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97-459: A tactic macromolecule in the IUPAC definition is a macromolecule in which essentially all the configurational (repeating) units are identical. Tacticity is particularly significant in vinyl polymers of the type - H 2 C-CH(R)- where each repeating unit with a substituent R on one side of the polymer backbone is followed by the next repeating unit with the substituent on the same side as

194-537: A coding system that represented long sequences of amino acids. This would allow for these sequences to be compared to try to find homologies . These codes can consist of either a one-letter code or a three-letter code. These codes make it easier and shorter to write down the amino acid sequences that make up proteins . The nucleotide bases are made up of purines ( adenine and guanine ) and pyrimidines ( cytosine and thymine or uracil ). These nucleotide bases make up DNA and RNA . These nucleotide base codes make

291-638: A melting point of 130 °C (266 °F). Below 0 °C, PP becomes brittle. The thermal expansion of PP is significant, but somewhat less than that of polyethylene. Propylene molecules prefer to join together "head-to-tail", giving a chain with methyl groups on every other carbon, but some randomness occurs. Polypropylene at room temperature is resistant to fats and almost 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 , tetralin and decalin . Due to

388-1014: A member state of the Chemical Weapons Convention (CWC), are of concern to chemical scientists and engineers around the globe and we stand ready to support your mission of implementing the CWC." According to the CWC, "the use, stockpiling, distribution, development or storage of any chemical weapons is forbidden by any of the 192 state party signatories." IUPAC is governed by several committees that all have different responsibilities. The committees are as follows: Bureau, CHEMRAWN (Chem Research Applied to World Needs) Committee, Committee on Chemistry Education, Committee on Chemistry and Industry, Committee on Printed and Electronic Publications, Evaluation Committee, Executive Committee, Finance Committee, Interdivisional Committee on Terminology, Nomenclature and Symbols, Project Committee, and Pure and Applied Chemistry Editorial Advisory Board. Each committee

485-525: A modifier. The catalysts are differentiated depending on the procedure used for fashioning catalyst particles from MgCl 2 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. Commercial synthesis of isotactic polypropylene

582-407: A random substituent. Atactic polymers are technologically very important. A good example is polystyrene (PS). If a special catalyst is used in its synthesis it is possible to obtain the syndiotactic version of this polymer, but most industrial polystyrene produced is atactic. The two materials have very different properties because the irregular structure of the atactic version makes it impossible for

679-402: A range, so the melting point is determined by finding the highest temperature of a differential scanning calorimetry chart. Perfectly isotactic PP has a melting point of 171 °C (340 °F). Commercial isotactic PP has a melting point that ranges from 160 to 166 °C (320 to 331 °F), depending on atactic material and crystallinity. Syndiotactic PP with a crystallinity of 30% has

776-543: A regular macromolecule all monomer units are normally linked in a head to tail configuration so that all β-substituents are separated by three carbon atoms. In head to head configuration this separation is only by two carbon atoms and the separation with tail to tail configuration is by four atoms. Head/tail configurations are not part of polymer tacticity but should be taken into account when considering polymer defects. Tacticity may be measured directly using proton or carbon-13 NMR . This technique enables quantification of

873-490: A wide range of useful products, such as face masks, filters, diapers and wipes. 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 large number of end-use applications for polypropylene are often possible because of

970-421: Is cyclohexanol : Basic IUPAC inorganic nomenclature has two main parts: the cation and the anion . The cation is the name for the positively charged ion and the anion is the name for the negatively charged ion. An example of IUPAC nomenclature of inorganic chemistry is potassium chlorate (KClO 3 ): IUPAC also has a system for giving codes to identify amino acids and nucleotide bases. IUPAC needed

1067-402: Is partially crystalline and non-polar . Its properties are similar to polyethylene , but it is slightly harder and more heat-resistant. It is a white, mechanically rugged material and has a high chemical resistance. Polypropylene is the second-most widely produced commodity plastic (after polyethylene ). Phillips Petroleum chemists J. Paul Hogan and Robert Banks first demonstrated

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1164-689: Is Germany. Germany's exclusion was a result of prejudice towards Germans by the Allied powers after World War I . Germany was finally admitted into IUPAC in 1929. However, Nazi Germany was removed from IUPAC during World War II . During World War II, IUPAC was affiliated with the Allied powers , but had little involvement during the war effort itself. After the war, East and West Germany were readmitted to IUPAC in 1973. Since World War II, IUPAC has been focused on standardizing nomenclature and methods in science without interruption. In 2016, IUPAC denounced

