# Strength and Ultrasonic Testing of Acrylic Foam Adhesive Tape
## 1 Introduction
It was discovered that mechanical fasteners created punctures in the waterproof layer of the roof, while ballasted footing fasteners added significant additional weight to the roof support structure. Therefore, adhesive bonding emerged as a favorable alternative. Acrylic adhesive tapes, specifically VHBTM tapes, offer sufficient strength without the need for mechanical fasteners or ballasts. These tapes also facilitate a convenient, fast, and efficient bonding process, as they do not require curing, unlike liquid adhesives. However, the water resistance of load-bearing joints has not been sufficiently studied and may be crucial for joints exposed to external environments. This study aims to determine the water resistance and durability of GPH-series VHBTM tapes, which are commonly used to bond various substrates, including many metals. The mechanical properties and failure modes of the samples were compared before and after a 21-day immersion in water. A significant decrease in strength was observed depending on the substrate material. Examination of the chemical changes in the acrylic tape and its leachate by means of infrared spectroscopy (FT-IR), X-ray fluorescence, and X-ray diffraction analysis explained the reduction in mechanical properties. The selected VHBTM tape showed high water resistance. However, the overall bond strength after immersion was significantly affected by a decrease in adhesion to the specified substrate. The water resistance of the acrylic adhesive tape GPH-110 GF was investigated to quantify the reduction in bond strength when water was applied to the adhesive bond. The tensile samples showed an average tensile strength of 0.13 MPa for the longitudinal system and 0.19 MPa for the longitudinal system. The average shear strength of the reference joint was determined to be 0.47 MPa for all tested substrates and 0.30 MPa for all tested substrates after immersion. Chemical analyses showed only minor changes in the chemical structure of the adhesive. After shear strength and shear modulus reduction analyses, it was shown that the smooth-surfaced samples had reduced shear strength by more than 39% due to poor interfacing between the adhesive tape and the substrate. Tapes are also used in construction, and research has also been conducted in this area. The purpose of the work [21] was to evaluate the airtightness of various building surfaces and adhesive tape systems by carrying out artificial aging. It was found that self-adhesive tapes based on acrylic adhesive provide full system tightness. In all cases, tapes applied to surfaces such as plywood, gypsum board, cement board, plastered cement board, and plastic board provided sufficient sealing. The non-destructive evaluation of adhesive joints, especially those used in automotive applications, is a significant concern. By the end of the last century, [PERSON] [22] had proposed various non-destructive methods for assessing adhesive joints. According to his research, the ultrasonic method provides a fairly good understanding of the properties of an adhesive joint. The quality of adhesive joints, examined using non-destructive methods, was also studied in [23]. In this study, three different composite-adhesive joints were examined. An immersion ultrasonic method and induction thermography were used. The researchers increased the efficiency of defect localization by using data fusion. The induction thermography method is very good at detecting defects related to current conduction. However, it cannot detect defects through which no current is flowing. Ultrasonic testing is far better at detecting inclusions of release film. Brass inclusions are more effectively detected by induction thermography. Different variants of bonded materials have been studied. In one study [24], the effect of adhesive distribution across the overlap area in bonded joints was examined. Incorrect adhesive application during manufacturing can lead to improper adhesive distribution.