PSI - Issue 13

Mark Kopietz et al. / Procedia Structural Integrity 13 (2018) 143–148 Kopietz et al. / Structural Integrity Procedia 00 (2018) 000 – 000

145

3

Table 1. List of used chemicals

Viscosity η

Density ρ [g/cm³]

Comp.

Name

Chemical nature

Purchased from

[mPa·s]

A

PI-Liner 3P Komp. A

~50 wt% aqueous sodium silicate solution with Na 2 O/SiO 2 ratio of 1:>1.6 - 2.6

600

1.55

Polinvent Ltd. (Gyál, Hungary) Polinvent Ltd. (Gyál, Hungary)

B (3P)

PI-Liner 3P W1 Komp. B

PMDI / TCPP / IPPP

310-370

1.24-1.26

4,4’ -diphenylmethane diisocyanate in a mixture with higher functionalized prepolymers (PMDI) Epoxidized linseed oil (ELO)

B (2P)

Ongronat® 2500

520-680

1.24

Borsodchem Zrt. (Kazincbarcika, Hungary) Akcros Chemicals Ltd. (Manchester, United Kingdom) BASF SE (Ludwigshafen, Germany)

Lankroflex™ L

1,300

1.03

Efka® WE 3110

Ethoxylated long chain alcohol in water

300

0.99

The ECR Glass fiber woven fabric mats with stitched tangled fibers and an area density of 1,050 g/m² were obtained from Fluvius GmbH (Düsseldorf, Germany). The mats were hand-impregnated using a resin amount of 1.6 l/m². After impregnation the laminates were folded to two-layers with tangled fiber layers on the outside. Subsequently, they were placed in a steel pressing tool (20 x 20 cm²) and cured under a pressure of 3 bar for 1 h at 25 °C in a Collin P 300 P/M hot press. After demolding the samples they were post-cured under ambient conditions without pressure. From the resulting plates specimens were cut by saw to gain 20 x 10 mm² sized and 3 mm thick samples for further testing. 2.2. Methods Cut samples were put into different solutions 2 days after preparing. The storage was performed in two separated runs, where deionized water (H 2 O) was chosen in the first run and hydrochloric acid (HCl) and sodium hydroxyl (NaOH) solutions (each 1 molar) in the second run. At various times samples were removed for short-beam shear (SBS) and gravimetric tests. Short beam shear (SBS) tests were performed according to DIN 2377. These tests were carried out on a Zwick/Roell Type 1445 universal testing machine. The gap was set to l v = 5∙ h = 15 mm, and all the tests were performed with a deformation rate of 1 mm/min. The interlaminar shear strength (ILSS) τ [MPa] was calculated by evaluating the maximum force F max [N] at initial crack as well as sample width b and height h [mm] after eq. 4: Gravimetric analysis was done with a weighing scale and the mass difference Δ m [mg] to the initial weight was calculated after eq. 5. ∆ m = m sample − m sample,initial (5) 3. Results and Discussion The overall stability of fiber reinforced composites (FRC) is generally dominated by a decent fiber/matrix adhesion, where the interlaminar shear strength τ (ILSS) served as an indicator. In consequence of the capillary action of the penetrating media the bonding between fibers and matrix and the load transfer may alter. 3.1. Impact of media on the interlaminar shear strength Media storage was performed in two separated runs where the ILSS of stored samples was determined over time compared to the ILSS of the non-stored samples (Air). In the first run deionized water (H 2 O) was used (Fig. 1, left), in the second run aqueous hydrochloric acid (HCl) and sodium hydroxide (NaOH) solutions, each 1 molar (Fig. 1, right). τ = 3 4 ∙ F b ∙ h (4)