1261-651: Is a book about soil structures and the molecular processes that occur in soil. Structure and Surface Reactions of Soil Particles is aimed at any researcher researching soil or in the field of anthropology . It goes into depth on topics such as: fractal analysis of particle dimensions; computer modeling of the structure; reactivity of humics; applications of atomic force microscopy; and advanced instrumentation for analysis of soil particles. Metal Speciation and Bioavailability in Aquatic Systems, Series on Analytical and Physical Chemistry of Environmental Systems Vol. 3

1358-468: Is a book about the effect of trace metals on aquatic life. This book is considered a specialty book for researchers interested in observing the effect of trace metals in the water supply. This book includes techniques to assess how bioassays can be used to evaluate how an organism is affected by trace metals. Also, Metal Speciation and Bioavailability in Aquatic Systems, Series on Analytical and Physical Chemistry of Environmental Systems Vol. 3 looks at

1455-407: Is a book that delves into aerosol science. This book is aimed as a reference for graduate students and atmospheric researchers. Atmospheric Particles goes into depth on the properties of aerosols in the atmosphere and their effect. Topics covered in this book are: acid rain ; heavy metal pollution; global warming ; and photochemical smog. Atmospheric Particles also covers techniques to analyze

1552-463: Is a book that discusses techniques and devices to monitor aquatic systems and how new devices and techniques can be developed. This book emphasizes the future use of micro-analytical monitoring techniques and microtechnology . In Situ Monitoring of Aquatic Systems: Chemical Analysis and Speciation is aimed at researchers and laboratories that analyze aquatic systems such as rivers, lakes, and oceans. Structure and Surface Reactions of Soil Particles

1649-517: Is a book that gives background information on thermal analysis and calorimetry . Thermoanalytical and calorimetric techniques along with thermodynamic and kinetic properties are also discussed. Later volumes of this book discuss the applications and principles of these thermodynamic and kinetic methods. Equations of State for Fluids and Fluid Mixtures Part I is a book that gives up to date equations of state for fluids and fluid mixtures. This book covers all ways to develop equations of state. It gives

1746-501: Is a colorless, cloudy material and can be used between −15 and +120 °C. Atactic polypropylene is used as a sealant, as an insulating material for automobiles and as an additive to bitumen . Polypropylene copolymers are in use as well. A particularly important one is polypropylene random copolymer ( PPR or PP-R ), a random copolymer with polyethylene used for plastic pipework . Polypropylene random crystallinity temperature ( PP-RCT ), also used for plastic pipework ,

1843-553: Is a common quantitative measure of tacticity. When the stereochemistry of a macromolecule is considered to be a Bernoulli process , the triad composition can be calculated from the probability P m of a diad being m type . For example, when this probability is 0.25 then the probability of finding: with a total probability of 1. Similar relationships with diads exist for tetrads. The definition of tetrads and pentads introduce further sophistication and precision to defining tacticity, especially when information on long-range ordering

1940-492: Is a measure of molecular weight of polypropylene. The measure helps to determine how easily the molten raw material will flow during processing. Polypropylene with higher MFR will fill the plastic mold more easily during the injection or blow-molding production process. As the melt flow increases, however, some physical properties, like impact strength, will decrease. There are three general types of polypropylene: homopolymer , random copolymer, and block copolymer . The comonomer

2037-410: Is a new form of this plastic. It achieves higher strength at high temperature by β- crystallization . Polypropylene is liable to chain degradation from exposure to temperatures above 100 °C. Oxidation usually occurs at the tertiary carbon centers leading to chain breaking via reaction with oxygen . In external applications, degradation is evidenced by cracks and crazing . It may be protected by

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2134-592: Is also known for standardizing the atomic weights of the elements through one of its oldest standing committees, the Commission on Isotopic Abundances and Atomic Weights (CIAAW). The need for an international standard for chemistry was first addressed in 1860 by a committee headed by German scientist Friedrich August Kekulé von Stradonitz . This committee was the first international conference to create an international naming system for organic compounds . The ideas that were formulated at that conference evolved into

2231-726: Is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is a member of the International Science Council (ISC). IUPAC is registered in Zürich , Switzerland , and the administrative office, known as the "IUPAC Secretariat", is in Research Triangle Park , North Carolina , United States . IUPAC's executive director heads this administrative office, currently Greta Heydenrych. IUPAC

2328-407: Is as biaxially oriented polypropylene (BOPP). These BOPP sheets are used to make a wide variety of materials including clear bags . When polypropylene is biaxially oriented, it becomes crystal clear and serves as an excellent packaging material for artistic and retail products. Polypropylene, highly colorfast, is widely used in manufacturing carpets, rugs and mats to be used at home. Polypropylene

