Authors:J. Suñol, J. Saurina, F. Carrasco, X. Colom, and F. Carrillo
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.
Authors:H. Carrillo, C. Martinez, L. Torres, N. Hertel, and F. Iskander
Zinalco and Zircaloy-4 samples were used in order to measure the gamma-ray attenuation coefficients for three different gamma-ray energies. Using the neutron activation analysis technique, the elemental composition of Zinalco and Zircaloy-4 was measured.
Authors:F. Iskander, H. Vega-Carrillo, and E. Manzanares-Acuña
The concentration of 14 elements in cigarette wrapping papers used in manufacturing 21 different Mexican cigarette brands
was measured using instrumental thermal neutron activation analysis. These elements are As, Ba, Ce, Co, Cr, Cs, Fe, K, Na,
Rb, Sb, Sc, Sr, Th and Zn. The concentration of the elements was compared with the reported concentration in similar studies
for elemental content in Pakistani, American, Chinese, Egyptian, Jordanian and Iranian cigarette wrapping papers.
Authors:H. Vega-Carrillo, F. Iskander, and E. Manzanares-Acuna
The concentration of 21 elements in cigarette tobacco in nine different brands manufactured and commercially available in Mexico has been determined using neutron activation analysis. The concentration range of the measured elements (in g g–1) were: As, (four brands) <0.55–3.24; Ba, 64–251; Br, (four brands) 49–136; Ce, <0.3–1.7; Co, 0.29–0.55; Cr, <0.8–2.4; Cs, 0.091–0.40; Eu, <0.03; Fe, 420–680; Hf, <0.03–0.13; K, (four brands) 18300–40300; La, (four brands) <0.2–0.66; Na, (four brands) 309–566; Rb, 19–50; Sb, <0.7; Sc, 0.13–0.22; Se, <0.7; Sm, (four brands) 0.07–0.14; Sr, 227–472; Th, <0.1–0.17 and Zn, 14–56. The results are compared with the literature values for the concentration of the above elements in cigarette tobacco from other countries.
Authors:H. Vega-Carrillo, F. Iskander, and E. Manzanares-Acuña
The concentration of thirty-four elements in twelve coffee brands has been measured using instrumental neutron activation analysis. The samples investigated included four brands of commercially available ground coffee and eight brands of soluble/instant coffee. The elements measured were Al, As, Ba, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Gd, Hf, K, La, Lu, Mg, Mn, Na, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, Ti, Tm, U, V, Yb and Zn. Twenty four elements were found to be below the detection limit in one or more samples. These elements were Ce, Cr, Fe, V, As, Eu, Ba, Dy, Gd, Hf, La, Lu, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, Ti, Yb, Tm, and U.
Authors:F. Carrillo, B. Defays, X. Colom, J. Suñol, and M. López-Mesas
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.
Authors:J. J. Suñol, D. Miralpeix, J. Saurina, F. Carrillo, and X. Colom
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.