Thermal cracking of flame retardant fabrics and non-flame retardant cotton fabrics
Classification:
flame retardant fabric
1 Materials and experiments
1.1 Flame retardant finishing of samples
The fabric used in the test is pure cotton bleached bed sheet, flame retardant CFR-201, hexamethylol melamine resin (HMM), softener CGF, etc. The equipment uses a Swiss BENZ prototype machine. Flame retardant finishing process: Dip padding Flame retardant finishing solution (two dips and two pads, rolling residue rate 80%) – pre-baking (98℃-105℃, 3min )–Baking (160℃, 3min)–Alkali washing–Soaping–Water washing–Drying. Process prescription: CFR-201
350g/L, HMM 80g/L, CGF 4g/L, urea 15g/L, H3PO4 17g/L, penetrant JFC lg/L.
1.2 Fragmentation-gas chromatography-mass spectrometry (PY-GC-MS) analysis
Instruments: HP HP5890 gas chromatograph, HP5989 mass spectrometer, CDS-l00 cracker, HP-5 capillary column 25m*0.2mm*O.5m. Test conditions: carrier gas flow rate 15m (He)/Min; inlet temperature 250°C; pyrolysis temperature 600°C; mass scan range 10-600; programmed temperature rise 50°C (5min) to 230°C; ion source 250°C; quadrupole The rod is 100℃; the injection amount is 2.094mg for the non-flame-retardant sample and 2.369mg for the Flame-retardant sample. 2
Experimental results and discussion
2.1 Test results
The PY-GC-MS pyrolysis spectra of flame-retardant and non-flame-retardant cotton fabrics were tested, as shown in Figure 1 and Figure 2.
2.2 Discussion
2.2.1 Thermal cracking of cellulose fibers
It is generally believed that the cleavage reaction of cellulose fibers can be divided into two situations. One is dehydration and carbonization of cellulose, producing water, carbon monoxide and solid residue; the other is depolymerization of cellulose to generate non-volatile liquid L-glucose, which is further cracked to produce low-glucose. Molecular weight cleavage products and the formation of secondary coke. In the presence of oxygen, the cleavage products of L-glucose are oxidized and burned to generate a large amount of heat, which in turn causes more cellulose to cleave. These two reactions compete with each other and are present throughout the entire process of cellulose cleavage [1]. Thermal cracking of cellulose fibers can be divided into three stages [2-3]: initial cracking stage, main cracking stage and residue cracking stage. Cracking at a temperature lower than 370°C belongs to the initial cracking stage, which is manifested by changes in the physical properties of the fiber and a small amount of weight loss, mainly related to the amorphous part of the cellulose fiber [2]. The pyrolysis at a temperature of 370°C to 431°C belongs to the main pyrolysis stage. Most of the pyrolysis products are produced at this stage. L-glucose is the main intermediate pyrolysis product, which is then decomposed into various flammable gas products. The main pyrolysis stage occurs in the crystalline region of the fiber. When the temperature is higher than 430°C, the cracking of cellulose fibers belongs to the residue cracking stage, mainly dehydration and carbonization, and the carbon content in the residue becomes higher and higher.
2.2.2 Cleavage products of cellulose fibers
The cracking of cellulose fibers is the key to determining the combustion performance of fibers (fabrics). Most of the cracking products of cellulose fibers are the fuel for fiber combustion. Searching in the spectrum library, 43 peaks on the spectrum were confirmed
(Some peaks cannot be separated), 43 possible cleavage products of cotton fiber were identified (three peaks detected duplicate products), and 28 cleavage products of flame-retardant cotton fiber were detected
(The products detected in one peak were repeated, and carbon monoxide and carbon dioxide were detected at the same time), and there were a variety of cleavage products that had not been detected before. The number of pyrolysis products of cotton fiber and flame-retardant cotton fiber is as follows: Cotton fiber: 2 types of non-flammable gases (H2O, C02), CO, 4 types of alcohols, 2 types of aldehydes, 15 types of ketones, 11 types of furans, benzene There are 1 type of ring, 2 types of esters, 4 types of ethers, and 1 type of riboglucan.
Flame retardant cotton fiber: 2 types of non-flammable gases
(H2O, C02), CO, 1 alcohol, 7 ketones, 13 furans, 1 ester, 1 ether, 1 riboglucan, and 1 nitrogen-containing compound.
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