Blending interphase

Functionalized Polyolefins and Aliphatic Polyamide Blends Interphase Interactions, Rheology, and High Elastic Properties of Melts... 

Theoretical Polymer Blend Interphase Thickness The structure and composition profile of polymer blend interphases is of current interest because (a) greater degrees of interfacial mixing between components in a binary mixture usually increases the mechanical strength of the material, and (b) observation of the degree of interfacial mixing at a model interface as a... 

CONFORMATION OF POLYMER CHAINS IN A POLYMER BLEND INTERPHASE... 

By definition, the free energy of mixing of a polymer blend interphase is positive, or else molecular mixing would continue to completion, and at equilibrium the interphase would vanish. Helfand and Tagami (10,11) developed a mean-field theory of polymer interfaces, or interphases, as they are now called. They were particularly interested in the equilibrium composition and interphase density across the interphase, the interfacial tension and thickness (see Section 12.3.7.2), and conformation of the polymer chains making up the interphase. 

Figure 12.19 An immiscible polymer blend interphase region. The central portions of the chains have a slight tendency to lie parallel to the nominal interface, while the chain ends tend to lie perpendicular.

A method for fabrication of films with thousands of alternating layers produced by layer multiplying coextrusion has been described, where the individual layers can approach the thickness of the blend interphase region [1142]. This method applied to PMMA/PC blends allowed thin PMMA nanolayers (> 5 nm) positioned between thicker PC layers. For PMMA layers > 12 nm, the interphase thickness was constant and equal to 12 nm. Oxygen permeability measurements... 

CompatibUization modifies the immiscible polymer blend interphase, reducing the interfacial energy and stabilizing the blend morphology. 

Silane coupling agents may contribute hydrophilic properties to the interface, especially when amino functional silanes, such as epoxies and urethane silanes, are used as primers for reactive polymers. The primer may supply much more amine functionality than can possibly react with the resin at the interphase. Those amines that could not react are hydrophilic and, therefore, responsible for the poor water resistance of bonds. An effective way to use hydrophilic silanes is to blend them with hydrophobic silanes such as phenyltrimethoxysilane. Mixed siloxane primers also have an improved thermal stability, which is typical for aromatic silicones [42]. 

The important yet unexpected result is that in NR-s-SBR (solution) blends, carbon black preferably locates in the interphase, especially when the rubber-filler interaction is similar for both polymers. In this case, the carbon black volume fraction is 0.6 for the interphase, 0.24 for s-SBR phase, and only 0.09 in the NR phase. The higher amount in SBR phase could be due to the presence of aromatic structure both in the black and the rubber. Further, carbon black is less compatible with NR-cE-1,4 BR blend than NR-s-SBR blend because of the crystallization tendency of the former blend. There is a preferential partition of carbon black in favor of cis-1,4 BR, a significant lower partition coefficient compared to NR-s-SBR. Further, it was observed that the partition coefficient decreases with increased filler loading. In the EPDM-BR blend, the partition coefficient is as large as 3 in favor of BR. 

It was concluded that the filler partition and the contribution of the interphase thickness in mbber blends can be quantitatively estimated by dynamic mechanical analysis and good fitting results can be obtained by using modified spline fit functions. The volume fraction and thickness of the interphase decrease in accordance with the intensity of intermolecular interaction. 

Source Schuster, R.H., Meier, J., and Kluppel, M., The Role of Interphase in Filler Partition in Rubber Blends, 156th Meeting of the Rubber Division, American Chemical Society, Orlando, FL, 1999, Paper No. 60. 

Examination of the fracture by SEM shows that although there is no interphase adhesion in uncompatibilized blends, adhesion between the phases increased and dispersed domains decreased... 

The mechanical properties of the blend of silane/size and bulk epoxy matrix (at concentrations representing likely compositions found at the fiber-matrix interface region) also suggest that the interaction of size with epoxy produces an interphase which is completely different to the bulk matrix material (Al-Moussawi et al., 1993). The interphase material tends to have a lower glass transition temperature, Tg, higher modulus and tensile strength and lower fracture toughness than the bulk matrix. Fig. 5.4 (Drown et al., 1991) presents a plot of Tg versus the amount of... 

Process of modification of the interfacial properties in an immiscible polymer blend that results in formation of the interphases and stabilization of the morphology, leading to the creation of a compatible polymer blend. 

The interphase between the continuous and the discontinuous polymer phases differs with respect to blend preparations. Solution-cast blends produce inclusions that are pulled away from the matrix, whereas injection-molded blends show HPL striations that are closely associated with the matrix. 

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