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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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Introduction Degree of polymerization (DP) is the main factor playing role in the ageing of cellulose fibers. Processes of ageing are associated with the degradation of cellulose macromolecules, increasing the proportion of low

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Abstract  

Thermal analysis was used to investigate the effect of the addition of magnesium chloride hexahydrate as a fire retardant to cellulosic fibers. The kinetics of the decomposition of the cellulosic material were first studied. The decomposition of the dry salt was also investigated and three steps disclosed. Then, the fabrics were impregnated into salt solutions of different concentrations and the loss in mass was followed by thermal analysis. The percent loss in mass was compared to that of pure cellulosic fabric at different temperatures. It was found that there is an appreciable improvement in fire retardation at a minimum percent add-on of the salt of 35%.

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Introduction The field of flame-retardancy of polymers has greatly developed and expanded during the last 20 years [ 1 ]. Most polymers and cellulosic fibers as organic materials are very sensitive to flame. Therefore, the

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of polymeric matrices, polyolefins are the most used to realize natural fiber reinforced (NFR) composites. Unless virgin cellulose fibers are mainly used as reinforcement in composites, in the last years recycled cellulose has been also proposed, in

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SiO 2 -coated regenerated cellulose fibres . Polym Degrad Stab . 92 : 1957 – 1965 10.1016/j.polymdegradstab.2007.08.010 . 12. Cireli , A , Onar , N , Ebeouglugil , MF , Kayatekin

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Pollack Periodica
Authors: Ivana Schwarzova, Nadezda Stevulova, Eva Singovszka, Eva Terpakova, and Jozef Junak

This article concerning natural cellulose fibers as reinforcement in composite materials in civil engineering. In this paper, the attention is given to industrial hemp specifically to the woody part of hemp plant called hemp hurds. The properties of natural fibers are mainly determined by the chemical and physical composition, such as structure of fibers.

The objective of presented research is to characterize raw and physically treated hemp fibers using Fourier transform infrared spectroscopy method. These natural fibers were used as filler into biocomposites and MgO-cement was used as alternative binder. Physico — mechanical properties (compressive strength, thermal conductivity, absorbability) of prepared composites were determined.

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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  

HDPE based composites were produced with 10-20-30 and 40% composite mass of wood fiber. The coupling agents were epolene and silane. The thermal behavior of composite samples was analyzed as a function of the coupling agent content, the exposure time and the wood fibers content by means of differential scanning calorimetry. Calorimetric curves of all samples of first and second heating shows a similar behavior. Some significant relation has been observed between the exposure time and the degree of crystallinity for the same percentage of fiber samples. A linear relation between the melting enthalpy average vs. content in cellulosic fibers is detected. Nevertheless, the fibers non-pretreated with coupling agent show a lower loss of crystallinity of the HDPE matrix at low wood fiber content (10%). A slight diminution of the melting peak temperature is detected as increasing the exposure time.

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