Polypropylene processing

Such repositioning inevitably means reduced production volume, and for the first time this century production in the last decade has been below that a decade earUer (Eig. 9). Most capacity reductions have been in North America and especiaUy eastern Europe. This has been offset in part by capacity increases in the Ear East. Rayon is no longer a significant component of carpets, and has lost the disposable diaper coverstock business to cheaper and more easUy processed polypropylene. It has, however, gained share in health and hygiene products and is now a principal component of tampons worldwide. 

During processing polypropylene melts under the action of transverse strain there occur strain-chemical conversions which can result in both decrease and increase in their molecular masses the mechanical effect on the rapidity and level of the occurring processes is considerably more prominent than the mere contribution of thermal and thermal-oxidative breakdown. These data necessitate studying the process of polymer destruction. For this purpose it would be most effective to apply the criterion of assessment of the intensity with which destructive processes happen in polymer melts. 

Polymer Engineering and Science 43,No.l, Jan.2003,p.40-54 IMPORTANCE OF TIMELY POLYMER SINTERING WHILE PROCESSING POLYPROPYLENE FOAMS IN ROTATIONAL MOLDING... 

Pressure filters have recently become the most widely used dewatering devices in the industry, due to improvements in the process. Polypropylene filter material is typically used. Pressures of 80 to 225 psi are employed used to force the sludge water through the filters, leaving a filter cake containing 25 to 35% solids. 

The commercial production of high-density polyethylene started almost at the same time in late 1956 by Phillips using a chromium-based catalyst in a medium-pressure process and by Hoechst using a Ziegler catalyst in a low-pressure process. Polypropylene production began in Montecatini and Hercules plants in 1957. Poly(l-butene) and poly(4-methyl-1-pentene) have been produced in small commercial quantities since about 1965. The commercial production of ethylene/propylene-based rubbers started in 1960 [241]. 

The second part of this study [92] considered this peculiar point that has considerable consequences in terms of fundamental aspects of both the photooxidation of nanocomposites and the durability of these materials. A special attention was given to the interactions between the antioxidant, the clay (montmorillonite), and the compatibilizing agent (maleic anhydride), in terms of influence of each component on the rate of oxidation of the polymeric matrix. Two kinds of stabilizers were tested a phenolic antioxidant (Scheme 15.14) generally used to process polypropylene and a redox antioxidant of the hindered amine light stabilizer (HALS) class (Scheme 15.15) that is used as long-term stabilizer for polypropylene. 

In the two-step process, polypropylene resin of typically MFR = 35 g/min and isotacticity above 90% is spun at 280°C at a low speed of 200 m/min. The spun fiber, which has a structure of low-oriented hexagonal crystallinity, is drawn at a low temperature of 60°C over seven rolls. The drawn fiber, still having a paracrystalline structure, is drawn again at a higher temperature of 110°C 140°C to change the paracrystallinity into a highly oriented... 

For mica minerals, aspect ratio is defined as the average ratio of the average diameter of all particles to the average thickness of all particles. Until recently it has been impossible to accurately determine aspect ratios of different products. Attempts at predicting aspect ratio were made by measurement of diameters and thickness of individual particles using scanning electron microscopy. It is now possible to make this measurement with modern particle size measurement equipment. Research is currently underway to determine and develop a correlation of the aspect ratio of mica in processed polypropylene composites to observed mechanical properties. 

AUg I, Lellinger D, Dudkin S M and Potschke P (2007) Gonductivity spectroscopy on melt processed polypropylene-multiwaUed carbon nanotube composites recovery after shear and crystallization. Polymer 48 1020-1029. 

Aminated olefin pol mers Ethylene/a-olefin copol mer composition, graft modified, ethylene/a-olefin copolymer composition, ethylene copol mer composition, and multi-stage olefin polymerization process Polypropylene resin expanded particles... 

Potschke P, Kobashi K, Villmow T, Andres T, Paiva MC, Covas JA (2011) Liquid sensing properties of melt processed polypropylene/poly (e-caprolactone) blends containing multiwalled carbon nanotubes. Compos Sci Technol 71 1451... 

Extrusion is frequent method for polypropylene processing. Polypropylene film unambiguously belongs to versatile packaging materials. Almost 90 % of plastics packaging is used in food applications. Other applications include film packaging for stationery products, cigarettes, and textiles [7-9]. 

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