Grafted samples, stannic chloride

Cotton with flame-retardant property was made by grafting with acrylamide and his-(heta-chloroethyl) vinylphosphonate, and subsequent treatment with stannic chloride. Thermal decomposition behaviors of unmodified and modified samples were studied under nitrogen atmosphere at 500 C. It was found that carbamoylethyl- and carboxyethylation, grafting and stannic chloride treatment increased the yield of char residue and water, but decreased that of tar. In flame-retardant cotton, the temperature of thermal decomposition onset and completion were lower than those in unmodified cotton. And the rate of thermal decomposition was slower than that in unmodified cotton. Phosphorus content in char residue did not change by thermal decomposition. But chlorine content introduced by grafting decreased by thermal decomposition. 

Stannic Chloride Treatment. M and C were treated with stannic chloride aqueous solution. Grafted samples were also treated with stannic chloride solution. After the treatment, weight increase by stannic chloride treatment was calculated. As weight increase by stannic chloride treatment was much different from the samples, the concentration of the treatments were changed from the samples. 

Figure 3. Effects of stannic chloride treatment on pyrolysis products of grafted samples. Key O, char , tar <3, water. A, mercerized cellulose (extent of grafting is 18.1%) B, carbamoylethylated and carboxyethylated cellulose (extent of...

LOI and Charred Area of Burned Fabric. Limited oxgen indices (LOI) of the samples and the result of flammability test are shown in Figure k, M burned completely by combustion in the air. C burned but left stiff char residue with figure of fabric after combustion in the air. Grafted samples and stannic chloride treated samples burned little. But stannic chloride treated samples of grafted samples were charred only at the point close to flame. LOI of the sample showed that M-G-Sn and C-G-Sn are self-extinguishable in the air. 

So it is clear that the difference of trunk polymer does not affect the pyrolysis behavior in grafted sample. Graft polymer affects the decomposition behavior. The TGA curves of stannic chloride treated samples showed that decomposition started at 250 C and ended at 320 C in the case of M. But in the case of C, decomposition started at 200 C and decomposed gradually and gradually. Char residue at i OO C was 39 and hl for stannic chloride treated samples of M and C, respectively. The effects of stannic chloride treatment are considered to be different between M and C. The TGA curves of stannic chloride treated samples after grafting indicated that decomposition started at 250 C and did not... 

Figure 5. TGA curves of unmodified and modified cellulose. A, mercerized cellulose (M) and carbamoylethylated and carboxyethylated cellulose (C) B, grafted samples of M and C C, stannic chloride treated cellulose of M and C D, stannic chloride treated cellulose of grafted samples.

Crystallinity Index. Crystallinity index of the samples charred partially and completely were measured by X-ray diffraction and shown in Table II. M kept crystal structure even at 320 C, but decomposed almost completely at 3 0 C. The decomposition was very abruptly. The result is consistent with that obtained by TGA. C decomposed gradually and gradually. The decomposition initiated already at 280°C and finished completely at 320 C. Grafted samples decomposed at lower temperatures than M. Stannic chloride treated samples decomposed at lower temperatures. This is most remarkable in C-G-Sn. It finished decomposition at 300 C. 

Phosphorus and Chlorine Contents. Phosphorus and chlorine contents of the samples in char residue at kOO C are shown in Table IV. Phosphorus content did not change by thermal decomposition in all samples. But chlorine content decreased by pyrolysis. Chlorine introduced by stannic chloride treatment hardly decreased, but that by grafting decreased easily by pyrolysis. Stannic chloride is not introduced in cotton in the form of stannic chloride, because the chlorine content of stannic chloride treated cellulose is very lower than that calculated from weight increase. X-ray diffraction trace of burned sample... 

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