Shrinkage residual density

A similar sorption isotherm has been published for 2500-year-old waterlogged alder 21). EMC values were consistently about twice as great as comparable values for recent wood over the entire hygroscopic range. Additional data collected in Table III include EMC values at or near 100% relative humidity for fir, alder, and a series of oak finds. In many cases the residual density values are greater than 100%, probably because of enhanced shrinkage affecting the determination of air-dry density rather than a com-... 

Figure 3, Longitudinal shrinkage ratio of old and recent wood as a function of residual density, from the data of Table IV.

Sample Solvent (vol%) Etoh/Form Igel Skeletal Density Linear Shrinkage Residual Weight (g/cnP) (%) 900<>C (%) ... 

Chemical and physical properties comprising residual stress, density, shrinkage, moisture absorption, impurities, etch rate etc. 

All aerogels stayed monolithic, but some showed volumetric shrinkage, which was attributed to residual water and ethanol after thewashing steps andcanreachupto 40% for high R/C and high dilution ratio. By variation of the synthesis conditions, a wide range of apparent densities (as low as 0.19 gcm ) and pore sizes can be covered. 

Annealing is the heat treatment of molded plastic parts subsequent to their processing in order to release residual stresses, in particular in thick-walled molded parts, and to initiate post crystallization in less-than-optimally crystallized molded parts. Annealing can lead to warping in the molded part caused by stress release and post-crystallization. Post-crystallization always leads to dimensional reduction (post-shrinkage), but on the other hand, it increases density and hardness [502]. 

The resulting polymer sheets were characterized by determination of the refractive index (10) and density (11). The uncorrected difference between the monomer and polymer specific gravity was taken as the polymerization shrinkage. Using the method of Loshaek and Fox (12) the percentage utilization of unsaturation was calculated from volume contraction based on the assumption of 23.0 cc change in volume per mole of double bonds. The percent of residual double bonds in the sheets was also determined by attenuated total reflectance infrared spectroscopy using a Perkin-Elmer Model 137-D Infracord Spectrophotometer and Buck Scientific Universal Reflectance Unit URU-101. 

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