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Impact of TiO2 particle size and content on the non-isothermal degradation mechanism of the poly(ɛ-caprolactone)

Poly(ɛ-caprolactone) (PCL) is the most promising biopolymer produced from renewable resources, which due to its flexibility and biodegradability has been used for food packaging, tissue engineering, wound dressings, and drug delivery. However, some shortcomings such as high cost, low melting temperature and low mechanical properties limit the industrial use of PCL. A possible solution could be inorganic particles, such as titanium dioxide (TiO2), or simply the combination of incorporated inorganic nanoparticles and a polymer matrix. Polymer (nano)composites are materials that generally have better properties than pure polymer in terms of mechanical properties, thermal and dimensional stability, fire and chemical resistance, and optical and electrical properties. In this work the effect of TiO2 particle size and content on degradation mechanism of the biodegradable poly(ɛ-caprolactone) was estimated. Kinetic analysis of the non-isothermal degradation of prepared composites was performed using Friedman method in combination with the multivariate non-linear regression method incorporated into Netzsch Thermokinetic 3.1 software. The kinetic parameters (activation energy, pre-exponential factor and kinetic model) were calculated and compared. The results indicated three-stage degradation mechanism for PCL composites with TiO2 microparticles. However, the PCL composites with TiO2 nanoparticles revealed four-stage degradation mechanism. This difference can be attributed to the interaction between the TiO2 nanoparticles and the volatile degradation products of PCL, which delays their diffusion from the molten nanocomposite. The diffusion is the result of the observed agglomeration of TiO2 nanoparticles in the PCL matrix.

Kinetic analysis ; nanoparticle ; polycaprolactone ; titanium dioxide

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