The impact of the polycaprolactone content on the properties of polyurethane networks

The influence of polycaprolactone content on the surface properties of polyurethane networks

“…The increase of D values for water occurs due to the decrease in crosslinking density, appearance of more pronounced microphase separation in PUNs with higher SS content and fact that size of water molecules is smaller than size of THF molecules. Similar trend of D for water, with somewhat lower values, was also obtained for the PUNs prepared using BH‐30 37 . This was expected to occur, since PUNs synthesized using BH‐20 as crosslinker have lower crosslinking density.…”

“…Functionality of the applied crosslinker is another factor that significantly affects swelling rate of PUNs. Namely, crosslinking density of PUNs based on PCL, IPDI, and hyperbranched polyester of the third pseudo generation (BH‐30) is approximately twice as big as crosslinking density of PUNs prepared with BH‐20 29,37 . Therefore, it is not surprising that equilibrium swelling degrees and swelling rate constants of PUNs investigated in this work in THF are higher than values obtained for the PUNs prepared with BH‐30 37 …”

“…However, only for the sample with the lowest PCL content (PUN IPDI ‐10) D for THF was higher than value obtained for adequate PUN prepared with BH‐30 37 . Namely, with increasing SS content from 20 to 50 wt%, D (THF) values of PUNs based on BH‐30 changed from 8.88 to 36.6 × 10 −8 cm 2 s −1 37 . This noticeable difference is probably caused by the pronounced increase of phase separation with SS content increase in samples based on BH‐30.…”

“…This was expected to occur, since PUNs synthesized using BH‐20 as crosslinker have lower crosslinking density. However, only for the sample with the lowest PCL content (PUN IPDI ‐10) D for THF was higher than value obtained for adequate PUN prepared with BH‐30 37 . Namely, with increasing SS content from 20 to 50 wt%, D (THF) values of PUNs based on BH‐30 changed from 8.88 to 36.6 × 10 −8 cm 2 s −1 37 .…”

“…The diffusion mechanism for THF and water through the PUNs was investigated using the power‐law expression as described elsewhere 30,37 . The diffusion mechanism for THF in PUNs could not be determined, since w t / w e values were for all PUNs higher than 0.6 ( w t and w e are the amount of solvent penetrated into samples at time t and when equilibrium swelling was achieved, respectively).…”