Oxygen index PMMA

Films containing about 10% CIRh(PPh3)3 in PMMA were prepared and subjected to oxygen index, TGA, and DSC measurements. The oxygen index, bottom ignition (1 1), increases from about 14 for pure PMMA to about 20 for the rhodium compound in PMMA. TGA analysis indicates that about 25% of the sample is non-volatile at 600°C and the glass transition temperature increases by about 15°C by DSC. 

Figure 14 shows that the heat loss by radiation becomes insignificant (the oxygen index becomes independent of pressure) at P > 0.3 atm for PMMA, and at P > 2 atm and P > 6 atm for poly(vinyl chloride) and Teflon, respectively. A weak pressure dependence of Y (1/P° ) accounts for extinction of the flame by convective... 

The isotherms in a PMMA rod specimen burning in an oxygen index flammability tester under an O2/N2 gas stream containing 21 % of oxygen were measured by Schif-fer and are illustrated in Figure 2.17. 

Phosphoms may be incorporated into PMMA to reduce flammability. Work carried out at Salford University has shown that MMA may be reacted with diethyl(methacryloxymethyl) phosphonate (DEMMP) to form a copolymer that provides a better flame retardant performance than a compound to which diethyl ethyl phosphonate (DEEP) has been added. DEEP has a similar stmcture to DEMMP and it might be expected that the two compounds confer a similar degree of flame reatardancy to PMMA at similar loadings. The rise in oxygen index is similar, 17.5 up to 22 at 3.5% of phosphoms in each case. However, the MMA/DEMMP copolymer is more thermally stable and gives better FR properties. It turns out that the DEEP plasticises PMMA whereas the copolymer has similar physical and mechanical properties to unprotected PMMA. 

Figure 6.2 The effect of filler particle size on the oxygen index of PMMA filled with...

The effect of the additives on the oxygen index of PMMA, PS and nylon-6, 6 has also been measured. [227). The results are shown in Table 5.5. The trend in oxygen index response for PMMA and PS is similar to the trend in the peak and average heat release rate data from the cone calorimeter. Scung reports similar results fo r polypropylene with additives or fillers, in their comparison between cone calorimeter and traditional tests (oxygen index, glow wire test, etc.) [229]. The correlation is very poor, however, between the LOI and rate of heat release for nylon-6,6 with silica gel / KjCOj additives. 

Results of refractive index measurements for PMMA and VMCH during oxygen RIE at 35mTorr and various incident RF power densities are tabulated in Table I. The values in the first column are those... 

The absorption of PVA in spectral range 190-300 nm is due to carbonyl chromophoric groups, which are obtained as a result of oxidation process with participation of atmospheric oxygen [76], The small increase in transmission in the spectral range of 185-193 nm, as indicated by the dependence of Aae =f(R, ) is in the case of PMMA due to the dynamic and concurrent processes of destruction and scission of the polymer macro-chains rmder the influence of gamma-irradiation ( - the spectral index of common loses of absorption and scattering forgiven sample) [76],... 

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