Polypropylene known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene. Polypropylene belongs to the group of polyolefins and is crystalline and non-polar, its properties are similar to polyethylene, but it is harder and more heat resistant. It has a high chemical resistance. Polypropylene is the second-most produced commodity plastic and it is used in packaging and labeling. In 2013, the global market for polypropylene was about 55 million tonnes. Phillips Petroleum chemists J. Paul Hogan and Robert Banks first polymerized propylene in 1951. Propylene was first polymerized to a crystalline isotactic polymer by Giulio Natta as well as by the German chemist Karl Rehn in March 1954; this pioneering discovery led to large-scale commercial production of isotactic polypropylene by the Italian firm Montecatini from 1957 onwards. Syndiotactic polypropylene was first synthesized by Natta and his coworkers.
After polyethylene, polypropylene is the most profitable plastic with revenues expected to exceed US$145 billion by 2019. The sales of this material are forecast to grow at a rate of 5.8% per year until 2021. Polypropylene is in many aspects similar to polyethylene in solution behaviour and electrical properties; the methyl group improves mechanical properties and thermal resistance, although the chemical resistance decreases. The properties of polypropylene depend on the molecular weight and molecular weight distribution, crystallinity and proportion of comonomer and the isotacticity. In isotactic polypropylene, for example, the methyl groups are oriented on one side of the carbon backbone; this arrangement creates a greater degree of crystallinity and results in a stiffer material, more resistant to creep than both atactic polypropylene and polyethylene. The density of is between 0.895 and 0.92 g/cm³. Therefore, PP is the commodity plastic with the lowest density. With lower density, moldings parts with lower weight and more parts of a certain mass of plastic can be produced.
Unlike polyethylene and amorphous regions differ only in their density. However, the density of polyethylene can change with fillers; the Young's modulus of PP is between 1300 and 1800 N/mm². Polypropylene is tough and flexible when copolymerized with ethylene; this allows polypropylene to be used as an engineering plastic, competing with materials such as acrylonitrile butadiene styrene. Polypropylene is reasonably economical. Polypropylene has good resistance to fatigue; the melting point of polypropylene occurs in a range, so the melting point is determined by finding the highest temperature of a differential scanning calorimetry chart. Isotactic PP has a melting point of 171 °C. Commercial isotactic PP has a melting point that ranges from 160 to 166 °C, depending on atactic material and crystallinity. Syndiotactic PP with a crystallinity of 30% has a melting point of 130 °C. Below 0 °C, PP becomes brittle; the thermal expansion of polypropylene is large, but somewhat less than that of polyethylene.
Polypropylene at room temperature is resistant to fats and all organic solvents, apart from strong oxidants. Non-oxidizing acids and bases can be stored in containers made of PP. At elevated temperature, PP can be dissolved in nonpolar solvents such as xylene and decalin. Due to the tertiary carbon atom PP is chemically less resistant than PE. Most commercial polypropylene is isotactic and has an intermediate level of crystallinity between that of low-density polyethylene and high-density polyethylene. Isotactic & atactic polypropylene is soluble in p-xylene at 140 °C. Isotactic precipitates when the solution is cooled to 25 °C and atactic portion remains soluble in p-xylene; the melt flow rate or melt flow index is a measure of molecular weight of polypropylene. The measure helps to determine how the molten raw material will flow during processing. Polypropylene with higher MFR will fill the plastic mold more during the injection or blow-molding production process; as the melt flow increases, some physical properties, like impact strength, will decrease.
There are three general types of polypropylene: homopolymer, random copolymer, block copolymer. The comonomer is used with ethylene. Ethylene-propylene rubber or EPDM added to polypropylene homopolymer increases its low temperature impact strength. Randomly polymerized ethylene monomer added to polypropylene homopolymer decreases the polymer crystallinity, lowers the melting point and makes the polymer more transparent. Polypropylene can be categorized as atactic polypropylene, syndiotactic polypropylene and isotactic polypropylene. In case of atactic polypropylene, the methyl group is randomly aligned, alternating for syndiotactic polypropylene and evenly for isotactic polypropylene; this has an impact on the thermal properties. The term tacticity describes for polypropylene how the methyl group is oriented in the polymer chain. Commercial polypropylene is isotactic; this article therefore always refers to isotactic polypropylene. The tacticity is indicated in percent, using the isotactic index.
