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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Polyvinyl alcohol size recovery and reuse via vacuum flash evaporation

Gupta, Kishor Kumar 09 April 2009 (has links)
Polyvinyl alcohol (PVA) desize effluent is a high COD contributor to towel manufacturing plant's Primary Oxygenation Treatment of Water operation, and being non-biodegradable, is a threat to the environment. When all-PVA/wax size is used in weaving, significant incentives exist to recover the synthetic polymer material from the desize wash water stream and reuse it. A new technology that would eliminate the disadvantages of the current Reverse Osmosis Ultrafiltration (UF) PVA recovery process is Vacuum Flash Evaporation (VFE). This research adapts the VFE process to the recovery and reuse of all-PVA size emanating from towel manufacturing, and compares the economics of its implementation in a model plant to current plant systems that use PVA/starch blend sizes with no materials/water recovery. After bench scale research optimized the VFE PVA recovery process from the desize effluent and determined the mass of virgin PVA that was required to be added to the final, recycled PVA size formulations. The physical changes in the recycled size film and yarn composite properties from those of the initial (conventional) slashing were determined using a number of characterization techniques, including DSC, TGA, SEM, tensile testing, viscometry, number of abrasion cycles to first yarn breaks, microscopy and contact angle measurements. Cotton chemical impurities extracted from the yarns during desizing played an important role in the recovered PVA film physical properties. The recovered PVA improved the slashed yarn weave ability. Along with recovered PVA, pure hot water was recovered from the VFE. Virgin wax adds to the final, recycled size formulations were determined to be unnecessary, as the impurities extracted into the desize effluent stream performed the same functions in the size as the wax. Using the bench results, the overall VFE process was optimized and demonstrated to be technically viable through six cycles, proof-of-concept trials conducted on a Webtex Continuous Pilot Slasher. Based on the pilot scale trials, comparative economics were developed. Incorporation of the VFE technology for PVA size recovery and recycling resulted in ~$3.2M/year in savings over the conventional PVA/starch/wax process, yielding a raw ROI of less than one year based on a $3M turnkey capital investment.
2

Aspects of precommercial thinning in heterogeneous forests in southern Sweden /

Fahlvik, Nils, January 2005 (has links) (PDF)
Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.
3

Aspects of precommercial thinning : private forest owners' attitudes and alternative practices /

Fällman, Karin, January 2005 (has links) (PDF)
Diss. (sammanfattning). Umeå : Sveriges lantbruksUniversity. / Härtill 4 uppsatser.
4

RE-PR/NT/NG

Seihine, Freja January 2023 (has links)
The growing demand for fast fashion and chea pgarments has led to a system of overproduction and overconsumption leaving tons of discarded textiles in landfills every year. This project investigates how textile waste can be up-cycled and redesigned into fashionable garments of higher value by merging textiles and applying surface design techniques. In this project two techniques were explored in relation to up-cycling, slashing and printing. Printing as a method to give new print designs and slashing as a tool to merge textiles together and create patterns and textures aiming to find new surface expressions and challenge the current up-cycling aesthetic. The outcome of the collection reveals various ways one can work with slashing and printing as a method to transform and elevate different types of garments and materials found within discarded textiles. It shows an example of how material exploration can guide the way to create garments and that by mixing textile design and fashion design one can explore different properties simultaneously.

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