Dataset for the hybrid non-toughened and toughened epoxy adhesive properties

In this article, the manufacturing and toughening effects on the material properties of epoxy adhesives used in wind turbine rotor blades are presented. Different adhesive materials are developed by combining SPABOND™ 820HTA (non-toughened) and SPABOND™ 840HTA (toughened) adhesives with the machine and manual mixing methods. Firstly, the manufacturing quality are compared between the two methods, in terms of void percentage and void volume using micro-computed tomography. Dynamical Mechanical analysis, uniaxial tensile testing, V-notch shear testing and single-edge-notch beam testing are carried out to evaluate the manufacturing and toughening effects. In these experiments, the digital image correlation technique is exploited to obtain the displacement and strain data. Origin ProⓇ and MATLAB R2021bⓇ are utilized for technical data analysis, plotting, smoothing, filtering, and averaging. The obtained data could be used to select the adhesive material based on the strength and stiffness requirements, develop failure criteria, and predict the thick adhesive joint behavior by finite element modeling.


Specifications
Materials science: Polymers and plastics Specific subject area Dynamic mechanical analysis, tensile, shear and fracture toughness properties of epoxy adhesives Type of data Table  Figure How the data were acquired Different experiments were carried out and the corresponding data were acquired as following: • Micro computed tomography using Ultratom μCT system (RX solutions) • Dynamic mechanical analysis using TA R Q800 series equipment.
• Uniaxial tensile testing using MTS R 810 Landmark servo-hydraulic machine with calibrated load cell of 5 kN. • V-notch shear testing Walter + bai (w + b) test machine with local of 50 kN. • Single-edge-notch bending test using MTS R Acumen equipped with 3 kN load cell. • Imaging for digital image correlation (DIC) using Point Grey -Grasshopper 3 camera (2.2 Megapixels) housing Fujinon HF35SA-1 35 mm F/1.4 lens. • Digital image correlation using VIC 2D-6 software from correlated solutions R • An inhouse developed LabVIEW R software for acquiring images and forces values from the test machine. • Sony XCG-5005E (5 Megapixels) camera with 2448 × 2048 pixels resolution. • Origin Pro R software for smoothing, filtering, and averaging the plots.

Data format
Raw Analyzed Filtered Description of data collection Avizo R software was used to reconstruct the micro-computed tomography images and analyse the void parameters of all adhesive materials. The storage modulus, tan delta and the glass transition temperature were identified by TA universal analysis R . The corresponding plots were plotted with Origin Pro R software. The average curves of multiple specimens with standard deviation were also realised with Origin Pro R software. The engineering stress and strain values were obtained through DIC analysis. From these values, the true stress and strain were calculated and smoothened using Origin Pro R software.

Value of the Data
• The effect of machine and manual-mixed manufacturing methods on the adhesive material properties are quantified with the presented data. • The adhesive toughening effect on the material properties is determined. Also, the relationship between tensile and shear properties is deducted. • An appropriate adhesive failure criterion can be developed with the available data.
• Data could be used to predict the thick adhesive joint/structure behavior using suitable finite element models.

Data Description
This article describes the raw, processed and analyzed data on the effect of manufacturing and toughening effect on the material properties of wind turbine blade adhesives. Herein, the data collection process and experimental data of each specimen of different adhesive materials groups are presented whereas the conclusive results are found in [1] . The plots ( Figs. 1-21 ) can be replicated using the published Mendeley data [2] . Table 1 provides the figure and table captions and their associated data file ( Tables 2 -28 ).

Materials
Recent growth in wind energy requires new adhesive materials to accelerate the wind turbine blade production rate. Rapid curing non-toughened and toughened epoxy adhesives are typically used for bonding the wind turbine blade components. SPABOND TM 820HTA (non-toughened) and SPABOND TM 840HTA (toughened) adhesives were hybridized and manufactured by two different mixing techniques. The machine and manual mixing techniques are described as M1 and M2, respectively. The pristine and hybrid adhesive compositions are mentioned in Table 29 . SP refers Spabond adhesive.

Manufacturing
The epoxy adhesive base and hardener material were weighed at a ratio of 100:33 and machine-mixed, as practiced by the wind turbine blade manufacturers. As shown in Fig. 22 , the mixed adhesive was dispensed on the bottom glass plate. The top glass plate was used to distribute the adhesive uniformly. These M1 adhesive panels were fabricated and provided by Gurit (UK) Ltd. The weighed adhesive base and hardener were manually mixed by using wooden spatula for 5-7 min . The M2, hand-mixing process introduced air bubbles that were partially removed by vacuum degassing for 7 min at a vacumm pressure of 0.95 bar. Due to the high viscous nature of adhesive, the air bubbles could not be eliminated. As depicted in Fig. 23 , an aluminum plate having side bars of 4 mm thickness was coated twice with a mold release agent, Sika R liquid wax-815 using a brush. The mold set up was dried for 15 ±5 min at the ambient temperature (20 °C ± 2 °C). The mixed adhesive was applied inside the mold cavity carefully using the adhesive spreader. Finally, the remaining adhesive were removed using a scraper.   Following the curing procedure, the DMA, tensile, V-notch and SENB test specimens were cut to the required dimensions using wate-jet cutting machine.

Experimental methods
The experimental set up details of micro CT scan, DMA, tensile, V-notch and SENB experiments are provided in Table 30, 31, 32, 33 and 34 , respectively. The force values from the test machine and the corresponding images from camera were collected by the Labview R software ( Fig. 25 ). The same frequency of 0.5 Hz (SENB) or 1 Hz (tensile and V-notch shear) used for the data acquisition. Further, the images were analysed by VIC2D 6 software to determine the engineering strain (tensile and V-notch shear) and deflection (SENB). The strain/delection values were matched with the recorded load values. Further the material properties were analysed with Matlab R2021b R software.

Ethics Statement
This work did not involve human subjects, animal experiments, or data collected from social media platforms.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability
Hybrid epoxy adhesive properties for wind turbine blade applications (Original data) (Mendeley Data).