PSI - Issue 45

Kentaro Yamauchi et al. / Procedia Structural Integrity 45 (2023) 125–131 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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adherends with the region of γs less than 20 mN/m. The aim of this study was to investigate the existence of the linear relationship in the region of γs less than 20 mN/m. The linear relationship was investigated for the case wherein the epoxy resin adhesive was diluted. The lack of data reported for the region of γs less than 20 mN/m can be mainly attributed to the difficulty associated with the preparation of low γs adherends. In this study, a low γs adherend was prepared by coating the adherend with a low γs layer such as a polytetrafluoroethylene (PTFE) particle dispersion layer. Using the low γs layer coated adherend, the behavior of the adhesion strength in the low γs region was studied. With respect to adhesion, various types of mechanisms were previously proposed, such as the mechanical bond theory by McBain et al. (1925), the intermolecular force theory by Browne (1927), the electrostatic theory by Deryagin et al. (1978), the diffusion theory by Voyutskii (1963), and the acid-base theory by Fowkes (1972) and Bolger et al. (1968) and so on. This study was conducted on the basis of the intermolecular force, which is the origin of the surface free energy. 2. Materials and methods 2.1. Sample preparation The low surface free energy adherend was prepared by coating the PTFE particle dispersed composite (HIREC 1100) manufactured by NTT-AT on a metal plate (Steel Plate Cold Commercial steel; SPCC). The other types of coated adherend are listed in Table l alongside common polymer adherends.

Table 1. Adherends for adhesion strength test.

Adherend

Specification HIREC1100

Manufactured NTT-AT (2022)

PTFE dispersion composite coated

Fluorine resin coated Silicone resin coated Silicone resin coated Polytetrafluoroethylene

INT333 KR400

Noda screen (2022)

Shin-Etsu Silicone KR400 (2022) Shin-Etsu Silicone KR4000G (2022)

KR4000G

PTFE-

Standard Test Piece (2022) Standard Test Piece (2022) Standard Test Piece (2022)

Polyethylene

PE

Polyethylene terephthalate

PET

Cemedine High Super 5 manufactured by Cemedine (2022) was used as the epoxy resin adhesive. Epoxy resin adhesives diluted by egg white were prepared. The amounts of egg white added to the epoxy resin were 10 vol.%, 20 vol.%, 40 vol.%, and 50 vol.%. The epoxy resin diluted by 40 vol.% egg white is shown in Fig. 1.

Fig. 1. The epoxy resin diluted by 40 vol.% egg white.