Quantification of isothermal crystallization of polyamide 12: Modelling of crystallization kinetics and phase composition

Paolucci, Fabio; Baeten, Dorien; Roozemond, Peter C.; Goderis, Bart; Peters, Gwm Gerrit

doi:10.1016/j.polymer.2018.09.037

Cited by 46 publications

(61 citation statements)

References 37 publications

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“…The final integrated intensity is fitted with a combination of a Gaussian and Lorentzian functions to determine the amorphous and crystalline fractions. Finally, the average degree of crystallinity is calculated by means of:χ=Atot−AamoAtot, where Atot is the total integrated area and Aamo is the area of the amorphous halo [21].…”

Section: Methodsmentioning

confidence: 99%

In Situ WAXD and SAXS during Tensile Deformation Of Moulded and Sintered Polyamide 12

2019

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To provide knowledge to improve the mechanical performance of Polyamide 12 (PA12) sintered products, we have studied experimentally the mechanical response and structure development under constant strain rate of compression moulded and laser sintered PA12 by means of in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) experiments. It is found that at low temperatures, i.e., below the glass transition temperature, the brittle failure of laser sintered samples is determined by the fast formation of voids that originate at the beginning of the macroscopic plastic deformation. This effect appears to be faster at temperatures below room temperature and it is less effective at higher temperatures. When tested at 120 ∘ C, sintered PA12 shows a better mechanical response in terms of yield stress and a comparable strain at break with respect to moulded PA12. This can be explained by considering that sintered samples have slightly thicker crystals that can sustain higher stress at high temperature. However, this also leads to the formation of a larger number of voids at low testing temperatures. This work does not attempt to quantify the micromechanics behind crystals deformation and disruption, but it provides a deeper insight in the difference between the mechanical response of moulded and sintered PA12.

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Section: Methodsmentioning

confidence: 99%

In Situ WAXD and SAXS during Tensile Deformation Of Moulded and Sintered Polyamide 12

2019

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“…The reader is referred to the dedicated literature for additional information on the topic, e.g. [100,101]. During the crystallisation stage, the effective thermo-physical properties defined in Eq.…”

Section: Models Of the Thermal Processmentioning

confidence: 99%

Laser-based additively manufactured polymers: a review on processes and mechanical models

et al. 2020

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Additive manufacturing (AM) is a broad definition of various techniques to produce layer-by-layer objects made of different materials. In this paper, a comprehensive review of laser-based technologies for polymers, including powder bed fusion processes [e.g. selective laser sintering (SLS)] and vat photopolymerisation [e.g. stereolithography (SLA)], is presented, where both the techniques employ a laser source to either melt or cure a raw polymeric material. The aim of the review is twofold: (1) to present the principal theoretical models adopted in the literature to simulate the complex physical phenomena involved in the transformation of the raw material into AM objects and (2) to discuss the influence of process parameters on the physical final properties of the printed objects and in turn on their mechanical performance. The models being presented simulate: the thermal problem along with the thermally activated bonding through sintering of the polymeric powder in SLS; the binding induced by the curing mechanisms of light-induced polymerisation of the liquid material in SLA. Key physical variables in AM objects, such as porosity and degree of cure in SLS and SLA respectively, are discussed in relation to the manufacturing process parameters, as well as to the mechanical resistance and deformability of the objects themselves. Graphic abstract

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“…16 during winding of layers 2-5. The PA12 polymer crystallizes between T g and T m with various growth rates [53,58] which is shown as the shaded area in Fig. 16.…”

Section: Crystallinity Evolutionmentioning

confidence: 99%

Non-uniform crystallinity and temperature distribution during adjacent laser-assisted tape winding process of carbon/PA12 pipes

Hosseini

Schäkel

Baran

et al. 2020

Int J Adv Manuf Technol

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The non-uniform temperature and crystallinity distributions present in carbon fiber–reinforced PA12 composite pipes, produced via laser-assisted tape winding (LATW), are investigated in this paper. The width of the laser source is usually larger than the substrate width which causes multiple heating and cooling of some regions of the (neighboring) substrate and hence temperature and crystallinity gradients during the adjacent hoop winding. A kinematic-optical-thermal (KOT) model coupled with a non-isothermal crystallinity model is developed to capture the transient temperature and crystallinity distributions for growing substrate thickness and width. The predicted temperature trends are validated with thermocouple and thermal camera measurements. The substrate temperature varies in the width direction up to 52%. This will lead to extra polymer remelting and possible degradation. The maximum variation of the crystallinity degree across the width is found to be 270% which shows agreement with the trend of the measured crystallinity degree. It is found that a more realistic description of the melting behavior of the matrix is needed to obtain a more accurate prediction of the crystallinity distribution.

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Quantification of isothermal crystallization of polyamide 12: Modelling of crystallization kinetics and phase composition

Cited by 46 publications

References 37 publications

In Situ WAXD and SAXS during Tensile Deformation Of Moulded and Sintered Polyamide 12

In Situ WAXD and SAXS during Tensile Deformation Of Moulded and Sintered Polyamide 12

Laser-based additively manufactured polymers: a review on processes and mechanical models

Non-uniform crystallinity and temperature distribution during adjacent laser-assisted tape winding process of carbon/PA12 pipes

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