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.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/3/12610668/index.pdf |
| Date | 01 July 2009 |
| Creators | Gunduz, Huseyin Ozgur |
| Contributors | Kaynak, Cevdet |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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