Positron Annihilation Studies of the Free Volumes in Nylon12/PVA Films Treated by Supercritical Carbon Dioxide

Li, Jingjing; Yin, Chongshan; Zhou, Yawei; Li, Gang; Yeh, Jen‐Taut; He, Chunqing

doi:10.12693/aphyspola.132.1552

Cited by 2 publications

(4 citation statements)

References 26 publications

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“…The free volume of blends Nylon12/PVA, treated with supercritical CO 2 , was studied using PALS [ 108 ]. Lifetime and intensity of o-Ps decrease with increasing content of PVA with respect to neat Nylon12, which is attributed to the higher crystallinity of PVA as well as the extra intermolecular hydrogen bonding between Nylon12 and PVA, acting as physical crosslinks that reduce the molecular mobility of Nylon12 and the free volume sizes.…”

Section: Discussion Of Some Pals Results In Polymeric Systemsmentioning

confidence: 99%

“…The solid lines represent the fitting relaxation curves of the three samples (reproduced from ref. [ 108 ] with permission from Acta Physica Polonica A. DOI: 10.12693/APhysPolA.132.1552).…”

Section: Figurementioning

confidence: 99%

“…The relative free volume increases linearly with the LiTFSI concentration up to 5 wt%, showing a drastic increment at higher loading, in agreement with an analogous behavior of the ionic conductivity (Figure 8). The free volume of blends Nylon12/PVA, treated with supercritical CO2, was studied using PALS [108]. Lifetime and intensity of o-Ps decrease with increasing content of PVA with respect to neat Nylon12, which is attributed to the higher crystallinity of PVA as well as the extra intermolecular hydrogen bonding between Nylon12 and PVA, acting as physical crosslinks that reduce the molecular mobility of Nylon12 and the free volume sizes.…”

Section: Bioplastics and Natural Polymersmentioning

confidence: 99%

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Probing the Free Volume in Polymers by Means of Positron Annihilation Lifetime Spectroscopy

Consolati

Nichetti²,

Quasso

2023

Polymers

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Positron annihilation lifetime spectroscopy (PALS) is a valuable technique to investigate defects in solids, such as vacancy clusters and grain boundaries in metals and alloys, as well as lattice imperfections in semiconductors. Positron spectroscopy is able to reveal the size, structure and concentration of vacancies with a sensitivity of 10−7. In the field of porous and amorphous systems, PALS can probe cavities in the range from a few tenths up to several tens of nm. In the case of polymers, PALS is one of the few techniques able to give information on the holes forming the free volume. This quantity, which cannot be measured with macroscopic techniques, is correlated to important mechanical, thermal, and transport properties of polymers. It can be deduced theoretically by applying suitable equations of state derived by cell models, and PALS supplies a quantitative measure of the free volume by probing the corresponding sub-nanometric holes. The system used is positronium (Ps), an unstable atom formed by a positron and an electron, whose lifetime can be related to the typical size of the holes. When analyzed in terms of continuous lifetimes, the positron annihilation spectrum allows one to gain insight into the distribution of the free volume holes, an almost unique feature of this technique. The present paper is an overview of PALS, addressed in particular to readers not familiar with this technique, with emphasis on the experimental aspects. After a general introduction on free volume, positronium, and the experimental apparatus needed to acquire the corresponding lifetime, some of the recent results obtained by various groups will be shown, highlighting the connections between the free volume as probed by PALS and structural properties of the investigated materials.

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Section: Discussion Of Some Pals Results In Polymeric Systemsmentioning

confidence: 99%

“…The solid lines represent the fitting relaxation curves of the three samples (reproduced from ref. [ 108 ] with permission from Acta Physica Polonica A. DOI: 10.12693/APhysPolA.132.1552).…”

Section: Figurementioning

confidence: 99%

Section: Bioplastics and Natural Polymersmentioning

confidence: 99%

See 1 more Smart Citation

Probing the Free Volume in Polymers by Means of Positron Annihilation Lifetime Spectroscopy

Consolati

Nichetti²,

Quasso

2023

Polymers

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“…The positron annihilation lifetime fundamentals will be discussed in the second section. Li et al [ 18 ] concentrated on the free-volume varieties of Nylon-12/PVA melt-blends treated in supercritical carbon dioxide (ScCO 2 ) using PAL spectroscopy. They found that the free volume opening size and its items declined with the increment in PVA content.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Transport Mechanism and Nanostructure of Nylon-6,6/PVA Blend Polymers

2022

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A casting technique was used to prepare poly(vinyl alcohol) (PVA) blend polymers with different concentrations of Nylon-6,6 to increase the free-volume size and control the ionic conductivity of the blended polymers. The thermal activation energy for some blends is lower than that of pure polymers, indicating that their thermal stability is somewhere in between that of pure Nylon-6,6 and pure PVA. The degree of crystallinity of the blend sample (25.7%) was lower than that of the pure components (41.0 and 31.6% for pure Nylon-6,6 and PVA, respectively). The dielectric properties of the blended samples were investigated for different frequencies (50 Hz–5 MHz). The σac versus frequency was found to obey Jonscher’s universal power law. The calculated values of the s parameter were increased from 0.53 to 0.783 for 0 and 100 wt.% Nylon-6,6, respectively, and values less than 1 indicate the hopping conduction mechanism. The barrier height (Wm) was found to increase from 0.33 to 0.72 for 0 and 100 wt.% Nylon-6,6, respectively. The ionic conductivity decreases as the concentration of Nylon-6,6 is blended into PVA because increasing the Nylon-6,6 concentration reduces the number of mobile charge carriers. Positron annihilation lifetime (PAL) spectroscopy was used to investigate the free volume’s nanostructure. The hole volume size grows exponentially with the concentration of Nylon-6,6 mixed with PVA. The Nylon-6,6/PVA blends’ free-volume distribution indicates that there is no phase separation in the blended samples. Mixing PVA and Nylon-6,6 resulted in a negative deviation (miscible blends), as evidenced by the interaction parameter’s negative value. The strong correlation between the free-volume size and other macroscopic properties like ionic conductivity suggests that the free-volume size influences these macroscopic properties.

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Positron Annihilation Studies of the Free Volumes in Nylon12/PVA Films Treated by Supercritical Carbon Dioxide

Cited by 2 publications

References 26 publications

Probing the Free Volume in Polymers by Means of Positron Annihilation Lifetime Spectroscopy

Probing the Free Volume in Polymers by Means of Positron Annihilation Lifetime Spectroscopy

Investigation of Transport Mechanism and Nanostructure of Nylon-6,6/PVA Blend Polymers

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