| abstract |
The invention relates to an impact modifier and a device and a method for the production thereof, as well as to a method for preparing a thermoset material, or a thermoset material precursor, from the impact modifier. The impact modifier comprises at least one copolymer selected from among A-B-A, A-B and A-B-C type block copolymers, in which: each block is linked to the other by means of a covalent bond or an intermediate molecule that is connected to one of the blocks by a covalent bond and to the other block by another covalent bond; A is a PMMA homopolymer or a copolymer of methyl methacrylate, A preferably being compatible with the resin; C is either (i) a PMMA homopolymer or a copolymer of methyl methacrylate or (ii) a polymer based on monomers or a mixture of vinyl monomers, and blocks A and C can be identical; and B is incompatible or partially compatible with the thermoset resin and incompatible with block A and optional block C. The impact modifier is characterised in that it takes the form of microgranules having a diameter of less than 1500 μm, advantageously less than 1000 μm, preferably between 400 and 1000 μm. The ratio of the standard deviation/mean size of the particles is less than 10%, preferably less than 5%. |