Vapor Absorption Process in Polyethylene Observed by PAL

Ito, Yasuo; López, Rafael; Sánchez, V.; Fucugauchi, Luz Alicia

doi:10.4028/www.scientific.net/msf.105-110.1597

Cited by 3 publications

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“…This agrees with previous work on polyethylene. [11][12][13][14] For PTMSP samples the size distributions after CO 2 and CH 4 sorption become less broad and shift to small values, that is, both I 3 and 4 and 3 and 4 are reduced. This behavior is in accordance with Langmuir-type sorption, in which dissolved gas molecules fill in free volumes, leading to a reduction in the o-Ps intensities and lifetimes.…”

Section: Resultsmentioning

confidence: 99%

Positron annihilation lifetime studies of gas sorption and desorption in polyethylene and poly[1‐(trimethylsilyl)‐1‐propyne]

Moh́sen

Gomaa

Schüt

et al. 2001

J of Applied Polymer Sci

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ABSTRACT:The variation of free-volume parameters (lifetime, intensity, and distribution) after sorption and desorption of CO 2 and CH 4 gases in the glassy polymer poly[1-(trimethylsilyl)-1-propyne] (PTMSP) and in the rubbery high-density polyethylene (HDPE) and low-density polyethylene (LDPE) were determined by the PAL technique. Size distributions deduced from PAL measurements reveal the presence of large free-volume holes in PTMSP with an average size of 0.725 nm 3 and intensity of 22% in addition to a free-volume hole size of 0.197 nm 3 with an intensity of 11%. In polyethylene free-volume hole sizes of 0.107 and 0.153 nm 3 with intensities of 21% and 25% could be deduced for HDPE and LDPE, respectively.

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Section: Resultsmentioning

confidence: 99%

Positron annihilation lifetime studies of gas sorption and desorption in polyethylene and poly[1‐(trimethylsilyl)‐1‐propyne]

Moh́sen

Gomaa

Schüt

et al. 2001

J of Applied Polymer Sci

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“…The source was sandwiched by two identical polymer samples and placed in one arm of the glass tube employed to carry out the sorption process. 18 The sample was evacuated at approximately llO°C for 30 min and then slowly cooled down to room temperature. After cooling, the sample was kept at room temperature for 1-2 days to allow the polymer chains to become stable by aging.…”

Section: Polypropylene (Pp) and Polytetrafluoroethylenementioning

confidence: 99%

Positron annihilation lifetime study of vapor sorption in polypropylene and polytetrafluoroethylene

Sánchez¹,

López²,

Fucugauchi³

et al. 1995

J of Applied Polymer Sci

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SYNOPSISPositron annihilation lifetime (PAL) spectra were measured for two different kinds of polymers: polypropylene (PP) and polytetrafluoroethylene (PTFE), during sorption of vapors of the following molecules: n-hexane, cyclohexane, benzene, methyl methacrylate, acrylic acid, and water. The behavior of ortho-positronium (0-Ps) annihilation parameters: lifetime, T,, and intensity, 13, can be explained by considering different sorption mechanisms in rubbery and glassy polymers. The mean size of the intermolecular-space holes and the relative free-volume fraction of PP and PTFE were estimated before and during the sorption process from the 0-Ps parameters obtained. Sorption of n-hexane, cyclohexane, and benzene in both polymers affect the 0-Ps component in a systematic way, for PP T~ and I3 tend to decrease, while in PTFE, 7, stay almost constant and I3 diminishes. These effects are interpreted in relation to the different states of the polymers studied rubbery for PP and glassy for PTFE. In case of methyl methacrylate molecules, the behavior of 0-Ps parameters was more complicated. For acrylic acid and water, their associated polarity provokes a diminution in I,, which is explained from the viewpoint of the spur model of positronium formation. Large changes in the mean size and the fraction of free volume, as well as their constant behavior in some cases, were interpreted to be due to positive or negative interactions, respectively, between vapor molecules and PP and PTFE, which could be correlated with the solvent-interaction parameters calculated. 0 1995 John Wiley & Sons, Inc.

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“…In the case of a species which fills the free-volume holes. gas-sorption experiment, Ito et al 39 reported that, at longer contact times, the polymer will be close Influence of Iodine on Crystalline and Crystalline/ to a swelled condition due to substantial gas sorpAmorphous Interface Regions tion. By analogy, for the present case, swelling seems to occur at later stages of sorption.…”

Section: / 8e45$$5165mentioning

confidence: 99%

Positron annihilation study of iodine sorption in acrylonitrile-butadiene-styrene

Ramani

Ramachandra

Ramgopal

et al. 1998

J. Appl. Polym. Sci.

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ABSTRACT:The influence of iodine on the free volume of acrylonitrile-butadiene-styrene (ABS) was investigated by positron annihilation lifetime spectroscopy (PALS). The results indicate the filling of free-volume holes, formation of a positronium-iodine compound (PsI 2 /PsI), and possible charge-transfer complexes (CTCs) in the initial stages and the swelling of iodine in the final stages of sorption. The present study also revealed that iodine acts as a chemical quencher of o-Ps. The average size of the free volume suggests that I 0 3 is the predominant species that fills up the free-volume holes during iodination. The diffusion process in the present case shows non-Fickian behavior and deviates from Fujita's free-volume concept as far as the fractional free volume and diffusion coefficient are concerned.

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Vapor Absorption Process in Polyethylene Observed by PAL

Cited by 3 publications

References 0 publications

Positron annihilation lifetime studies of gas sorption and desorption in polyethylene and poly[1‐(trimethylsilyl)‐1‐propyne]

Positron annihilation lifetime studies of gas sorption and desorption in polyethylene and poly[1‐(trimethylsilyl)‐1‐propyne]

Positron annihilation lifetime study of vapor sorption in polypropylene and polytetrafluoroethylene

Positron annihilation study of iodine sorption in acrylonitrile-butadiene-styrene

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