Positron Annihilation Lifetime Studies on Free Volume Changes in Polymers by CO&lt;sub&gt;2&lt;/sub&gt; Conditioning

Tanaka, Kenji; Ito, Masamichi; Kita, Hideki; Okamoto, Katsutomo; Ito, Yasuo

doi:10.4028/www.scientific.net/msf.175-178.789

Cited by 3 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In Figure 2 the permeability coefficients (P) of CO 2 gas for PTMSP, HDPE, and LDPE are represented as a function of the mean free-volume size (V). Included also are the results obtained previously on polyimides 10,11 and in poly(ethylene terephthalate) (PET), 3 as well as in the copolyesters PEC(30)T and PEC(65)P. The data could be fitted using the empirical equation P ϭ k 1 exp (k 2 V) suggested by Yang et al 3 The fitting parameters k 1 and k 2 were found to be 1.13 ϫ 10 Ϫ9 and 0.01, respectively. It is interesting to note that in PTMSP the small free-volume size deviates significantly from the fitting line, indicating that the large free-volume size seems to be responsible for its large gas permeability.…”

Section: Resultsmentioning

confidence: 74%

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

View full text Add to dashboard Cite

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.

show abstract

Section: Resultsmentioning

confidence: 74%

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

View full text Add to dashboard Cite

show abstract

“…Several groups have recently reported on PAL studies on polyimides; − however, only a few papers focused on moisture absorption . In the present work, we utilize PAL spectroscopy to investigate the effect of water sorption on the free volume in polyimide 6FDA-ODA.…”

Section: Introductionmentioning

confidence: 99%

“…Given a sufficiently large concentration of cavities in the sample, the Ps density is largely restricted to these open volumes, and the o-Ps pick-off lifetimes, which are typically in the nanosecond range, can be evaluated to estimate the size of the cavities. [10][11][12] Several groups have recently reported on PAL studies on polyimides; [13][14][15][16][17][18][19][20][21] however, only a few papers focused on moisture absorption. 20 In the present work, we utilize PAL spectroscopy to investigate the effect of water sorption on the free volume in polyimide 6FDA-ODA.…”

Section: Introductionmentioning

confidence: 99%

Water in Local Free Volumes of Polyimides: A Positron Lifetime Study

et al. 1999

View full text Add to dashboard Cite

Positron annihilation lifetime (PAL) spectroscopy was used to study the effect of water uptake on the free volume in 6FDA-ODA polyimide (PI2566, DuPont). Orthopositronium (o-Ps) lifetime (τ 3 ) and intensity (I 3) data were analyzed assuming a Gaussian size distribution of preexisting (excess free volume) holes and further assuming that holes occupied by water molecules would not be detected in the measurement. When exposed to humidity, both the mean hole volume and the number of holes not occupied by water molecules decrease with increasing relative humidity, as indicated by decreasing τ 3 and I 3. Our PAL results correlated with humidity-induced mass uptake and volume expansion support a model according to which water absorption in polyimides occurs in two stages. At relative humidities smaller than about 30%, water is absorbed mostly in large, preexisting holes, with each hole typically occupied by a single water molecule. At larger humidities, an increasing fraction of the sorbed water molecules will occupy sites other than preexisting empty holes. A multiple occupation of larger holes by water molecules is discussed as a possible mechanism.

show abstract

Reasons for the deviation of I1/I3 and τ1 from the expected lifetime parameters of positronium annihilation in polymers

Dlubek

Eichler

Hübner

et al. 1999

Nuclear Instruments and Methods in Physics Research Section B:

View full text Add to dashboard Cite

Positron Annihilation Lifetime Studies on Free Volume Changes in Polymers by CO<sub>2</sub> Conditioning

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]

Water in Local Free Volumes of Polyimides: A Positron Lifetime Study

Reasons for the deviation of I1/I3 and τ1 from the expected lifetime parameters of positronium annihilation in polymers

Contact Info

Product

Resources

About