Molecular weight commercial polymers

Polymerization-structure-properties. BCMO is polymerized by the cationic way in different inert solvents. Alkylaluminum compounds yield polymers of high molecular weight. Commercial polymers may reach molecular weights of 250,000-300,000. 

Formaldehyde f6r- mal-d9- hld, fer- [ISV form- + aldehyde] (1872) (formic aldehyde, methanal, oxymethylene) n. HCHO. A colorless gas with a pungent, suffocating odor, obtained most commonly by the oxidation of methanol or low-boiling petroleum gases such as methane, ethane, etc. The gas is difficult to handle, so it is sold commercially in the form of aqueous solutions (formalin), solvent solutions, as its oligomer, paraformaldehyde, and as the cyclic trimer, 1,3,5-trioxane (a-trioxym-ethyl-ene). High-molecular-weight, commercial polymers of formaldehyde are called poly-oxymethylene or acetal resin. Formaldehyde is also used in the production of other resins such as phenolic resin (phenol-formaldehyde) and amino resin (urea formaldehyde). Syn methylene oxide, methanal. See formalin. 

Molecular weights of polymers that function as bridging agents between particles are ca 10 —10. Ionic copolymers of acrylamide are the most significant commercially (see Acrylamide POLYMERS). Cationic comonomers include (2-methacryloyloxyethyl)trimethylammonium salts, diethyl aminoethyl methacrylate [105-16-8], and dimethyldiallylammonium chloride [7398-69-8], anionic comonomers include acryUc acid [79-10-7] and its salts. Both types of polyacrylamides, but especially the anionic, can be more effective in the presence of alum (10,11). Polyetbylenimine and vinylpyridine polymers, eg, po1y(1,2-dimethy1-5-viny1pyridiniiim methyl sulfa te) [27056-62-8] are effective but are used less frequentiy. 

Polystyrene [9003-53-6] (PS), the parent of the styrene plastics family, is a high molecular weight linear polymer which, for commercial uses, consists of - 1000 styrene units. Its chemical formula (1), where n = - 1000, tells htde of its properties. 

Unfortunately Nafion materials have not found commercial application as catalysts because of their extremely high cost. There were several attempts to use supported catalysts made by applying of low-molecular-weight Nafion polymer from solutions onto inert supports. However, such catalysts could only be used in very few reactions between nonpolar reagents in other cases the surface catalytic layer was easily washed away from the surface. 

Commercial poly(styrene) or narrow molecular weight distribution polymer with Mw > 50,000... 

SRM 705 is the narrow molecular-weight-distribution sample the other SRM 706, by contrast, is a broad molecular-weight-distribution polymer, the result of a thermal polymerization which more closely resembles commercially available polymers. Both of these were supplied by the Dow Chemical Co. (Certain commercial equipment, instruments, or materials are identified in this paper in order to specify adequately the experimental procedure. In no case does such identification imply recommendation or endorsement by the National Bureau of Standards, nor does it imply that the material or equipment identified is necessarily the best available for the purpose.)... 

The reaction with aromatic diamines is catalyzed by carboxylic acid and leads to high molecular weight linear polymers [43]. By controlling the molar ratio of the reactants this reaction has been used to produce low molecular weight pol-yaspartimides end-capped with maleimide (Fig. 11). Such types of oligomers called Kerimid were formerly commercialized by Rhone-Poulenc. 

The lower molecular weight LP-3, LP-33 and ZL-1400 C polymers are used as elastomeric modifiers, particularly for epoxy coatings and adhesives. Owing to their low molecular weight these polymers have the lowest viscosities of commercially available LPs. This low viscosity is particularly beneficial under cold conditions. Even at 4°C the polymers have viscosities which are considerably lower than those associated with standard unmodified bisphenol A [diglycidyl ether of bisphenol A (DGEBA)] epoxy resins at 25°C. 

---