This study is devoted to the degradation pathway (bio, photo degradation and photo/bio) of Poly(Lactic acid) PLA polymers by means of melt viscoelasticity. A comparison was made between three PLA polymers with different microstructures (L, D stereoisomers). Biodegradability was determined during composting by burying the polymer films in compost at 58 °C.
View Article and Find Full Text PDFThe biodegradation of four poly(l-lactic acid) (PLA) samples with molecular weights (MW) ranging from approximately 34 to 160kgmol(-1) was investigated under composting conditions. The biodegradation rate decreased, and initial retardation was discernible in parallel with the increasing MW of the polymer. Furthermore, the specific surface area of the polymer sample was identified as the important factor accelerating biodegradation.
View Article and Find Full Text PDFThe photostability and photobactericidal properties of PdTPPC (Pd(ii)-5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin)-ZnAl/PU (polyurethane) composite films have been studied in order to investigate their applicability as new photodynamic surfaces. These films comprise a PdTPPC porphyrin photosensitizer intercalated between the lamella of ZnAl layered double hydroxide and dispersed (1 wt%) into a polyurethane matrix. The study of the photophysical behaviour shows that the ZnAl LDH host enhances the chemical stability of the PdTPPC guest by minimizing photobleaching and quenching aggregation effects.
View Article and Find Full Text PDFThree commercially available biodegradable polymers, two different aromatic-aliphatic copolyesters and polylactic acid, intended for the fabrication of agricultural mulching films, in addition to other applications, were subjected to a series of tests with the aim of studying the relationship between their photooxidation and biodegradation. Photooxidation resulted in the rearrangement of polymeric chains, in the case of both copolyesters the events led to polymeric chain crosslinking and the formation of insoluble polymeric gel. The tendency was significantly more pronounced for the copolyester with the higher content of the aromatic constituent.
View Article and Find Full Text PDFPoly(butylene succinate) (PBS) nanocomposite structure was studied as a function of the filler percentage loading. The resulting state of dispersion was evaluated by XRD and TEM, and the interfacial attrition between PBS chain and lamellar platelets by the melt rheological properties. Hybrid organic inorganic (O/I) layered double hydroxide (LDH) organo-modified by oleate anions was used as filler.
View Article and Find Full Text PDFMesh size distributions (MSDs) of swollen cross-linked styrene copolymer networks have been measured by thermoporometry using CCl(4) as a probe liquid. All numerical relationships required for the calculation of the MSD were established for both the liquid-to-solid and the solid-to-solid thermal transitions of CCl(4) and successfully validated on test samples. It was found that the polymer network, for both thermally and photo-cross-linked materials, was completely built in about 4 h of exposure.
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