No abstract

A new sort of nanofluids phase change materials (PCMs) is developed by suspending small amount of TiO 2 nanoparticles in saturated BaCl 2 aqueous solution. The resulting nanofluids PCMs possess remarkably high thermal conductivities compared to the base material. Cool storage/supply experiments conducted in a small apparatus have shown the excellent phase change performance of the nanofluids PCMs. The cool storage/supply rate and the cool storage/supply capacity all increase greatly those that of BaCl 2 aqueous solution without added nanoparticles. The higher thermal performances of nanofluids PCMs indicate that they have a potential for substituting conventional PCMs in cool storage applications.

Lyocell fibers were produced from a cheap pulp with a high hemicellulose content and from a conventional pulp with a high a-cellulose content. The mechanical properties, supermolecular structure, fibrillation resistance, and dyeing properties as well as the fibril aggregation size of the high hemicellulose Lyocell fiber and high a-cellulose Lyocell fiber were compared. The results showed that the high hemicellulose spinning solution could be processed at a higher concentration, which improved the mechanical properties and the efficiency of the fiber process. Compared with the high a-cellulose Lyocell fiber, the high hemicellulose Lyocell fiber had better fibrillation resistance and dyeing properties. Therefore, it is feasible that this cheap pulp with a high hemicellulose content can be used as a raw material for producing Lyocell fibers.

In the present paper the difference in the structure and properties of Lyocell fibers with different hemicelluloses content was investigated. The supermolecular structure and the morphological characterization were compared. The fibril aggregation size was estimated by the crosspolarization magic-angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13 C-NMR) spectroscopy. Meanwhile, the difference in the mechanical, the fibrillation resistance and the dyeing properties of Lyocell fiber with different hemicelluloses content was also ana-

Prediction of MW scale and MWD of cellulose by means of a rheology‐based method is developed. In this method, for the cellulose/NMMO·H2O solution, it is assumed that the cellulose MW values calculated by the Rouse terminal relaxation time can be regarded as the peak MW on the MWD curves of cellulose. Consequently, it is realized that the reciprocal of the frequency is converted to the MW scale, obtaining MWD scale curves of cellulose. Meanwhile, the obtained results are compared with those measured by the GPC method. The comparison shows that the calculated peak MW values are approximately equal, the calculated PDI values and MWD curves have the same trends. Consequently, it may be feasible to compare the MW scale and MWD of cellulose by using the rheology‐based method. In addition, the rheology‐based method is simple and fast. Therefore, it is a useful and easy way to analyze the MW scale and MWD of cellulose in the fiber industry. POLYM. ENG. SCI., 48:102–106, 2008. © 2007 Society of Plastics Engineers