The index is measured by determining the fraction of the polymer insoluble in boiling heptane. Commercially available polypropylenes have an isotactic index between 85 and 95%; the tact
Sarah Cowell Le Moyne was an American stage actress in New York City, famous for her readings of Robert Browning's poetry, her work with the Henry Street Settlement and Playhouse. Her stage debut was in 1878 as a member of Albert Marshman Palmer's company in A Celebrated Case at the Union Square Theatre. In 1888 Cowell married fellow actor William J. Le Moyne and the two of them lived together on 34th Street. In 1898 she returned to the stage in a production of Clyde Fitch's The Moth and the Flame at the Lyceum Theatre, she was known for her "fine understanding and careful elocution" and in 1902 published her reminiscences. After her husband's death in 1905 she continued to act as Mrs. Le Moyne. During her stage career, Cowell performed in at least fifteen Broadway shows and continued as director of the 466 Grand Street branch of the Henry Street Playhouse until her death in 1915
Cerveceria de Baja California, is located in the City of Mexicali, is one of a handful of Mexican microbrews. The product they brew is Cucapá Beer; this name comes from one of the five Indian tribes that live in the Mexicali Valley. The Cucapá tribe was the first settlers of the region and their love for water and nature took them to live in the Colorado River delta; the tradition of nature, the water of the river, the geographical location and the initiative of being the first people to explore the region is what makes Cerveza Cucapá as unique as the Cucapá tribe's ancestors. Cucapá Clasica4.5% ABV Blond Ale. This golden colored beer with a fruity and flowery aroma is medium bodied with a taste of malt and sweet citrus, it is paired well with light meats and fish. Cucapá Obscura4.5% ABV American Brown Ale. Deep chestnut brown color with a medium brown head. Sweet toffee, roasted nuts, brown sugar aromas follow through to a smooth, body with roundness and depth. Finishes with a rich dark roasted nut, baker's chocolate, an earthy hop fade.
Cucapá Chupacabras Pale Ale5.8% ABV American Pale Ale. Wildly hopped with fresh cascade and centennial hops. Deep copper color with a lacy taupe head. Rich creamy dark caramel, dark chocolate, roasted nut aromas follow through to a rich medium-full body with layers of citrus marmalade and earthy hops on the long finish. Cucapá Trigueña3.5% ABV Wheat Ale. This wheat ale is refreshing. A golden color and light body with a taste of malt and wheat. Cucapá Honey4.5% ABV Amber Ale. Deep golden amber color with a frothy white head. Rich aromas of caramel, roasted grains, earthy, citrusy hop aromas. A frothy entry leads to a dry-yet-fruity medium body of candied citrus peels, mild spice and toasted grains. Finishes with a long, citrus-accented, piney fresh hop fade. Cucapá Light3.5% ABV Light Lager. Flavorful light lager with reduced alcohol and calories. Cucapá Barleywine10.0% ABV Barleywine. Dark reddish mahogany color. Roasted malt and dark caramel aromas. A rich, thick entry leads to a sweet molasses and chocolate covered citrus flavors.
Finishes with a mild, bitter hop fade. Cucapá Jefe4.5% ABV This Hefeweizen style beer without filtration process, made with wheat and malt. The Cucapá Jefe has a bright peach color. Cucapá Mestiza4.5 % ABV. Has a complete body and a distinguish hop flavor. Cerveceria de Baja California Cucapá - Official website. Wine Warehouse - California Distributor Little Guy Distributing - Arizona Distributor Union Tribune - "Mexican Beer Gets Serious"