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Abstract  

Lyocell, modal and viscose fibers were subjected to mercerization or to solar degradation. The ulterior thermal degradation was analyzed by means of differential scanning calorimetry (DSC). Thermal analysis shows wide exothermic processes that began between 250 and 300C corresponding to the main thermal degradation and are associated to a depolymerization and decomposition of the regenerated cellulose. Thermal degradation was analyzed as a function of concentration and time. Lyocell fiber is the most stable under thermal degradation conditions. Furthermore, mercerized samples are initially more degraded and present a lower thermal stability.

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Abstract  

In the present work Lyocell fibers were subjected to graft copolymerization of poly-N-isopropylacrylamide (pNIPAAm) thermosensitive polymer. The thermal degradation and stability of lyocell/pNIPAAm copolymers gels were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). pNIPAAm/lyocell copolymers are thermally stable and more resistant to temperature than lyocell fibres. Thermal characterization was analyzed as a function of percentage by mass of the pNIPAAm grafted. It has been shown that for pNIPAAm/lyocell copolymers, degradation occurs at higher temperature when increasing the degree of grafting.

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Summary New regenerated cellulose fibers were developed during the last decades as environmentally friendly systems. In this work, three fibers: lyocell, modal and viscose were subjected to an enzymatic treatment. Likewise, different lyocell fibers were washed in a Na2CO3 solution under severe conditions. Analysis was performed by means of differential scanning calorimetry, thermogravimetry and scanning electron microscopy. In all samples, at low temperature, water desorption was detected. Furthermore, thermal analysis shows wide exothermic processes that began between 250 and 300°C corresponding to the main thermal degradation and it is associated to a depolymerization and decomposition of the regenerated cellulose. It is accompanied with mass more than 60% mass loss. Kinetic analysis was performed and activation energy values 152-202 kJ mol-1 of the main degradation process are in agreement with literature values of cellulose samples.

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. Wu , QL , Pan , N , Deng , KM , Pan , D 2008 Thermogravimetry-mass spectrometry on the pyrolysis process of Lyocell fibers with and without catalyst . Carbohydr Polym 72 : 222 – 228 10.1016/j.carbpol.2007

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. Carrillo , F , Defays , B , Colom , X , Suñol , JJ , Lopez-Mesas , M . Thermal degradation of lyocell/poly- N -isopropylacrylamide graft copolymer gels . J Therm Anal Calorim . 2009 ; 97 : 945 – 948 . 10.1007/s10973

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