Investigations of morphology of moisture-cured silicone–urethanes

✍ Scribed by Janusz Kozakiewicz; Helena Janik; Ryszard Kwiatkowski; Andrzej Wlochowicz

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 460 KB
• Volume: 11
• Category: Article
• ISSN: 1042-7147
• DOI: 10.1002/(sici)1099-1581(200002)11:2<82::aid-pat940>3.0.co;2-#

✦ Synopsis

Results of studies on synthesis and properties of siloxane±urethane prepolymers as well as on selected properties of moisture-cured silicone±urethanes have already been published. In this paper, some results of investigations of the effect of chemical structure of such silicone±urethane polymers on their phase seggregation investigated using mainly (TEM) transmission electron microscopy and small-angle x-ray scattering (SAXS) techniques are presented.

It was found in TEM studies that in siliconeurethanes obtained by moisture-curing of NCO-terminated prepolymers prepared from siloxane oligomer diols (SOD) and isophoronediisocyanate (IPDI), two factors determine the morphology of samples: length of siloxane chain and NCO/OH ratio. SAXS investigations showed that these silicone±urethanes had a lamellar structure. It was found that the long period of this structure changed from 4 to 9 nanometers as the siloxane chain length increased nine times. The increase of the long period correlated with the decrease of Young's modulus of the corresponding samples. TEM investigations of silicone± urethanes obtained by moisture-curing of NCO-terminated prepolymers prepared from the blends of SOD and polyoxypropylenediol (PPG) revealed complex morphology which depended on the SOD/PPG ratio.