synopsisStudies on t,he peel behavior of pressuresensitive tape comprising a polyester backing and polyacrylate adhesive have shown that, in peeling from a plane glass surface, three fundamentally different modes of peeling may be distinguished, depending upon the rate of pulling. At low rates, deformation by flow of the adhesive appears to determine the peel behavior and the peel force is strongly rate dependent. At high rates, little or no viscous deformation of the adhesive occurs and the peel force is independent of rate. At intermediate pulling rates, cyclical instability of mode of failure involving alternate storage and dissipation of elastic energy in the backing, results in the phenomenon of "slipstick" peeling, in which failure is jerky and regular. Results have been obtained which show how the pulling rates a t which transitions from one mode of peel to another occur, and the peel force values for a given type of failure, depend upon such factors as molecular weight of adhesive, thickness of adhesive, thickness of backing film, and angle of peeling.

No abstract

No abstract

Polymers have the obvious advantages of flexibility in design and cost effectiveness to fabricate a lab-on-a-chip (LOC) device. Polyether ether ketone (PEEK) in particular is very attractive choice as it adds biocompatibility in addition to the possibility of hematic sealing in a 3D design. Hereby, we extend our previous successful technology of autohesive hermetic bonding of medical implants into lab-on-a-chip devices. We explore a conceptual 3D micro channels design with hermetic potential using PEEK and PS sheets. A hermetic and mechanically strong (through tensile test) 3D multilayer device was obtained using plasma treatment with oxygen and methane as precursors followed by pressing at temperature near of Tg + 20 of the polymer with the lowest Tg (PS). This nanotexturing technique is also used to facilitate thermal and mechanical stability of the microchannels for microfluidic applications. X-ray tomography measurements showed that 3D polymer made chips, at certain plasma and press bonding conditions, have structural integrity and no deformation were detected in channels shape post thermal pressing process. The dimension stability of channels and reservoirs and the rigid interfacial region at PEEK-PS make this chip design attractive and feasible for advanced lab-on-a-chip applications.

No abstract