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Accelerated photooxidation under ultraviolet (UV) test of polyamide 11 (PA11) films filled with unmodified vermiculite clay at 5 wt% was investigated up to 600 h. Film samples of ~60-[micro]m thick were prepared by melt compounding using a cast extruder and exposed to UV light irradiation at [lambda] > 295 nm. Fourier transform infrared (FTIR) spectra indicated similar structural changes occurring in both PA11 and PA11 /unmodified vermiculite nanoclay (UVMC) nanocomposite along the photooxidation process, resulting in imides and carboxylic acids as the main carbonyl products. It was however observed that the formation rate of carbonyls in the PA11 /UVMC nanocomposite was slower than neat PA11. This behavior is consistent with the yellowing index evolution determined by ultraviolet-visible (UV-vis) spectroscopy. Further, the photooxidation stability of the samples was also evaluated by the onset oxidation temperature determined by differential scanning calorimetry. The results indicated a better stability of the nanocomposite film than neat PA11, corroborating well the data obtained by FTIR and UV-vis techniques., INTRODUCTION Polyamide 11 (PA11) is a bio-based engineering thermoplastic derived from a renewable resource (castor oil) [1]. It is biocompatible and has the advantage of being less hydrophilic than the [...]

Halloysite nanotubes (HNTs) were successfully incorporated as flame retardants in polyamide-11 (PA11) after their modification with methyl phosphonic acid. Fourier transform infrared spectroscopy, thermal gravimetric analysis (TGA) and pyrolysis-gas chromatography-mass spectrometry were used to evidence the functionalization of the clay. Raw and modified HNTs were then incorporated by melt mixing in PA11 at 20 wt%. Compositions containing both ammonium polyphosphate (APP) and HNTs were also prepared. TGA and pyrolysis combustion flow calorimeter exhibited enhancement in thermal stability upon incorporation of both raw and modified halloysite nanotubes while APP causes degradation at lower temperature. Cone calorimeter data showed that modified halloysite acts by forming an insulating barrier during the combustion, which limits heat and mass transfers. Moreover, elemental analysis of sample residues after cone test evidenced that a part of the phosphorus of the modified halloysite was transferred to the gaseous phase. These results suggest the full potential of halloysite as fire retardant agent for polyamides., INTRODUCTION Polyamide-11 (PA11) is a biocompatible commercial aliphatic polymer with excellent characteristics such as good oil resistance or low coefficient of friction and has the advantage to be less hydrophilic [...]

Blends of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polylactide (PLA) with different PHBV/PLA weight ratios (100/0, 75/25, 50/50, 25/75, 0/100) were prepared by melt compounding. To improve the miscibility between the two components of the blend, low amount of compatibilizing agent (5 wt%), obtained by grafting maleic anhydride onto PHBV, was used. When compared with the uncompatibilized blends, the compatibilizer presence induces a greater interfacial adhesion. The effect of Cloisite 30B (C30B) on the blend morphology and the blend properties was also investigated. The morphology of the different blends as well as the evolution of their material properties were discussed in terms of the nanoclay and compatibilizing agent contents. A synergistic effect of compatibilizer and C30B was highlighted leading to an improved miscibility of the two blend components. The resulting properties were correlated with the morphology observed for the different blends., INTRODUCTION During this last decade, much attention has been focused on both biodegradable polymers that can be produced from renewable resources and polymer layered silicate nanocomposites [1-3]. Among all these [...]