Diffusion coefficient and equilibrium solubility of water molecules in biodegradable polymers

Water Sorption Thermodynamics and Mass Transport in Poly(ϵ‐Caprolactone): Interactional Issues Emerging from Vibrational Spectroscopy

“…As expected, the diffusivities calculated thereby are in good agreements with each other; in particular, the analysis of the stretching band gives a value of 4.93 × 10 − 7 cm 2 s − 1 , while that of the bending peak returns a diffusivity of 5.2 × 10 − 7 cm 2 s − 1 (i.e., a ≈ 5% discrepancy). The experimental value of diffusivity obtained in this work by FTIR spectroscopy experiments agrees satisfactorily with previous data measured gravimetrically by Yoon et al [ 33 ] As shown in Figure 6 A and B, the distinctive feature of Fickian behavior consisting of a linear trend of the sorption curve as a function of the square root of the time, up to a value of A ( t ) /A inf equal to 0.6, is evident. In Figure 7 , the evolution of the stretching absorbance as a function of time during the differential sorption tests is reported for all the investigated activities ( p / p 0 ).…”

Water Vapor Permeability of Poly(L‐lactide)/Poly(D‐lactide) Stereocomplexes

“…As expected, water vapor transmission became slow with an increase in t c or decrease in T a , i.e., with an increase in X c , as reported in previous papers. [16][17][18]21] The normalized WVTR at thickness of 25 mm and P were estimated from the slopes of water vapor transmission plot against time in Figure 3. The obtained normalized WVTR and P were summarized in Table 1 and P is plotted in Figure 4 as a function of X c .…”

“…[21] The composition of L-lactyl and D-lactyl units has no significant effect on the WVP of PLA, [21] whereas the incorporated e-caprolactone units dramatically increased the WVP of PLA. [17] As can be expected, the WVP became lower with an increase in crystallinity (X c ), [16][17][18]21] whereas the addition of 10 wt.-% of montmorillonite layered silicate lowered WVP of PLLA by 50%. [20] In these cases, the crystalline regions and montmorillonite layered silicate act as barriers for water molecule permeation.…”

“…With respect to the gas permeability including water vapor permeability (WVP) of poly(lactide) [i.e., poly(lactic acid), PLA] based materials numerous investigations have been carried out. [11,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Among the gas permeability, WVP is an important factor, when the polymers are used as food packages, containers, bottles, and so on. The molecular weight effect was insignificant for WVP of PLLA as far as the number-average molecular weight (M n ) was in the range of 9.2 Â 10 4 to 4.8 Â 10 5 g Á mol À1 .…”

Water Sorption Studies in a RGP Contact Lens Polymer Paraperm by Positron Lifetime Technique

“…In this equation D and S are independent of concentration. We have determined the D values from the sorption experiment and the solubility S of water is calculated as grams of water sorbed per grams of polymer sample [36]. Then we have plotted P as a function of sorption time.…”