Rubber-modified polyamide

Muratoglu, O. K., Argon, A. S., Cohen, R. E., and Weinberg, M. (1995a) Toughening mechanism of rubber-modified polyamides, Polymer, 36, 921-930. 

Gonzalez, L, Eguiazabal, J. L, and Nazabal, J. 2005. Compatibilization level effects on the structure and mechanical properties of rubber-modified polyamide-6/clay nanocomposites. Journal of Polymer Science Part B-Polymer Physics 43 3611-3620. 

Muratoglu O K, Argon A S, Cohen R E and Weinberg M (1995) Ibugheiiiiig mechanism of rubber-modified polyamides. Polymer 36 921-930. 

The outstanding impact toughness of the commercial impact modified polyamides is attributed to the small particle size of rubber dispersion and their good degree of adhesion to the polyamide matrix. Typical morphologies of compatibilized polyamide/elastomer blends are shown in Figure... 

At lesser rubber levels, heavy duty solventless coatings models based on dlethylenetrlamlne or fatty polyamide cures, showed elastomer-modification (10 phr rubber level) to advantage in Gardner impact, mandrel bend and corrosion-resistance testing (41). Impact testing (direct and reverse) gave 110 and 60 in-lbs, respectively for the rubber-modified fatty polyamide cured epoxy coating (14 days at R.T.), whereas a control formulation tested 10 in-lbs in each mode. 

One can rationalize a need for small rubber inclusions in some of the newer approaches to waterborne and high solids epoxy coating systems. Water-thinned epoxy coating compositions are described (48) where the two-component system consists of a nitrile rubber modified epoxy resin in the epoxide component and a styrene/ butadiene/methylmethacrylate latex modifier for an emulsion-based polyamide hardener component. Showing improved adhesion, impact and water resistance, the paint has good wetting characteristics and can be formulated to a high solids content at low viscosity. 

The main engineering polymers are polyamides (nylon 6,6 and 6), polycarbonates (bisphenol A-derived), polyphenylene oxides (PS-modified), acetals, polyesters (PETP and poly butylene terephthalate) and polyfluorocar-bons (mainly PTFE). Together with the synthetic elastomers and rubber-modified thermosets they make up the bulk of added-value products. 

Figure 16.28 Thermal energy required to heat thermoformable amorphous and crystalline polymers to their respective forming temperatures. HOPE, High density polyethylene at 960 kg/m MDPE, Medium-density polyethylene at 945 kg/m LDPE, Low-density polyethylene at 920 kg/m POM,- Polyoxymethylene PA-6, Polycaprolactam or polyamide PP, Homopolymer polypropylene, PS, General purpose polystyrene MIPS, Medium-impact or rubber-modified polystyrene ABS, Polyacrylonitrile-polybutadiene-polystyrene terpolymer PMMA, Polymethylmethacrylate FPVC, Flexible polyvinyl chloride RPVC, Rigid polyvinyl chloride.

Commercial ABS/PA blends compete for the same type of applications as the impact modified polyamides. Presumably due to their lower heat resistance and slightly inferior low-temperature notched Izod impact strengths, their applications have been somewhat limited compared to those of rubber toughened polyamides. However, ABS/PA blends exhibit better processability, faster cycle times due to faster set up, and easier ejectability of the parts fi om the mold (higher modulus at mold temperature). In addition, the higher dimensional stability and the lower warpage of ABS/PA blend compared to the impact modified polyamides may be useful in some electronic applications. 

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