This project investigated the potential for the regeneration of fibres from cotton-based waste garments. The project focused on the preparation of the cotton waste pulps and assessed the suitability of the prepared material for regeneration of ReCell fibres. Mechanical processes have been developed to degrade the fabrics into a fibrous pulp potentially allowing easier fibre dissolution and purification in the fibre regeneration processes. Wet degradation and dry degradation methods were evaluated and the optimal method identified. It was established that the wet deconstruction method could produce fibres with longer length and lesser degradation of the cellulose than the dry deconstruction method. The pulp produced by wet deconstruction methods could be formed into sheets which were stronger than the pulp produced by the dry deconstruction methods. Although the cotton pulp reclaimed by the wet deconstruction methods requires extra energy to dry, it is still the most attractive processing route since the pulp will be transported to the fibre spinning plant in the form of dry cellulosic sheets. Methods for stripping off the easy care finishes in order to increase dissolution of the cellulosic garments were optimised. The stripping performance was assessed by fibre degradation, contents of the easy care finishes, and solubility of the stripped fibres in selected solvents. It was established that a combination of acidic and alkaline treatment can effect the removal of all easy care finishes and enable efficient dissolution of the pulps for fibre making. ReCell fibres were produced from 100% reclaimed material and a blend of reclaimed cotton pulp and wood pulp and structural and mechanical properties were characterised and compared to the existing Lyocell fibres. It was established that for easy separation of non-cellulosic material from the cellulose-based waste garment pulp the fibres must be modified to avoid formation of tufts. Fibre enrichment by gravity separation was recommended as a pre-requisite process prior to wet cyclone separation and the optimisation of the process was recommended for future work. ReCell processing of dyed waste garments, fibre spinning, fabric construction and wet processing of ReCell fibres have been recommended for future work. The results from this project will be used for pilot tests and later commercial production of ReCell fibres by Lenzing Company. Commercial production of ReCell fibres will contribute to the reduction of economic and environmental challenges caused by textile wastes. Moreover, the findings have identified a potential reduction of pressure on raw material for fibre production by providing an alternative source of material for regeneration of cellulosic fibres.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 119-147). Available also in a digital version from Dissertation Abstracts.

Two organophosphorus compounds, namely diethyloxymethyl-9-oxa-10- phosphaphenanthrene-10-oxide (DOPAC) and diethyl (2,2-diethoxyethyl) phosphonate (DPAC) were applied on cotton cellulose to impart non-carcinogenic and durable (in alkaline washing) flame retardant property to it. Some acidic catalysts, sodium dihydrogen phosphate (NaH2PO4), ammonium dihydrogen phosphate (NH4H2PO4) and phosphoric acid (H3PO4), were successfully used to settle acetal linkage between cellulose and flame retardant (FR) compound. Appreciable limiting oxygen index (LOI) values of 24% and 23.9% were achieved in case of the samples treated with FR compound DPAC along with the combined acidic catalyzing effect of NaH2PO4+H3PO4 and NaH2PO4+NH4H2PO4. A distinguishing outcome of total heat of combustion (THC) 3.27 KJ/g was revealed during pyrolysis combustion flow calorimetry (PCFC) test of the treated sample. In respect of thermal degradation, low temperature dehydration in conjugation with sufficient amount of char residue (30.5%) was obtained in case of DOPAC treated sample. Consistently, the temperature of peak heat release rate (TPHRR) (325°C) of DPAC treated sample supported the expected low temperature pyrolysis in condensed phase mechanism. Subsequent thermogravimetric analysis (TGA) also reported inspiring weight retention% of the treated samples. Furthermore, for both of the flame retardant compounds, effect of different catalysts, considering both individual and combined, effect of solvents, and overall the optimization of the process parameters were studied in detail. / Program: Magisterutbildning i textilteknologi