2425-421: Is between 0.895 and 0.93 g/cm . 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, crystalline and amorphous regions differ only slightly in their density. However, the density of polyethylene can significantly change with fillers. The Young's modulus of PP

2522-413: Is between 1300 and 1800 N/mm². Polypropylene is normally tough and flexible, especially when copolymerized with ethylene . This allows polypropylene to be used as an engineering plastic , competing with materials such as acrylonitrile butadiene styrene (ABS). Polypropylene is reasonably economical. Polypropylene has good resistance to fatigue . The melting point of polypropylene occurs in

2619-483: Is called an m diad (formerly meso diad , as in a meso compound , now proscribed). If a diad consists of units oriented in opposition, the diad is called an r diad (formerly racemo diad , as in a racemic compound, now proscribed). In the case of vinyl polymer molecules, an m diad is one in which the substituents are oriented on the same side of the polymer backbone: in the Natta projection, they both point into

2716-439: Is desirable. Tacticity measurements obtained by carbon-13 NMR are typically expressed in terms of the relative abundance of various pentads within the polymer molecule, e.g. mmmm , mrrm . The primary convention for expressing tacticity is in terms of the relative weight fraction of triad or higher-order components, as described above. An alternative expression for tacticity is the average length of m and r sequences within

2813-413: Is easy to coat, print and laminate to give the required appearance and properties for use as a packaging material. This process is normally called converting . It is normally produced in large rolls which are slit on slitting machines into smaller rolls for use on packaging machines. BOPP is also used for stickers and labels in addition to OPP. It is non-reactive, which makes BOPP suitable for safe use in

2910-456: 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, a bi-directional stenter process or a double-bubble blown film extrusion process. Biaxial orientation increases strength and clarity. BOPP is widely used as a packaging material for packaging products such as snack foods, fresh produce and confectionery. It

3007-423: Is given as 185 to 220 °C, the density as 0.936 to 0.946 g·cm . The β-modification is in comparison somewhat less ordered, as a result of which it forms faster and has a lower melting point of 170 to 200 °C. The formation of the β-modification can be promoted by nucleating agents, suitable temperatures and shear stress. The γ-modification is hardly formed under the conditions used in industry and

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3104-832: Is made up of members of different National Adhering Organizations from different countries. The steering committee hierarchy for IUPAC is as follows: Chemical Nomenclature and Structure Representation Division (Division VIII) Current officers of the Executive Committee : Scientists framed a systematic method for naming organic compounds based on their structures. Hence, the naming rules were formulated by IUPAC. IUPAC establishes rules for harmonized spelling of some chemicals to reduce variation among different local English-language variants. For example, they recommend " aluminium " rather than "aluminum", " sulfur " rather than "sulphur", and " caesium " rather than "cesium". IUPAC organic nomenclature has three basic parts:

3201-447: 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. 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. Modern supported Ziegler-Natta catalysts developed for

3298-427: Is manufactured using melt processing with either chemical or physical blowing agents. Expansion of PP in solid state, due to its highly crystalline structure, has not been successful. In this regard, two novel strategies were developed for expansion of PP. It was observed that PP can be expanded to make EPP through controlling its crystalline structure or through blending with other polymers. When polypropylene film

3395-465: Is meant to be a compilation of other IUPAC works. The second edition of this book was published in 1997. This book made large changes to the first edition of the Compendium of Chemical Terminology . These changes included updated material and an expansion of the book to include over seven thousand terms. The second edition was the topic of an IUPAC XML project. This project made an XML version of

3492-483: Is meant to give an overview of a technique based on fractal geometry and the processes of environmental systems. This book gives ideas on how to use fractal geometry to compare and contrast different ecosystems . It also gives an overview of the knowledge needed to solve environmental problems. Finally, Biophysical Chemistry of Fractal Structures and Processes in Environmental Systems shows how to use

3589-418: Is ongoing to the present. For example, making polypropylene from bio-based resources is a topic of interest in the 21st century. Polypropylene is in little aspects similar to polyethylene , especially in solution behavior and electrical properties. The methyl group improves mechanical properties and thermal resistance, although the chemical resistance decreases. The properties of polypropylene depend on

3686-457: Is poorly understood. The mesomorphic modification, however, occurs often in industrial processing, since the plastic is usually cooled quickly. The degree of order of the mesomorphic phase ranges between the crystalline and the amorphous phase, its density is with 0.916 g·cm comparatively. The mesomorphic phase is considered as cause for the transparency in rapidly cooled films (due to low order and small crystallites). Syndiotactic polypropylene

