Flame retardancy of polyamide compounds and micro/nano composites

Gündüz, Hüseyin Özgür
In the first part of this dissertation, glass fiber reinforced/unreinforced polyamide 6 (PA6) and polyamide 66 (PA66) were compounded with three different flame retardants, which were melamine cyanurate, red phosphorus and brominated epoxy with antimony trioxide, by using an industrial scale twin screw extruder. Then, to investigate flame retardancy of these specimens, UL-94, Limiting Oxygen Index (LOI) and Mass Loss Cone Calorimeter (MLC) tests were carried out. In addition to flammability tests, thermogravimetric analysis (TGA) and tensile testing were performed. Results of the tensile tests were evaluated by relating them with fiber length distributions and fracture surface morphologies under scanning electron microscope (SEM). Incorporation of melamine cyanurate (MCA) to PA6 led to some increase in LOI value and minor reductions in Peak Heat Release Rate (PHRR) value. However, it failed to improve UL-94 rating. Moreover, poor compatibility of MCA with PA6 matrix caused significant reductions in tensile strength. Brominated epoxy in combination with antimony trioxide (Br/Sb) was compounded with both glass fiber reinforced PA6 and PA66. Br/Sb synergism was found to impart excellent flammability reductions in LOI value and UL-94 as V-0 rating. Effectiveness of Br/Sb flame retardant was also proven by the MLC measurements, which showed excessive reductions in PHRR and Total Heat Evolved (THE) values. On the other hand, Br/Sb shifted the degradation temperature 100°C lower and decreased the tensile strength value, due to poor fiber-matrix adhesion and decreased fiber lengths. Red phosphorus (RP), when introduced to glass fiber reinforced PA66 induced V-0 rating in UL-94 together with significant increase in LOI value, and major decrease in PHRR. Degradation temperature was 20°C lower while mechanical properties were kept at acceptable values compared to neat glass fiber reinforced PA66. In the second part of this dissertation, to investigate synergistic flame retardancy of nanoclays; glass fiber reinforced PA6 was compounded by certain nanoclay and an organo-phosphorus flame retardant (OP), which contains aluminum phosphinate, melamine polyphosphate and zinc borate, in a laboratory scale twin screw extruder. Exfoliated clay structure of the nanocomposites was assessed by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM), while thermal stability and combustion behaviors were evaluated by TGA, LOI, UL-94 and MLC. Replacement of a certain fraction of the flame retardant with nanoclay was found to significantly reduce PHRR and THE values, and delay the ignition. Moreover, remarkable improvements were obtained in LOI values along with maintained UL-94 ratings. Residue characterization by ATR-FTIR and SEM ascribed the enhanced flame retardancy of nanocomposite specimens to the formation of a glassy boron-aluminum phosphate barrier reinforced by clay layers at the nanoscale.


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In this study, the High Density Polyethylene (HDPE) and Low Density Polyethylene (LDPE) blends prepared by Plasticorder Brabender were strengthened by adding Carbon Black (CB). Blends were prepared at 190 °C. Amounts of LDPE were changed to 30, 40, 50 and 60 percent by the volume and the percent amounts of CB were changed to 5, 10,15, 20 and 30 according to the total volume. Thermal and morphological properties were investigated by using Differential Scanning Calorimeter (DSC), Scanning Electron Microscope ...
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Organoclay nanocomposites were prepared by ultrasound-assisted solution intercalation technique based on polystyrene containing brominated epoxy and a combination of brominated epoxy and antimony oxide. Aspects of nanomorphology and nanodispersion were investigated by X-ray diffraction and transmission electron microscopy whereas flammability and reaction to fire were evaluated using limiting oxygen index, UL-94, and mass loss calorimeter tests. Polystyrene/brominated-epoxy-blend-based nanocomposites showed...
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Çavdar, Seda; Usanmaz, Ali; Department of Polymer Science and Technology (2007)
In this work, EPDM rubber was compounded with increasing amount of filler (FEF N 550 type carbon black), process oil (saturated mineral oil), vulcanizing agent [di (t-butylperoxy) diisopropyl benzene, i.e., BBPIB] and diene [5-ethylidenebicyclo(2.2.1)-hept-2-ene, i.e., ENB] in order to investigate mechanical and rheological properties. Effect of Increasing amount of filler was investigated by using FEF N 550 type carbon black in 35, 70, 87.5, 105 phr. Decrease in scorch times of vulcanization reactions, ts2...
Citation Formats
H. Ö. Gündüz, “Flame retardancy of polyamide compounds and micro/nano composites,” M.S. - Master of Science, Middle East Technical University, 2009.