• Dave, Foram
• Tormey, David
• Mulrennan, Konrad
• Sherlock, Richard

Abstract

<p>Poly(lactic acid) (PLA) is a bioresorbable aliphatic polyester. It has varying rates of degradation influenced by factors including its percentage of crystallinity (χ) and glass transition temperature (Tg). In order to improve its bioresorbability for medical applications modification of the polymer is required. Many approaches are considered in the literature including bulk modification. The aim of the present study is to assess the efficacy of CO2 laser modification by characterising PLA material before and after laser treatment. Extruded PLA sheets were used for laser trials. A Design of Experiments (DoE) methodology was used to set various combinations of levels for laser power and scanning speed. It was found that CO2 laser processing of PLA induces bulk property changes. The increase in laser interaction with the polymer led to a decrease in the percentage crystallinity (χ). This trend was observed from the first heat scan of Differential Scanning Calorimetry (DSC). For both the first and second heat scan, ANOVA revealed that there was a statistical significance of scanning speed on the crystallisation temperature (Tc) and χ. There were some permanent changes in the polymer matrix due to laser treatment. XRD analysis evidinced similar behaviour. By controlling χ, one can control the bioresorption of the polymer. The percentage contribution of surface layers of the polymer to bulk property modification needs further investigation.</p>

Topics

• impedance spectroscopy
• surface
• polymer
• x-ray diffraction
• experiment
• glass
• glass
• thermogravimetry
• glass transition temperature
• differential scanning calorimetry
• crystallinity