Nanocellulose and chitosan have recently started to get attention as environmentally friendly piezoelectric materials for sensor and energy harvesting applications. Conversely, current commercially available flexible piezoelectric films made of for example polyvinylidene difluoride (PVDF) are relatively expensive and made from non-renewable materials. We measured the piezoelectric responses (2-8 pC/N) for solvent casted films based on nanocellulose, microcrystalline chitosan and their blends. In addition, the tensile properties of the piezoelectric films were characterized to find out if chitosan could be used to enhance the flexibility of the brittle nanocellulose films. Based on the results, plain chitosan is an interesting piezoelectric material itself. In addition, blending nanocellulose and chitosan could be a potential method for tailoring the properties of solvent casted low cost, green piezoelectric films. media. Depending on the chitin source, the degree of deacetylation should reach approximately 50% before this solubility is achieved. (Rinaudo, 2006) In nature, chitosan is reportedly produced by only some fungi (Grifoll-Romero et al., 2018). Nanocellulose and chitosan have been studied for numerous applications due to their simple water based solution processing, renewable raw material sources, low cost, biocompatibility
Understanding the degradation of a composite material is crucial for tailoring its properties based on the foreseen application. In this study, poly-L,DL-lactide 70/30 (PLA70) was compounded with silicate or phosphate bioactive glass (Si-BaG and P-BaG, respectively). The composite processing was carried out without excessive thermal degradation of the polymer and resulted in porous composites with lower mechanical properties than PLA70. The loss in mechanical properties was associated with glass content rather than the glass composition. The degradation of the composites was studied for 40 weeks in Tris buffer solution Adding Si-BaG to PLA70 accelerated the polymer degradation in vitro more than adding P-BaG, despite the higher reactivity of the P-BaG. All the composites exhibited a decrease in mechanical properties and increased hydrophilicity during hydrolysis compared to the PLA70. Both glasses dissolved through the polymer matrix with a linear, predictable release rate of ions. Most of the P-BaG had dissolved before 20 weeks in vitro, while there was still Si-BaG left after 40 weeks. This study introduces new polymer/bioactive glass composites with tailorable mechanical properties and ion release for bone regeneration and fixation applications.
The emergence of
transient electronics has created the need for
bioresorbable conductive wires for signal and energy transfer. We
present a fully bioresorbable wire design where the conductivity is
provided by only a few micrometers thick electron-beam evaporated
magnesium layer on the surface of a polymer fiber. The structure is
electrically insulated with an extrusion coated polymer sheath, which
simultaneously serves as a water barrier for the dissolvable magnesium
conductor. The resistance of the wires was approximately 1 Ω
cm–1 and their functional lifetime in buffer solution
was more than 1 week. These properties could be modified by using
different conductor materials and film thicknesses. Furthermore, the
flexibility of the wires enabled the fabrication of planar radio frequency
(RF) coils, which were wirelessly measured. Such coils have the potential
to be used as wireless sensors. The wire design provides a basis for
bioresorbable wires in applications where only a minimal amount of
metal is desired, for example, to avoid toxicity.
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