Propylene-based polymers polypropylenes

Polyethers are typically products of base-catalyzed reactions of the oxides of simple alkenes. More often than not, ethylene oxides or propylene oxides and block copolymers of the oxides are used. A polypropylene oxide-based polymer is built and then capped with polyethylene oxides. An interesting aspect of this chemistry is the use of initiators. For instance, if a small amount of a trifunctional alcohol is added to the reactor, the alkylene oxide chains grow from the three alcohol end groups of the initiator. Suitable initiators are trimethylol propane, glycerol or 1,2,6 hexanetriol. The initiator is critical if one is to make a polyether foam for reasons that we will discuss shortly. 

Application To produce propylene-based polymers including homopolymer polypropylene, random and heterophasic impact and specialty impact copolymers using Spheripol process technology. 

Product specifications The process can produce a broad range of propylene-based polymers, including homopolymer polypropylene, random copolymers and terpolymers, heterophasic impact and specialty impact (up to 25% bonded ethylene) copolymers as well as high stiffness, high-clarity copolymers. 

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. 

It is traditional to begin books about polyurethanes by defining the class of polymers that has come to be known as polyurethanes. Unlike olefin-based polymers (polyethylene, polypropylene, etc.), the uniqueness of polyurethane is that it results not from a specific monomer (ethylene, propylene, etc.), but rather from a type of reaction, specifically the fonnation of a specific chemical bond. Inevitably, the discussion in traditional books then progresses to the component parts, the production processes, and ultimately the uses. This is, of course, a logical progression inasmuch as most tests about polyurethanes are written for and by current or aspiring PUR (the accepted abbreviation for conventional polyurethanes) chemists. Unlike discussions about polyolefins where the monomer, for the most part, defines the properties of the final product, a discussion of PURs must begin with the wide variety of constituent parts and their effects on the resultant polymers. 

Propylene content in EPM rubber can be determined with the help of IR spectra. A propylene band near 1155 cm 1 has been widely used [79] for EPM analysis, frequently in combination with the polyethylene band at 721 cm"1. Tacticity is important in EPM rubber, and the bands at 1229 and 1252 cm"1 are characteristic of syndiotactic and isotactic structures, respectively, (both bands are present in atactic polypropylene as well). Polymer structure may vary in the relative tactic placement of adjacent head to tail propylene units and in the sequence distribution of base units along the chain. Some of them can be identified [80] by infrared spectra, such as isolated or head to tail propylene units ... 

The Ziegler-Natta catalysts have acquired practical importance particularly as heterogeneous systems, mostly owing to the commercial production of linear high- and low-density polyethylenes and isotactic polypropylene. Elastomers based on ethylene-propylene copolymers (with the use of vanadium-based catalysts) as well as 1,4-cz s-and 1,4-tran.y-poly(l, 3-butadiene) and polyisoprene are also produced. These catalysts are extremely versatile and can be used in many other polymerisations of various hydrocarbon monomers, leading very often to polymers of different stereoregularity. In 1963, both Ziegler and Natta were awarded the Nobel Prize in chemistry. 

Steric defects in isotactic polypropylene, which involve the appearance of isolated r diads or pairs of r diads, may be considered on a pentad level (Figures 3.45a and b respectively). The 13C NMR signals associated with occasional stereoerrors in the propylene isotactic polymers produced by chiral metallocene-based catalysts (pairs of r diads) indicate that the polymerisation stereochemistry is governed by the enantiomorphism of catalytic sites an error pentad distribution close to mmmr.mmrr.mmrm-.mrrm = 2 2 0 1 is observed... 

Composition (type of polymeric components). The base polymer (which is to be modified) may be an amorphous polymer [e.g., polystyrene (PS), styrene-acrylonitrile copolymer, polycarbonate, or poly(vinyl chloride)], a semicrystalline polymer [e.g., polyamide (PA) or polypropylene (PP)], or a thermoset resin (e.g., epoxy resin). The modifier may be a rubber-like elastomer (e.g., polybutadiene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, or ethylene-propylene-diene copolymer), a core-shell modifier, or another polymer. Even smaller amounts of a compatibilizer, such as a copolymer, are sometimes added as a third component to control the morphology. 

LyondellBasell Polypropylene Propylene Gas-loop reactor technology, Sperizone process, based on Multi-Zone Circulating Reactor (MZCR) concept, produces polypropylene-based polymers, including homopolymer polypropylene (PP), random, heterophasic impact and specialty dual-composition copolymers 13 2010... 