3783-759: Is relatively well received as being useful for reviewing chemical toxicology. Macromolecular Symposia is a journal that publishes fourteen issues a year. This journal includes contributions to the macromolecular chemistry and physics field. The meetings of IUPAC are included in this journal along with the European Polymer Federation , the American Chemical Society , and the Society of Polymer Science in Japan. The Experimental Thermodynamics books series covers many topics in

3880-533: Is the Compendium of Analytical Nomenclature (the "Orange Book"; 1st edition 1978). This book was revised in 1987. The second edition has many revisions that come from reports on nomenclature between 1976 and 1984. In 1992, the second edition went through many different revisions, which led to the third edition. Pure and Applied Chemistry is the official monthly journal of IUPAC. This journal debuted in 1960. The goal statement for Pure and Applied Chemistry

3977-769: Is the recognized world authority in developing standards for naming the chemical elements and compounds . Since its creation, IUPAC has been run by many different committees with different responsibilities. These committees run different projects which include standardizing nomenclature , finding ways to bring chemistry to the world, and publishing works. IUPAC is best known for its works standardizing nomenclature in chemistry, but IUPAC has publications in many science fields including chemistry, biology, and physics. Some important work IUPAC has done in these fields includes standardizing nucleotide base sequence code names; publishing books for environmental scientists, chemists, and physicists; and improving education in science. IUPAC

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4074-443: Is to "publish highly topical and credible works at the forefront of all aspects of pure and applied chemistry." The journal itself is available by subscription, but older issues are available in the archive on IUPAC's website. Pure and Applied Chemistry was created as a central way to publish IUPAC endorsed articles. Before its creation, IUPAC did not have a quick, official way to distribute new chemistry information. Its creation

4171-518: Is typically 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. [REDACTED] Polypropylene can be categorized as atactic polypropylene (aPP), syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP). In case of atactic polypropylene,

4268-416: Is usually carried out either in the medium of liquid propylene or in gas-phase reactors. Commercial synthesis of syndiotactic polypropylene is carried out with the use of a special class of metallocene catalysts. They employ bridged bis-metallocene complexes of the type bridge-(Cp 1 )(Cp 2 )ZrCl 2 where the first Cp ligand is the cyclopentadienyl group, the second Cp ligand is the fluorenyl group, and

4365-420: The substituents , carbon chain length, and chemical affix. The substituents are any functional groups attached to the main carbon chain. The main carbon chain is the longest possible continuous chain. The chemical affix denotes what type of molecule it is. For example, the ending ane denotes a single bonded carbon chain, as in "hexane" ( C 6 H 14 ). Another example of IUPAC organic nomenclature

4462-536: The IUPAC Council during the General Assembly. Below is the list of IUPAC Presidents since its inception in 1919. Polypropylene Polypropylene ( PP ), also 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

4559-549: The Pacific Ocean are a result of reduced chlorophyll for phytoplankton production. It does this by reviewing information from research in the 1990s. This book goes into depth about: chemical speciation; analytical techniques; transformation of iron; how iron limits the development of high nutrient low chlorophyll areas in the Pacific Ocean . In Situ Monitoring of Aquatic Systems: Chemical Analysis and Speciation

4656-633: The Terrestrial Ecosystem gives techniques to analyze minerals, microorganisms, and organic components together. This book also has a large section positing why environmental scientists working in the specific fields of minerals, microorganisms, and organic components of soil should work together and how they should do so. The Biogeochemistry of Iron in Seawater is a book that describes how low concentrations of iron in Antarctica and

4753-500: The Terrestrial Ecosystem is about how minerals, microorganisms, and organic components work together to affect terrestrial systems . This book identifies that there are many different techniques and theories about minerals, microorganisms, and organic components individually, but they are not often associated with each other. It further goes on to discuss how these components of soil work together to affect terrestrial life. Interactions Between Soil Particles and Microorganisms: Impact on

4850-487: The Thermodynamic Properties of Multiple Phases is a book that includes multiple techniques that are used to study multiple phases of pure component systems. Also included in this book are the measurement techniques to obtain activity coefficients , interfacial tension , and critical parameters . This book was written for researchers and graduate students as a reference source. Atmospheric Particles

4947-423: The Thermodynamic Properties of Single Phases is a book that gives an overview of techniques for measuring the thermodynamic quantities of single phases. It also goes into experimental techniques to test many different thermodynamic states precisely and accurately. Measurement of the Thermodynamic Properties of Single Phases was written for people interested in measuring thermodynamic properties. Measurement of

