Polypropylene continued

The original, simplest polyolefins, polyethylene and polypropylene, continue to dominate the scene, even after two decades, to such an extent that no other polyolefin even appears on the production charts. Nevertheless, a great many (we may assume all) available olefins have been tested, and many have been found capable of being converted to stereoregular polymers. As was mentioned above, poly(l-butene) and poly(4-methy1-1-pentene) are being offered commercially and may be expected to achieve significant volume in the future. Isotactic and syndiotactic polystyrene are of much theoretical interest (26) but are not yet commercial products. 

The polypropylene continuous phase was transparent and epoxy phase appeared dark in the optical micrograph. However, the cause of elongated structure was not fully understood. The formation of elongated structure could be due to the friction between carbon black coated dispersed particles and the matrix (61), which decreased the interfacial tension between the immiscible polymers (63) or both (64). Based on extraction studies and thermogravimetric analysis, it was concluded that nearly all the carbon black particles were located in the epoxy matrix. 

Polypropylene/continuous glass fiber composite pipes design principles... 

Propylene requirements for acrylates remain small compared to other chemical uses (polypropylene, acrylonitrile, propylene oxide, 2-propanol, and cumene for acetone and phenol). Hence, cost and availabihty are expected to remain attractive and new acrylate capacity should continue to be propylene-based until after the turn of the century. 

Polypropylene fibers are used in every aspect of carpet constmetion from face fiber to primary and secondary backings. Polypropylene s advantages over jute as carpet backing are dimensional stabiUty and minimal moisture absorption. Drawbacks include difficulty in dyeing and higher cost. Bulked-continuous-filament (BCF) carpet yams provide face fiber with improved crimp and elasticity. BCF carpet yams are especially important in contract carpets, characterized by low dense loops, where easy cleaning is an advantage. 

It is axiomatic that sales analysis depends on detailed records of sales of a specific chemical to a specific company. Paramount to the success of such studies is the existence of data recorded on a systematic and continuous basis. It follows that these studies are done best by an ia-house staff on products already produced by the company. However, on occasion, a product new to the company can be studied by the ia-house group with the assistance of their field sales force. For example, a producer of polypropylene could use its people to secure data on the consumption of other thermoplastics by their customers. Such an exercise might identify opportunities for a new producer, but a more detailed marketing research study would probably be done before entry iato the new product area was made. 

The majority of spunbonded fabrics are based on isotactic polypropylene and polyester (Table 1). Small quantities are made from nylon-6,6 and a growing percentage from high density polyethylene. Table 3 illustrates the basic characteristics of fibers made from different base polymers. Although some interest has been seen in the use of linear low density polyethylene (LLDPE) as a base polymer, largely because of potential increases in the softness of the final fabric (9), economic factors continue to favor polypropylene (see OlefinPOLYMERS, POLYPROPYLENE). 

Polyethylene. Traditional melt spun methods have not utilized polyethylene as the base polymer because the physical properties obtained have been lower compared to those obtained with polypropylene. Advances in polyethylene technology may result in the commercialization of new spunbonded stmctures having characteristics not attainable with polypropylene. Although fiber-grade polyethylene resin was announced in late 1986 (11,12), it has seen limited acceptance because of higher costs and continuing improvements in polypropylene resin technology (see Olefin POLYMERS, POLYETHYLENE). 

Fibers. Polypropylene fibers are extensively used in carpeting. Bulked continuous filament yams are commonly used in carpet facing in the level loop carpets used in commercial buildings however, nylon remains the dominant face yam in tufted household carpets. The advantages of polypropylene carpeting are superior stain resistance and low moisture absorbance. Polypropylene sHt tape fibers are heavily used in carpet backing. 

Polypropylene. PP is a versatile polymer, use of which continues to grow rapidly because of its excellent performance characteristics and improvements in its production economics, eg, through new high efficiency catalysts for gas-phase processes. New PP-blend formulations exhibit improved toughness, particularly at low temperatures. PP has been blended mechanically with various elastomers from a time early in its commercialisation to reduce low temperature brittleness. 

The use of TAG as a curing agent continues to grow for polyolefins and olefin copolymer plastics and mbbers. Examples include polyethylene (109), chlorosulfonated polyethylene (110), polypropylene (111), ethylene—vinyl acetate (112), ethylene—propylene copolymer (113), acrylonitrile copolymers (114), and methylstyrene polymers (115). In ethylene—propylene copolymer mbber compositions. TAG has been used for injection molding of fenders (116). Unsaturated elastomers, such as EPDM, cross link with TAG by hydrogen abstraction and addition to double bonds in the presence of peroxyketal catalysts (117) (see Elastol rs, synthetic). 

TDA-derived polyols are made by alkoxylation. Polypropylene oxide adducts of I DA (14) and TDA-initiated polyether polyols (13,15) are used in rigid polyurethane foams and continue to be included in new formulations (62) as well as older appHcations. 

Polypropylene is used in battery cases and in the replacement of metal parts in automobiles. It is also widely used in consumer products, eg, kitchen wares, trays, toys, and packaging materials. Its future appHcations are expected to include an increased portion of the fibers and filaments markets, especially for continued growth in carpet backing and carpet face yams. Film, both oriented and unoriented, is also expected to be a significant growth market for polypropylene. 

Polypropylene sheet has been used most extensively however, thermoplastic polyester, polycarbonate, and nylon versions are available (see Elastomers, synthetic Polycarbonates). Continuous strand glass fiber mat is the typical reinforcement. The limited number of sheet suppHers reduces potential for competitive pricing. 

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