Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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FRP etching to improve joint strength

Acid EtchingContinuità di rinforzoContinuity of reinforcementEtching acidoFiber Reinforced PolymersFPR CoatingFPR JoiningGiunzione FPRRivestimento FPR


The invention consists of an innovative chemical method capable of improving the properties of adhesive joints for FRP (Fiber Reinforced Polymers): in particular, through an acid etching process, the invention allows to create interfaces capable of being infiltrated by the joining material, increasing the mechanical strength of a joint between two components or the adhesion of a coating on the FRP.

Technical features

Different techniques to join FPR (such as laser welding, pin welding, thermal etching and others) are known and used in different sectors, but none of them guarantees the integrity and continuity of the fibers embedded in the polymer matrix. The acid etching of the polymer matrix on the FRP surface only, leaves the fibers intact. Through a localized heating during the etching process it is also possible to accelerate the reaction time and further improve the mechanical performances. Etching is also able to increase the wettability of the material when the initial value is not enough for creating strong joints or coatings.

Possible Applications

  • Biomedical: prosthesis junctions;
  • Aerospace: junctions for satellite components;
  • Automotive: joints for car components, vehicle lightening;
  • Structural joints: joints between FRPs for applications in the construction, civil, industrial, wind, oil & gas, naval sectors.


  • The fibers embedded in the polymeric matrix are not destroyed during etching;
  • Simple process;
  • Low cost process;
  • Joint mechanical performance improvement;
  • Improvement of coating adhesion on FRP.