Epoxy polymer particles

Hence, the stated above results have shown that melt viscosity extreme change of nanocomposites HDPE-EP could be described within the framework of the fractal model. The main structural parameter, controlling this effect, is the change of the fractal dimension of macromolecular coil in melt. The main physical cause, defining the mentioned effect, is a partial interaction of HDPE matrix and epoxy polymer particles. In this case the... 

Bauman, A.D., High-value engineering materials from scrap rubber. Rubber World, 212, 30, 1995. Bagheri, R., Wilbams, M.A., and Pearson, R.A., Use of surface modified recycled rubber particles for toughening of epoxy polymers, Polym. Eng. Sci., 37, 245, 1997. 

The residue produced from the 350°C run contained discernible resinite particles. In contrast, examination of the fluorescence of residues from the two 370° runs in blue light showed that little resinite was left undissolved other than that incorporated within a matrix of other macerals. Instead, a diffuse fluorescence had been imparted to the epoxy resin embedding medium. Presumably, the epoxy was able to dissolve some of the liquefied resin remaining after extraction with ethyl acetate. In the residue from the run at 400°C, only one discrete resinite particle was observed among the many coal particles embedded in the epoxy polymer. It appears that in a short time at 350°, most, but not all, of the resinite undergoes liquefaction. All other material in the sample needs considerably more severe treatment. 

Of the several types of the polymer-modified mortars and concretes used for various construction applications, latex-modified mortar and concrete are by far the most widely used materials. Latex-modified mortar and concrete are prepared by mixing a latex, either in a dispersed liquid or as a redispersible powder form with fresh cement mortar and concrete mixtures. The polymers are usually added to the mixing water just as other chemical admixtures, at a dosage of 5-20% by weight of cement. Polymer latexes are stable dispersions of very small (0.05-5 pm in diameter) polymer particles in water and are produced by emulsion polymerization. Natural rubber latex and epoxy latex are exceptions in that the former is tapped from rubber trees and the latter is produced by emulsifying an epoxy resin in water by the use of surfactants [87]. 

Fig. 13. Optical micrograph of fra-ture surface of glass-filled epoxy polymers showing the crack front pinned between glass particles 22) (Arrow indicates direction of crack growth)...

The theory has been examined by measuring the ratio K,c/Klcs as a function of j/g, as shown in Fig. 17. The theoretical lines have been fitted to the experimental points by choosing suitable values of the critical distance, c, which is the only fitting parameter. The agreement between theory and experiment has been found to be equally good for many different epoxy polymers cured with many different hardeners, both unmodified 44- 45,51), rubber-modified 45) and containing glass particles 22) and even, under certain circumstances, for structural adhesive joints S3). Values of critical stress, ct,c, and distance, c, for various epoxy materials, obtained from bulk and... 

The use of a convective macroporous polymer as an alternative support material instead of silica for the preparation of protein-based CSPs has successfully been demonstrated by Hofstetter et al. [221]. Enantioseparation was performed using a polymeric flow-through-type chromatographic support (POROS-EP, 20 pm polymer particles with epoxy functionalities) and covalently bound BSA as chiral SO. Using flow rates of up to 10 ml/min, rapid enantiomer separation of acidic compounds, including a variety of amino acid derivatives and drugs, could be achieved within a few minutes at medium efficiencies, typical for protein chiral stationary phases (Fig. 9.13). 

Bauman B D, Surface-modified Polymer Particles and Short, Chopped Fiber in Epoxies, SPI Conference, San Francisco, CA 1995. 

We have used this model to investigate stress distributions in and around the rubber particle, or around a void, in a matrix of epoxy polymer. This chapter describes the modeling of stress concentrations in rubber-toughened epoxy and gives a simple model for predicting the fracture energy, Gc, of such a material. 

The aforementioned analyses were essentially elastic in nature. However, Huang and Kinloch (7,8) developed a two-dimensional, plane-strain model to analyze the stress fields around the dispersed rubbery particles in multiphase, rubber-modified epoxy polymers. The epoxy matrix was modeled as either an elastic or elastic-plastic material. Their work revealed that the plane-strain model predicted higher stress concentrations within the glassy polymeric matrix than the axisymmetric model. Furthermore, they successfully applied their... 

Boy Boynton, M. J., Lee, A. Fracture of an epoxy polymer containing recycled elastomeric particles. Appl. Polym. Sci. 66 (1997) 271-277. 

Formation of weak boundary layers is confirmed by a study of the molecular mobility of filled epoxy polymers. The availabihty of the solid surface results in a decrease of the molecular mobihty in the boundary layer [21] as a result of limiting the conformation set and adsorption interactions of the polymer molecules with a solid body at the boundary. The nature of the filler surface has little effect on the molecular mobility of the epoxy polymer and on the change of mobility of its side-groups and segments. It has been concluded [21] that the primary role in the change of mobility is played by geometric limitation of the number of possible conformations of macromolecules close to the surface of the particles, i.e., by the entropy factor rather than by energetic interactions of the surfaces. 

Study of the morphological features of EEC indicate precipitation in the course of the epoxy resin cm"e of particles of the discrete phase of the rubber, the dispersion of which in the epoxy polymer matrix has a considerable effect on the mechanical properties of the latter. If the rubber particles are large enough, they can be detected by optical microscopy, but the most important results are obtained by electron microscopy. 

Hypotheses have been advanced to explain the increase of the impact strength of the epoxy resins by the integration of finely dispersed rubbers. There is an assumption [139] that the rubber particles in the epoxy polymer matrix absorb the impact energy in the manner of mechanical damping. In this case the dissipation of the excess energy occurs mainly inside the formed interphase layer with decreased density of the cohesion energy. In addition, to provide max-... 

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