abbreviations Usage of “p ” versus “pp.” versus “pg.” to denote page numbers and page ranges English Language & Usage Stack Exchange


Polypropylene is one plastic that can be used for products now and can be recycled into products for the future as well. More than 93 percent of the urine samples examined in a CDC study contained BPA concentrations. It’s important to note, however, that some newer research does point to toxicity in certain polypropylene containers. Per Strunk and White’s Elements of Style, p. is used to denote 1 page, pp. to denote a range of pages.

  • The tacticity of polypropylene can be chosen by the choice of an appropriate catalyst.
  • The high surface-area and naturally oleophilic polypropylene nonwovens are ideal absorbers of oil spills with the familiar[citation needed] floating barriers near oil spills on rivers.
  • As the melt flow increases, some of the physical properties of the plastic decreases, however, such as impact strength.
  • Since the early 1980s production and consumption have increased significantly, owing to the invention of more efficient catalyst systems by Montedison and the Japanese Mitsui Petrochemical Industries, Ltd.

Polypropylene, a synthetic resin built up by the polymerization of propylene. One of the important family of polyolefin resins, polypropylene is molded or extruded into many plastic products in which toughness, flexibility, light weight, and heat resistance are required. It is also spun into fibres for employment in industrial and household textiles. Propylene can also be polymerized with ethylene to produce an elastic ethylene-propylene copolymer.

Understanding Polypropylene Plastics

The tacticity of polypropylene can be chosen by the choice of an appropriate catalyst. All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. Understanding its importance will allow you to appreciate it to the fullest.

The flow rate is a measure of molecular weight and this determines how easily it will flow during processing. As the melt flow increases, some of the physical properties of the plastic decreases, however, such as impact strength. The melt flow rate (MFR) or melt flow index (MFI) is a measure of molecular weight of polypropylene.

Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. Ropes, cable insulation, roofing membranes, storage boxes, disposable bottles, plastic pails, and other items are also made using this type of plastic. When you consider the impact of this plastic on your everyday use, you will see that it is one plastic that most people just cannot live without.

  • A small patch of the material is placed over the spot of the hernia, below the skin, and is painless and rarely, if ever, rejected by the body.
  • This research hasn’t changed the FDA’s or the EPA’s recommendations for the use of polypropylene.
  • Connect and share knowledge within a single location that is structured and easy to search.

Isotactic polypropylene is produced at low temperatures and pressures, using Ziegler-Natta catalysts. The polymer shares some of the properties of polyethylene, but it is stronger, stiffer, and harder, and it softens at higher temperatures. (Its melting point is approximately 170 °C [340 °F].) It is slightly more prone to oxidation than polyethylene unless appropriate stabilizers and antioxidants are added. Polypropylene is blow-molded into bottles for foods, shampoos, and other household liquids. It is also injection-molded into many products, including appliance housings, dishwasher-safe food containers, toys, automobile battery casings, and outdoor furniture.

Polypropylene Terpolymer

Very thin sheets (≈2–20 µm) of polypropylene are used as a dielectric within certain high-performance pulse and low-loss RF capacitors. Polypropylene is also used in particular roofing membranes as the waterproofing top layer of single-ply systems as opposed to modified-bit systems. Polypropylene is also used as an alternative to polyvinyl chloride (PVC) as insulation for electrical cables for LSZH cable in low-ventilation environments, primarily tunnels. This is because it emits less smoke and no toxic halogens, which may lead to production of acid in high-temperature conditions. You can tell you’re using a polypropylene container if the number 5 surrounded by a triangle is on the bottom of the container. Nearly everything we eat, drink, or own contains plastic or is contained in plastic.

p. American Dictionary

These catalysts are activated with special cocatalysts containing an organoaluminum compound such as Al(C2H5)3 and the second type of a modifier. The catalysts are differentiated depending on the procedure used for fashioning catalyst particles from MgCl2 and depending on the type of organic modifiers employed during catalyst preparation and use in polymerization reactions. Two most important technological characteristics of all the supported catalysts are high productivity and a high fraction of the crystalline isotactic polymer they produce at 70–80 °C under standard polymerization conditions.

British Dictionary definitions for pp (2 of

Some plastics, like those that contain BPA or other harmful chemicals, can negatively affect our bodies or the world we live in. The APA style of referencing, which I have most frequently used, requires that p. is used for single page references or citations (Book Title, p. 13) while for multiple pages you must cite it as (pp. 35-40). I have not encountered pg to be used, but I do use it in informal note taking. Atactic polypropylene, on the other hand, lacks any regularity which makes it unable to crystallize and amorphous. This research hasn’t changed the FDA’s or the EPA’s recommendations for the use of polypropylene.

The properties of PP are strongly affected by its tacticity, the orientation of the methyl groups (CH3 in the figure) relative to the methyl groups in neighboring monomer units. Commercially available isotactic polypropylene is made with two types of Ziegler-Natta catalysts. The first group of the catalysts encompasses solid (mostly supported) catalysts and certain types of soluble metallocene catalysts.

Many physical finishing techniques can also be used on polypropylene, such as machining. Surface treatments can be applied to polypropylene parts in order to promote adhesion of printing ink and paints. Bisphenol A (BPA) is a chemical used in the manufacturing of polycarbonate plastics.

Such isotactic macromolecules coil into a helical shape; these helices then line up next to one another to form the crystals that give commercial isotactic polypropylene many of its desirable properties. Polypropylene can be categorized as atactic polypropylene (aPP), syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP). In case of atactic polypropylene, the methyl group (-CH3) is randomly aligned, alternating (alternating) for syndiotactic polypropylene and evenly for isotactic polypropylene. This has an impact on the crystallinity (amorphous or semi-crystalline) and the thermal properties (expressed as glass transition point Tg and melting point Tm). When polypropylene film is extruded and stretched in both the machine direction and across machine direction it is called biaxially oriented polypropylene. Two methods are widely used for producing BOPP films, namely, the tenter process and tubular process.

The most common shaping technique is injection molding, which is used for parts such as cups, cutlery, vials, caps, containers, housewares, and automotive parts such as batteries. The related techniques of blow molding and injection-stretch blow molding are also used, which involve both extrusion and molding. The properties of PP are strongly affected by its tacticity, the orientation of the methyl groups (CH3) relative to the methyl groups in neighboring monomer units (see above).


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