Propylene-alkene copolymers

Expanding on this idea, Hawker et al. copolymerized an alkene functionalized TEMPO derivative with propylene or 4-methylpentene using a cationic metallocene compound to prepare an a-olefin based macroinitiator for graft copolymerization (Mn=28,000,Mw/Mn=1.80 or Mn=6080,Mw/Mn=1.65) (Scheme 42) [295]. Heating the propylene-based copolymer to 123 °C in the presence of 200 equivalents of St increased its molecular weight to Mn=210,000 with Mw/Mn=... 

Random copolymers of ethylene and a-olefins (l-aUcenes) can be obtained with Ziegler-Natta catalysts, the most important being those of ethylene and 1-butene (LLDPE) and of ethylene and propylene (EPM or EPR and EPDM). Some reactivity ratios are listed in Table 9.5. Tha ratios vary with the nature and physical state of the catalyst and in most instances, r r2 is close to unity. However, all these values show that ethylene is much more reactive than higher alkenes. Copolymers produced using Ziegler-Natta catalysts usually have a wide range of compositions. This may be due to the presence of different active sites in the catalyst giving rise... 

Ethylene can be copolymerized with alkene compounds or monomers containing polar functional groups, such as vinyl acetate and acrylic acid. Branched ethylene/ alkene copolymers are essentially the same as LDPE, since in commercial practice a certain amount of propylene or hexene is always added to aid in the control of molecular weight. 

Fig. 28 Dependence of elution volume on average chemical composition of copolymers, (a) ethylene-1-butene copolymers, (b) propylene-1-alkene copolymers stationary phase Hypercarb mobile phase gradient 1-decanol/TCB temperature 160°C detector ELSD. (Reprinted fi om [161] and [162] with permission of Springer Science -l- Business Media and Elsevier Limited)...

Partitioning of branches in both polyethylene and isotactic polypropylene copolymers was also investigated by Hosoda et al. [41, 42]. Ethylene-alkene and propylene-alkene statistical copolymers were degraded by fuming nitric acid to selectively remove their amorphous phase. The degree of branch inclusion in the residual crystalline phase was then determined by solid-... 

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 . 

Random copolymers of ethylene and 1-butene or propylene are more flexible and more resistant to environmental stress cracking than ldpe. Some of the newer commercial lldpe plastics are copolymers of ethylene and alpha alkenes, such as 1-hexene. 

Copolymers of propylene are used as additives for improving the impact resistance of stiff polymers, such as nylon 66. Some of the new readily pro-cessible commercial PPs are copolymers of propylene and alpha alkenes. 

We have studied the alkane and alkene yields from the radiolysis of copolymers of ethylene with small amounts of propylene, butene and hexene. These are examples of linear low density polyethenes (LLDPE) and models for LDPE. Alkanes from Ct to C6 are readily observed after irradiation of all the polymers in vacuum. The distribution of alkanes shows a maximum corresponding to elimination of the short-chain branch. This is illustrated in Figure 8 for the irradiation of poly (ethylene-co-1-butene) containing 0.5 branches per 1,000 carbon atoms at 20 C. 

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. 

Linear low-density polyethylene (LLDPE)440-442 is a copolymer of ethylene and a terminal alkene with improved physical properties as compared to LDPE. The practically most important copolymer is made with propylene, but 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene are also employed.440 LLDPE is characterized by linear chains without long-chain branches. Short-chain branches result from the terminal alkene comonomer. Copolymer content and distribution as well as branch length introduced permit to control the properties of the copolymer formed. Improvement of certain physical properties (toughness, tensile strength, melt index, elongation characteristics) directly connected to the type of terminal alkene used can be achieved with copolymerization.442... 

With the sole exception of the random ethylene-propylene copolymers, for industrial applications heterogeneous catalysts have been used for alkene polymerisations. Ethylene-propylene statistical copolymerisation has been carried out using homogeneous vanadium-based catalysts [28]. 

Scheme 42. Copolymerization of propylene and an alkene-functional TEMPO moiety followed by CRP of St to produce a graft copolymer [295]...

Low density polyethylene is one of the most widely used packaging plastics. It is a member of the polyolefin family. Olefin, which means oil-forming, is an old synonym for alkene, and was, originally, the name given to ethylene. Alkenes are hydrocarbons containing carbon-carbon double bonds, such as ethylene and propylene. In the plastics industry, olefin is a common term that refers to the family of plastics based on ethylene and propylene. The term polyolefin strictly applies to polymers made of alkenes, whether homopolymers or copolymers. It includes the family of polyethylene, and the family of polypropylene. 

The water-soluble polymers we have examined that have LCST behavior include poly(alkene oxide)s and poly(A -alkyl acryIamide)s.(/4-/d) The poly(alkene oxide)s we used are mainly triblock copolymer of ethylene oxide, propylene oxide and ethylene oxide with the ratio of ethylene oxide/propylene oxide adjusted to create a more or less hydrophobic polymer with a lower or higher LCST, respectively. The poly-(alkene oxide)s contain terminal hydroxyl groups that can be manipulated synthetically to form ligands for catalyst ligation. The reactions shown in equation 2 illustrate the typical chemistry used to prepare ligands and catalysts with these polymers. 

Carbonylation of some alkenes catalyzed by a cationic Pd complex yields polyketones, which are alternating copolymers. The polyketone 19 of ethylene or propylene named carilon is produced commercially by Shell [10]. A Chain-transfer mechanism for the alternating copolymerization of CO and ethylene was proposed... 

The partial molar quantities of mixing were determined for normal and branched alkanes (O5 — Cio), cyclohexane, benzene and tetrachloromethane in polyisobutylene [57]. Partial molar enthalpies of mixing were measured for normal alkenes in low and high density polyethylene, polypropylene, polybutene-1, polystyrene, poly(methyl acrylate), poly(vinyl chloride), polyCN-isopropyl-acrylamide), ethylene-vinyl acetate copolymer, ethylene-carbon oxide copolymer [88] normal, branched and cyclic alkanes, benzene, n-butylbenzene, ois- and ra s-decalin, tetraline and naphthalene in polystyrene at 183, 193 and 203°C [60] these solutes in poly (methyl acrylate) [57] n-nonane, n-dodecane and benzene in polystyrene in the range 104.8 — 165.1 C [71] O7—C, C12 normal alkanes and aromatic hydrocarbons in polystyrene at an average temperature of 204.9°C [72], C7—Cg normal alkanes in poly(ethylene oxide) at an average temperature of 66.5 "C [72] normal alkanes in ethylene oxide—propylene oxide block copolymers (Pluronics L 72, L 64 and F 68) at the same average temperature [72]. 

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