Search

A novel reactive flame retardant (FR) based on methionine containing P, N and S flame retardant elements was synthesized for application to cotton fabrics. It was found that the cotton fabrics finished with this flame retardant had excellent flame retardancy and high durability. The limiting oxygen index of the fabric treated with 29% methionine-based FR was as high as 43.9%, and was 37.7% after 50 laundering cycles. Thermogravimetry and thermogravimetry coupled with Fourier transform infrared spectroscopy (FTIR) tests showed that the flame retardant (FR) changed the cellulose decomposition pathway so that a large amount of residue was formed and only a small amount of combustible gases was generated. Scanning electron microscopy showed that the treated fibers were swollen, implying that the FR molecules entered the interior of the fibers, while X-ray diffraction results suggested that the FR have little effect on the cellulose structure. FTIR and X-ray photoelectron spectroscopy results demonstrated that the methionine-based FR contains P, N and S elements, the FR and cellulose formed stable P(= O)–O–C and –COOC– covalent bonds, while microscale combustion calorimetry experiments showed that the total heat release of the treated cotton fibers decreased considerably and the tensile strength of the finished cotton fabrics decreased slightly relative to those of the raw cotton. The free formaldehyde content of the treated cotton was tested, and the results showed that no free formaldehyde was detected in the treated cotton. These results show that the methionine-based FR is a highly effective biologically-based and durable flame retardant. [ABSTRACT FROM AUTHOR]

In this study, a novel flame retardant (FR) for cotton fabrics was synthesized, namely, ammonium salt of diethylenetriaminepenta(methylene-phosphonic acid) (ADTPMPA), using diethylenetriaminepenta(methylene-phosphonic acid) (DTPMPA) and urea, and its structure was comfirmed by H NMR, C NMR and P NMR. The ADTPMPA reacted with the -OH groups of cellulose macro molecules to form P-O-C covalent bonds. LOIs of cotton fabrics finished with 70 and 90 g/L ADTPMPA reached to 40.0 and 41.5% respectively; after 40 laundering cycles, their LOIs were 26.5 and 26.7% respectively. The treated cotton fabrics still kept soft. FTIR spectroscopy confirmed -P-O-C bonds between ADTPMPA and cellulose, and X-ray diffraction revealed the formation of cellulose II structures in the finishing process. SEM suggested that ADTPMPA molecule permeates the inner space of the cotton fibers. TG result indicated that the treated cotton fibers retain more residue than the original fibers. Cone calorimetry test result showed that the treated cotton fabric had lower PHRR and THR than that of original cotton fabric. The results suggested that the ADTPMPA treated cotton fabrics had condense phase flame retardant mechanism. [ABSTRACT FROM AUTHOR]

A novel high-phosphorous-containing flame-retardant ammonium salt of ethylenediamine tetramethylenephosphonic acid (AEDTMPA) with reactive -P=O(ONH) groups was synthesized and characterized using Fourier transform infrared spectroscopy and nuclear magnetic resonance. The results showed that AEDTMPA could react with the -OH groups of cellulose molecules to form P-O-C covalent bonds. The finished cotton fabrics had high flame retardancy and excellent durability. The limiting oxygen index value of 100 g/L AEDTMPA-treated cotton fabric was 48.0 % and decreased to 31.2 % after 50 laundering cycles. In the vertical flammability test, the treated cotton fabrics exhibited no afterflame and afterglow, and the char length was only 30 mm. Thermogravimetry and cone calorimetry tests showed that the treated cotton fabric had higher char yield, lower decomposition temperature, and much lower peaks of heat release rate and total heat release than those of untreated cotton fabric. The morphologies of the cotton and residues of the fabrics were investigated using scanning electron microscopy, and the crystal structure of the sample fibers was analyzed using X-ray diffraction. The finished cotton fabrics were soft. [ABSTRACT FROM AUTHOR]

The present article is addressed to investigating the effect of different fabric grammages (mass per area unit) on cotton combustion. To this aim, 100, 200 and 400 g/m cotton fabrics were tested when exposed to (1) two different heat fluxes (25 and 35 kW/m) under a cone calorimeter, (2) a methane flame in horizontal or vertical flame spread tests or (3) a propane flame in Limiting Oxygen Index tests, and (4) when pyrolysed and further oxidised in pyrolysis-combustion flow calorimetry (PCFC). The collected results demonstrated a precise relationship between fabric grammage and cotton combustion behaviour. Indeed, when exposed to a 35-kW/m heat flux, the higher the fabric grammage, the higher the total heat release during combustion was; the opposite trend was observed when the same fabrics were pyrolysed and further oxidised in PCFC. This finding was ascribed to the different scenarios described by these instrumentations; indeed, the cone calorimeter was able to reproduce cotton combustion in a well-ventilated context in the presence of air (thus, oxygen), while PCFC only represented the combustion of pyrolysis products. However, both techniques indirectly evidenced a linear dependence of char formation as a function of fabric grammage: the higher the fabric grammage, the larger the amount of char formed was. The same trend was also observed during horizontal and vertical flame spread tests. In conclusion, the present article is intended to show how cotton combustion may be affected by fabric grammage as well as how such behaviour is influenced by the experimental conditions in which it is investigated. [ABSTRACT FROM AUTHOR]

Fire resisting property was imparted to cellulosic paper by the application of a bio-enriched version of a banana pseudostem sap (BPS) as well as the only BPS, obtained as a byproduct during fibre extraction from the pseudostem. The papers were evaluated for their flame retardant property by measurement of limiting oxygen index and vertical flammability. They were also characterized by thermogravimetry, scanning electron microscopy and energy dispersive X-ray analysis. The bio-enriched BPS treated paper was found to exhibit a better flame retardancy with distinguished char length, compared to the control and the only BPS treated paper. The impartment of flame resisting property to a paper by the BPS, along with its charring behaviour has been discussed and the mechanism thereon has been postulated. The BPS application was found to enhance the oxygen required for the burning of the paper and reduce its burning rate by promoting more dehydration and char formation. The imparted fire retardant finish found durable to weathering, did not cause any significant loss in tear and tensile properties of the paper. [ABSTRACT FROM AUTHOR]

Cotton fabrics have been treated with two different finishing compositions based on urea (U) and ammonium dihydrogen phosphate (AP) in order to enhance their flame retardancy properties, particularly referring to the resistance to a flame application (namely, Limiting Oxygen Index tests) and to an irradiative heat flux of 35 kW/m (by cone calorimetry). The collected results have proven a remarkable increase of cotton flame resistance: indeed, the fabrics treated with the high concentrated bath showed a LOI increase of 121 % (from 19 for neat cotton, to 42 %) and did not ignite under 35 kW/m heat flux. Thermogravimetry coupled with pyrolysis-combustion flow calorimetry has demonstrated efficient features of the proposed flame retardant system as char-promoter for cotton. In order to reduce the amounts of U and AP employed in the selected formulations, the use of water glasses (WG) has been explored. A very low WG amount has proven to be effective in halving U and AP contents, maintaining the same fire performances already provided by the high concentrated finishing bath. Furthermore, WG have turned out to act as synergistic species as demonstrated by evaluating the synergistic effectiveness parameter. [ABSTRACT FROM AUTHOR]