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5044-430: The aPP obtained this way is not completely amorphous but can still contain 15% crystalline parts. Atactic polypropylene can also be produced selectively using metallocene catalysts, atactic polypropylene produced this way has a considerably higher molecular weight. Atactic polypropylene has lower density, melting point and softening temperature than the crystalline types and is tacky and rubber-like at room temperature. It

5141-509: The ability to tailor grades with specific molecular properties and additives during its manufacture. For example, antistatic additives can be added to help polypropylene surfaces resist dust and dirt. 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. Expanded Polypropylene (EPP) has been produced through both solid and melt state processing. EPP

5238-704: The atmosphere and ways to take atmospheric samples. Environmental Colloids and Particles: Behaviour, Separation and Characterisation is a book that discusses environmental colloids and current information available on them. This book focuses on environmental colloids and particles in aquatic systems and soils. It also goes over techniques such as techniques for sampling environmental colloids, size fractionation, and how to characterize colloids and particles. Environmental Colloids and Particles: Behaviour, Separation and Characterisation also delves into how these colloids and particles interact. Biophysical Chemistry of Fractal Structures and Processes in Environmental Systems

5335-554: The book that includes over seven thousand terms. The XML version of the book includes an open editing policy, which allows users to add excerpts of the written version. IUPAC and UNESCO were the lead organizations coordinating events for the International Year of Chemistry , which took place in 2011. The International Year of Chemistry was originally proposed by IUPAC at the general assembly in Turin , Italy. This motion

5432-638: The bridge between the two Cp ligands is -CH 2 -CH 2 -, >SiMe 2 , or >SiPh 2 . These complexes are converted to polymerization catalysts by activating them with a special organoaluminium co-catalyst, methylaluminoxane (MAO). Atactic polypropylene is an amorphous rubbery material. It can be produced commercially either with a special type of supported Ziegler-Natta catalyst or with some metallocene catalysts. Melting process of polypropylene can be achieved via extrusion and molding . Common extrusion methods include production of melt-blown and spun-bond fibers to form long rolls for future conversion into

5529-418: The chain. Isotactic and syndiotactic polymers are instances of the more general class of eutactic polymers, which also includes heterogeneous macromolecules in which the sequence consists of substituents of different kinds (for example, the side-chains in proteins and the bases in nucleic acids). In vinyl polymers the complete configuration can be further described by defining polymer head/tail configuration. In

5626-522: The desired level. Other techniques sensitive to tacticity include x-ray powder diffraction , secondary ion mass spectrometry (SIMS), vibrational spectroscopy (FTIR) and especially two-dimensional techniques. Tacticity may also be inferred by measuring another physical property, such as melting temperature, when the relationship between tacticity and that property is well-established. IUPAC The International Union of Pure and Applied Chemistry ( IUPAC / ˈ aɪ juː p æ k , ˈ juː -/ )

5723-470: The effect of an equipment setup on an experiment. Fundamental Toxicology is a textbook that proposes a curriculum for toxicology courses. Fundamental Toxicology is based on the book Fundamental Toxicology for Chemists . Fundamental Toxicology is enhanced through many revisions and updates. New information added in the revisions includes: risk assessment and management; reproductive toxicology; behavioral toxicology; and ecotoxicology . This book

5820-522: The fields of thermodynamics. Measurement of the Transport Properties of Fluids is a book that is published by Blackwell Science . The topics that are included in this book are low and high-temperature measurements, secondary coefficients, diffusion coefficients , light scattering , transient methods for thermal conductivity , methods for thermal conductivity, falling-body viscometers, and vibrating viscometers . Solution Calorimetry

5917-530: The fractal approach to understand the reactivity of flocs , sediments, soils, microorganisms, and humic substances. Interactions Between Soil Particles and Microorganisms: Impact on the Terrestrial Ecosystem is meant to be read by chemists and biologists that study environmental systems. Also, this book should be used as a reference for earth scientists, environmental geologists, environmental engineers, and professionals in microbiology and ecology. Interactions Between Soil Particles and Microorganisms: Impact on

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6014-467: The genome of an organism much smaller and easier to read. The codes for amino acids (24 amino acids and three special codes) are: Principles and Practices of Method Validation is a book entailing methods of validating and analyzing many analytes taken from a single aliquot . Also, this book goes over techniques for analyzing many samples at once. Some methods discussed include chromatographic methods, estimation of effects, matrix-induced effects, and

