Nanoclay and crystallinity effects on the hydrolytic degradation of polylactides

Instructive composites for bone regeneration

“…[368] For example, in the case of medical devices comprising polymers it is suggested that T should be not higher than 60°C as above it non-linear changes would occur in many polymer systems. [353][354][355][356][357]368] Calcium phosphate ceramics are thermally instable for temperatures higher than 850°C, [369][370] -free gels usi ers of our gro s having differ pastes respe and the lack o v.) preserved mistry. [295] The ro in phosph es approximately te ceramic gr pectively.…”

“…From  rel we could determine the inherent ( inh ) and intrinsic (<>) viscosity (Solomon-Ciută equation). [356] Then, by using MarkHouwink equation, the weight average molecular weight (M w ) of the polymers was calculated, as follows: [337] …”

“…We then dissolved again the polymers in chloroform (Sigma-Aldrich) at a concentration of 0.1 g dL -1 and determined the intrinsic viscosity (<>) using an Ubbelohde (ASTM) viscometer (0C, PSL-Rheotek, Burnham on Crouch, United Kingdom) at 25±0.1°C. The intrinsic viscosity of the polymers was calculated with the Solomon-Ciută equation [356] as follows:…”

“…[387,392] This fact has large impact on the development of polylactde(s)-based products in an industrial context, which require cost-effective and time-saving reliable procedures. Thus, accelerated degradation studies by mean of various tricks such as increasing the pH [393] and the temperature [354,356,394,395] of the degrading fluid or applying ultrasounds [396] have been proposed. So far, increasing the temperature of the degrading fluid has shown to be the most reliable method to model the (long-term) degradation behavior of polymer-based materials.…”

“…T g ) of the considered polymer to avoid unwanted effects due to polymer state transitions. [354][355][356][357]368] A phosphate buffered saline (PBS; Invitrogen, Darmstadt, Germany) solution having initial pH of 7.5±0.05 was used. Sterile granules of each composite (75±0.5 mg) were carefully weighed before use (m 0 ) and soaked in 30 mL PBS at 55±0.5°C for five weeks.…”