Polyolefin Homopolymers

Westphal and co-workers [3] investigated the microstructure of low density polyethylene which had been subjected to photooxidation in a weatherometer in ovens at 60 °C and 100 °C. 

Molecular management of polyolefin properties requires advanced analytical technology that can provide detailed compositional and microstructural information of the polyolefin product. In principle, structural information can be obtained by breaking the polymer into short sequences, which are then analysed. Indeed, Py-MS has been used for many years to characterise polymers in this manner [4-7]. However, chemical information can be lost if the pyrolysates undergo additional fragmentation when they are ionised, which is often the case with polyolefins. 

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Polyolefin homopolymers include polyethylene (PE), polypropylene (PP), poly-butene-1 (PB), polymethylpentene-1 (PMP), and higher polyolefins. Table 1.2 shows the structures of commercial polyolefin homopolymers. 

Polyolefin blends of commercial importance are normally made via two methods blending in the melt either during polymerization or mechanically after the polymerization process. The first method, called in-reactor blending, involves the blending of different polyolefins (homopolymers, random, and block copolymers) in a polymerization reactor. This is enabled by the presence of multiple catalyst species... 

Solution concentrations of 0.5% are usually prepared in vials or dissolution vessels and injection of 1-5 mg of polymer are loaded onto the column in analytical TREF. The more sensitive detectors should be used to allow for the lowest concentration possible in order to reduce co-crystallization and entrapment effects. Polyolefin homopolymers, which elute in a narrow temperature range, may often result in column plugging, especially if they have large molar mass in those cases, a lower concentration of sample should be used for injections. 

Impact-resistant properties, especially at low temperatures, low-temperature toughness, melt-processing properties, and dimensional stability of thermoplastic polyurethane elastomers are improved by the addition of a carbonyl-modified polyolefin [54,55]. These improvements are particularly useful for reinforced polyurethanes. Small amounts of polyolefin homopolymer or copolymer with TPU blends are useful for molding plastic articles by injection molding, extrusion, calendering, or similar process for molding thermoplastic articles [56]. 

For saturated polyolefin homopolymers, reactivity is LLDPE -I- polystyrene was heated with peroxide. ... 

In the following data acquisition, the same 163 standard polymer samples used in the former edition were adopted as a set of representative ones utilized in versatile fields, which include representative synthetic polymers [a) polyolefins (homopolymers) (001— 007), b) vinyl polymers with ethylene units (copolymers) (008—015), c) vinyl polymers with styrene units (016—028), d) vinyl polymers with styrene derivatives (029—035), e) acrylate-type polymers (036—049), f) chlorine-containing vinyl polymers (050-059), g) fluorine-containing vinyl polymen (060—066), h) the other vinyl polymers (067—070), i) diene-type elastomers (071—081), j) polyamides (082-090), k) polyacetals and polyethers (091—095), 1) thermosetting polymers (096—106), m) polyimides and polyamide-type engineering plastics (107—114), n) polyesters (115—126), o) the other engineering plastics with phenylene skeletons (127—138), p) sificone polymers (139—143), and q) polyurethanes (144—147)] along with some natural polymers [r) cellulose-type polymers (148-155) and s) the other some natural polymers (156-163)]. 

Chem. Descrip. Amorphous polyolefin homopolymer Uses Processing aid, lubricant, release agent, dispersant for polyolefins and rubbers used in hot-melt and pressure-sensitive adhesives, tapes and labels, footwear and leather, automotive applies. 

With most homopolymers and copolymers the apparent viscosity is less dependent on temperature and shear stress (up to 10 dyn/cm ) than that of the polyolefins, thus simplifying die design. On the other hand the melt has a low elasticity and strength and this requires that extruded sections be... 

For the homopolymer we can observe that the backbone is the same as for the previously examined polyolefins but the pendant groups are different. Properties vary with the degree of polymerization (generally 1500 up to 3000 units per chain), the structure and the possible addition of or copolymerization with a rubber. 

Finally, there is need for a systematic study of the synthesis of different types of well-defined block copolymers free of homopolymer impurities. In particular the block copolymers consisting of polyolefin blocks and polar monomer unit blocks are expected to exhibit new characteristic properties owing to the effect of microphase separation. 

The technologies that have been developed for the production of polyolefins, olefin homopolymers and copolymers are slurry, solution and gas-phase polymerisation bulk polymerisation of propylene in the liquid monomer as a special case of the slurry process has also emerged. The fundamental differences in the various olefin polymerisation processes reflect the different approaches that have been devised to remove the substantial heat of polymerisation. In addition, processes can be operated in a batch or a continuous mode. In the batch process the reagents are loaded into a polymerisation vessel, the polymer forms and the vessel is emptied before a new charge of reagents is introduced. In the continuous process, the catalyst precursor, activator and other necessary... 

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