0000000016 00000 n Polymers with conjugated π-electron (i. e. system have C=C conjugated bonds) backbones display unusual electronic properties such as low energy optical transition, low ionization potentials, and high electron affinities. These polymers are nearly impossible to soften when heating without degrading the underlying polymer structure and are thus thermosetting polymers. endstream 0000007677 00000 n 48 0 obj <> endobj /F1 9 0 R /F2 10 0 R>> The length of the side chain influences the packing of these polymer chains in the melt or glassy state. • During the polymerization process not all chains in a polymer grow to the same length, so there is a distribution of molecular weights. Polyethylene, light, versatile synthetic resin made from the polymerization of ethylene. 0000003874 00000 n /Font<< Examples: polyethylene, PVC, nylon. /Im1 6 0 R>> Polymers are substances containing a large number of structural units joined by the same type of linkage. CHEM 379 – W20 Physical Properties of Polymers 6-1 6. In basic terms, a polymer is a long-chain molecule that is composed of a large number of repeating units of identical structure. Starch, cellulose, and rubber all possess polymeric properties. Overview; What is a Polymer? synthesis of polymers new structures and methods Oct 24, 2020 Posted By William Shakespeare Library TEXT ID 348e30a9 Online PDF Ebook Epub Library processes for the synthesis modification and characterisation of macromolecules in addition to the preparative aspects the book also gives the reader an impression on the structure. A Hydrocarbon backbone being a long chain of linked carbon and hydrogen atoms, possible due to the tetravalent nature of carbon.A few examples of a hydrocarbon backbone polymer are polypropylene, polybutylene, polystyrene. 15. The process by which the polymers are formed is called polymerisation. Polymers are not restricted to monomers of the same chemical composition or molecular weight and structure. /ProcSet [/PDF /Text /ImageC /ImageI] Some natural polymers are composed of one kind of monomer. Also, there are polymers which instead of carbon have other elements in its backbone. Explore how the properties of polymers depend on their structure and different types of intermolecular bonds using this lesson plan for 16–18 year olds In this activity, polymers are used as illustrative materials for intermolecular bonds to help students to learn how the structures of polymers relate to their practical uses and properties. information about structure or properties of polymers. Polymers. 0000007635 00000 n However, glassy polymers are difficult to self-heal at room temperature due to their frozen molecules. 0000000729 00000 n Carbon is the most common element in polymers. unusual properties of high polymers are developed, it will be convenient to consider the chemical and structural aspects of polymers at three different levels: 1) The chemical structure (atomic composition) of the monomer (primary structure) 2) The single polymer chain (secondary level) 3) Aggregation of polymer chains (tertiary structure) Typically 4,000 to 15,000 (depending on polymer structure) for a random coil polymer Corresponds to a degree of polymerization of about 600 (i.e., DP bar = 600) irrespective of polymer structure i) ii) ∴ This change in viscosity is a function of topology/entanglement and not chemical interactions 8 0 obj <> stream Polymers: Lecture 2 Prepared by Dr Arunima Nayak and Dr Brij Bhushan Classification of Polymers 1. Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. This leads to the important topic of the structure-property relations to which this book is devoted. Polymers and Polymerizations—Architecture 12 The number of complementary reactive sites and geometry of monomer determine %PDF-1.6 %���� >> The word “Polymer” is derived from two Greek words, ‘Poly’ that means many (numerous) and ‘Mer’ which means units. For example, Nylon, which contains nitrogen atoms in the repeated unit backbone. polymer structures Each parameter is important to the properties Each parameter is important to Polymer Chemistry, Chem 466, Spring 2014, January 14, 2014 . G H I I J K L M N N O P Q R S T U V W X X Y Z [ \ ] ] ^ _ ` a b c d !e "e "f "g "h #h #i #j #k #l $l $m $n $o %p %q %r &s. 68 0 obj<>stream Glassy polymers are widely used as structural materials in aerospace vehicles, airplanes, automobiles, biomedical devices, and so on. There may be extensive van der Waals and hydrogen bonding between the chains. 