Flame retardancy effects of zinc borate and nanoclay in ABS, and boron compounds in PET

Özkaraca, Ayşe Çağıl
In this thesis there were two main purposes, the first one being to investigate effects of zinc borate (ZB) on the flammability behavior of ABS when used with and without a traditional brominated flame retardant (BFR) / antimony trioxide (AO) system. The second purpose was to investigate contribution of nanoclays (NC) to the flame retardancy performance of the same traditional BFR compound with various combinations of AO and ZB again in ABS matrix. For these purposes, materials were melt compounded by using a laboratory scale twin-screw extruder, while specimens were produced by injection or compression molding. Flame retardancy of the specimens were investigated by Mass Loss Cone Calorimeter (MLC), Limiting Oxygen Index (LOI) measurements and UL-94 vertical burning tests. Other characterization techniques required in this thesis were; X-ray diffraction analysis, scanning and transmission electron microscopy, thermogravimetric analysis and tensile tests. Studies for the first purpose indicated that almost all flame retardancy parameters were preserved when antimony trioxide were replaced with zinc borate as much as in the ratio of 1:3. Residue analyses revealed that predominant flame retardancy mechanism of traditional system was gas phase action, while zinc borate contributes especially in the condensed phase action by forming thicker and stronger char layer. Investigations for the second purpose basically concluded that use of nanoclays improved all flame retardancy parameters significantly. Residue analyses pointed out that nanoclays especially contribute to the formation of stronger and carbonaceoussilicate char acting as a barrier to heat and flammable gases and retarding volatilization via tortuous pathway. As an additional third purpose in this thesis, usability of three boron compounds (zinc borate ZB, boric acid BA, boron oxide BO) with two traditional flame retardants (organic phosphinate OP and melamine cyanurate MC) in neat PET and recycled PET were also examined leading to some promising results in MLC parameters.


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Citation Formats
A. Ç. Özkaraca, “Flame retardancy effects of zinc borate and nanoclay in ABS, and boron compounds in PET,” M.S. - Master of Science, Middle East Technical University, 2011.