6111-414: The heat in an autoclave . Its heat resistance also enables it to be used as the manufacturing material of consumer-grade kettles . Food containers made from it will not melt in the dishwasher, and do not melt during industrial hot filling processes. For this reason, most plastic tubs for dairy products are polypropylene sealed with aluminum foil (both heat-resistant materials). After the product has cooled,

6208-660: The hinge to maximise strength. Polypropylene is used in the manufacturing of piping systems, both ones concerned with high purity and ones designed for strength and rigidity (e.g., those intended for use in potable plumbing, hydronic heating and cooling, and reclaimed water ). This material is often chosen for its resistance to corrosion and chemical leaching, its resilience against most forms of physical damage, including impact and freezing, its environmental benefits, and its ability to be joined by heat fusion rather than gluing. Many plastic items for medical or laboratory use can be made from polypropylene because it can withstand

6305-691: The human body as implantable mesh devices. The degraded material forms a tree bark-like layer at the surface of mesh fibers. PP can be made translucent when uncolored but is not as readily made transparent as polystyrene , acrylic , or certain other plastics. It is often opaque or colored using pigments. Polypropylene is produced by the chain-growth polymerization of propene : [REDACTED] The industrial production processes can be grouped into gas phase polymerization, bulk polymerization and slurry polymerization. All state-of-the-art processes use either gas-phase or bulk reactor systems. The properties of PP are strongly affected by its tacticity ,

6402-651: The lids are often made of somewhat more flexible LDPE so they can snap onto the container to close it. Polypropylene can also be made into disposable bottles to contain liquid, powdered, or similar consumer products, although HDPE and polyethylene terephthalate are commonly also used to make bottles. Plastic pails, car batteries, wastebaskets, pharmacy prescription bottles, cooler containers, dishes and pitchers are often made of polypropylene or HDPE, both of which commonly have rather similar appearance, feel, and properties at ambient temperature. An abundance of medical devices are made from PP. A common application for polypropylene

6499-742: The limitations of the use of bioassays to observe the effects of trace metals on organisms. Physicochemical Kinetics and Transport at Biointerfaces is a book created to aid environmental scientists in fieldwork. The book gives an overview of chemical mechanisms, transport, kinetics, and interactions that occur in environmental systems . Physicochemical Kinetics and Transport at Biointerfaces continues from where Metal Speciation and Bioavailability in Aquatic Systems leaves off. IUPAC color code their books in order to make each publication distinguishable. One extensive book on almost all nomenclature written (IUPAC nomenclature of organic chemistry and IUPAC nomenclature of inorganic chemistry) by IUPAC committee

6596-407: The methyl group (-CH 3 ) 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 T g and melting point T m ). The term tacticity describes for polypropylene how the methyl group is oriented in

6693-424: The molecular arrangement of the polymer chains. The crystalline modifications are categorized into the α-, β- and γ-modification as well as mesomorphic (smectic) forms. The α-modifications is predominant in iPP. Such crystals are built from lamellae in the form of folded chains. A characteristic anomaly is that the lame are arranged in the so-called "cross-hatched" structure. The melting point of α-crystalline regions

6790-444: The molecular weight and molecular weight distribution, crystallinity, type and proportion of comonomer (if used) and the iso tacticity . 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 that is more resistant to creep than both atactic polypropylene and polyethylene. The density of PP

6887-441: The official IUPAC nomenclature of organic chemistry . IUPAC stands as a legacy of this meeting, making it one of the most important historical international collaborations of chemistry societies . Since this time, IUPAC has been the official organization held with the responsibility of updating and maintaining official organic nomenclature . IUPAC as such was established in 1919. One notable country excluded from this early IUPAC

6984-458: The orientation of the methyl groups ( CH 3 ) relative to the methyl groups in neighboring monomer units. A Ziegler–Natta catalyst is able to restrict linking of monomer molecules to a specific orientation, either isotactic, when all methyl groups are positioned at the same side with respect to the backbone of the polymer chain, or syndiotactic, when the positions of the methyl groups alternate. Commercially available isotactic polypropylene

7081-400: The other hand, lacks any regularity, which prevents it from crystallization, thereby creating an amorphous material. Isotactic polypropylene has a high degree of crystallinity , in industrial products 30–60%. Syndiotactic polypropylene is slightly less crystalline, atactic PP is amorphous (not crystalline). Is polypropylene can exist in various crystalline modifications which differ by

7178-409: The pharmaceutical and food industry. It is one of the most important commercial polyolefin films. BOPP films are available in different thicknesses and widths. They are transparent and flexible. As polypropylene is resistant to fatigue, most plastic living hinges , such as those on flip-top bottles, are made from this material. However, it is important to ensure that chain molecules are oriented across

