Crystal self-nucleation in polyamide 11

Jariyavidyanont, Katalee; Janke, Andreas; Androsch, René

doi:10.1016/j.tca.2019.02.006

Cited by 14 publications

(16 citation statements)

References 26 publications

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“…Rather than it may be considered that the semi-crystalline morphologies and the possible rigid amorphous fraction strongly depend on T c . For demonstration, Figure 4 shows AFM images obtained on samples crystallized at 60 °C (left) [ 68 ] and at 156 °C (right) [ 69 ].…”

Section: Resultsmentioning

confidence: 99%

“…Here we follow the idea for distinguishing relaxation on one side and crystallization/ordering on the other side by largely different memory effects after endothermic enthalpy-recovery or melting/disordering, respectively. While after enthalpy-recovery the structural state of the amorphous phase is recovered, after melting/disordering a non-fully randomized melt, that is, so-called self-nuclei [ 49 , 65 , 68 , 69 ], may exist which during further annealing would promote renewed crystallization and ordering, and consequently lead to observation of melting/disordering at higher temperature. However, such melting/disordering peaks at successively higher temperature are not detected but only the enthalpy-recovery peak at T g , thus excluding glass-crystallization/ordering as origin of the endothermic sub- T g peaks on subsequent heating.…”

Section: Resultsmentioning

confidence: 99%

“…The top left insets are sketches of the morphology of the crystals and their coupling with the surrounding amorphous structure. Reprinted/adapted from [ 68 ] (left) and [ 69 ] (right), with kind permission from Elsevier.…”

Section: Figurementioning

confidence: 99%

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Enthalpy Relaxation of Polyamide 11 of Different Morphology Far Below the Glass Transition Temperature

Androsch

Jariyavidyanont

Schick

2019

Entropy

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Polyamide 11 (PA 11) samples of different supermolecular structure, including the crystal-free glass and semi-crystalline PA 11 of largely different semi-crystalline morphology, were prepared by fast scanning chip calorimetry (FSC). These samples were then annealed at different temperatures well below the glass transition temperature Tg. The main purpose of the low-temperature annealing experiments was the calorimetric detection of mobility of chain segments at temperatures as low as −40 °C (≈Tg − 80 K) where still excellent impact resistance is predicted. It was found that annealing PA 11 at such low temperature, regardless the thermal history and supermolecular structure including crystallinity as well as crystal shape and size, permits distinct enthalpy relaxation at rather short time scale with the structural changes reverting on subsequent heating as detected with pronounced sub-Tg-enthalpy-recovery peaks. The main glass transition, associated to large-amplitude segmental mobility, as well as relaxations at temperatures only slightly below Tg are even more distinctly sensitive to the crystal morphology. In contrast to spherulitically grown lamellar crystals, presence of high-specific-surface area nanometer-sized ordered domains causes a shift of the glass transition temperature of the amorphous phase to higher temperature, proving stronger coupling of ordered and amorphous phases than in case of lamellae. In addition, the increased coupling of the crystalline and amorphous phases slows down the cooperative rearrangements on annealing the glass slightly below Tg. The performed study contributes to further understanding of the spectrum of structural relaxations in PA 11 including the effect of presence of crystals. Enthalpy relaxation and consequently the reduction of entropy at temperatures slightly below Tg strongly depends on the semi-crystalline morphology, while an only minor effect is seen on low-temperature annealing at Tg − 80 K, possibly indicating different molecular mechanisms for the processes occurring in both temperature ranges. The low-temperature process even seems proceeding in the crystalline fraction of the material.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Enthalpy Relaxation of Polyamide 11 of Different Morphology Far Below the Glass Transition Temperature

Androsch

Jariyavidyanont

Schick

2019

Entropy

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“…The maximum crystal fraction, similar as in case of other linear polyamides, is well below 50%, however, contributing to its balanced property profile [27]. Further dedicated studies about semi-crystalline morphologies of PA 11 forming, e.g., at high supercooling of the melt, or developed upon self-nucleation are available in the literature [34,35]. At room temperature, PBS has a rubbery mobile amorphous fraction, with a glass transition below −30 °C [36], as well as sizable RAF, whose vitrification/devitrification was quantified in [37] as a function of the cooling rate.…”

Section: Introductionmentioning

confidence: 99%

Polyamide 11/Poly(butylene succinate) Bio-Based Polymer Blends

2019

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The manuscript details the preparation and characterization of binary blends of polyamide 11 (PA 11) and poly(butylene succinate) (PBS), with PA 11 as the major component. The blends are fully bio-based, since both components are produced from renewable resources. In addition, PBS is also biodegradable and compostable, contrarily to PA 11. In the analyzed composition range (up to 40 m% PBS), the two polymers are not miscible, and the blends display two separate glass transitions. The PA 11/PBS blends exhibit a droplet-matrix morphology, with uniform dispersion within the matrix, and some interfacial adhesion between the matrix and the dispersed droplets. Infrared spectroscopy indicates the possible interaction between the hydrogens of the amide groups of PA 11 chains and the carbonyl groups of PBS, which provides the compatibilization of the components. The analyzed blends show mechanical properties that are comparable to neat PA 11, with the benefit of reduced material costs attained by addition of biodegradable PBS.

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“…In order to observe and compare the morphology of the PA6 and its copolyamides clearly during the isothermal process, they were supercooled at a specific temperature for 7 min (which guaranteed that their crystal growth was completed). As shown in Figure 6 , a crystal pattern was detected under the isothermal process, the neat PA6 tend to form sheet crystals with a larger size and high packing density, and the copolyamides tended to form smaller spherical (three-dimensional) or discoid (two-dimensional) crystals [ 15 , 22 , 57 , 58 , 59 , 60 , 61 ]. Considering the result of crystallization kinetics, it is evident that the copolyamides preferred to exist in the crystalline form of two dimensions.…”

Section: Resultsmentioning

confidence: 99%

Effect of Bis (2-Aminoethyl) Adipamide/Adipic Acid Segment on Polyamide 6: Crystallization Kinetics Study

et al. 2020

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The crystallization behavior of novel polyamide 6 (PA6) copolyamides with different amounts of bis (2-aminoethyl) adipamide/adipic acid (BAEA/AA) segment was investigated. The wide-angle X-ray diffraction (WAXD) results showed that as the amount of BAEA/AA segment increased to 10 mole%, the crystalline forms of all PA6 copolyamide were transferred from the stable α-form to the unstable γ-form because of the complex polymer structure. According to studies of crystallization kinetics, the Avrami exponent (n) values for all copolyamide samples ranged from 1.43 to 3.67 under isothermal conditions, implying that the crystallization is involved in the two- to three-dimensional growth at a high temperature of isothermal condition. The copolyamides provided a slower crystallization rate and higher crystallization activation energy (ΔEa) than neat PA6. Polyamide containing 10 mole% of BEAE/AA content exhibited a unique crystallization behavior in the coexistence of the α and γ forms. These results deepen our understanding of the relationship between BAEA/AA content, crystal structure, and its crystallization behavior in low-melting PA6, and they make these types of copolyamides useful for their practical application.

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Crystal self-nucleation in polyamide 11

Cited by 14 publications

References 26 publications

Enthalpy Relaxation of Polyamide 11 of Different Morphology Far Below the Glass Transition Temperature

Enthalpy Relaxation of Polyamide 11 of Different Morphology Far Below the Glass Transition Temperature

Polyamide 11/Poly(butylene succinate) Bio-Based Polymer Blends

Effect of Bis (2-Aminoethyl) Adipamide/Adipic Acid Segment on Polyamide 6: Crystallization Kinetics Study

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