Fengyu Quan

The effect of zinc ion content on flame retardance and thermal degradation of alginate fibers

The study employs limiting oxygen index (LOI) measurements, cone calorimetry (CONE) and thermogravimetric analysis (TGA) to examine the catalytic effect of zinc ion content on the flame retardance and thermal degradation of alginate fibers. LOI results show that all zinc alginate fibers are intrinsically flame retardant, with LOI values of over 27.0, as compared with about 24.5 for alginic acid fiber. The heat release rate (HRR) and total heat release values of zinc alginate fibers (obtained from CONE) are significantly less than those of alginic acid fiber, and decrease with increasing zinc ion content. TGA indicates that char formation increases and maximum thermal weight-loss rate is reduced when zinc content in the fibers is increased. The residues of zinc alginate fibers keep their shapes better than those of the alginic acid fiber. Further discussion of the combustion process and flame retardant mechanism is presented.

Influence of alkaline metal ions on flame retardancy and thermal degradation of cellulose fibers

Cellulose-Na and cellulose-K fibers are obtained by alkalization and etherification of viscose fiber. Flame retardancy and thermal degradation of cellulose-Na and cellulose-K fibers are investigated using limiting oxygen index (LOI), cone calorimetry (CONE), thermal gravimetry (TG), and differential TG (DTG). The LOI values of cellulose-Na and cellulose-K fibers are 33 and 30, compared with about 20 for viscose fiber. In CONE studies, cellulose-Na and cellulose-K fibers show much lower heat release rates, total heat release and effective heats of combustion than viscose fiber does. In addition, TG and DTG studies reveal that the second initial degradation temperature, the temperature of maximum degradation rate and the maximum degradation rate for cellulose-Na and cellulose-K fibers are much lower than those of viscose fiber. Cellulose-Na and cellulose-K fibers generate much more residue or carbonaceous char than viscose fiber does. Scanning electron microscopy studies of combustion residues after LOI testing indicate that cellulose-Na and cellulose-K fibers produce massive, thick residue crusts.

Structure and Properties of PVA/SiO2 Interpenetrating Polymer Network Materials Prepared by the Sol-Gel Method

Organic–inorganic interpenetrating polymer network (IPN) materials were prepared by hydrolysis and condensation of tetraethoxysilane (TEOS) in poly(vinyl alcohol) (PVA) solution. The structure and morphology of the IPNs were investigated by infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The thermal properties were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). FTIR spectroscopy showed the formation of Si–O–C and Si–O–Si bonds in the system. TEM demonstrated a homogeneous dispersion of silica in the PVA matrix when the amount of TEOS added was appropriate. DSC and TGA revealed that, compared with pure PVA films, the hybrid films exhibited a higher glass transition temperature (Tg) and high thermal stability.