The choice of date range is arbitrary. The number of journal articles for each year was obtained from a search of electronic version of English-based polymer and polymer-related journals using the keywords polyolefin and blends. Within polyolefin keyword, the subkeywords used in the search were polyethylene (PE, LLDPE, LDPE, HDPE, UHMWPE, PE, etc.), polypropylene (PP, iPP, sPP, aPP, etc.), polybutene-1, poly-4-methylpentene-l, ethylene-diene monomer, ethylene-propylene-diene terpolymer, ethylene propylene rubber, thermoplastic olefins, natural rubber (NR), polybutadiene, polyisobutylene (PIB), polyisoprene, and polyolefin elastomer. For the polyolefin blends patent search, polymer indexing codes and manual codes were used to search for the patents in Derwent World Patent Index based on the above keywords listed in the search strategy. 

Another test occasionally run on these compounds is percent secondary hydroxyl content, as determined by C NMR spectroscopy (145). This is a measure of polypropylene oxide base material with one end uncapped by polyethylene oxide groups. This value is generally very low for EO/PO copolymers in the surfactant range, but can be more significant for analogous polymers made with butylene oxide rather than propylene oxide (146). 

Olefin—at least 85% by weight ethylene, propylene, or other olefin-based polymers polypropylene most common... 

Mention should be made of the nomenclature for the polymer. Industrially the materially is invariably known in the English-speaking world as polypropylene. However, the lUPAC name for the monomer is propene and until 1975 the recommended lUPAC name was polypropene, a term very rarely used. The latest lUPAC rules base the name of a polymer on the constitutional repeating unit, which in this case is a propylene unit (c.f. a methylene unit for polyethylene) and this leads to the name poly(propylene) (i.e. with brackets). In this volume the more common, unbracketed but still unambiguous name will be used. 

A manufacturer considering using a thermoplastic elastomer would probably first consider one of the thermoplastic polyolefin rubbers or TPOs, since these tend to have the lowest raw polymer price. These are mainly based on blends of polypropylene and an ethylene-propylene rubber (either EPM or EPDM) although some of the polypropylene may be replaeed by polyethylene. A wide range of blends are possible which may also contain some filler, oil and flame retardant in addition to the polymers. The blends are usually subject to dynamic vulcanisation as described in Section 11.9.1. 

Medintseva, T.I., Dreval, V.E., Erina, N.A., and Prut, E.V., Rheological properties thermoplastic elastomers based on isotactic polypropylene with an ethylene-propylene-diene terpolymer, Polym. Sci. A, 45, 2032, 2003. 

Collins et al. reported in 1995 that catalysts based on hafnium are desirable for the production of elastomeric polypropylene in that they polymerize propylene to a high molecular weight polymer and are indefinitely stable under typical polymerization conditions [8], Based on the theory that hafnium as a catalytic center leads to a significant increase of molecular weight in propene polymerization compared with the zirconium-based catalyst, Rieger et al. searched for hafnocene systems to obtain polymers with new properties. 

Propylene polymerization processes have undergone a number of revolutionary changes since the first processes for the production of crystalline polypropylene (PP) were commercialized in 1957 by Montecatini in Italy and Hercules in the United States. These first processes were based on Natta s discovery in 1954 that a Ziegler catalyst could be used to produce highly isotactic polypropylene. The stereoregular, crystalline polymers produced by this technology had sufficiently attractive economic and property performance that they became significant commercial thermoplastics in a remarkably short period. 

Soluble catalysts based on vanadium compounds polymerize propylene to polypropylene of syndiotactic or atactic structure 73 sc,. Both types of polypropylenes are soluble in hydrocarbons, independent of the molecular weight of the polymers, even at a low temperature of —78 °C. Therefore, the polymerization system remains homogeneous during the polymerization. 

The Mw/Mn ratio is usually equal to 5-10 for polyethylene [49,64,66,67, 123,244-247], A much lower polydispersity is displayed by polymers obtained in polymerisation with homogeneous metallocene catalysts the Mw/Mn ratio usually does not significantly exceed a value of 2 [22,95,101,112,138,140], By polymerising propylene with soluble vanadium-based Ziegler-Natta catalysts at low temperature, a very narrow molecular weight distribution of the polypropylene has been found (the Mw/Mn ratio usually reaches values of 1.15-1.25) and a linear increase in its Mn with time has been observed, indicating a noticeable living character of the polymerisation [75,76,241],... 

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