1. 1 Synergistic action of fluorine-containing additives in bromine/antimony fire retardant ABS Ali DURAN POLYMER TECHNOLOGY SEMINER

2. 2 RESULTS AND DISCUSSION  The effect of PTFE is quite evident at oxygen concentrations 23-26%, where the slope of the curve is large, whereas it tends to vanish if combustion is carried out in any oxygen excess above 27%,  The effect of SbF 3 on combustion rate is similar to that of PTFE and does not seem to depend on its concentration,

3. 3 RESULTS AND DISCUSSION  As far as the combustion times are concerned, the results presented in fig. 2 again show the similarity between the effect of PTFE and that of SbF 3 at relatively high concentration vs. the combustion time (SQT) of FR ABS,  In both cases the initial instability of the flame in FR ABS shown by the low increase of SQT with O 2 increase (22-25%),  However, FR ABS exceeds the limiting combustion rate already at O 2 concentration of 23.5%, shown in fig. 1,

4. 4 RESULTS AND DISCUSSION  FR ABS with very low concentration of SbF 3 shows a trend qualitatively similar to that of PTFE or 0.2 phr SbF 3 containing FR ABS,  Moreover, in tis case, the intermediate unstable flame regime is reached at larger SQT (> 180 S.),  Because of the parallel behaviour of PTFE and SbF 3 might be one of the truly active fire retardant agents,  In its presence the combustion proceeds at a very low rate but the extinguishment of the flame is rather delayed,  In forced combustion conditions the additional effect of the fluorine containing compound is no longer sagnificiant and the fire retardance is restricted to that of the synergic Br/Sb system,

5. 5 RESULTS AND DISCUSSION  In fig. 3 the TG of ABS, FR ABS and PTFE-containing FR ABS are reported together with the calculated TG for the FR ABS system assuming no interaction occuring amongst the components,  By comparing the experimental and calculated TG of FR ABS, the role played by the polymer in the thermal behaviour can be deduced because the experimental curve shows a weight loss larger than the calculated one in the BTBPE degredation temperature range (370-390 0 C),

6. 6 RESULTS AND DISCUSSION  Moreover, the amount of char stable at 700 0 C is larger than expected for a simple additive behaviour,  Interaction is supposed to take place between the polymer and the FR system and not between the FR components because it has already been reported that BTBPE and Sb 2 O 3 do not react at relatively low heating rate,

7. 7 CONCLUSION  It has been shown that the effect of SbF 3 on combustion of FR ABS is parallel to that of PTFE reducing the rate of combustion of ABS in mild combustion conditions,  Furthermore, both compounds induce crosslinking in ABS on heating,  Thus, it is likely that SbF 3 or (SbF 5 ) created in situ could be responsible for the effect of PTFE on the combustion of ABS fire retarded with the Br/Sb system,  However further work is necessary to understand the mechanism of the fire retardant action.