A degradation study of polyamide 11/vermiculite nanocomposites under accelerated UV test

Abstract

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‐μm thick were prepared by melt compounding using a cast extruder and exposed to UV light irradiation at λ > 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. POLYM. ENG. SCI., 59:2449–2457, 2019. © 2019 Society of Plastics Engineers

Manufacturing and Characterization of Coatings from Polyamide Powders Functionalized with Nanosilica

“…After 500 h exposure, there are no meaningful structural changes that could imply a noticeable deterioration due to their exposure to solar radiations. Kaci et al [ 39 ] suggest that UV exposure of PA11 promotes the appearance of imide photooxidation products, being absorption bands located at 1736 and 1690 cm −1 , and the formation of carboxylic acid groups (band located at 1713 cm −1 ). The FTIR of developed coatings ( Figure 2 c) suggests that these phenomena cannot be discarded in the PA11 coatings, although longer exposure times would be required to completely assure it.…”

“…Besides, it should be noted that the 0% coating is the material with the lowest T g after the xenon exposure. As the destruction or formation of new types of bondings under xenon radiation only occur at a limited extent ( Figure 2 ), the decrease in T g after exposure to xenon may be linked to some chain scission [ 39 ], that in this case, is more pronounced in the 0% coating. Therefore, silica nanoparticles seem to partly balance the chain scission of the PA11 by new bond formation from the formed free radicals, maybe due to their already checked effect to enhance polymerization [ 11 ].…”

Synthesis and physicochemical investigation of imide‐functionalized silica nanocomposites

“…Here, the imide functionalized silica (IM/SiO 2 ) was used to reinforce the polyimide matrix. [25][26][27] These aromatic imide groups to be used for silica network modification are thermally stable, and their inclusion can increase the mechanical and thermal properties of polyimide. 28,29 For the synthesis of IM/SiO 2 network structures, alkoxysilane terminated amic acid (AAs) were prepared by adjusting the stoichiometry of pyromellitic dianhydride (PMDA), 4, 4-oxydianaline (ODA), 1, 5-diaminonaphthalene (DAN), and aminopropyltriethosilane (APTES).…”

“…A novel approach was tried for the compatibilization of organic and inorganic phases. Here, the imide functionalized silica (IM/SiO 2 ) was used to reinforce the polyimide matrix 25–27 . These aromatic imide groups to be used for silica network modification are thermally stable, and their inclusion can increase the mechanical and thermal properties of polyimide 28,29 .…”

Combined effect of palygorskite and melamine polyphosphate on flame retardancy properties of polyamide 11 nanocomposites

“…Polyamide 11 (PA11) is an important commercial polymer obtained from renewable resources (castor oil). It is an attractive polyamide used as an engineering polymer in various industrial sectors from automotive to offshore oilfield applications (Kaci et al, 2019). This is due to its excellent performance related to low moisture sorption, good chemical resistance and easy processability (Zhang et al, 2004(Zhang et al, , 2012.…”