7275-443: The plane or both point out of the plane. The stereochemistry of macromolecules can be defined even more precisely with the introduction of triads. An isotactic triad ( mm ) is made up of two adjacent m diads, a syndiotactic triad (also spelled syndyotactic ) ( rr ) consists of two adjacent r diads , and a heterotactic triad ( rm ) is composed of an r diad adjacent to an m diad . The mass fraction of isotactic ( mm ) triads

7372-463: The polymer chain. Commercial polypropylene is usually isotactic. This article therefore always refers to isotactic polypropylene, unless stated otherwise. The tacticity is usually indicated in percent, using the isotactic index (according to DIN 16774). The index is measured by determining the fraction of the polymer insoluble in boiling heptane . Commercially available polypropylenes usually have an isotactic index between 85 and 95%. The tacticity effects

7469-427: The polymer chains to stack in a regular fashion. The result is that, whereas syndiotactic PS is a semicrystalline material, the more common atactic version cannot crystallize and forms a glass instead. This example is quite general in that many polymers of economic importance are atactic glass formers. In eutactic macromolecules, substituents may occupy any specific (but potentially complex) sequence of positions along

7566-817: The polymer molecule. The average m-sequence length may be approximated from the relative abundance of pentads as follows: M S L = m m m m + 3 2 m r r r + 2 r m m r + 1 2 r m r m + 1 2 r m r r 1 2 m m m r + r m m r + 1 2 r m r m + 1 2 r m r r {\displaystyle MSL={\frac {mmmm+{\tfrac {3}{2}}mrrr+2rmmr+{\tfrac {1}{2}}rmrm+{\tfrac {1}{2}}rmrr}{{\tfrac {1}{2}}mmmr+rmmr+{\tfrac {1}{2}}rmrm+{\tfrac {1}{2}}rmrr}}} Isotactic polymers are composed of isotactic macromolecules (IUPAC definition). In isotactic macromolecules all

7663-412: The polymerization of propylene and other 1-alkenes to isotactic polymers usually use TiCl 4 as an active ingredient and MgCl 2 as a support. The catalysts also contain organic modifiers, either aromatic acid esters and diesters or ethers. These catalysts are activated with special co-catalysts containing an organoaluminium compound such as Al(C 2 H 5 ) 3 and the second type of

7760-514: The polymerization of propylene in 1951. The stereoselective polymerization to the isotactic was discovered by Giulio Natta and 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 also first synthesized by Natta. Interest in polypropylene development

7857-443: The polymers physical properties . As the methyl group is in isotactic propylene consistently located at the same side, it forces the macromolecule in a helical shape , as also found in starch . An isotactic structure leads to a semi-crystalline polymer . The higher the isotonicity(the isotactic fraction), the greater the crystallinity, and thus also the softening point, rigidity, e-modulus and hardness. Atactic polypropylene, on

7954-662: The previous one, the other side as the previous one or positioned randomly with respect to the previous one. In a hydrocarbon macromolecule with all carbon atoms making up the backbone in a tetrahedral molecular geometry , the zigzag backbone is in the paper plane with the substituents either sticking out of the paper or retreating into the paper. This projection is called the Natta projection after Giulio Natta . Monotactic macromolecules have one stereoisomeric atom per repeat unit, ditactic to n-tactic macromolecules have more than one stereoisomeric atom per unit. The orderliness of

8051-479: The strengths and weaknesses of each equation. Some equations discussed include: virial equation of state cubic equations; generalized Van der Waals equations ; integral equations; perturbation theory; and stating and mixing rules. Other things that Equations of State for Fluids and Fluid Mixtures Part I goes over are: associating fluids, polymer systems, polydisperse fluids, self-assembled systems, ionic fluids, and fluids near their critical points. Measurement of

8148-468: The substituents are located on the same side of the macromolecular backbone. An isotactic macromolecule consists of 100% m diads , though IUPAC also allows the term for macromolecules with at least 95% m diads if that looser usage is explained. Polypropylene formed by Ziegler–Natta catalysis is an example isotactic polymer. Isotactic polymers are usually semicrystalline and often form a helix configuration. In syndiotactic or syntactic macromolecules

8245-618: The substituents are placed randomly along the chain. The percentage of m diads is understood to be between 45 and 55% unless otherwise specified, but it could be any value other than 0 or 100% if that usage is clarified. With the aid of spectroscopic techniques such as NMR , it is possible to pinpoint the composition of a polymer in terms of the percentages for each triad. Polymers that are formed by free-radical mechanisms such as polyvinyl chloride are usually atactic. Due to their random nature atactic polymers are usually amorphous . In hemi isotactic macromolecules every other repeat unit has

