This data set supports the article titled “Post-tensioning method for prestressing fiber-reinforced polymer laminates” submitted to “Communication Materials,” currently under review by the journal and pending acceptance for publication. This dataset supports a paper publication on a prestress conditioning method that involves applying tensile loading to a laminate cured under standard processing conditions and inducing stress relaxation in the matrix through post-curing thermal treatment. It includes experimental data on the tensile testing of untreated and pre-stressed vitrimer-matrix crossply laminates. In addition, real-time images of the specimen edge to monitor cracking density in the transverse plies of both untreated and prestressed specimens are provided

Tests were conducted on specimens that were cut from a panel produced through resin infusion. The fiber reinforcements used were unidirectional carbon fabric layers, specifically 24K with a weight of 300 g/m². The stacking sequence of these layers followed the configuration [02, 902]s. The matrix material was an epoxy-based vitrimer developed by Cidetec (Donostia-San Sebastian, Spain), which holds the patent for this composition. It consisted of commercially available functional epoxy groups, DGEBA (Araldite LY1564), combined with a hardener that enabled dynamic cross-linking based on aromatic disulfide species (4-Aminophenyl disulfide). During mixing, the NH equivalents were adjusted to 1.1 per epoxy group. The laminate was then cured at 140ºC for 3 hours.

The resulting panel measured 300 x 300 mm² and had a thickness of 2.3 mm. Specimens cut from this panel were 250 mm long and 20 mm wide. Prior to testing, the sides of the specimens were polished using medium grit (350 mesh) followed by fine grit (1200 mesh). Mechanical testing was performed using a two-column tabletop MTS Insight50 electromechanical testing machine equipped with a 50 kN load cell. Six specimens were tested. Two of them were not post-tensioning conditioned (A-Notreat and B-Notreat), while four of them undergoing post-tensioning conditioning according to the follwing methodology:

• Pre-heating the laminate to 165ºC.

• Applying loadin the longitudinal direction while allowing the matrix to fully relax the induced stress. The duration of the stress relaxation process was 1 hour. The constant force applied during the post-tensioning conditioning was:

  Specimen name: C-7.5 Constant force applied during post-tensioning conditioning: 7.5 kN

  Specimen name: D-7.5 Constant force applied during post-tensioning conditioning: 7.5 kN

  Specimen name: E-10 Constant force applied during post-tensioning conditioning: 10 kN

  Specimen name: F-10 Constant force applied during post-tensioning conditioning: 10 kN

• Cooling to room temperature.

• Releasing the load.

After conditioning, the specimens were subjected to a tensile test with a maximum load of 20 kN. Strain was measured using a contact clip-on mechanical extensometer. Real-time monitoring of matrix cracking in the 90º middle layers was performed. A Canon EOS 550D digital camera, equipped with a 100 mm f/2.8 Macro L IS USM lens, was used to capture high-resolution images (18 megapixels) of a 50 mm section of the specimen edge, positioned midway between the grips. The camera took photos every 5 seconds using the camera's software.