Elastomers dispersions

Low, B.Y., Anderson, K.L., Vincent, M.. Gardener, S.D., Pittman, C.U. and Hacketl, R.M. (1995a). Toughened carbon fiber/epoxy composites the relative influence of an elastomer interpha.se and elastomer dispersed in the matrix. Composites Eng. 5, 437-457. 

Fluoro-elastomers dispersed in a resin, e.g., PI, PAI, PSF, PEI, PES, PEEK, PPS, PPE, etc. moldings flexible, elastic, self-lubricating, having excellent chemical and thermal resistance Movak et al., 1994... 

Increasing the crosslink density of the elastomer dispersion results in improvements of the strength and tension set of the blend. The difference between the earlier commercial grades of partially cured EPDM/PP blends (TPR, Uniroyal) and the more recent commercial grades of completely cured EPDM/PP blend is in the improved elastomeric properties, viz. reduced compression and tension set and improved flexural fatigue. More important, the chemical resistance and resistance to oil swelhng is improved. Typical properties of commercial dynamically vulcanized EPDM/PP blend (Santoprene ) are shown in Table 15.13. 

Although the dynamically vulcanized blends such as EPDM/PP (Santoprene ) and NBR/PP (Geolast ) have sometimes been referred in the literature as semi-IPNs, we considered them as blends of crosslinked elastomer dispersions in a thermoplastic matrix and as such treated them under the elastomer blends. There is yet another class of thermoplastic/thermoset blend system in which a minor amount of the crosslinkable monomer(s) is allowed to polymerize in the thermoplastic matrix forming a loose network. 

The PIB macroinitiators can also initiate living anionic polymerization of a wide variety of functional monomers, such as vinyl pyridine, N,N-dimethylacryl-amide, and a variety of protected monomers, such as silylated 2-hydroxyethyl methacrylate. Polymerization studies with these monomers are in progress. The resulting products are potential new thermoplastic elastomers, dispersing agents, blending compounds, emulsifiers, non-ionic surfactants, biomaterials etc. 

Chem. Desaip. Poiydimethyisiioxane elastomer dispersed in a odorless hydrocarbon... 

Polymer blends may be defined as intimate mixtures of two kinds of polymers, with no covalent bonds between them. Historically, the oldest and simplest method involves mechanical blending, where a plastic and a noncrosslinked elastomer are blended either on open rolls or through extruders (Matsuo, 1968). Materials prepared in this manner usually contain several percent of elastomer dispersed in a plastic matrix, as shown schematically in Figure 2.1. 

Uses Dispersant, protective colloid, stabilizer of nat. and syn. elastomers dispersant, suspending agent, stabilizer for latexes, pesticides pigment grinding aid for paints wetting agent for cotton and rayon plasticizer for mortar and concrete Trade Name Synonyms Rhodacal RM/77-D... 

Odler, L, and Liang, L. (1992) Physico-mechanical properties of cementitious systems modified by elastomer dispersions, in Proceedings 7th International Congress on Polymers in Concrete, Moscow, pp. 201-212. 

The specific composition of the TPO blend produced depends on the balance of flexural modulus (stiffness) and impact toughness (drop impact and notched Izod) properties needed to meet the target performance specifications. In the formulation of TPO blends, the polypropylene is used normally as the major component, i.e., as the matrix phase, to provide the needed rigidity and thermal stability, while the elastomer dispersion provides the low-temperature impact toughness. A minor amount of a mineral filler such as talc provides additional stiffness and dimensional stability to the TPO. Hence, the levels of elastomer and mineral filler modifiers are carefully adjusted to achieve the desired balance of properties in the TPO. 

Surprisingly, it is possible to make two different 50/50 blends of plastics and elastomers and obtain very nearly both of the results predicted by the above examples. This depends on the morphology, and particularly on phase continuity see Figure 4.3. When the plastic phase is continuous in space and the elastomer dispersed (Figure 10.6a), the material will be stiff, and substantially exhibit upper bound behavior. On the other hand, when the elastomer is continuous and the plastic discontinuous (Figure 10.66), a much softer material results and a lower bound situation prevails. The rubber phase is much more obviously discontinuous in the models represented in Figures 10.6c and 10.6d. 

Compounding of soluble elastomers, dispersions, and liquid components is described in detail in [255, pp. 23-61]. 

Epoxies have been toughened with elastomer-dispersed phases with a decrease in modulus. Work by Balakrishnan et al. [35] utilized organo-montmorillonite as a dispersed phase in elastomer-toughened epoxies to recover this lost modulus. The montmorillonite was modified with octadecyl ammonium ion. The elastomer-dispersed phase in the epoxy was prepared by free radical polymerization of acrylic monomer within the epoxy. The acrylic elastomer-dispersed phase had epoxy functionality provided through the utilization of glycidyl methacrylate as a comonomer. 

The morphology of the composites were carefully analyzed by WAXS and TEM for the montmorillonite and AFM for the elastomer-dispersed phase. The additional mechanical property that was measured in this work was the CTE with the same equipment, TMA 7, and protocol that was employed in the second article in this series (see above). 

Chem. Descrip. Tallow and coconut fatty acid salts Uses Lubricant, process aid for all elastomers dispersant, pigment wetting agent for better disp. in mixing improves release from processing equip. improves compd. flow... 

The somewhat finer elastomer dispersion for TPO B may be the result of its lower viscosity ratio. Despite this... 

Since temperature had the most significant effect on TPO A morphology, TPO B was only molded at one low temperature and one high temperature condition set (Table 2 Conditions 3 and 5 Figures 2 and 3). Even though TPO B was molded under appreciably different conditions, there was no significant change in its elastomer dispersion. 

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