Polyolefin polypropylene homopolymer

Thermoplastic polyolefin (TPO) is a generic name that refers to polyolefin blends usually consisting of some fraction of polypropylene (PP), polyethylene (PE) or polypropylene block copolymer (PP-b-EP or BCPP ), and a thermoplastic olefinic rubber, with or without a mineral reinforcing filler such as talc or wollastonite. Common rubbers include ethylene propylene rubber (EPR), EPDM rubber, ethylene-octene (EO) copolymer mbber, ethylene-butadiene (EB), and styrene-ethylene-butadiene-styrene (SEBS) block copolymer rubbers. Currently, there are a great variety of commercial polypropylene homopolymers, PP block copolymers, and olefinic rubbers available to make a wide range of TPO blends with densities ranging from 0.92 to 1.1. 

Interestingly, aPP found less use in blends with thermoplastic polymers irrespective of the high number of related patents. The new generation aPP, produced by metallocene synthesis, may change this scenario (see also the chapter Elastomeric polypropylene homopolymers using metallocene catalysts ). Blending of HMW-aPP with polyolefins may result in a new mechanical property profile, e.g. rubberlike resilience. Such products may compete with those made of flexible PVC. 

Figure 2.14 shows the relative notch sensitivities of some polyolefins. Among the polyolefins, the low-melt-index polypropylene copolymer (GMT 61) has the lowest notch sensitivity, whereas the higher-melt-index polyethylene and polypropylene homopolymers have the highest. 

The list of flexible polymeric roll materials suitable for atmospheric plasma processing is expansive. Mainstream resin types include polypropylene (homopolymers, heterophasic copolymers, and random copolymers), polyethylene (low, medium, and high density polyethylene resins), a family of specialty polyolefins which includes polybutene-1, advanced polypropylene resins from in-reactor alloying processes and polypropylene compounds, and fiuoropolymers. By process type, these materials (in mono- or multiple layers) can be generally represented by the following ... 

With metallocene catalysts, not only homopolymers such as polyethylene or polypropylene can be synthesized but also many kinds of copolymers and elastomers, copolymers of cyclic olefins, polyolefin covered metal powders and inorganic fillers, oligomeric optically active hydrocarbons [20-25]. In addition, metallocene complexes represent a new class of catalysts for the cyclopolymerization of 1,5- and 1,6-dienes [26]. The enantio-selective cyclopolymerization of 1,5-hexadiene yields an optically active polymer whose chirality derives from its main chain stereochemistry. 

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. 

These homopolymers have structure units as shown in Fig. 2.1, where the asterisk indicates asymmetric carbon atoms. Thus, polypropylene (PP), poly (butene-1) (PB1), and poly(4-methylpentene-l) (P4MP1) have different tactic forms. The most important commercial polyolefins are polyethylene, polyisobutene, and the isotactic forms, that is, iPP, iPBl, and iP4MPl. Polyisobutene was first polymerized by the IG Farbenindustries (BASF) in the late 1920s. Polyethylene was first polymerized by ICI in the late 1930s in a branched form (1). Linear polyethylene... 

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. 

Polypropylene, a homopolymer polyolefin engineering plastic provides excellent chemical resistance, purity and it is the lightest of all commercial plastics. PP offers innovative solutions to many challenges that face the automotive industry today. Its low density compared to traditional materials significantly contributes to fuel economy and reduced material costs. Its excellent noise, vibration, and harshness (NVH) properties contribute to enhanced passenger comfort. Thus, PP has become the most important thermoplastic material in automobile industry. PP homopolymers, random copolymers, and impact copolymers are used in products such as automotive parts and battery cases, carpeting, electrical insulation, and fabrics. 

Polyolefin materials used for the battery separator are based on a homopolymer or a blend of polyethylene (PE) and polypropylene (PP) in a number of combinations between high density polyethylene (HOPE) and ultrahigh molecular weight polyethylene (UHMWPE). The methods for manufacturing the microporous polyolefin membranes can be divided into the dry process and wet process. Both processes contain an extmsion step to produce a thin film, and employ one or more orientation steps to impart porosity and increase tensile strength. The membranes made by diy process show a distinct slit-pore microstmcmre, while those by wet process feamre interconnected spherical or elliptical pores. 

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