Modelling pure polyamide 6 hydrolysis: Influence of water content in the amorphous phase

Deshoulles, Q.; Gall, Maelenn Le; Dréanno, Catherine; Arhant, Maël; Priour, Daniel; Gac, Pierre‐Yves Le

doi:10.1016/j.polymdegradstab.2020.109435

Cited by 32 publications

(35 citation statements)

References 33 publications

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“…Prolonged oven storage provides suitable conditions for thermo-oxidative degradation as PA-12 powder is exposed to high temperatures, in the presence of oxygen, for extended time periods [5,10,16,24,37,52,53]. This results in rapid chain scission and significant reductions in molecular weight [21,36,48,52,53]. As such, melting point depression occurs due to the acidic degradation products of thermo-oxidation [53].…”

Section: Storage Times Greater Than 100 Hmentioning

confidence: 99%

“…Within PA-12, degradation involves an auto-oxidation mechanism whereby hydrogen atoms are abstracted from the polymer backbone, causing a loss of amide groups, and a reduction in hydrogen bonding between adjacent polymer chains [22,24,54,58,59]. This contributes to a significant decrease in molecular weight [5,16,36,48], as well as substantial reductions in strength and EAB [24,37,54,55,57,59,67].…”

Section: Mechanical Properties Of Pa-12 Plaquesmentioning

confidence: 99%

“…During oven storage, morphological and structural changes to PA-12 could be attributed to two different phenomena, lamellar thickening via thermal annealing [28,40,48] or chemi-crystallisation, which is initiated by degradation [36][37][38]48,52]. Due to the macromolecular nature of semi-crystalline polymer chains, they usually contain a high number of entanglements, which can limit further crystallisation [38].…”

Section: Mechanical Properties Of Pa-12 Plaquesmentioning

confidence: 99%

“…At the powder bed temperature, physical aging and degradation processes may occur Polymers 2022, 14, 2682 3 of 20 simultaneously and interact with each other [10,12]. For example, chain scission alters the morphology of PA-12, which can increase secondary crystallisation through chemicrystallisation [36][37][38]. Conversely, cross-linking may reduce secondary crystallisation by restricting motion and reorganisation of polymer chains [21].…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Physical Aging and Degradation on the Re-Use of Polyamide 12 in Powder Bed Fusion

et al. 2022

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Powder bed fusion (PBF) is an additive manufacturing (AM) technique which offers efficient part-production, light-weighting, and the ability to create complex geometries. However, during a build cycle, multiple aging and degradation processes occur which may affect the reusability of the Polyamide 12 (PA-12) powder. Limited understanding of these phenomena can result in discarding re-usable powder unnecessarily, or the production of parts with insufficient properties, both of which lead to significant amounts of waste. This paper examines the thermal, chemical, and mechanical characteristics of PA-12 via an oven storage experiment that simulates multi jet fusion (MJF) conditions. Changes in the properties of PA-12 powder during oven storage showed two separate, time-dependent trends. Initially, differential scanning calorimetry showed a 4.2 °C increase in melting temperature (Tm) and a rise in crystallinity (Xc). This suggests that secondary crystallisation is occurring instead of, or in addition to, the more commonly reported further polycondensation process. However, with extended storage time, there were substantial reductions in Tm and Xc, whilst an 11.6 °C decrease in crystallisation temperature was observed. Fourier transform infrared spectroscopy, a technique rarely used in PBF literature, shows an increased presence of imide bonds—a key marker of thermo-oxidative degradation. Discolouration of samples, an 81% reduction in strength and severe material embrittlement provided further evidence that thermo-oxidative degradation becomes the dominant process following extended storage times beyond 100 h. An additional pre-drying experiment showed how moisture present within PA-12 can also accelerate degradation via hydrolysis.

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Section: Storage Times Greater Than 100 Hmentioning

confidence: 99%

Section: Mechanical Properties Of Pa-12 Plaquesmentioning

confidence: 99%

Section: Mechanical Properties Of Pa-12 Plaquesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Effect of Physical Aging and Degradation on the Re-Use of Polyamide 12 in Powder Bed Fusion

et al. 2022

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“…A new kinetic model considering water content increase is proposed. The model is used to predict the leakage of macromolecules from the polymer into the oceans [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Behavior of Polymer Materials Exposed to Aging in the Swimming Pool: Focus on Properties That Assure Comfort and Durability

Čubrić

Matković

2021

Polymers

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The degradation of polyamide (PA) and polyester (PES) polymers is under intense study due to growing concerns about the accumulation of plastics in soils and oceans. Previous studies confirm that ageing degrades PA and PES at the molecular level. However, researchers have not addressed the development of protocols for aging textile materials in swimming pools, and few data are available on the effects of aging on comfort and durability. This research addresses the development of the aging protocol for PA and PES swimwear materials, its implementation, and the evaluation of properties that assure comfort and durability after specific periods of exposure. The tests include microscopic analysis, tensile tests, determination of fluid transport phases and drying period. The results revealed changes in the surface of the material in terms of fibrillation (more pronounced after outdoor aging). There is a positive correlation between the exposure duration and the breaking force (R2 ranges from 0.85 to 0.98), with a stronger correlation for the PA materials. The decrease in breaking force due to aging is up to 40%, indicating significantly reduced durability. The change in breaking force follows the changes in mass (R2 = 0.867). In terms of comfort assurance, outdoor aging of materials should have a greater negative impact than indoor ageing.

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Environmental Risks and Human Health Impact of Microplastic Pollution

Ezeh,

Agu

2024

Emerging Contaminants and Associated Treatment Technologies

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Modelling pure polyamide 6 hydrolysis: Influence of water content in the amorphous phase

Cited by 32 publications

References 33 publications

The Effect of Physical Aging and Degradation on the Re-Use of Polyamide 12 in Powder Bed Fusion

The Effect of Physical Aging and Degradation on the Re-Use of Polyamide 12 in Powder Bed Fusion

Behavior of Polymer Materials Exposed to Aging in the Swimming Pool: Focus on Properties That Assure Comfort and Durability

Environmental Risks and Human Health Impact of Microplastic Pollution

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