanical analysis, this blend offered potential applications in fields which required high impact strength. Blends which contained Joncryl experienced a decrease in storage modulus. Furthermore, rheological studies confirmed that the viscosity of the PBAT/PLA/Silk powder blends decreased, which indicated possible weakening of hydrogen bonds between the silk chains, caused by the reaction between the epoxy groups of Joncryl. This reaction provides a possible method to improve the processability of this natural polymer and to improve its distribution in polymer blends.

Aluminum specimens were covered with SiO2 film by a sol-gel coating and then anodized galvanostatically in a neutral borate solution. Time variations in the anode potential during anodizing were monitored, and the structure and dielectric properties of the anodic oxide films were examined by transmission electron microscopy, Rutherford backscattering spectroscopy, and electrochemical impedance measurements. It was found that anodizing of aluminum coated with SiO2 films leads to the formation of anodic oxide films, which consist of an outer Al-Si composite oxide layer and an inner Al2O3 layer, at the interface between the SiO2 film and the metal substrate. The capacitance of anodic oxide films formed on specimens with a SiO2 coating was about 20% larger than without a SiO2 coating. In the film formation mechanism, the conversion of Al2O3 to Al-Si composite oxide at the interface between the inner and outer layers is discussed in terms of inward transport of Si-bearing anions across the outer layer. © 2001 The Electrochemical Society. All rights reserved.

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