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SynopsisVinyl bromide was used as a model for bromine-containing flame retardants in developing methodology for localizing flame retardants either on the surface of the filament, uniformly throughout it, or predominantly a t the core. SEM-x-ray microprobe techniques were used in the verification of the location of the flame retardant in the filament. The flame retardance efficiency of PVBr was then correlated with its location in the filament. Grafting other bromine-containing flame retardants showed a wide range of efficiencies which depended not only upon the location of the graft within the filament but also upon the structure of the compound. For the various bromine homopolymer grafts, the apparent thermal stability of the graft and its flame retardance efficiency may be simply related to the alpha aliphatic hydrogen-to-bromine ratio. The lower this ratio is, the higher the efficiency. VBr copolymers and terpolymers showed wider variation in flame retardance efficiencies. This is attributed to large variations in melt viscosity of the different grafted materials. The grafts showed only small changes in their melting points and minimal changes in tenacity and stiffness. However, grafting induced large increases in the elongation.
SynopsisVinyl bromide was used as a model for bromine-containing flame retardants in developing methodology for localizing flame retardants either on the surface of the filament, uniformly throughout it, or predominantly a t the core. SEM-x-ray microprobe techniques were used in the verification of the location of the flame retardant in the filament. The flame retardance efficiency of PVBr was then correlated with its location in the filament. Grafting other bromine-containing flame retardants showed a wide range of efficiencies which depended not only upon the location of the graft within the filament but also upon the structure of the compound. For the various bromine homopolymer grafts, the apparent thermal stability of the graft and its flame retardance efficiency may be simply related to the alpha aliphatic hydrogen-to-bromine ratio. The lower this ratio is, the higher the efficiency. VBr copolymers and terpolymers showed wider variation in flame retardance efficiencies. This is attributed to large variations in melt viscosity of the different grafted materials. The grafts showed only small changes in their melting points and minimal changes in tenacity and stiffness. However, grafting induced large increases in the elongation.
ZUSAMMENFASSUNG:Die Sorption und die Diffusionsgeschwindigkeit von Methylmethacrylatdampf sowie die Gleichgewichtsquellung ungestreckter und verschieden stark gestreckter Polypropylenfasern wurden untersucht. Die Kristallinitat der Proben wurde durch Tempern gesteigert. Gleichgewichtsquellung und Sorption der Proben andern sich bei der Streckung entgegengesetzt zur Anderung der Orientierung und der Kristallinitat. Das durch Tempern auftretende Ansteigen der Kristallinitat beeinflufit die Quellungs-und Sorptionsergebnisse ebenfalls, besonders bei weniger stark orientierten Proben. Die Diffusionskonstante wird in erster Linie durch die Anderung der Orientierung beeinflufit, was durch den Unterschied der Aktivierungsenergien der ungestreckten und gestreckteu Proben bestatigt wird. SUMMARY:The equilibrium swelling and sorption, and the ,diffusion coefficient of methylmethacrylat vapour in unstretched and to various degrees stretched polypropylene fibres were determined. The crystallinity of the fibres increased by heat treatment. The equilibrium swelling and sorption alter inversely with the change of orientation and cristallinity. The alteration of the specific gravity respectively the crystallinity as a consequence of heat treatment is appreciated by the sorption and swelling results, especially a t less oriented specimens. The diffusion coefficient is influenced first of all by the change of orientation, which is demonstrated by the difference of activation energies of stretched and unstretched specimens too. Einfuhrung
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