The hydration of TENCEL (R) cellulose fibres studied using contrast variation in small angle neutron scattering

A small angle neutron scattering (SANS) contrast variation study was perfor med to investigate the presence of air filled voids in fully hydrated Tence l(R) cellulose fibres. The data indicate that there are very few, if any, a ir filled voids within the water swollen fibres. A three phase scattering p ower analysis together with additional information from water inbibtion mea surements show that the volume fraction of air filled voids in water swolle n Tencel fibres is probably zero, but has an upper limit of 0.02. In a complementary experiment, a H2O/D2O mixture was prepared with the same neutron scattering length density as air. The difference between the SANS patterns from air and water swollen fibres persists when the fibres are swo llen in an air/water contrast matched H2O/D2O mixture. The data qualitative ly agrees with the analysis of time resolved SAXS data which indicated that the void size increases on drying, and the void volume fraction decreases on drying water swollen Tencel fibres (Crawshaw J, Cameron RE. Polymer, in press, Crawshaw J. PhD thesis. Changes in cellulose microstructure during p rocessing. University of Cambridge, 1997). (C) 1999 Elsevier Science Ltd. A ll rights reserved.