Physical properties of cellulosic materials related to moisture changes
- 403 Downloads
Moisture affects the mechanical properties of paper to a high degree. Moreover, the creep properties of paper may be highly affected while the relative humidity is changing, exhibiting mechano-sorptive creep. The reasons for the great sensitivity to moisture changes of papers are not fully explained. In this study, thin papers were examined during sorption processes and the moisture content within the paper, paper length and dynamic elastic modulus during RH changes were measured. It is demonstrated that the dimensional changes of the paper exactly reflected the changes in moisture content within the sample. During both absorption and desorption, the elastic modulus changed so that it was lower than the equilibrium value corresponding to its moisture content. This was especially evident during absorption where the modulus dropped below the equilibrium value at the end RH, i.e. the value was approached from below. The modulus drop was highly related to RH changes made at higher RH and could possibly be related to the softening of carbohydrates.
KeywordsElastic Modulus Moisture Sorption Moisture Change Initial Inability Humidity Change
This work was performed as part of the Paper Mechanics research programme at Innventia AB. The financing companies: Billerud, Eka Chemicals, Mondi Packaging Frantschach, M-real, Peterson & Son, Stora Enso, Södra, Tetra Pak, Voith and International Paper are gratefully acknowledged for their support.
- Back E, Salmén L, Richardson G (1983) Transient effects of moisture on the strength properties of paper and wood-based materials. Svensk Papperstidn 87(6):61–71Google Scholar
- Byrd VL (1972) Effect of relative humidity changes on compressive creep response of paper. Tappi 55(11):1612–1613Google Scholar
- Caulfield DF (1994) Ester crosslinking to improve wet performance of paper using multifunctional carboxylic acids, butanetetracarboxylic and citric acid. Tappi J 77(3):205–212Google Scholar
- Coffin DW, Habeger CC (2001) The mechanics of sorption-induced transients in the loss tangent. JPPS 27(11):385–390Google Scholar
- Jarrell TD (1927) Effect of atmospheric humidity on the moisture content of paper. Paper Trade J 85:47–51Google Scholar
- Kajanto I, Niskanen K (1998) Dimensional stability. In: Niskanen K (ed) Paper physics, vol 16. Springer, Helsinki, pp 222–259Google Scholar
- Salmén L (1990) On the interaction between moisture and wood fiber materials. In: Caulfield DF, Passaretti JD, Sobczynski SF (eds) Materials interactions relevant to the pulp, paper, & wood ind, vol 197. Materials Research Society, Pittsburgh, pp 193–201Google Scholar