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The vinyl phosphonic acid a phosphorus-based monomer has been polymerized on the cotton fabric with the aid of a cationic surfactant and 2, 2/ -azobis(2-methypropionamidine) dihydrochloride (AIBA) an initiator with the aim to improve flame retardancy of fabric for the fire safety. The thermal and burning behaviour of treated fabric are studied using thermogravimetry (TG) and limiting oxygen index flammability test (LOI), respectively. This treatment alters the path of degradation of treated cotton fabric sample (CF-PVPA-3) having 1.2% phosphorus, which increased the carbonaceous residue up to 28.2% at 600°C in an inert atmosphere at the expense of flammable products. The LOI value of 28.5 % of treated cotton fabric indicates the attainment of flame retardant property

Epoxy/nanoclay composites containing ammonium polyphosphate (AP) were prepared by in situ polymerization method using compression molding machine. XRD patterns indicated the formation of epoxy/clay nanocomposites. The glass transition temperature measured by DSC was increased with the addition of nanoclay as well as AP separately in epoxy matrix but decreased when nanoclay and AP added together. On adding AP, the epoxy composites showed early start of degradation but after 400 °C composites became stable and gave high char yield in thermogravimetic analysis. Epoxy composites containing 10% AP accomplished the flame retardant property with V-0 rating in UL-94 test.

This work was focused on the development of flame retardant cotton fabric by coating with intumescent formulations containing different polymers and inorganic additives. The thermal degradation study was carried out using thermogravimetric and differential scanning calorimeter techniques, and the flame retardancy behaviour was evaluated by auto flammability and limiting oxygen index tests. Coated cotton fabric samples give rise to high char yields on heating with lower degradation temperature at the expense of volatile products. The action of intumescent coating materials was found concurrent with the process of decomposition of cotton fabric on heating. The FTIR spectra of chars of coated cotton fabric indicated the catalyzed dehydration of cotton cellulose and contribution of phosphorus for formation of carbonaceous char. The coated cotton fabric samples have achieved better flame retardant properties and were not ignited during auto flammability test.

In this study, a commercially available phosphorus-based methacrylate ester was polymerized on cotton fabric by a variation of admicellar polymerization to make it flame retardant. The resulting film of polymerized phosphorus monomer formed on the cotton surface was characterized by Fourier Transform Infrared spectroscopy and Scanning Electron Microscopy. Thermal properties were studied by Thermogravimetrical analyses which showed that the treated cotton fabric has higher char yield and lower decomposition temperature than untreated cotton fabric. Auto 45° flammability test was performed to understand the burning behaviour of treated cotton fabrics. Untreated cotton fabric burned the entire length of a 6.5 cm sample to ashes in 41 s. The treated cotton fabrics did not ignite during test and passed the flammability test with a residual char of 1 cm length. The durability of treated cotton fabric with flame retardant property was also investigated by repeated home-launderings.

Thermal degradation and stability of polypropylene-nanoclay composites containing organic phosphinate (OP) and ammonium polyphosphate (AP) flame retardants with maximum total 20 per cent loading was carried out using thermogravimetry (TG) and differential scanning calorimetry (DSC) analyses in inert atmosphere. Kinetic methods such as Broido, Horowitz-Metzger and Coats-Redfern were applied to study the mechanism of degradation of materials. The thermal stability of PP/PPgMA/AP/15A nanocomposite containing total 20 per cent loading is increased by 20 o C in comparison to that of control sample and also gives high char yield (14.4 %) due to presence of exfoliated clay and phosphorylating effect of AP in condensed phase. The random nucleation (first order) mechanism is found the most probable mechanism for PP composites degradation from kinetic study. The future prospective of the study is to develop superior fire safe polymeric materials. Copyright © 2013 VBRI press.

PA66/nanoclay nanocomposites with flame retardant (dimelamine phosphate) and other supportive additives (ammonium pentaborate, zinc borate and potassium nitrate) were prepared by melt blending method using single screw extruder. The prepared nanocomposites were characterized by XRD and FTIR techniques. The thermal properties were analysed using thermogravimetry and differential scanning calorimetry. A significant reduction in flame spread rate in UL-94 horizontal test was observed on inclusion of ammonium pentaborate to PA66/nanoclay/dimelamine phosphate composite. Copyright © 2012 VBRI Press.

