Radiolytic crosslinking and chain scission in aliphatic and alkyl-aromatic polyamides. Part I

Lyons, B. J.; Glover, L. C.

doi:10.1016/1359-0197(90)90073-q

Cited by 6 publications

(9 citation statements)

References 12 publications

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“…[1][2][3][4][5][6][7][8][9][10] Charlesby 1 was the first to note that high-energy radiation from atomic pile crosslinked polyiminohexamethyleneiminoadipoyl [i.e., polyamide-6,6 (PA66)]. The crosslinking of PA66 by high-energy electrons from resonant transformer-type cathode ray equipment was also observed by Lawton et al 2 Little 3 reported that pile irradiation of PA66 in air resulted in a rapid loss of strength with a considerable increase in carboxyl end groups.…”

Section: Introductionmentioning

confidence: 87%

“…On the whole, G(S)/G(X) values of 3.0, 3.2, and 2.8 were on the higher side (Ͼ1.0), which implied that the scission probability for air-irradiated PA66 was relatively high. Lyons and Glover 10 reported G(S)/G(X) values of 1.2-1.4 for PA66 irradiated under a nitrogen atmosphere. However, Schnabel 22 reported a G(S)/G(X) value of 3.4 for the room-temperature irradiation of PA66.…”

Section: Gel-content Measurementsmentioning

confidence: 98%

“…All of the tests except water absorption were carried out within 5 days of the radiation date to minimize postirradiation oxidation. Previous researchers 10 annealed PA66 in a nitrogen atmosphere for 30 min at 448 K immediately after irradiation to remove trapped free radicals and, thereby, prevented postirradiation oxidation from influencing the polymer response. However, in industrial practice, such elaborate methods of annealing are generally not present.…”

Section: Gel-content Measurementsmentioning

confidence: 99%

“…The effect of high-energy radiation on several polyamides, including PA66, was also studied by Ueno 9 and Lyons and Glover. 10 However, literature covering the relationship between the structure and the thermal, mechanical, dynamic mechanical, and stress relaxation behaviors of polyamides irradiated by electron beam in air is scanty. Moreover, to the best of our knowledge, high-temperature electron-beam irradiation of polyamides has not been reported so far.…”

Section: Introductionmentioning

confidence: 99%

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Effect of ambient‐temperature and high‐temperature electron‐beam radiation on the structural, thermal, mechanical, and dynamic mechanical properties of injection‐molded polyamide‐6,6

Sengupta

Sabharwal

Tikku³

et al. 2005

J of Applied Polymer Sci

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Electron-beam irradiation of injection-molded specimens of polyiminohexamethyleneiminoadipoyl (better known as polyamide-6,6) was carried out in air at ambient temperature (303 K) and a high temperature (393 K). Most of the irradiated specimens were tensile dumbbells, although a few were cylinders for compressive stress relaxation testing. A few representative samples were dipped in triallyl cyanurate (TAC) solution before ambient-temperature irradiation. The gel content of the specimens increased with radiation dose and the temperature of irradiation. Moreover, the TAC-treated specimens showed an increase in gel content over the neat specimens irradiated at the same dose levels. Wide-angle X-ray scattering and differential scanning calorimetry studies revealed that the crystallinity decreased with increasing radiation dose. Irradiation at the high temperature and treatment with TAC further decreased the crystallinity compared to irradiation at ambient temperature. As determined from compressive stress relaxation and mechanical and dynamic mechanical properties, the optimized radiation dose for ambient-temperature radiation was 200 kGy. The gels had a stiffening effect, and the rate of relaxation decreased significantly. The water-uptake characteristics of the tensile specimens were investigated; this revealed a decrease in the water absorption tendency with increasing gel content.

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Section: Introductionmentioning

confidence: 87%

Section: Gel-content Measurementsmentioning

confidence: 98%

Section: Gel-content Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of ambient‐temperature and high‐temperature electron‐beam radiation on the structural, thermal, mechanical, and dynamic mechanical properties of injection‐molded polyamide‐6,6

Sengupta

Sabharwal

Tikku³

et al. 2005

J of Applied Polymer Sci

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“…Principally, this method can be applied to all polymers that predominantly undergo cross-linking upon irradiation. Although polyamide-6 belongs to this group of polymers, 5,6 radiation-induced cross-linking is not very favourable because of the rather low 100 eV yield for cross-linking GðXÞ ¼ 0:67 and the fact that simultaneously main-chain cleavage occurs with a 100 eV yield GðSÞ ¼ 0:67. The latter process counteracts network formation.…”

Section: à4mentioning

confidence: 98%

Fire retardance in polyamide‐6. The effects of red phosphorus and radiation‐induced cross‐links

Balabanovich

Levchik

et al. 2001

Fire and Materials

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Red phosphorus contained in non-irradiated polyamide-6 at concentrations up to 12.5 does not significantly improve the fire resistance of the polymer. It weakens the thermal stability of the polymer as reflected by a decrease in the onset temperature for mass loss from 4078C to 3638C, but causes char formation as indicated by m res ¼ 13 wt%, the non-volatile residue at 6008C. Irradiation of polyamide-6, loaded with red phosphorus, with 60 Co-g-rays generates intermolecular cross-links resulting in an improved fire resistance. However, the absorbed dose necessary to achieve improvement is too high (>1 MGy) from a practical point of view. This inconvenience is overcome by applying triallyl cyanurate (TAC) as a cross-linking promoter. Typically, polyamide-6 containing 5 wt% TAC and 12.5 wt% red phosphorus exposed to a g-ray dose of 22 kGy yields a V-0 rating (in the mode A UL 94 test) concurrently with a small increase in the onset temperature for mass loss and a drastic increase in the residue non-volatile at 6008C.

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Molecular and macromolecular structure changes in polyamide 11 during thermal oxidation – Kinetic modeling

Okamba-Diogo

Richaud

Verdú

et al. 2015

Polymer Degradation and Stability

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The oxidation kinetics of unstabilized polyamide 11 thin film under oxygen pressures up to 2.0 MPa was studied by means of ferrous ion method for hydroperoxides titration, size exclusion chromatography (SEC) for molar weight measurements and in situ FTIR monitoring for carbonyl build up. Oxidation was shown not to be limited by oxygen diffusion which militates in favor of the use of a simple kinetic model for simulating experimental data. The kinetic parameters of this model were estimated from literature for initiation and propagation, and from selective experiments such as ageing under several oxygen pressures for the estimation of the termination rate constants, or exposures under inert atmosphere to investigate the solid state polymerization effects and tentatively check the boundary conditions of the model. The kinetic model simulates satisfyingly the overall experimental results using the minimal number of adjustable parameters (except for some reactions difficult to be experimentally isolated and studied).

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Radiolytic crosslinking and chain scission in aliphatic and alkyl-aromatic polyamides. Part I

Cited by 6 publications

References 12 publications

Effect of ambient‐temperature and high‐temperature electron‐beam radiation on the structural, thermal, mechanical, and dynamic mechanical properties of injection‐molded polyamide‐6,6

Effect of ambient‐temperature and high‐temperature electron‐beam radiation on the structural, thermal, mechanical, and dynamic mechanical properties of injection‐molded polyamide‐6,6

Fire retardance in polyamide‐6. The effects of red phosphorus and radiation‐induced cross‐links

Molecular and macromolecular structure changes in polyamide 11 during thermal oxidation – Kinetic modeling

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