Measurement methods of dimensional stability | |
| Author | Kitsakorn Locharoenrat |
| Call Number | AIT RSPR no.PP-00-03 |
| Subject(s) | Paper--Wet strength Paper sizing |
| Note | A research study submitted in pa1iial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | The target of this work was to study systems for measuring dimensional stability of paper and to plan and design dimensional stability measurement equipment for AIT/ PPT, as well as to study the measurement of dimensional stability in a sheet. The simplest sheet dimensioning device would be used to measure dimensional changes for copy papers; from Thailand, from overseas (Finland and USA), and laboratory handsheets. Coefficient of Moisture Expansion (CME) for hygroexpansion and wet expansion were then evaluated by measuring the ratio between the change in dimension and change in moisture content according to TAPPI and SCAN standards. In this study, the method used for determining hygroexpansion of sheet was solution method (saturated salt solution). This method was suitable for generating a fixed humidity condition in a closed system within 1 hour. There was a fan for keeping a uniformly distribution of relative humidity in a chamber. The system was very simple and easy to construct for both hygroexpansion and wet expansion tester. The results revealed that the freely-dried sheets show higher CME (hygroexpansion and wet expansion), and more sensitivity in CME to changes in fiber/fiber bonding than restraint-dried sheet. For copy paper, CME (hygroexpansion and wet expansion) in CD increased clearly, whilst CME in MD was constant zero. Moreover, there were variables affecting the dimensional stability, such as beating level, filler content, cyclic humidity conditions to be studied. Coefficient of variation within a single laboratory test was approximately 12%. Confidence limit for the mean was 0.54 at 95% confidence level. Reliability was quite correct if testing could be done fast. The more time used for weighing after taking the sample from system, the poorer the reliability. For wet expansion, Coefficient of variation within a single laboratory test was about 4%. Confidence limit for the mean was +2.12 at 95% confidence level. Although solution method was simple and inexpensive, it limited for creating a specified humidity conditions. Testing should be carried out within a standard constant temperature/humidity room, for example 50%RH and 23C because it effected on the accuracy of measurements. Other solution methods might be applied in place of salt solution method, such as water-sulfuric acid solutions, for comparing theirs efficiency and improving the measurement systems. In addition to solution methods, automated humidity generators were more versatile for different kinds of environmental effect testing and should be further studied in the future. |
| Year | 2000 |
| Type | Research Study Project Report (RSPR) |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Pulp and Paper Technology (PP) |
| Chairperson(s) | Retulainen, Elias |
| Examination Committee(s) | Ruhanen, Mauno;Nazhad, Mousa M. |
| Scholarship Donor(s) | Government of Finland |
| Degree | Research Studies Project Report (M. Sc.) - Asian Institute of Technology, 2000 |