SynopsisThe chemical microstructural analysis (CMA) developed by Rowland and his school was applied to Vuloniu and bacterial cellulose and the results compared to those obtained with cellulose from cotton linters. It was found that the surface reactivity of Vulonia was very small, roughly one half of that found for bacterial and cotton cellulose. Vuloniu and bacterial cellulose crystals were found to be of high surface perfection as their surface O(

Abstract. Dry extract, ellagitanins, free ellagic acid, whisky-lactone, eugenol and vanillin have been quantified for a sample set of 61 pedunculate oaks (Quercus robur L.) and 72 sessile oaks (Quercus petraea Liebl.) originating from 6 different forests. Despite a very high interindividual variability, pedunculate oak shows higher level of dry extract, ellagitanins and free ellagic acid but lower level in volatil compounds compared to sessile oak. Inside a same species, differences between forests are less marked. Extractible compounds level is poorly correlated to the grain (ring width). Regarding cambial age, it might have its significance but lack of scientific data could not permit to conclude in that sense. Our results suggest that cooperage oak selection should be based on a species-provenance combination rather than on the grain or the provenance solely.

Acetoxypropylcellulose (APC) and propionic, n‐butyric, isobutyric, valeric, isovaleric, hexanionic, and heptanionic acid esters of hydroxypropylcellulose (HPC) (respectively PPC, BPC, iBPC, VPC, iVPC, HexPc, and HepPc) were prepared and characterized by differential scanning calorimetry, chromatography, polarizing microscopy, chemical methods, and spectroscopy. All these esters form thermotropic cholesteric liquid crystalline phases. The glass (Tg) and clearing (Tc) transition temperatures were determined. The stability interval of the mesophases appears to be greater in the case of longer‐linear side chains. The mesophases of APC, PPC, iBPC, VPC, and iVPC exhibit reflection bands in the visible region, at wavelengths that depend on temperature, moisture content, size and number of substituents, and degree of polymerization ( \[ \overline {{\rm DP}} \] ). The pitch of the cholesteric helical structure increases with side chain length and with increasing temperature. At room temperature, a fingerprint‐like pattern can be observed for HepPc. No reversal in the sense of the pitch with temperature variations was observed. The pitch of BPC increases with moisture content and with decreasing values of the degree of esterification ( \[ \overline {{\rm DE}} \] ) and \[ \overline {{\rm DP}} \] . A theory for cholesteric mesophases composed of helical rod‐like species and a model of elastic bend chain have been compared to the experimentally observed changes in the pitch with temperature and with the length of the side chain substituents (for iBPC, iVPC, BPC, PPC, and APC) and \[ \overline {{\rm DE}} \] and \[ \overline {{\rm DP}} \] (for BPC). © 1994 John Wiley & Sons, Inc.