Polypropylene general plastic

Laboratory tests indicated that gamma radiation treatment and cross-linking using triaHylcyanurate or acetylene produced a flexible recycled plastic from mixtures of polyethylene, polypropylene, general-purpose polystyrene, and high impact grade PS (62). 

Since the painting aspect is not the prime reason for the selection it follows that the type of paint and the method of application must be suited to the plastic further, the properties that make a material useful in engineering often also make it harder to paint satisfactorily. As an indication, generally it is easier to paint ABS and polycarbonate than nylon, and easier to paint nylon than polyethylene or polypropylene. Other plastics that can give problems in painting include acetal (polyformaldehyde) and poly(phenylene oxide). 

Plastics. Polypropylene is inexpensive and is most popular when temperatures do not exceed 250°F. Caution is required where hot spots are likely, e.g., due to heat of solution. Other plastics may be better for higher temperatures, but these tend to be more expensive. Generally, plastic Pall rings are stiffer and resist softening more than other shapes because of their internal "arms. ... 

Unfilled polypropylene generally is not recommended for use in load-bearing applications, because the plastic creeps rapidly even under moderate stresses. Glass-reinforced grades, however, can be used in high-load applications. Polypropylene also has good unnotched and excellent notched impact strength. Polypropylene s heat resistance is much superior to that of polyethylene. 

Some plastics, such as polymethyl methacrylate, decompose under thermal exposure into their monomers. Other plastics, such as polypropylene, generally form an entire spectrum of decomposition products. 

Polyolefins. Interest has been shown in the plasticization of polyolefins (5) but plasticizer use generally results in a reduction of physical properties (12), and compatibiHty can be achieved only up to 2 wt %. Most polyolefins give adequate physical properties without plasticization. There has been use of plasticizers with polypropylene to improve its elongation at break (7) although the addition of plasticizer can lower T, room temperature strength, and flow temperature. This can be overcome by simultaneous plasticization (ca 15 wt % level) and cross-linking. Plasticizers used include DOA. 

Corrosion. Aqueous solutions of citric acid are mildly corrosive toward carbon steels. At elevated temperatures, 304 stainless steel is corroded by citric acid, but 316 stainless steel is resistant to corrosion. Many aluminum, copper, and nickel alloys are mildly corroded by citric acid. In general, glass and plastics such as fiber glass reinforced polyester, polyethylene, polypropylene, poly(vinyl chloride), and cross-linked poly(vinyl chloride) are not corroded by citric acid. 

FRP, plastics (polyvinyl chloride, polyethylene, polypropylene, and other similar materials), and rubber are general use and are recommended for alum solutions. Care must be taken to provide adequate support for these piping systems, with close attention given to spans between supports so that objectionable deflection will not be experienced. The alum solution should be injected into a zone of rapid mixing or turbulent flow. 

Efforts to improve IUDs have led to the use of medicated devices. Two types of agents are generally used—contraceptive metals and steroid hormones. The metal device is exemplified by the CU-7, a polypropylene plastic device in the shape of the number 7. Copper is released by a combination of ionization and chelation from a copper wire wrapped around the vertical limb. This system is effective for up to 40 months. 

Polypropylene film is found in a variety of applications. Films are thin plastic sheets with thicknesses less than 250 pm. Applications for these films include candy mappers, plastic label material, electrical capacitors (which requires very pure polymer), and fiber glass insulation backing. There are two general categories of polypropylene films unoriented and oriented. Films are manufactured through either a cast or a blown film extrusion process. Oriented films exhibit improved strength relative to unoriented films. This means that they can be... 

ISO 15874-1 2003 Plastics piping systems for hot and cold water installations - Polypropylene (PP)-Parti General... 

HTPC (Hybrid ThermoPlastic Composite) bumper beams made by Plastic Omnium are used by General Motors on the Pontiac Montana, Chevrolet Venture and Oldsmobile Silhouette. Continuous woven fibres are overmoulded with a long or short fibre reinforced polypropylene to save weight (6 kg), enhance impact resistance (20-40%) and integrate numerous functions such as reinforcement ribs. The process is fully automated. 

Thermoplastic Polymers. Most thermoplastic polymers are used in high-volume, widely recognized applications, so they are often referred to as commodity plastics. (We will elaborate upon the distinction between a polymer and a plastic in Chapter 7, but for now we simply note that a plastic is a polymer that contains other additives and is usually identified by a variety of commercial trade names. There are numerous databases, both in books [1] and on the Internet [2], that can be used to identify the primary polymer components of most plastics. With a few notable exceptions, we will refer to most polymers by their generic chemical name.) The most common commodity thermoplastics are polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and polystyrene (PS). These thermoplastics all have in common the general repeat unit -(CHX-CH2)-, where -X is -H for PE, -CH3 for PP, -Cl for PVC, and a benzene ring for PS. When we discuss polymerization reactions in Chapter 3, we will see that all of these thermoplastics can be produced by the same type of reaction. 

A wide range of rubbers are available for successful use as materials of construction and are applied in areas such as handling inorganic salt solutions where metals are unsuitable. The use of rubber linings is widespread in equipment such as tanks, pipes, and drums and most other critical chemical equipment. However, their use is limited to moderate temperatures, and they are generally suitable for use in abrasive duties. Some of the more commonly used plastics are PVC, PTFE and polypropylene. 

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