Polyolefins polyisoprene

Aqueous metal working lubricants Polyolefins, polyisoprene France 1,505,020 1967 Union Carbide... 

Olefins or alkenes are defined as unsaturated aliphatic hydrocarbons. Ethylene and propylene are the main monomers for polyolefin foams, but dienes such as polyisoprene should also be included. The copolymers of ethylene and propylene (PP) will be included, but not polyvinyl chloride (PVC), which is usually treated as a separate polymer class. The majority of these foams have densities <100 kg m, and their microstructure consists of closed, polygonal cells with thin faces (Figure la). The review will not consider structural foam injection mouldings of PP, which have solid skins and cores of density in the range 400 to 700 kg m, and have distinct production methods and properties (456). The microstructure of these foams consists of isolated gas bubbles, often elongated by the flow of thermoplastic. However, elastomeric and microcellular foams of relative density in the range 0.3 to 0.5, which also have isolated spherical bubbles (Figure lb), will be included. The relative density of a foam is defined as the foam density divided by the polymer density. It is the inverse of the expansion ratio . 

Polyisoprene (rubber), chlorinated polyethylene Wood, complex silicates (cement or ceramic tile), carpet (nylon, polyester, polyolefin)... 

POLYOLEFIN. A class or group name for thermoplastic polymers derived from simple olefins among the more important are polyethylene, polyproplene, polybutenes, polyisoprene, and their copolymers. Many are produced in the form of fibers. This group comprises the largest tonnage of all thermoplastics produced. 

The living character of organolithium polymerizations makes such processes ideally suited for the preparation of pure as well as tapered-block copolymers. Diene-olefin pure-block copolymers have become important commodities because of their unique structure-property relationships. When such copolymers have an ABA or (AB) X [A = polyolefin, e.g., polystyrene or poly(a-methylstyrene) B = polydiene, e.g., polybutadiene or polyisoprene and X = coupling-agent residue] arrangement of the blocks, the copolymers have found use as thermoplastic elastomers (i.e., elastomers that can be processed as thermoplastics). 

Th-FFF can be applied to almost all kinds of synthetic polymers, like polystyrene, polyolefins, polybutadiene, poly(methyl methacrylate), polyisoprene, polysulfone, polycarbonate, nitrocelluloses and even block copolymers [114,194,220]. For some polymers like polyolefins, with a small thermal diffusion coefficient, high temperature Th-FFF has to be applied [221]. Similarly, hydrophilic polymers in water are rarely characterized by Th-FFF, due to the lack of a significant thermal diffusion (exceptions so far poly(ethylene oxide), poly(vi-nyl pyrrolidone) and poly(styrene sulfonate)) [222]. Thus Th-FFF has evolved as a technique for separating synthetic polymers in organic solvents [194]. More recently, both aqueous and non-aqueous particle suspensions, along with mixtures of polymers and particles, have been shown to be separable [215]. 

The list of examples of successful Th-FFF separations of lipophilic polymers is extensive and includes polystyrene [29,34,76,118,144,164,165,168,196,200,345-350], polyisoprene [55,110,144,196,349,350], polytetrahydrofuran [144,196,349,350] and poly(methyl methacrylate) [55,110,144,196,349,350], polybutadiene [349], poly(ethyl methacrylate), poly(n-butyl methacrylate), polyfoctadecyl methacrylate), poly(a-methylstyrene), poly(dimethylsiloxane), poly (vinyl acetate), po-ly(vinyl chloride) and poly(vinyl carbazole) [144],polyethylene [351] and other polyolefins [221]. The polyolefin separations were achieved in a special high temperature channel [15,351]. Asphaltenes have also been separated with Th-FFF [352]. 

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. 

Percolation networks 211,257 Pinning 211, 213, 257 Plasticizer 251, 252 Poly(2-chlorostyrene)/polystyrene 251 Polydienes, anionic, ds-structure 167 Polydispersity 184, 209, 269 Polyethylene 227, 228, 253 Polyethylethylene 252, 269, 285 Polyisoprene 213, 263, 279 Polyolefin 94... 

These concepts for formation of miscible blend of elastomers with similar or near equivalence of solubility parameters require the components to be similar in properties. Thus a wide variation in the properties of the elastomer blends by changing the relative amounts of the two elastomers is not typical since it is unlikely that, for example, a nonpolar polyolefin elastomer and a polar elastomer like acrylate would be similar in solubility parameters. This relative invariance in the properties of the blend compared to the components is an inherent limitation on the basic, economic, and technological need for elastomer blends, which is to generate new properties by blends of existing materials. Similar or near equivalence of solubility parameters can be difficult to predict from chemical structure. For example, chemically distinct 1,4-polyisoprene and 1,2-polybutadiene are miscible, but isomeric 1,2-polybutadiene and 1,4-polybutadiene are immiscible. It is illustrative of this concept that an apolar hydrocarbon elastomer and a highly polar elastomer such as an acrylate cannot have, under any practical structural manifestation for either, a similar solubility parameter and thus be miscible. 