The PA6/organoclay nanocomposites with organic phosphinate (OP) or ammonium polyphosphate (APP) and pentaerythritol (PER) flame retardant additives were prepared by melt blending process using a twin screw extruder. The structure and morphology of nanocomposites formed were studied by X-ray diffraction and transmission electron microscopy, which indicated that the clay (Cloisite 30B) was intercalated and/or exfoliated into the PA6 matrix. Thermal behaviour was evaluated by thermogravimetric analysis. The small shift in TG curve to lower temperature in the initial stage of degradation on addition of OP to PA6 shows the mild catalysing effect of OP on degradation of PA6 in the presence of clay whereas the onset temperature of degradation of PA6 on addition of equal amount of APP is found to be decreased by about 100 °C due to decomposition of APP and strong catalysing effect of phosphoric acid released from APP. The cone calorimeter test showed that on addition of 15% OP and 5% 30B to PA6 have reduced the PHRR by 77%. From thermal and combustion behaviour, PA6/OP/30B sample having 5% 30B and 15% OP is found more effective in reducing burning propensity of PA6.

SUMMARY In order to develop polymer-clay nanocomposites with reduced flammability by incorporation of char-forming conventional nitrogen and phosphorus based flame retardants at low loading levels, the polypropylene-clay nanocomposites were prepared by melt blending method with Cloisite 15A (15A), organic phosphinate (OP) and ammonium polyphosphate (AP) additives. Thermal analysis shows that addition of 5% 15A along with 15% (w/w) OP in polypropylene (PP)/PPgMA increases the thermal stability of PP/PPgMA/OP/15A composite by 82 °C showing synergistic effect, and the PP/PPgMA/AP/15A sample with same loading becomes thermally stable by 70 °C. Cone calorimeter analysis of the PP/PPgMA/OP/15A and PP/PPgMA/AP/15A composites measures the reduction in peak heat release rate values by 66% and 58%, respectively. Addition of 20% OP to PP/PPgMA enhances the limiting oxygen index (LOI) value and gives V-2 rating of UL-94 test. Further, on replacing 5% OP with 5% 15A for PP/PPgMA/OP/15A sample without changing the total 20% loading, the LOI value increases further slightly but give no UL-94 rating. Also, PP/PPgMA/AP/15A sample with same loading similar to that of PP/PPgMA/OP/15A sample shows an enhancement in LOI value and gives no rating in UL-94 test. No relation was observed between LOI values and UL-94 test rating in the present study. Copyright © 2012 John Wiley & Sons, Ltd.

In order to achieve acceptable levels of flame retardancy of polymers, phosphorus-based flame retardant (FR) additives at about 20–30% w/w are required which is too high for conventional synthetic fibres. To know whether more finely sized particles of conventional FRs with or without nanoclay are more effective at the same concentration, composites of PA6 with bentonite and ammonium polyphosphate (APP) have been prepared by melt processing in a twin-screw extruder. XRD peaks and TEM images of PA6/Org-bentonite composite show partially ordered intercalation and ordered exfoliation. Thermal analysis in He shows that thermal stability of PA6 nanocomposite has increased by 18 °C compared with pure PA6 during degradation after 425 °C but it has decreased by 100 °C on inclusion of APP in PA6/nanoclay composites. The char yield is increased by 20% in PA6/bentonite/APP composites. No effect on thermal stability or char yield is observed by reducing the particle size of APP.

BACKGROUND: The kinetics of the thermal decomposition of cellulosic materials is of interest from the viewpoint of flame retardancy for safety, optimization of incineration processes and reducing energy production from fossil sources and associated pollution. One essential step in these processes is the thermal degradation through mass and energy transport, which determines the rate of evolution of various types of products from cellulosic materials. RESULTS: Kinetic parameters have been determined using various model-based and model-free methods in the thermal degradation of cellulose up to 700 °C in helium atmosphere. The values of the activation energy obtained in isothermal processes and non-isothermal processes have been found to be not far from each other. From the integral method, the random nucleation (F1)-type mechanism has been found most probable for cellulose degradation having an activation energy, Ea, in the range 156.5–166.5 kJ mol−1, lnA = 20–23 min−1, for first-order reaction during its decomposition process at heating rates of 2, 5 and 10 °C min−1. Based on the high correlation coefficient, many types of mechanisms seem equally good for non-isothermal degradation of cellulose. CONCLUSION: The linear correlation coefficient has a limitation for verifying the correctness of a reaction mechanism in the study of degradation kinetics. Therefore, the correctness of a mechanism should be considered on the basis of comparing the kinetic parameters obtained from isothermal as well as non-isothermal methods. Copyright © 2008 Society of Chemical Industry

