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A novel methodology was used to create a highly porous foam-formed paper that is bonded with highly refined cellulose fiber. In this process, cellulose pulp suspension at various consistencies (0.5, 1.0, 1.5, and 2%) was dispersed in water, followed by foam formation under high shear forces in the presence of a surfactant. Various drying methods were used to achieve foam formation. These included freeze-drying (FD), vacuum-dewatered air-drying (VAD), and dewatered freeze-drying (VFD). Increasing the pulp's consistency and changing the drying techniques from freeze-drying to air-drying resulted in a more compact morphological structure and increased density of foam-formed paper samples. Densification of foam-formed samples was measured using a Dynamic Mechanical Analysis (DMA) machine and a sample with densification at lowest strain value was obtained by a 10 wt% addition of microfibrillated cellulose fiber (MFC). At 10 wt% MFC addition, denser foam-formed paper samples with enhanced microstructure were obtained. Air filtration efficiency and acoustic properties of foam-formed paper were also characterized and optimized by the addition of MFC. [ABSTRACT FROM AUTHOR]

Abstract: Fungi are among the most degradative organisms inducing biodeterioration of paper-based items of cultural heritage. Appropriate conservation measures and restoration treatments to deal with fungal infections include mechanical, chemical, and biological methods, which entail effects on the paper itself and health hazards for humans. Three different conservation treatments, namely freeze-drying, gamma rays, and ethylene oxide fumigation, were compared and monitored to assess their short- (one month, T1) and long-term (one year, T2) effectiveness to inhibit fungal growth. After the inoculation with fungi possessing cellulose hydrolysis ability — Chaetomium globosum, Trichoderma viride, and Cladosporium cladosporioides — as single strains or as a mixture, different quality paper samples were treated and screened for fungal viability by culture-dependent and -independent techniques. Results derived from both strategies were contradictory. Both gamma irradiation and EtO fumigation showed full efficacy as disinfecting agents when evaluated with cultivation techniques. However, when using molecular analyses, the application of gamma rays showed a short-term reduction in DNA recovery and DNA fragmentation; the latter phenomenon was also observed in a minor degree in samples treated with freeze-drying. When RNA was used as an indicator of long-term fungal viability, differences in the RNA recovery from samples treated with freeze-drying or gamma rays could be observed in samples inoculated with the mixed culture. Only the treatment with ethylene oxide proved negative for both DNA and RNA recovery. Therefore, DNA fragmentation after an ethylene oxide treatment can hamper future paleogenetic and archaeological molecular studies on the objects. [Copyright &y& Elsevier]

The article studies the application of the freeze-drying process to water-damaged archival and library materials. By soaking samples for 18 hours and draining for 5 hours, reproducible soaked samples were obtained; the amount of absorbed water was 121 ± 1 % in relation to the initial dry weight. The method was reproducible, simple and economic. The freeze-drying and evaporative-drying of soaked samples resulted in the complete drying of the paper in 18 hours, without excessive damage. With regard to antique documents, especially those containing miniatures or paintings, re-conditioning of dried, brittle paper is recommended, before handling.

Vacuum freeze-drying of frozen wet papers was investigated experimentally. A freeze-drying facility was built to study the process by monitoring the various physical parameters (pressure, sample temperature, heater temperature, water content of the sample and cold panel temperature). A simple phenomenological model was developed to explain experimental results. The values of the physical parameters were optimized to make the process cost effective. [ABSTRACT FROM AUTHOR]