Figure 12.1 shows how the structure of polyolefins affects the observed patterns of chemiluminescence response in oxygen at 120 °C. As expected, the degradability decreases in the order polyisoprene > polybutadiene > polypropylene > polyethylene in correspondence with the amount of C=C double bonds and tertiary carbon atoms in the polymer structure. 

This group of Ziegler-Natta catalysts is stereospecific for the polymerisation of a-olefins and 1,3-dienes the products are mainly isotactic polyolefins (polypropylene, polystyrene, and so on) and 3 5-l,4-polydienes (polybutadiene, polyisoprene, and so on). 

It is proposed that this is due to attack of carbonyl oxides, in their biradical form, on the rubber double bonds. Typical diene rubbers (polyisoprene and polybutadiene) have rate constants several orders of magnitude greater than polymers having a saturated backbone (polyolefins). Other unsaturated elastomers having high reaction rates with ozone include styrene-butadiene (SBR) and acrylonitrile-butadiene (NBR) rubbers. As an example, Polychloroprene (CR) is less reactive than other diene rubbers, and it is therefore inherently more resistant to attack by ozone. 

PNVC-g-PI Poly(N-vinyl carbazole)-grayt-polyisoprene PO Polyolefins... 

A pioneer group of researchers in UKM has extensively studied utilization of liquid natural rubber (LNR) as a compatibilizer on various NR/polyolefin blends. LNR was produced by photodegradation of NR in toluene and exposure to the ultraviolet for 6 h. The LNR has the same microstructure as NR but with a short polyisoprene chain (of diflerent molecular weight, M )- The Mw of LNR is around 50,000 whereas for NR is 900,000. The formation of new functional groups such as H, C-O and C=0 via oxidation of photochemical sensitization of NR. The presence of the new functional groups is shown in Figure 17.1. The LNR with some active terminals like -OH is... 

Thermoplastic polyolefin (TPO) elastomers are typically composed of ethylene propylene rubber (EPR) or ethylene propylene diene M (EPDM) as the elastomeric segment and polypropylene thermoplastic segment. LDPE, HDPE, and LLDPE copolymers ethylene vinyl acetate (EVA), ethylene ethylacrylate (EEA), ethylene, methyl-acrylate (EMA) and polybutene-1 can be used in TPOs. Hydrogenation of polyisoprene can yield ethylene propylene copolymers, and hydrogenation of 1,4- and 1,2-stereoisomers of S-B-S yields ethylene butylene copolymers. ... 

Kiran, E. and Gillham, J. (1976) Pyrolysis-molecular weight chromatography A new on-line system for analysis of polymers. II. Thermal decomposition of polyolefins Polyethylene, polypropylene, polyisoprene J. Appl. Polym. Sci. 20, 2045-2068. 

Finally, the poor solubility of fluorinated polyolefins can also be exemplified by the phase behavior of fluorinated polyisoprenes and polybutadienes in SC-CO2 (see Figure 13.3) [18], A pressure of 1000 bar and a temperature of 60°C were thus... 

A manufactured fiber in which the fiber-forming substance is a hydrocarbon such as natural rubber, polyisoprene, polybutadiene, copolymers of dienes and hydrocarbons, or amorphous (noncrystalline) polyolefins."... 

Field flow techniques have been reviewed in a number of articles [148-150]. Sedimentation field flow fractionation has found use in the separation of PVC [151, 152], polystyrene [151-153], poly(methyl methacrylate) [153, 154], poly (vinyl toluene) [155] and poly(glycidyl methacrylate) latexes [156] to produce particle-size distributions and particle densities. It has also been applied in polymer-aggregation studies [157], pigment [157] quality control and in the separation of silica particles [158] and its performance has been compared with that of ultracentrifugation [159]. Thermal field flow fractionation has been used successfully in the characterisation of ultra-high-molecular-weight polystyrenes [160, 161], poly(methyl methacrylate), polyisoprene, polysulphane, polycarbonate, nitrocellulose, polybutadiene and polyolefins [162]. In the difficult area of water-soluble polymers, poly(ethylene glycol), poly(ethylene oxide), poly(vinyl pyrrolidone) and poly(styrene sulphonate) have been analysed [163, 164]. In addition, compositional separations have been achieved for polystyrene-poly(methyl methacrylate) mixes [165] and comparisons between TFFF and SEC have been made [166]. 

Petroleum resins 1,3-Polypentadiene Polyolefins c/5-l,4-Polyisoprene Liquid polybutadiene (>60% cis 1,4)... 

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