Groundwood + softwood (bleached sulphite), sizing, filler

Ingredients

Groundwood, softwood (bleached sulphite), kaolin, alum

Preparation Steps

Original Recipe Text

Model paper sample P3 represents low-quality acidic groundwood paper. It consists of groundwood and softwood (bleached sulphite) cellulose with a high lignin content (approximately 30%). It includes fillers such as kaolin and sizing agents like alum (aluminum sulphate) (p. 812). The pH is acidic at 5.9. The paper was subjected to accelerated ageing in a climatic chamber (RH 59%, 90°C) and closed vials to mimic the environment inside books (p. 809, 812).

Evidence

"Groundwood + softwood (bleached sulphite), sizing, filler... P3... pH 5.9... Lignin High (app. 30%)... Ash content, wt% 20 (kaolin, alum)"

Remarks

Sample P3 shows the highest oxidation extent compared to pure cellulose papers (P1, P2), reflecting its ash and lignin content (p. 815). Lignin acts as an oxidation catalyst and source of radicals, but it also appears to suppress the oxidation of cellulose to more oxidized forms like -COOH by oxidizing itself (p. 811, 815). The presence of hemicellulose in this paper type complicates the calculation of mean molecular mass (p. 814).