Polypropylene resins, characteristic

Polyethylene. Traditional melt spun methods have not utilized polyethylene as the base polymer because the physical properties obtained have been lower compared to those obtained with polypropylene. Advances in polyethylene technology may result in the commercialization of new spunbonded stmctures having characteristics not attainable with polypropylene. Although fiber-grade polyethylene resin was announced in late 1986 (11,12), it has seen limited acceptance because of higher costs and continuing improvements in polypropylene resin technology (see Olefin POLYMERS, POLYETHYLENE). 

Lu, F.M. Spruiell, J.E. (1987). The influence of resin characteristics on the high speed melt spinning of isotactic polypropylene. I. Effect of molecular weight and its distribution on structure and mechanical properties of as-spun filaments JAppl. Polym. Sci., Vol.34, Issue 4, pp.1521-1539. 

The molecular structure and morphology of individual polypropylene resins can be readily modified at the reactor stage via new catalyst systems. Postblends of available resins with various additives promote impact resistance, controlled rheology, thermal stability, and other desirable characteristics of the polymer matrix. The incorporation of chemical coupling agents and mineral-filler or glass-... 

The final combination of ingredients promotes an adhesive bond between the polymer matrix and load-bearing glass-fiber reinforcement. Consequently, the physicochemical characteristics of the microstructure based on the interphase design determine the ultimate mechanical and other properties of filled or glass-fiber reinforced polypropylene resins. 

Permanent internal antistatic agent for use in polyethylene, polypropylene, polystyrene, ABS, HIPS and SAN resins. Characteristics ... 

The next major commodity plastic worth discussing is polypropylene. Polypropylene is a thermoplastic, crystalline resin. Its production technology is based on Ziegler s discovery in 1953 of metal alkyl-transition metal halide olefin polymerization catalysts. These are heterogeneous coordination systems that produce resin by stereo specific polymerization of propylene. Stereoregular polymers characteristically have monomeric units arranged in orderly periodic steric configuration. 

The most common advanced composites are made of thermosetting resins, such as epoxy polymers (the most popular singlematrix material), polyesters, vinyl esters, polyurethanes, polyimids, cianamids, bismaleimides, silicones, and melamine. Some of the most widely used thermoplastic polymers are polyvinyl chloride (PVC), PPE (poly[phenylene ether]), polypropylene, PEEK (poly [etheretherketone]), and ABS (acrylonitrile-butadiene-styrene). The precise matrix selected for any given product depends primarily on the physical properties desired for that product. Each type of resin has its own characteristic thermal properties (such as melting point... 

The Fmoc amino acyl resin (4-8 mg) in a 10-mL polypropylene syringe fitted with a polyethylene disc was stirred or shaken in piperidine/DMF (3 7,1 mL) for 30 min. MeOH (5mL) was then added and the soln was filtered and diluted with MeOH up to a total volume of 25 mL. The resultant fulvene-piperidine adduct has a characteristic UV absorption at 301 nm (e = 7 800 M cm ). For reference, a piperidine/DMF/MeOH (0.3 0.7 24) soln was prepared and the result was compared to a free Fmoc amino acid soln of known concentration treated under identical conditions. The loading (mmol g or pmol mg ) = (A301 X 0.025 L x 10 pmol/mol/7800 M cm x 1 cm x mg of resin). 

A large diffusion may be found also for composite materials, carbon, or metal based. In the first case different types of polymeric resins (thermoplastics, such as polypropylene, polyethylene, and PVDF, or thermosettings, such as epoxies and phenolics) are filled with carbonaceous powders (graphite or carbon blacks), to provide a material characterized by very high chemical stability in the fuel cell environment and satisfactory properties of electrical conductivity, but which cannot offer sufficient robustness at thickness lower than 2 mm. The metal composite plates are essentially based on combinations (sandwiches of different layers) of stainless steel, porous graphite, and polycarbonates, with the aim to exploit the characteristics of different materials. Their fabrication can be more complex but this is compensated by the possibility to incorporate other functional components, such as manifolds, seals, and cooling layers. 

The past growth of polypropylene and that projected for the future are due to the improvements in the properties of fibers made from the resin and an increased knowledge of how to take advantage of some of its unique characteristics. 

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