Cellulose arylphosphonate compounds have been synthesized and investigated by the kinetics of thermal degradation by thermogravimetry (TG) and differential scanning calorimetry (DSC) from ambient temperature to 600°C. Various kinetic and thermodynamic parameters such as energy, entropy and free energy of activation have been obtained from TG curves using the Broido method and transition state theory. The high values of enthalpy change (1016 and 1025 J g−1) of decomposition and oxidation reactions corresponding to the last two exotherms of the DSC curves of cellulose are decreased to a greater extent in the case of cellulose arylphosphonate compounds. The values of activation energy for the decomposition stage of cellulose arylphosphonate compounds lie in the range 25–49 kJ mol−1 and are found to be lower than that of pure cellulose, namely 165 kJ mol−1 in air atmosphere. Scanning electron micrographs of phosphorylated cotton cellulose and chars show furrowed and fractured surfaces although the morphology of the original fibres remains largely unchanged. Furthermore, higher char yields of cellulose derivatives leads to the conclusion that such derivitisation may give rise to flame-retardant treatments for cellulosic materials. Copyright © 2004 Society of Chemical Industry

This paper presents the effect of nanoclay content on structure and mechanical properties of phosphorylated epoxy containing 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as flame retardant. The nanoclay up to 4 wt% was blended with phosphorylated epoxy containing 2.5wt% phosphorus content and molded out after curing. The internal structure of prepared samples was analyzed by X-ray diffraction (XRD) and transmission electron microscope (TEM) methods. The surface morphology was analyzed by field emission scanning electron microscope (FESEM). The mechanical properties were measured using Universal Testing Machine (UTM). The results of XRD and TEM reveal mixed type of structure (intercalated and exfoliated) of samples. The mechanical properties (tensile and flexural strength) are found maximum for phosphorylated epoxy sample containing 2.0 wt% nanoclay.

The kinetics of thermal degradation of PA6 composites containing intumescent flame retardant and inorganic additive was studied by using various model-free methods such as Flynn-Wall-Ozawa, Kissinger, Coats-Redfern Modified and model-based Coats-Redfern method at three heating rates 5, 10 and 20°C/min under nitrogen atmosphere. Model-free methods suggested the simple reaction mechanism for pure PA6 and complex multistep mechanism for flame retarded PA6 composites. The activation energy values obtained from three model-free methods were comparable to each other. Model-based Coats-Redfern method suggested the random nucleation and growth mechanism for both PA6 and PA6/AP760 samples but the degradation mechanism is changed to phase boundary controlled mechanism on further addition of inorganic additives. The change of activation energy values indicated that inorganic additives acted as catalyst during major degradation stage but at later stage of charring they acted as strong barriers to prevent escaping of volatile materials.

In this paper, PA6/clay nanocomposites containing flame retardant additives such as ammonium polyphosphate (AP760), zinc phosphate and zinc borate were prepared by melt blending method. The resulting nanocomposites were characterized by X-ray diffraction and Fourier Transform Infrared spectroscopy (FTIR). X-ray diffraction patterns indicated the formation of intercalated structure in PA6 nanocomposites. FTIR analysis of residues obtained at 400°C revealed the formation of aromatic carbonaceous char and the presence of nitrile chain ends in the degradation products of PA6 composites. Thermogravimetric analysis and UL-94 test were performed to determine thermal stability and flammability of nanocomposites. Synergistic effects were observed on addition of zinc borate with AP760 in PA6/clay nanocomposites for increasing thermal stability by 38°C. The PA6/AP760 composite containing 20 wt% of AP760 without clay achieved flame retardancy with V-2 rating in UL-94 test.