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International Journal of Adhesion and Adhesives
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Item type:Publication, An in vitro bone-to-bone adhesion test method using the compression shear test(Elsevier, 2021-12); ; ; ; The development of new bone adhesives is severely restricted due to the lack of a standard test method to examine their bond strength. Therefore, this study presents an in vitro bone-to-bone adhesion test method based on a compression shear test using cortical bone specimens (35 × 15 × 3 mm). The zero-gap lap joint test configuration was used to measure the bonding strengths of two soft tissue adhesives (Histoacryl® and BSA-Glue) and a bone cement (Palacos® LV). For reproducible bonding results, it is crucial to work with specimen having reproducible surface, dimensions and where and how they were taken from a bone. Therefore, this is a focus of the work. The adhesive strengths were determined under dry and physiological conditions to evaluate the reliability of the test procedure. Furthermore, the influence of previous acid etching of the bone surface was also investigated. The adhesives achieved bond strengths of 5.5 MPa (Histoacryl®), 3.2 MPa (BSA-Glue) and 2.8 MPa (Palacos® LV) under dry conditions. Under physiological conditions, the measured adhesive strengths of all three bonding materials decreased by around 90%. The acid etching led to a higher presence of reactive amino groups on the bone surface and improved the adhesion of Histoacryl® and BSA-Glue. The Palacos® LV bone cement suffered a reduction in adhesion as the acid smoothened the bone surface, resulting in less mechanical interlocking. The proposed test method is based on known standards and enables the usability of medical adhesives as a bone adhesive to be evaluated in a reproducible manner.journal articleBand:11121 35 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Influence of high-temperature and high-humidity aging on the material and adhesive properties of addition curing silicone adhesives(Elsevier Science, 2021-09-01); ; ; Silicones are commonly used as sealants when high-performance materials are required due to harsh environmental conditions. To ensure a proper sealing function, the buildup of adhesion to the adherends is a prerequisite that is often addressed by the addition of adhesion promoters. However, the investigation of the fundamental adhesion mechanisms of silicones has been widely neglected. This work focuses on adhesive bond properties with aluminum adherends without the usage of adhesion promoters. The influence of high-temperature and high-humidity aging on the adhesive bond and material properties is examined. For this purpose, we formulated an addition curing silicone adhesive with a known composition. Aging took place for up to 56 d at different temperatures ranging from room temperature to 150 °C. In addition, we examined the influence of moisture by applying high-humidity conditions (85 °C/85% relative humidity). Changes in bulk material properties were characterized by stress at break, strain at break, Shore A hardness and swelling degree. Moreover, Fourier-transform infrared (FTIR) spectroscopy provided information about the chemical processes. The adhesive properties were determined using lap-shear joints. At high-temperature aging, the strain at break decreases while the hardness of the bulk material increases. A lower degree of swelling suggests an increasing cross-linking density. At the same time, lap-shear strengths increase and cohesive fracture patterns indicate a substantial buildup of adhesion. The samples aged under high-humidity conditions show a more complicated behavior. The increase in cross-linking density proceeds slower compared to high-temperature conditions (130 °C and 150 °C) but reaches higher values after 56 d. Lap-shear strengths tend to be lower compared to high-temperature storage and are accompanied by a significant amount of adhesive failure. FTIR spectroscopy reveals reactions of the residual hydrosiloxane groups of the cross-linking agent. However, these reactions are insufficient to fully explain the observed behavior. Therefore, reactions of the siloxane backbone are suggested. Although no specific adhesion promoters were used, high-temperature conditions enabled a substantial adhesion buildup of addition curing silicones on aluminum adherends under dry conditions. In contrast, humid conditions disturb adhesion buildup and are rather unfavorable for adhesion.journal article163 315