8342-432: The substituents have alternate positions along the chain. The macromolecule comprises 100% r diads , though IUPAC also allows the term for macromolecules with at least 95% r diads if that looser usage is explained. Syndiotactic polystyrene , made by metallocene catalysis polymerization , is crystalline with a melting point of 161 °C. Gutta percha is also an example syndiotactic polymer. In atactic macromolecules

8439-403: The succession of configurational repeating units in the main chain of a regular macromolecule , a regular oligomer molecule, a regular block, or a regular chain. Two adjacent structural units in a polymer molecule constitute a diad . Diads overlap: each structural unit is considered part of two diads, one diad with each neighbor. If a diad consists of two identically oriented units, the diad

8536-411: The tacticity distribution by comparison of peak areas or integral ranges corresponding to known diads (r, m), triads (mm, rm+mr, rr) and/or higher order n -ads, depending on spectral resolution. In cases of limited resolution, stochastic methods such as Bernoullian or Markovian analysis may also be used to fit the distribution and predict higher n -ads and calculate the isotacticity of the polymer to

8633-527: The tertiary carbon atom, PP is chemically less resistant than PE (see Markovnikov rule ). Most commercial polypropylene is isotactic and has an intermediate level of crystallinity between that of low-density polyethylene (LDPE) and high-density polyethylene (HDPE). 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 (MFR) or melt flow index (MFI)

8730-520: The tubs are often given lids made of a less heat-resistant material, such as LDPE or polystyrene. Such containers provide a good hands-on example of the difference in modulus, since the rubbery (softer, more flexible) feeling of LDPE with respect to polypropylene of the same thickness is readily apparent. Rugged, translucent, reusable plastic containers made in a wide variety of shapes and sizes for consumers from various companies such as Rubbermaid and Sterilite are commonly made of polypropylene, although

8827-607: The use of chlorine as a chemical weapon . The organization pointed out their concerns in a letter to Ahmet Üzümcü, the director of the Organisation for the Prohibition of Chemical Weapons (OPCW), in regards to the practice of utilizing chlorine for weapon usage in Syria among other locations. The letter stated, "Our organizations deplore the use of chlorine in this manner. The indiscriminate attacks, possibly carried out by

8924-401: The use of various polymer stabilizers , including UV-absorbing additives and anti-oxidants such as phosphites (e.g. tris(2,4-di-tert-butylphenyl)phosphite ) and hindered phenols, which prevent polymer degradation . Microbial communities isolated from soil samples mixed with starch have been shown to be capable of degrading polypropylene. Polypropylene has been reported to degrade while in

9021-529: Was adopted by UNESCO at a meeting in 2008. The main objectives of the International Year of Chemistry were to increase public appreciation of chemistry and gain more interest in the world of chemistry . This event is also being held to encourage young people to get involved and contribute to chemistry. A further reason for this event being held is to honour how chemistry has made improvements to everyone's way of life. IUPAC Presidents are elected by

9118-510: Was decided that the journal would reprint old journal editions to keep all chemistry knowledge available. The Compendium of Chemical Terminology , also known as the "Gold Book", was originally worked on by Victor Gold . This book is a collection of names and terms already discussed in Pure and Applied Chemistry . The Compendium of Chemical Terminology was first published in 1987. The first edition of this book contains no original material, but

9215-474: Was discovered much later than isotactic PP and could only be prepared by using metallocene catalysts . Syndiotactic PP has a lower melting point, with 161 to 186 °C, depending on the degree of tacticity. Atactic polypropylene is amorphous and has therefore no crystal structure. Due to its lack of crystallinity, it is readily soluble even at moderate temperatures, which allows to separate it as by-product from isotactic polypropylene by extraction . However,

9312-644: Was established in 1919 as the successor of the International Congress of Applied Chemistry for the advancement of chemistry . Its members, the National Adhering Organizations, can be national chemistry societies , national academies of sciences , or other bodies representing chemists. There are fifty-four National Adhering Organizations and three Associate National Adhering Organizations. IUPAC's Inter-divisional Committee on Nomenclature and Symbols ( IUPAC nomenclature )

9409-537: Was first suggested at the Paris IUPAC Meeting of 1957. During this meeting the commercial publisher of the journal was discussed and decided on. In 1959, the IUPAC Pure and Applied Chemistry Editorial Advisory Board was created and put in charge of the journal. The idea of one journal being a definitive place for a vast amount of chemistry was difficult for the committee to grasp at first. However, it

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