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Accelerated ageing is an often-used tool in conservation research, yet difficult to apply to parchment due to the materials inherent heat sensitivity. The complexity of this organic material makes the analysis of its deterioration especially challenging. An attempt to develop a non-heat ageing protocol for parchment is described in this paper. The work was performed within the scope of a MA-thesis at the State Academy of Art and Design Stuttgart. Samples of a modern new limed goat parchment and pieces of reconstituted parchment made from bovine hide powder were subjected to a combination of light ageing and dynamic ageing at moderate temperatures. All samples were analysed with the goal to observe degradation on as many structural levels as possible: colour measurement via VIS spectrometry and light-microscopic observation of fibre damage were employed to assess visible changes. Shrinkage temperature (Ts) was measured as an indicator for the amount of intact intrafibrillar bonds and the determination of the maximum moisture absorption capacity gave an impression on the parchments overall level of hygroscopy. In addition, PMF (Peptid Mass Fingerprinting) via MALDI/MS TOF was performed on extracts from unaged and light aged goat parchment. The results of the different types of analysis showed significant degradation on different structural levels of the parchment, indicating that accelerated ageing of parchment that uses a combination of light and dynamic ageing may be a viable alternative to the more commonly applied thermal ageing. [ABSTRACT FROM AUTHOR]

The water vapour sorption behaviour of Sitka spruce was analysed based on the parallel exponential kinetics (PEK) model. The PEK model deconvolutes the sorption kinetics curve into two exponential kinetics processes (fast and slow) which have characteristic times and moisture contents associated with them. The sorption kinetics was examined at different temperatures enabling the determination of activation energies for the sorption kinetic processes throughout the hygroscopic range (from 5% to 95% relative humidities). The physical interpretation of the PEK model is also discussed. [ABSTRACT FROM AUTHOR]

Moisture sorption isotherms of Granny Smith apples hot-air dried and texturized by Controlled Sudden Decompression (D´ etente Instantann´ee Contr¿ol´ ´ee DIC) were determined and compared using a gravimetric method. The DIC has been developed to confer a porous structure to partially dehydrated foods by expanding them and facilitating the drying process at lower water content. The samples were stored in a chamber; the relative humidity is controlled by an atomizing humidifier at 20, 30 and 40_C, and relative humidities ranging from 10% to 90%. The sorption capacity decreased with increasing temperature at a given water activity. The hysteresis effect was not significant for both of the dried and texturized apples. The experimental sorption data were fitted to 8 various isotherm models including two parameter relationships (BET, Halsey, Smith, Henderson, Oswin), three parameter equations (Ferro-Fontan, GAB) and four parameter equations (Peleg). A non-linear least square regression software was used to evaluate the model's constants. The goodness of fit of each isotherm was quantified through the mean relative percentage deviation modulus E. The Ferro-Fontan, Peleg, GAB and Oswin equations were best for characterizing the sorption behaviour of Granny Smith apples for a whole range of temperatures and water activities studied. The surface area corresponding to the monolayer was determined for the texturized apples and compared to the dried samples. The results showed that the treatment by DIC increases the surface area of apples. For understanding the water properties and calculating the energy requirements phenomena, net isosteric heat was evaluated by the applying Clausius-Clapeyron equation. [ABSTRACT FROM AUTHOR]

Moisture sorption isotherms of osmotically dehydrated sweet peppers were determined at 15oC, 30oC and 40oC using static desiccator techniques. In the study, seven levels of water activity in range of 0.08 to 0.91 were used by the use of saturated salt solutions. The isotherms were found to be sigmoid type and of BET classification II. Out of seven sorption models i.e. BET, modified BET, Hasley, Caurie, GAB, Oswin and Smith, fitted to the experimental data, Oswin model was found to be the best for accurate prediction of moisture sorption isotherm with highest value of coefficient of determination (R2) and lowest values of standard error (SE) and relative deviation parentage (Rd). The value of monolayer moisture content of the osmotically dehydrated sweet pepper was found to be 3.037%, 3.934% and 4.432% (db) at 15oC, 30oC and 40oC respectively. The values of net isosteric heat of sorption as calculated by Clausius-Clapeyron equation showed a regular fall with increase in moisture content. [ABSTRACT FROM AUTHOR]

The moisture sorption behavior of pectin films formulated with different sorbitol content was evaluated and films with different equilibrium moisture contents were obtained. Different models were used to describe the moisture sorption isotherms (MSI) of pectin films, sorbitol and pectin powder. Based on changes observed in MSI, sorbitol was found to strongly interact with pectin polymers. Incorporation of sorbitol in pectin films resulted in lower equilibrium moisture contents at low to intermediate water activities (aw), but much higher moisture contents at aw > 0.53. Estimates of monolayer moisture values (1.53 - 3.81 g H2O kg-1 solids) were obtained by the application of Guggenheim-Anderson-DeBoer (GAB) model. A differential mechanical analyzer (DMA) was used for mechanical properties of formulated films while a differential scanning calorimeter (DSC) was used for thermal properties and glass transition temperature (Tg). With both DMA and DSC tests, the strong plasticizing action of water and sorbitol was evident. Tg vs. moisture content data were successfully fitted to the Fox empirical model. Multi-frequency DMA measurements provided estimates for the apparent activation energy (Ea) of the second glass transition in the range of 131-184 kJ/mol; the values for Ea decreased with increasing sorbitol concentration. Water vapor permeability (WVP) and mechanical properties of the films were also analyzed under varying sorbitol and moisture contents. Increasing moisture or addition of sorbitol to pectin films increased the elongation at break, but decreased the tensile strength, modulus of elasticity and Tg, and increased WVP of the films. [ABSTRACT FROM AUTHOR]

Presents a study on the equilibrium moisture content (EMC) of semi-defatted pumpkin seed flour. Temperature used to determine the EMC of the flour; Equations used to verify the description of the sorption isotherms; Experimental data obtained for adsorption and desorption.

When wood is subjected simultaneously to load and moisture content changes below the fiber saturation point, the mechano-sorptive effect may be observed as an additional deformation that cannot be attributed to simple superposition of elastic deformation, free shrinkage or swelling, or creep in steady climate conditions. The phenomenon has been subject to research for more than half a century. Although numerous mathematical models and detailed theoretical descriptions have been proposed over time, the basic mechanism of mechano-sorption has remained unclear, the experimental data are scattered and lack logical classification, and the experimental determination of its basic parameters on a material level, understood as a local property decoupled from artifacts of the testing protocol, remains a serious challenge. In this paper basic requirements for adequate experimental methods for comprehensive determination of the mechano-sorptive behavior of wood are proposed and briefly discussed. The principal requirements are that the experimental research on mechano-sorption is focused on the material level properties and elementary loading modes (tension and compression); that proper attention is paid to the effect of changing distribution of moisture content within the tested volume; and that the tests are designed so that a comprehensive separation of strain components is enhanced. [ABSTRACT FROM AUTHOR]