Composition and Chemical Paper Testing

The fiber composition of paper is determined with a Hght microscope (fiber microscopy). Due to the varying fiber morphology, both the fiber raw material and the pulping process can be determined. Chemical dyeing methods are used for contrast enhancement and quantitative determination of fiber composition (ZM IV/ 55/74 TAPPI T 401 om-93, Harders-Steinhauser, Paseradas). 

The term moisture content refers to the amount of water in the paper in equiHb-rium with a defined ambient cHmate. It is determined gravimetrically in accordance with ISO 287 (1985). A dry sample is produced by drying the paper to constant weight at 105 °C. The moisture content is expressed in percent, based on the moist sample. 

Chemical testing is used to determine the components of paper. This is of significance in papermaking for quahty control and process control. Another important field of chemical paper testing is the control of papers for the packaging of food. 

The entire spectrum of analytical methods used for the chemical testing of paper ranges from gravimetric methods to spectroscopy, electrochemical and enzymatic methods, as well as sensoric tests on taste and odour and microbiological tests. 

Most of the testing methods to determine the composition are destructive. The components to be determined must be extracted with water or organic solvents. 

---