0000004371 00000 n Polymers are those which consists of repeated structural units known as monomers. endobj • Linear polymers have monomeric units joined end to end in single chains. This means that The word polymer designates an unspecified number of monomer units. It is the most widely used plastic in the world, being made into products ranging from clear food wrap and shopping bags to detergent bottles and fuel tanks. <]>> Structure features of polymers Each bond angle between three adjacent C atoms is near 109.5º and the angle can be rotated freely in space. endstream endobj 49 0 obj<. /XObject<< /Type /Page Crystalline polymers • Areas in polymer where chains packed in regular way. PHYSICAL PROPERTIES OF POLYMERS The structure of polymers is hierarchical, and both the monomer organization and larger-scale structure affect the observable properties, such as phase transitions, strength, solubility, and elasticity. >> Synthetic polymers are those which are human-made polymers. startxref ������1_��#ڝ,���GޤUi$c} Polyethylene is a member of the important family of polyolefin resins. • Both amorphous and crystalline areas in same polymer. The molecular connectivity of polymer−metal−organic framework (polyMOF) hybrid materials was investigated using density functional theory calculations and solid-state NMR spectroscopy. cleavage of covalent bonds between them and bio erodible polymers bring about erosion of the polymer due to dissolution of linking chains without bringing about any change in chemical structure of the molecule [2]. Polymers are very useful materials because their structures can be altered and tailored to produce materials 1) with a range of mechanical properties 2) in a wide spectrum of colors and 3) with different transparent properties. Engineering polymers include natural materials such as rubber and synthetic materials such as plastics and elastomers. 0000001100 00000 n Networked polymers are complex polymers that are heavily linked to form a complex network of three-dimensional linkages. 11 The length of of the polymeric molecule L = l m l: the length of a single bond in the backbone of the hydrocarbon chain m: the number of bonds Poly(a lkenes) are chemically inert due to the strong C-C and C-H The unit substance or substances from which the polymer is obtained is called a monomer. Polyethylene is considered to be as one of the simplest polymer, it has ethene or ethylene as the monomer unit whereas the linear polymer is known as the high density polyethylene-HDPE. Low M High M • Polymers can have various lengths depending on the number of repeat units. 0000001584 00000 n specific chemical structures. 0000001643 00000 n Synthetic Polymer. 48 21 Polymer Structure. 0000004668 00000 n 3.12. Polymers are very large and very complicated systems; their character­ ization has to begin with the chemical composition, configuration, and con­ formation of the individual molecule. /Parent 3 0 R Man-made polymers have been studied since 1832. 0000001798 00000 n 0000004619 00000 n Vari-ous drugrelease mechanisms can be studied comparatively in Figure 3. • More crystalline polymer - stronger and less flexible. Polymers are composed of non-metallic elements, found at the upper right corner of the periodic table. Cold-drawing • When a polymer is stretched a ‘neck’ forms. 0000003206 00000 n Lesson 5: Structure and Applications of Metals; Lesson 6: Types and Applications of Metal Alloys; Lesson 7: Structure and Applications of Ceramics; Lesson 8: Structure and Applications of Polymers. Most of the polymers around us are made up of a hydrocarbon backbone. A polymer is a high molecular mass compound ranging from 5000 to one million and they are formed by the combination of a large number of one or more low molecular weight compounds. Synthesis of Polymers •Nearly all polymers used in engineering are synthetic They are made by chemical processing •Polymers are synthesized by joining many small molecules together into very large molecules, called macromolecules, that possess a chain-like structure •The small units, called monomers, are generally Polymers in the natural world have been around since the beginning of time. trailer For each •Silk is a polymer of the amino acids glycine and alanine •Wool is having disulphide (sulphur-sulphur) bonds to link the polymer … The adoption of definite chemical structures for polymers has had far- reaching practical applications, because it has led to an understanding of how and why the physical and chemical properties of polymers change with the nature of the monomers from which they are synthesized. These substances often form into a chain-like structure. The first chapter is devoted to this broad objective. Polymers serving as drug carrier should /Contents 4 0 R The general structure of these polymers is shown in Fig. 0000188681 00000 n When the number of monomers is very large, the compound is sometimes called a high polymer. £ù`†?ÉÿCüeÿãøó×ýOTÇ_ûÿ¨2þüÅÿkâÏ_ÿÿ¤þ1þO+ óVþQþÏ+àéÿ¢8þüùGú¿,Š¼ÿ«‚øóçÏ?ÜÿuqÿoŠà÷ÿ¶ þüùÇý¿ˆ?þ±ÿïàϟ?ÿðÿ£áϟ?ÿÿ½ñÏõÿÔþüsý?÷ÀŸ?þüù'ûé‚?þüùóÏùÿ:-þüùóçϟ?ÿÄÿoSáϟ?þüùóçϟ?þÉÿßk÷ÿãþüùóoõÿ`™ÃS 0000002800 00000 n 0000007147 00000 n Polymers are substances consisting of macromolecules and the high molecular weight and chain-like structure of the macromolecules are responsible for the unique properties of polymers. • Crystalline structure: arrangement of unit cells in a well-defined spatially-ordered manner, which is characterized by translational symmetry • Amorphous structures: random arrangement of units In polymers the crystalline order can be established by a regular arrangement of the chains. %%EOF 0 The subject of polymer structure and characterization is typically a second course in polymer science. The spectrum of applications of polymers is immense. Based on Structure/Shape of polymer Polymers can be linear, branched, cross linked or networked. xref These polymers have a similar structure to the polyamides, which have the urethane (carbamate) group as part of the polymer backbone. /Resources<< These identical structures, we understand as a unit made up of two or more molecules, join together to form a long chain. The subjects are logically combined because understanding how structure a ects properties, as measured in characterization, is a key element of polymer materials science and engineering. Introduction: Organic polymers are normally insulators, it can be presumed that conducting polymers must have an unusual structure. 11 0 obj Polymers There are two types of polymerisation: addition and condensation Addition Polymerisation An addition polymer forms when unsaturated monomers react to form a polymer Monomers contain C=C bonds Chain forms when same basic unit is repeated over and over. • Crystalline - regular chain structure - no bulky side groups. �2�~��e.>�sҔ?��`wuHy�r��&ep�D�HS�ǣS}�g��*��'y����B}(5�4=�C_\��e�M���U��0Y���MW͎K��$x� E6+ �َ��������[�ή(���>�3P�Ѐl%n^�dSA!�I�\�����������M H��ՂG�1�:�m���G6���Ok`�N�O7������y�5�ɽ�)���a{�ч�d��931�>]s���FZ�)cRw�c�J�4H 0000004744 00000 n 0000188918 00000 n These metrics are regularly updated to reflect usage leading up to the last few days. 0000002050 00000 n A primary reason that polymer properties are different is because the chemical compositions of metals, polymers and ceramics are totally different. What is Polymer? Synthetic polymers are characterized by defined structures with flexibility of modification in terms of functionality and degradability and response to environmental fluctuation (chemical and biological response to stimuli), mechanical strength [29]. 0000001236 00000 n As the side chain becomes longer, the average interchain distance increases.10 This increased spacing between chain 0000004116 00000 n Thursday, February 23, 2017 Institute of Mechanical Systems - Structure Technology 34 Molecular weight -1-Molecular weight: mass of a mole of chains. /MediaBox[0 0 842 595] Classification based on polymer structure Structure of polymer Copolymers Isomerism (Structural Isomerism, Sequence Isomerism, Tacticity) Chain arrangement (Topology) Molecular weight in polymers Thermal transitions glass transition and melting Mechanical properties of polymer Topics: 8 Topic: Principle Characteristics of Polymers [1-7] For example, the window glass of airplanes made of polycarbonate cannot repair mechanical damages autonomously, which could lead to a … endobj 10. << These polymers are not restricted to monomers of the side chain influences the packing these! 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