Rubber-modified polymers relationships

W. Heckmann, G.E. McKee, F. Ramsteiner, Structure-property relationship in rubber modified amorphous thermoplastic polymers, in Mechanical Properties of Polymers Based on Nano-Structure and Morphology, ed. by F.J. Balta-Calleja, G.H. Michler (Taylra- and Francis, London, 2005), pp. 429-479... 

New elastic polymeric materials (resistance to higher stroke or air) can be obtained by using physical modification methods, but using this method, two phases (PS and rubber) in the mixture were formed. Small rubber particles spread as a PS layer and, after awhile, the relationship between the layers decreases and rubber particles gather in the upper layer of the materials. This can be the cause of the loss of resistance of the materials. These material disadvantages have stimulated the polymer synthesis to increase the PS resistance to higher physico-mechanical properties, such as higher temperature and stroke for the chemical modification of PS with various functional modifiers. 

As explained earlier, most authors quote nominal mbber contents rather than mbber phase volumes, and there is therefore very little information in the literature on the relationship between Oyc and 0 for mbber-modified plastics. A rare exception occurs in the work of Oxborough and Bowden vdio measured yield stresses in tension and compression for a series of HIPS polymers ccmtaining composite rubber particles. Their results are presented in Fig. 7. Equation (9) underestimates the yield stresses both in tension and compression, and it must be concluded fiiat the effective area model does not provide a satisfactory basis for correlating yield data in this class of material. Either the model itself must be modified in some way, or some allowance must be made for load sharing with the mbber particles, if the effective area apprcrach is to be retained. 

The conunon polymers for plastics, rubbers and fibers have been produced at a large industrial scale. It appears difficult to modify them from the early stage of the preparation route. Currently, most of modificatimis either via physical methods or via chemical treatments are based on their structure—property relationships. The specific functimial polymers for coatings, adhesives, adsorption resins and filtration membranes occupy a relatively small market, and their modifications often start from monomer synthesis. 

Wong, S. W. and Mai, Y. W. 1999. Effect of rubber functionality on microstructures and fracture toughness of impact-modified nylon 6,6/pol5 ropylene blends 1. Structure-property relationships. Polymer 40 1553-1566. 

Miscellaneous Forces. Force measurements on polymer surfaces or between chemically modified SFM tips and polymer surfaces yielded important insight into fundamental force vs separation distance relationships for, eg, polymer colloidal particles (207), mechanochemical behavior of individual macromolecules (see section Entropic and Enthalpic Elasticity) (87-96,99), but also adhesion information directly relevant for practical applications, such as electrochemically controlled adhesion (208) or toner particle-rubber interactions relevant for xerographic applications (209,210). 

The polymers have a viscosity range from 0.5 cP for hexamethyldisiloxane to several million centipoise for gums used in silicone rubber manufacture. Molecular weight-viscosity relationships have been described earlier [48]. Copolymers have also been described using modified synthetic approaches [50,51]. 

Figure 7.8 [17] shows the relationship between the viscosity ratio of a polyamide-rubber binary blending system and the size of domain particles obtained by mixing and kneading with a twin screw extruder [16-18]. Generally, it is easier to obtain the fine domain size under conditions where the two melt viscosities are close. Furthermore, the domain size reduction easily occurs when the surface tension tt between each polymer particle is low, even if there exists a considerable melt-viscosity difference. This means that both the addition of a compatibilizer or interfacial copolymerization reactions result in lower surface tension and, consequently, the domain size reduction is effectively accelerated. To analyze the domain size in polyblending, the Weber Number Wg or the following modified... 

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