附着力

Abstract(#br)In nanoindentation tests for soft polymers, the elastic modulus estimated from the Hertz model varies with applied force, implying the effect of adhesion work needs to be considered in contact theory. In this article, a hybrid method of combining the Hertz model and the Johnson–Kendall–Roberts (JKR) model is presented, to analytically explain the descending phenomenon of the modulus estimation by considering adhesive effects.

Abstract(#br)Adhesion tests were performed on single macroscopic pillars as model systems for artificial gecko surfaces. Polydimethylsiloxane macropillars with 400\u003cce:hsp sp=\"0.25\"/\u003eμm diameter and aspect ratios ranging from 1 to 5 were fabricated. The tip geometries were modified to achieve spherical, flat and mushroom shaped tips. Unlike spherical tips, flat tip pillars exhibited a strong angle dependency of the pull-off force. For mushroom shaped tips the pull-off force was tilt angle dependent only for low preload, where no complete tip contact was formed.

Abstract(#br)The objective of this work is enhancing the clearcoat resistance against simulated tree gum (Arabic gum) using surface active additives including hydroxyl-functional polydimethyl siloxane (PDMS) and hydroxyl-functional silicone polyacrylate which are able to reduce gum adhesion to the clearcoat surface by reducing its surface free energy and work of adhesion. Using a contact angle measuring device, the surface free energy, contact angle and work of adhesion were obtained.

Abstract(#br)Surface treatment of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) fibers was conducted with coupling agents such as epoxy silane, amino silane, and titanate to improve the adhesion characteristics of PVDF-HFP fibers and polydimethylsiloxane (PDMS). The adhesion strength was largest when 4\u003cce:hsp sp=\"0.25\"/\u003ewt% amino silane was used for surface treatment, showing a 250% improvement compared to the untreated case.

Abstract(#br)Polydimethylsiloxane (PDMS) film was treated with RF low-pressure plasmas (LPPs) made of mixtures of oxygen and argon for increasing surface polarity, minimizing hydrophobic recovery (i.e. retard ageing) and increasing adhesion to acrylic adhesive tape for medical use. Statistical design of experiments has been used for determining the most influencing experimental parameters of the LPP treatment of PDMS. Water contact angle values (measured 24\u003cce:hsp sp=\"0.25\"/\u003eh after treatment) and the O/C ratio obtained from XPS experiments were used as response variables.

Abstract(#br)An active navigation of self-propelled miniaturized robot along the intestinal tract without injuring the soft tissue remains a challenge as yet. Particularly in this case an effective control of the interfacial friction and adhesion between the material used and the soft tissue is crucial. In the present study, we investigated the frictional and adhesive properties between polydimethylsiloxane (PDMS, microscopically patterned with micro-pillar arrays and non-patterned with a flat surface) and rabbit small intestinal tract using a universal material tester.

Abstract(#br)Micropatterned polymer surfaces that operate at various temperatures are required for emerging technical applications such as handling of objects or space debris. As the mechanical properties of polymers can vary significantly with temperature, adhesion performance can exhibit large variability.

Abstract(#br)Because of the wide practical applications of soft materials, the surface contact and adhesive behaviors need to be comprehensively understood. Here, we systematically investigated the effect of bulk viscoelasticity and surface wetting on the dynamic behavior of contact and adhesion of soft polydimethylsiloxane (PDMS) surfaces.