Polymer blend composition gradients

Fig. 13 Illustration of a method for producing polymer blend composition gradient libraries. A and B are the polymer solutions to be blended.

Eidelman, N. Characterization of combinatorial polymer blend composition gradients by FTIR microspectroscopy. J. Res. Natl. Inst. Stand. Technol. 109, 219-231 (2004)... 

Then the content of the syringe was dispensed in a strip on a glass slide and a doctor blade was used to spread the solution in the orthogonal direction. The phase behavior of the blend can be determined directly by visual inspection of the sample (Fig. 2, right). Similarly, it was also possible to create gradients in both polymer blend composition and film thickness by accelerating the movement of the doctor blade when spreading the blend solution [8]. 

Agari, Y, Shimada, M., Ueda, A. and Nagai, S. (1996) Preparation, characterization and properties of gradient polymer blends discussion of poly(vinyl chloride)/poly (methyl methacrylate) blend films containing a wide compositional gradient phase. Macromol. Chem. Phys., 197, 2017-2033. 

Region between phase domains in an immiscible polymer blend in which a gradient in composition exists [3]. 

Fig. 14 Creation of a single specimen polymer blend phase diagram from orthogonal polymer composition and temperature gradients. The polymers are polystyrene and poly(vinyl methyl ether) (PVME) a composition library placed orthogonal to a temperature gradient b completed gradient library polymer blend phase diagram. White points are data derived from traditional measurement for comparison. See text for details, (b reproduced with permission from [3])...

In flow the challenge has been to write convincing equations that couple concentration and composition gradients to elastic stresses and the bulk flow field. When done within a two-fluid model for polymer solutions transitions in light-scattering patterns seen in experiment may be explained. Extensions to polymer blends are potential candidates as explanations of shear-induced shifts of the spinodal and biphasic islands seen experimentally. - ... 

In addition to molecular weight, thermal FFF is used to measure transport coefficients. For example, the measurement of thermodiffusion coefficients is important for obtaining compositional information on polymer blends and copolymers (see the entry Thermal FFF of Polymers and Particles). Thermal FFF is also used in fundamental studies of thermodiffusion because it is a relatively fast and accurate method for obtaining the Soret coefficient, which is used to quantify the concentration of material in a temperature gradient. However, the accuracy of Soret and thermodiffusion coefficients obtained from thermal FFF experiments depends on properly accounting for several factors that involve temperature. In order to understand the effect of temperature on transport coefficients, as well as the effect on thermal FFF calibration equations, a brief outline of retention theory is given next. 

Cheng and English edited ACS symposium series which covers the solution and solid state NMR investigations for dendrimers, cellulose, polyurethane, polyolefins biopolymers, copolymers and so on. Spiess described a historical overview of role of NMR spectroscopy in polymer science. Newmark summarizes the two dimensional and pulsed gradient diffusion NMR experiments and their applications to polymers Shit et al. reviewed the analysis of polymer molecular weight and copolymer composition by NMR. Sasanuma summarized the the analysis of polyethers and polysulfides by NMR and theoretical calcula-tions Ardelean et al described the principle and its applications of diffusion studies by NMR. Roy et al summarized the structural analysis of Novolak resins by multidimensional NMR. Reviews about NMR study of surfactant polymer blends and the structural elucidation of supramocules are published. 

The sample must be representative of the material as a whole, and the lower limit of the sample mass may be determined by the homogeneity of the sample. This is especially true of composites and polymer blends, where frequently 10 mg of sample are required before a representative sample can be prepared. When a large amount of sample is to be analysed the heating rate should be decreased accordingly to compensate for the increased temperature gradients in the sample. 

The polymer-based miscible systems can be either intermolecular mixtures, for instance polymer solutions and blends, or intramolecular mixtures, such as block copolymers, star-shape multi-arm copolymers, grafted copolymers, random copolymers, and gradient copolymers with a composition gradient from one chain end to the other. Polymer-based miscible systems can phase separate into segregated phases with stable interfaces, or crystallize into crystalline ordered phases. In other words, there are two types of phase transitions, phase separation and crystallization. Under proper thermodynamic conditions, two phase transitions may occur simultaneously. The interplay of these two transitions will dictate the final morphology of the system. In the following, we will choose polymer solutions as typical examples to introduce the polymer-based miscible systems. 

Gradient block copolymer in which there is a gradual change of composition at the junction between the two blocks from pure AAAAAAAA type to pure BBBBBBBB type. The tapered block copolymers are reported to be more efficient than pure AB block copolymers as compatibilizers of polymer blends. Tapping cutting threads in the walls of a circular hole. 

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