Fillers for Cold-Cast Polyurethane

These must be hydrolytically inert and dry to prevent their reaction with the diisocyanate present. Also they must be neutral in pH to prevent longterm hydrolytic instability in the cured product. Examples of suitable materials are soft round clays, barium sulphate (barytes), whitings etc. [Pg.404]

There is no filler reinforcement of the polyurethane akin to the reinforcement which takes place when reactive or particulate fine particle size fillers are added to non-strain-crystallizable millable elastomers. Fillers in polyurethane reduce strength approximately in proportion to their volume they too, however, increase stiffness and hardness and are cheaper to use for this purpose than additional diisocyanate which gives the same result through hard-segment increase. [Pg.404]

New concepts in filler reinforcement of PUs are being developed and the following are examples of the philosophy being developed. [Pg.404]

Polymer Polyols (BP Chemicals) are dispersions of polystyrene acrylonitrile copolymer particles of 0-5-F5/im in polyether polyols sterically stabilized with non-aqueous dispersants (NAD). Use of these with the conventional urethane polyols enables elastomers of relatively high hardness, high strength and exceptionally high elongation at break to be [Pg.404]

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