Sizing composition for reinforcing fibres and applications thereof

A method of improving an adhesion of reinforcing fibres with respect to an organic matrix forming with the fibres a part made of a composite material, comprising:

• sizing a surface of the fibres with an elastomer film bearing thiol functions comprising:
• soaking the fibres in a sizing composition comprising a polybutadiene prepolymer that can form an elastomer film on the surface of the fibres by polymerization and crosslinking, the polybutadiene prepolymer comprising at least two epoxy functions;
• a cross-linking agent for cross-linking the polybutadiene prepolymer, the cross-linking agent comprising at least three reactive functions, at least one of the three reactive functions being a thiol function;
• and a catalyst for catalyzing the cross-linking of the polybutadiene prepolymer by the cross-linking agent, the catalyst comprising at least one tertiary amine function;
• removing the fibres from the sizing composition;
• heat treating the fibres so removed from the sizing composition for polymerizing and cross-linking the polybutadiene prepolymer, whereby the elastomer film bearing thiol functions forms on the surface of the fibres;
• bringing the fibres with the surface so sized into contact with a resin that can be cured by a chain transfer polymerization;
• and
• curing the resin by the chain transfer polymerization.

A method of manufacturing a part made of a composite material comprising reinforcing fibres in an organic matrix, comprising:

• sizing a surface of the fibres comprising:
• soaking the fibres in a sizing composition comprising a polybutadiene prepolymer that can form an elastomer film on the surface of the fibres by polymerization and crosslinking, the polybutadiene prepolymer comprising at least two epoxy functions;
• a cross-linking agent for cross-linking the polybutadiene prepolymer, the cross-linking agent comprising at least three reactive functions, at least one of the three reactive functions being a thiol function;
• and a catalyst for catalyzing the cross-linking of the polybutadiene prepolymer by the cross-linking agent, the catalyst comprising at least one tertiary amine function;
• removing the fibres from the sizing composition;
• heat treating the fibres so removed from the sizing composition for polymerizing and cross-linking the polybutadiene prepolymer, whereby the elastomer film bearing thiol functions forms on the surface of the fibres;
• bringing the fibres with the surface so sized into contact with a resin that can be cured by a chain transfer polymerization;
• and
• curing the resin by the chain transfer polymerization.

A method of sizing a surface of reinforcing fibres with an elastomer film bearing thiol functions, comprising:

• soaking the fibres in a sizing composition comprising a polybutadiene prepolymer that can form an elastomer film on the surface of the fibres by polymerization and crosslinking, the polybutadiene prepolymer comprising at least two epoxy functions;
• a cross-linking agent for cross-linking the polybutadiene prepolymer, the cross-linking agent comprising at least three reactive functions, at least one of the three reactive functions being a thiol function;
• and a catalyst for catalyzing the cross-linking of the polybutadiene prepolymer by the cross-linking agent, the catalyst comprising at least one tertiary amine function;
• removing the fibres from the sizing composition;
• and
• heat treating the fibres so removed from the sizing composition for polymerizing and cross-linking the polybutadiene prepolymer, whereby the elastomer film bearing thiol functions forms on the surface of the fibres;
• wherein the polybutadiene prepolymer comprises at least two repetitive units chosen from the units of formulas (I) and (II):
• and at least two repetitive units of formula (III):