Effects of thermal exposure on the physicochemical properties of polyamides

Valko, Emery I.; Chiklis, Charles K.

doi:10.1002/app.1965.070090820

Cited by 32 publications

(11 citation statements)

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“…This study was performed at 200°C on unfilled nylon for time periods up to 36 h in a nitrogen or an oxygen atmosphere. Their findings and others (2)(3)(4) have provided various reaction mechanisms for the degradation of nylon.…”

Section: Introductionmentioning

confidence: 93%

Adaptation of photoacoustic fourier transform infrared spectroscopy for studying the thermal oxidation of nylon 66 at 150°c correlated to mechanical properties

Murty

Yehl

1990

Polymer Engineering & Sci

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Oven aged tensile bars of heat stabilized, glass reinforced nylon 66 material were studied by Fourier transform infrared (FTIR) spectroscopy using a photoacoustic detector. Flat weighed scrapings were removed from tensile bars whose tensile strength, elongation, impact, molecular weight, and thermal properties had previously been measured. Using the amide I band of nylon 66 as an internal standard, the thermal oxidation of nylon was followed using a commercially available photoacoustic detector. The infrared absorbance spectra demonstrate the formation of carbonyl stretching vibrations due to the thermal oxidation of nylon with a band center at 1713 cm−1 whose width at half height is 40 cm−1. The difference infrared spectra support reaction mechanisms dealing with an Initial increase in the degree of polymerization followed by transamidation reactions with subsequent formation of an α, β unsaturated carbonyl species and chain scissioning. By using data related to the percent retention of certain physical properties which had also been measured on these tensile bars, subtractive infrared spectroscopy yielded additional fundamental information regarding nylon 66 degradation. Consequently, nylon products being used in underhood automotive applications are currently being investigated for thermal oxidative degradation using this rapid and relatively non‐destructive photoacoustic FTIR technique for durability considerations.

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Section: Introductionmentioning

confidence: 93%

Adaptation of photoacoustic fourier transform infrared spectroscopy for studying the thermal oxidation of nylon 66 at 150°c correlated to mechanical properties

Murty

Yehl

1990

Polymer Engineering & Sci

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“…The increase of tensile strength and modulus flexural property during reprocessing can be explained by an increase of molecular weight. 9,10 The gel permeation chromatography (GPC) technique was used to obtain the change in average molecular weight (M w and M n ) of the nylon-6 virgin with respect to the reprocessed material. The results of the M w and M n are shown in Figures 6 and 7, respectively.…”

Section: Characterization and Mechanical Testingmentioning

confidence: 99%

Physical-mechanical properties and morphological study on nylon-6 recycling by injection molding

Lozano-González¹,

Rodriguez-Hernandez

Santos³

et al. 2000

J. Appl. Polym. Sci.

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ABSTRACT:The effect of the multiple recycling of nylon-6 by injection molding on its physical-mechanical properties and morphology was studied after each cycle of injection. These studies were made in order to know how many times it is possible to recycle the nylon-6 without significant loss of the physical-mechanical properties. Optical and electronic microscopy were used to evaluated the morphology. Molecular weight changes were determinated by gel permeation chromatography (GPC). The nylon-6 was recycled 10 times, until the eighth cycle the properties of the material did not suffered any change. Changes of 10 -15% in the properties between nylon-6 with 10 cycles of injection and virgin material were observed. An exception was the percentage of elongation that decreased 70% gradually until in the tenth cycle of injection. The results from GPC show that the molecular weight of nylon-6 increased with recycling (M w ϭ 17% and M n ϭ 14%). With the reprocess was also observed the presence of gels.

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“…Thus, it is important to investigate the interaction between simultaneously in the interior. Valko and Chiklis 10 showed that the molecular weight deprocess-induced degradation and the magnitude of degradation during subsequent service. Figure creases on heating in the presence of air but increases on heating in the presence of antioxidants 1 is a schematic illustration of process-induced and service-induced degradation on the individual or in a nitrogen atmosphere.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7][8][9][10] The literature (4-10) addresses changes in calorimetric behavior, 4,5 infrared (IR) absorption bands, [6][7][8] and mechanical properties. [8][9][10] It is also known that the surface region of a thermally aged polyamide material will undergo more severe degra- Figure 1 Schematic illustration of process-induced dation than the interior. 9,11 Molecular weight deand service-induced degradation of the individual termination 9,11 showed that the molecular weight phases of glass-fiber-reinforced thermoplastics.…”

Section: Introductionmentioning

confidence: 99%

Effect of thermal-oxidative aging on mechanical, chemical, and thermal properties of recycled polyamide 66

Eriksson

Boydell²,

Eriksson³

et al. 1997

J. Appl. Polym. Sci.

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This article addresses the effect of thermal aging on unreinforced and glassreinforced recycled polyamide 66. As an accelerated test, injection-molded test bars were aged at 110, 140, and 170ЊC for up to 4000 h in air to simulate service life. FTIR spectroscopy demonstrated that the oxidative degradation primarily occurred between the surface and a depth of 0.5 mm. Furthermore, the degradation in the surface region was more pronounced with recycled as well as unstabilized materials. Reprocessing resulted in a faster increase of carbonyl groups, a decrease in melting peak temperature, and elongation at break during subsequent aging. Because of process-induced fiber shortening, however, the elongation at break of recycled reinforced samples was always at least as high as that of virgin samples for up to 4000 h of aging at 140ЊC. The decrease in melting peak temperature as determined by differential scanning calorimetry (DSC) indicated that the surface or boundary regions of the crystallites in the material are affected by aging. The loss in elongation at break for the reinforced material was shown to correlate with the reduction in melting peak temperature of material taken from the surface region of aged samples. The contribution of the degraded surface region to the properties was studied by removal of surface layers prior to testing. The degradation in the surface region was the sole cause, even of glass fiber-reinforced polyamide, for the embrittlement of aged samples. Furthermore, aging-induced changes in tensile strength and modulus were independent of the removal of the surface region, indicating that these properties are controlled by changes occurring in the bulk of the material.

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Effects of thermal exposure on the physicochemical properties of polyamides

Cited by 32 publications

References 0 publications

Adaptation of photoacoustic fourier transform infrared spectroscopy for studying the thermal oxidation of nylon 66 at 150°c correlated to mechanical properties

Adaptation of photoacoustic fourier transform infrared spectroscopy for studying the thermal oxidation of nylon 66 at 150°c correlated to mechanical properties

Physical-mechanical properties and morphological study on nylon-6 recycling by injection molding

Effect of thermal-oxidative aging on mechanical, chemical, and thermal properties of recycled polyamide 66

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