Polypropylene product families

Metallocene catalysts have been applied to a number of key product families across the chemical industry. Today, polyolefins and styrenics are either commercial or in development with additional polymers and specialty chemicals in the R D pipeline. The work in polyolefins has focussed on polyethylene, polypropylene (isotactic, syndiotactic, and atactic), and cyclic olefins. 

Metallocene-catalyzed polyolefins represent the latest wave of developments in the history of the polyolefin industry. These catalyst systems have been applied to a number of key product families across the chemical industry including polyethylene, polypropylene, cyclic olefins, styrenics, and specialty chemicals. Activity in the various metallocene technologies is proceeding on a global basis, with many participants already involved in alliance arrangements. 

New developments in polyolefin-based materials have created a family of polypropylene products with a wide range of physical properties, including the ability to be easily recycled. When utilized by automotive and product designers as a part of a design for disassembly strategy, these compatible materials will vield large sub-assemblies that can be reclaimed with a minimum of handling. 

In a time when prices for oil are continuously rising, hafnocene catalysts enable production of high-tech materials in a relatively cheap way. Hafnocenes are the key to a family of high and ultrahigh molecular weight polypropylenes whose material properties can be individually and simply varied. To help comprehend the importance... 

This class of materials includes the family of plastics based on ethylene and propylene (Robertson, 2006). Low, linear, and high density PE and polypropylene (PP) materials are common food packaging materials. The use of polyolefins, such as PE and PE terephthalate (PETE) in contact with foods and beverages is common. However, contact with foods, especially under conditions of heat or long duration, can potentially impact sensory characteristics of the contained product. Packaging should be carefully selected, especially for applications that involve heat treatment at high temperatures while in contact with foods. 

Last year, production of one family of plastics, polyethylene, exceeded three billion pounds. This includes low, medium, and high density resins. Two other families, the vinyls and polystyrene including copolymers, reached production levels over two billion pounds. A fourth family, the phenolics, now has reached the billion pound production mark. Polypropylene, which was a plastics industry infant at the beginning of the decade, will probably join the billion pound club by 1970. 

A most significant example, which was also provided by the Symyx team, deployed the same methodology to uncover an entirely new family of isospecific propylene polymerization catalysts. The Symyx team, in collaboration with Dow Chemical, discovered and developed a new catalyst class, and a new commercial solution process for the production of isotactic polypropylene-based elastomers and plastomers. " ... 

The polyallomers constitute the class of block copolymers where both components are capable of crystallizing independently (Coover et al, 1966 Hagenmeyer and Edwards, 1966, 1970 Eastman Chemical Products, n.d.). The most important member of this family contains crystalline, stereoregular polypropylene as the major component and polyethylene as the minor component. As expected for a block copolymer, these products differ greatly in behavior from mechanical blends of polyethylene and polypropylene, and also from their random copolymers, poly(propylene-co-ethylene). When crosslinked with a diene monomer, the latter copolymers are known as EPDM rubbers (Lee et a/., 1966 Rodriguez, 1970, Chapter 13), while the former blends are of apparently little interest. In Figure 6.28 and 6.29 the... 

MBA Polymers, of Richmond, CA, with funding from the American Plastics Council, developed automated sortation techniques for plastics from computers and electronics. The mixture of resins is sorted by family, with the major products polypropylene, high-im-pact polystyrene, acrylonitiile/butadiene/styrene (ABS), polycarbonate (PC), and ABS/PC blends. 

Homopolymer PP is the most widely used polypropylene material in the HPP, RCP, and ICP family of products. It is made in several different reactor designs using catalysts that link the monomers together in a stereospecific manner, resulting in polymer chains that are crystallizable. Whether they crystallize and to what extent depends on the conditions under which the entangled mass of polymer chains transitions from the melt to the solid state or how a heat-softened solid PP material is strained during a further fabrication procedure like fiber drawing. 

Control of polymer stereochemistry is a major research area in academic and industrial laboratories. This is because polymers with different stereochemistries often have very different properties. For example, atactic polypropylene is a gummy, sticky paste sometimes used as a binder, while isotactic polypropylene is a rugged plastic used for bottle caps. Recent advances (see the Going Deeper highlight on the next page and Chapter 13) have greatly improved the ability to control polymer stereochemistry, leading to commercial production of new families of polymers with unprecedented properties. 

Polyolefins constitute the largest volume class of polymeric materials. Polyethylene, polypropylene, and ethylene-propylene rubber are major products in this family, with many subset variations with each material. Polyethylene variants include high density polyethylene (HDPE), low density polyethylene (LDPE), ultrahigh molecular weight polyethylene (UHMWPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE) and various ethylene copolymers (including comonomers of vinyl acetate, ethyl and methyl acrylate, acryhc acid and methacryhc acid and their metal salts (ionomers)). Polypropylene has fewer variations, of which low amounts of ethylene are included while maintaining crystaUinity. More recently, ethylene-styrene copolymers have been introduced. 

The inherent properties of polymers of the poly isobutylene family, particularly the chemical inertness, age and heat resistance, long-lasting tack, flexibility at low temperatures, and the favorable FDA position on selected grades, make these products commercially attractive in a variety of pressure-sensitive and other adhesives, in automotive and architectural sealants, and in coatings. An added dimension is achieved in the blendability of the polyisobutylene polymers with each other and with other adhesive polymers such as natural rubber, styrene-butadiene rubber, EVA, low molecular weight polyethylene, and amorphous polypropylene to achieve specific properties. They can, for example, be blended with the highly unsaturated elastomers to enhance age and chemical resistance. A description of poly isobutylene polymer family use in adhesive and sealant applications follows. 

Door-panels - Polypropylene materials allow the production of integral structures of aesthetic and functional elements produced within the same family of... 

Just recently a new polyolefin wax family had been developed by using metallocene catalyst technology. The family of waxes includes polyethylenes and specialty grades of polypropylenes and copolymers. These low viscosity and low softening point resins have already been successfully used as dispersing aids in the production of master-batches, in adhesives and sealants as well as in fibre glass coatings for composites [2],... 

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