Mechanisms for the modification of nylon 6,12 by gamma irradiation

Menchaca, Carmina; Álvarez-Castillo, A.; Martínez-Barrera, Gonzalo; López-Valdivia, H.; Carrasco, Héctor; Castaño, V. M.

doi:10.1504/ijmpt.2003.003468

Cited by 43 publications

(27 citation statements)

References 1 publication

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“…22 The new peak at 1740 cm −1 , adjacent to the increased amide CO band at 1630 cm −1 , can be attributed to the CO stretching of ketones, aldehydes, and carboxylic acids formed by air DBD treatment. The intensification of the characteristic IR peaks for −CH 3 (1380 cm −1 ) and the appearance of the peak for the −CH 2 bend (1470 cm −1 ) and the CH in-plane bend (1420 cm −1 ) also suggest the formation of hydrocarbon fragments on the plasma-treated PA66 surface.…”

Section: Resultsmentioning

confidence: 98%

Size and Aging Effects on Antimicrobial Efficiency of Silver Nanoparticles Coated on Polyamide Fabrics Activated by Atmospheric DBD Plasma

Zille

Fernandes

Francesko

et al. 2015

ACS Appl. Mater. Interfaces

110

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This work studies the surface characteristics, antimicrobial activity, and aging effect of plasma-pretreated polyamide 6,6 (PA66) fabrics coated with silver nanoparticles (AgNPs), aiming to identify the optimum size of nanosilver exhibiting antibacterial properties suitable for the manufacture of hospital textiles. The release of bactericidal Ag(+) ions from a 10, 20, 40, 60, and 100 nm AgNPs-coated PA66 surface was a function of the particles' size, number, and aging. Plasma pretreatment promoted both ionic and covalent interactions between AgNPs and the formed oxygen species on the fibers, favoring the deposition of smaller-diameter AgNPs that consequently showed better immediate and durable antimicrobial effects against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. Surprisingly, after 30 days of aging, a comparable bacterial growth inhibition was achieved for all of the fibers treated with AgNPs <100 nm in size. The Ag(+) in the coatings also favored the electrostatic stabilization of the plasma-induced functional groups on the PA66 surface, thereby retarding the aging process. At the same time, the size-related ratio (Ag(+)/Ag(0)) of the AgNPs between 40 and 60 nm allowed for the controlled release of Ag(+) rather than bulk silver. Overall, the results suggest that instead of reducing the size of the AgNPs, which is associated with higher toxicity, similar long-term effects can be achieved with larger NPs (40-60 nm), even in lower concentrations. Because the antimicrobial efficiency of AgNPs larger than 30 nm is mainly ruled by the release of Ag(+) over time and not by the size and number of the AgNPs, this parameter is crucial for the development of efficient antimicrobial coatings on plasma-treated surfaces and contributes to the safety and durability of clothing used in clinical settings.

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Section: Resultsmentioning

confidence: 98%

Size and Aging Effects on Antimicrobial Efficiency of Silver Nanoparticles Coated on Polyamide Fabrics Activated by Atmospheric DBD Plasma

Zille

Fernandes

Francesko

et al. 2015

ACS Appl. Mater. Interfaces

110

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“…A mechanism for chain scission occurring in the amorphous zone of the nylon 6,12 at high radiation dose which takes into account the Compton Effect has been proposed [Menchaca et al, 2003]. In the same work, cross-link is under consideration in the low dose region.…”

Section: Gamma Radiation 92mentioning

confidence: 99%

“…In the same work, cross-link is under consideration in the low dose region. An study of the low gamma irradiation dose (up to 50 kGy) has shown that the cross-link process is taking place in the amorphous zone of the nylon 6,12 [Menchaca et al, 2003;Menchaca et al, 2008]. When gamma radiation at low dose is applied both, the fusion temperature and the crystallinity degree show evidence of increments [Thanki et al, 2001], as well as a partial and repairable damage in the amorphous zone, is reported [Malek et al, 2001].…”

Section: Gamma Radiation 92mentioning

confidence: 99%

“…At 15 kGy and 50 kGy the melting point for gamma irradiated fibers is above or at least at the same temperature compared to the non-irradiated fibers. This phenomenon is attributed to the cross-link or partial damage [Wilson, 1974;Menchaca et al, 2003], and the decrease in the fusion temperature is ascribed to the chain scission or permanent damage that yields oligomers [Ramesh, 1999]. Gamma irradiation causes both immediate and time dependent changes in the mechanical properties and there is considerable experimental evidence that the time dependent effects arise from the presence of long lived free radicals.…”

Section: Polymeric Materials: Resin and Fibersmentioning

confidence: 99%

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Gamma Radiation as a Novel Technology for Development of New Generation Concrete

Martínez-Barrera¹,

Campos²,

Ureña-Núñez³

2012

Gamma Radiation

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“…By contrast, there is great interest in studying the radiation stability of polymers [2], as well as the change in chemical, mechanical and physical properties [3], aiming for future applications [4][5][6][7]. However, relatively few reports have been published on the effect of gamma radiation on nylons: mechanical properties [8], melting point decrease [9,10], degree of crystallinity [11][12][13], surface modification [14,15] and additional polymerization [9]. Moreover, there is controversy about the mechanism followed by the gamma-irradiated polymers.…”

Section: Introductionmentioning

confidence: 99%

Post-irradiation effects on gamma-irradiated nylon 6,12 fibers

Menchaca‐Campos

Martínez-Barrera²,

López-Valdivia

et al. 2013

Journal of Polymer Engineering

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Post-irradiation effects on nylon 6,12 crystalline fibers gamma-irradiated 6 years previously (6YI) were studied, including thermal stability and morphology; their relationship with storage time was also studied. The results of these studies were compared with those obtained for nonirradiated (NI) and namely freshly irradiated (FI) crystalline fibers. The results include analyses like thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM) and optical images for (6YI and FI) both kinds of nylon 6,12 fibers. The results showed that the most prominent effect is related to the reaction progress. The chain scission and/or crosslinking mechanisms, as well as the free radicals, allow proceeding with the reaction, and consequently, changes on the properties of the FI samples. The melting point, degree of crystallinity, degradation temperature and morphology prove that additional chemical reactions and surface modifications keep occurring in the fibers long after the irradiation process has ended. With storage time, the surface becomes rougher, the color turns yellowish, the melting point diminishes and the degree of crystallinity increases.

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Mechanisms for the modification of nylon 6,12 by gamma irradiation

Cited by 43 publications

References 1 publication

Size and Aging Effects on Antimicrobial Efficiency of Silver Nanoparticles Coated on Polyamide Fabrics Activated by Atmospheric DBD Plasma

Size and Aging Effects on Antimicrobial Efficiency of Silver Nanoparticles Coated on Polyamide Fabrics Activated by Atmospheric DBD Plasma

Gamma Radiation as a Novel Technology for Development of New Generation Concrete

Post-irradiation effects on gamma-irradiated nylon 6,12 fibers

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