For this thesis project, a method to analyze the dewatering time for the drainage process during laboratory sheet making on a Finnish sheet former was developed. The resulting method proved to deliver very reliable information about the dewatering time and the transient speed of the sheet making process. The method was then used for two studies to find how fiber types, refining and/or slower dewatering conditions affects sheet properties, like formation and tensile strength. The first study compared the difference in formation and strength between softwood and hardwood fibers at three different drainage restrictions. The second study was performed to understand the effect of refining on dewatering time and the connection to resulting sheet properties. The results of both studies showed that at low grammages, the fiber web that was formed did not affect the dewatering time and speed regardless of the type of fibers or refining level. This meant that the drainage for low grammages sheets was solely controlled by the drainage restriction of the draining pipe on the sheet former. In addition, tensile strength and formation of the sheets did not vary significantly between the different dewatering speeds tested and the differences where more related to fiber properties than to the modified conditions of the dewatering of the sheet making process.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-172445 |
| Date | January 2015 |
| Creators | PULGAR NEIRA, HUGO ALEJANDRO |
| Publisher | KTH, Skolan för kemivetenskap (CHE) |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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