Inherent viscosities during processing

Table 7. Typical Progression of Inherent Viscosities During Processing of a Folyazonethine ...

An inherent assumption when using the above dynamic techniques is that the complex viscosity gives a good representation of the steady-shear viscosity during the curing reaction. This has been validated for many systems. However, care should be taken when relating the effects of cure on complex viscosity to the processing viscosity in other words the Cox Merz rule or a similar relationship must be validated. 

About the process of enzymatic destmction was judged by the falling of the intrinsic viscosity [t ] of CHT. The intrinsic viscosity in a solution of acetic acid was determined at 25 C, using the method of Irzhak and Baranov [1], To determine the initial values of the intrinsic viscosity of CHT solution [t ] was used at a concentration of c = 0.15 g/dL. To determine the values of intrinsic viscosity during the enzymatic digestion [t]], CHT dissolved in acetic acid to which was added a solution of the enzyme preparation maintained for a certain time. Then, a process of enzymatic destmction was quenched by boiling the original solution for 30 min in a water bath. Next, from the initial concentration of the solution c, a solution to determine the inherent viscosity at a concentration of c = 0.15 g/dL was made. The process of enzymatic destmction was performed at 36"C. 

The three-dimensional displacements inherent to NIL require resist materials that easily deform under an applied pressure and/or elevated temperature. These resists must have a low viscosity during imprinting, a Young s modulus less than that of the mold, and a low sheer modulus. It should also be mentioned that the resist material should have excellent adhesion to the substrate, provide high-quality, uniform film thickness through deposition via spin-coating, and have sufficient thermal and mechanical properties for subsequent processes. When determining the type of NIL resist to use, one should consider the critical dimensions of the pattern, pattern density, release properties from the mold, required imprint temperature and pressure, etch selectivity for subsequent pattern transfer, and route to eventual removal by dissolution or other processes. 

Step coverage — From the process flow schematics shown previously, it is apparent that printed transistors inherently have substantial topology within their cross-sectional structure. As a consequence, step coverage becomes an important parameter in process optimization. Given the large steps (typically several tens of nm or more) and the use of relatively thin subsequent layers, it is important that the layers cover each other adequately liquids must be able to coat the vertical sidewaUs of steps during a multilayer print process. This places constraints on fluid viscosity, evaporation rate, wetting, etc. 

As stated above, conventional synthetic fibres may be rendered inherently flame retardant during production by either incorporation of a flame retardant additive in the polymer melt or solution prior to extrusion or by copolymeric modification before, during, or immediately after processing into filaments or staple fibres. Major problems of compatibility, especially at the high tanperatures used to extrude melt-extruded fibres like polyamide, polyester, and polypropylene and in reactive polymer solutions such as viscose dope and acrylic solutions, have ensured that only a few such fibres are commercially available. A major problem in developing successful inherently flame retardant fibres based on conventional fibre chemistries is that any modification, if present at a concentration much above 10wt% (whether as additive or comonomer), may seriously reduce tensile properties as well as the other desirable textile properties of dyeability, lustre and appearance, and handle, to mention but a few. 

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