Influence of plasticizers on thermal properties and crystallization behaviour of poly(lactic acid) films obtained by compression moulding

[EN] Neat and plasticized poly(lactic acid) (PLA) films were obtained by compression moulding. Three different plasticizers, at concentrations of 5 and 10%, were used: poly(ethylene glycol) (PEG) of 1000 and 4000gmol(-1) molecular weights and a commercial plasticizer, Palamoll (R) 638. Crystallization behaviour and glass transition of PLA films were analysed using differential scanning calorimetry and X-ray diffraction. Films were also characterised in terms of structural, tensile, barrier and optical properties. The addition of the three plasticizers reduced the glass transition temperature (T-g) while promoting the crystallization of PLA in the compression-moulded films, depending on their type and concentration. PEG 4000 enhanced the crystallization more than PEG 1000 and Palamoll (R) 638, the latter being that which induced the lowest degree of crystallization. The T-g value of the PLA amorphous phase was reduced by the addition of plasticizers, proportionally to their concentration. Nevertheless, all of the plasticized films exhibited similar elastic modulus and were less resistant to break and less extensible due to the greater induced crystallinity. PEG 4000 markedly reduced the film stretchability whereas this effect was less marked when Palamoll (R) 638 was used. (c) 2016 Society of Chemical IndustryMuller, J.; Jiménez Marco, A.; González Martínez, MC.; Chiralt, A. (2016). Influence of plasticizers on thermal properties and crystallization behaviour of poly(lactic acid) films obtained by compression moulding. Polymer International. 65(8):970-978. doi:10.1002/pi.5142S97097865

Fabrication of PEOT/PBT nanofibers by atmospheric pressure plasma jet treatment of electrospinning solutions for tissue engineering

This study focuses on the enhanced electrospinning of 300-Polyethylene oxide-polyethylene oxide terephthalate/polybutylene terephthalate (PEOT/PBT). An atmospheric pressure plasma jet for liquid treatment is applied to a solution with 9 w/v% PEOT/PBT dissolved in either chloroform (CHCl3), CHCl3 + N,N-dimethylformamide (DMF), CHCl3 + methanol (MeOH), or CHCl3 + hexafluoroisopropanol (HFIP). For all conditions, the plasma-treated samples present better-quality fibers: less or no-beads and uniform fiber diameter distribution. Except for CHCl3 + DMF, no significant changes to the material bulk are detected, as shown with size exclusion chromatography (SEC). X-ray photoelectron spectroscopy (XPS) spectra performed on nanofibers record an increase in C-C bonds for the CHCl3 + DMF combination upon plasma modification, while a shift and slight increase in oxygen-containing bonds is found for the CHCl3 + HFIP and CHCl3 + MeOH mixtures. MTT assay shows no-cytotoxic effects for CHCl3 + DMF, while a better cellular adhesion is found on nanofibers from CHCl3 + MeOH and CHCl3 + HFIP. Among the examined additives, MeOH is preferable as it produces beadless electrospun nanofibers with an average diameter of 290 +/- 100 nm without causing significant changes to the final nanofiber surface properties

Biodegradable hollow fibers containing drug-loaded nanoparticles as controlled release system

A ‘multiple’ delivery system was studied, consisting of hollow microfibres containing drugloaded nanoparticles. Both fibres and nanoparticles are made of biodegradable polymers, so that the system does not need any surgical operation to be removed. The main advantage of the system is that it allows the contemporaneous release of different kinds of drugs. Copolymers of poly(lactic acid) and ε -caprolactone were used for the preparation of the fibres through both wet and dry–wet spinning procedures. Two types of nanoparticles, gelatin and poly(DL-lactide-co-glycolide) nanoparticles, were prepared by simple water-in-oil and oil-in-water emulsions, respectively. Drugs such as dexamethasone and methotrexate were used to load the particles. The technique employed for the preparation of the nanoparticles filled fibres was described and the drug release characteristics of this system were investigated and compared with those of the free nanoparticles