Chemistry
Condensation Polymers
Condensation polymers are formed through a chemical reaction that involves the elimination of a small molecule, such as water or alcohol. This process links monomers together to form a polymer chain. Examples of condensation polymers include nylon, polyester, and proteins. The reaction typically requires the presence of a catalyst and occurs at high temperatures.
Written by Perlego with AI-assistance
Related key terms
1 of 5
12 Key excerpts on "Condensation Polymers"
eBook - PDFThe Elements of Polymer Science and Engineering
An Introductory Text for Engineers and Chemists
- Alfred Rudin(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
This line of reasoning takes us into a more detailed con-sideration of polymerizations in this and succeeding chapters. A condensation polymer is one in which the repeating unit lacks cer-tain atoms which were present in the monomer(s) from which the polymer was formed or to which it can be degraded by chemical means. Condensa-155 156 OH OH H O C H , Ο ] • 2 C H 2 0 ' (excess) A L K A L I N E CONDITION S CH Ο 5 Step-Growth Polymerizations ' R E S O L E ' T Y P E PRODUCTS C U R E HOCH NETWORK P O L Y M E R (b) OH 3 ΓOJ +2CH 2 0-ACIDIC CONDITIONS OH OH CH2 OH NOVOLAC TYPE PRODUCTS CURE with added hexamethylene tetramine NETWORK POLYMER Fig. 5-1. Phenol-formaldehyde polymers, (a) Character of resole^-type resins nor-mally produced with excess formaldehyde under alkaline conditions; (b) ''novolac^-type resins normally made with excess phenol under acidic conditions. (a) OH Ο 5.1 Condensation and Addition Polymers 157 tion polymers are formed from bi- or polyfunctional monomers by reac-tions which involve elimination of some smaller molecule. Polyesters (e.g., 1-5) and polyamides like 1-6 are examples of such thermoplastic polymers. Phenol-formaldehyde resins (Fig. 5-1) are thermosetting con-densation polymers. All these polymers are directly synthesized by con-densation reactions. Other Condensation Polymers like cellulose (1-8) or starches can be hydrolyzed to glucose units. Their chemical structure in-dicates that their repeating units consist of linked glucose entities which lack the elements of water. They are also considered to be Condensation Polymers although they have not been synthesized yet in the laboratory. In addition polymers, by contrast, the recurring units have the same structures as the monomer(s) from which the polymer was formed. Ex-amples are polystyrene (1-1), polyethylene (1-3), styrene-methyl meth-acrylate copolymers (1-35), and so on.
- Manas Chanda, Salil K. Roy(Authors)
- 2008(Publication Date)
- CRC Press(Publisher)
Thus a condensation polym er may be defined as one whose synthesis involves elimination of small molecules or whose repeating unit lacks certain atoms present in the monomer(s). With the development of poly mer science and the synthesis of new poly mers, the prev ious definition of condensation poly mer is inadequate. For example, in polyurethanes ( Table 1.2), which are classified as Condensation Polymers, the repeating unit has the same net composition as the two monomers (i.e., a diol and a diisocyanate), which react without eliminating any small molecule. To overcome such problems, chemists have introduced a definition which describes Condensation Polymers as consisting of structural units joined by internal functional groups such as ester sulfide ether carbonate and sulfone linkages. amide imide urethane C O O = O = − − − − − O O C NH = O = O = − − − − C NH N CO − CO − O = − − − − − − S − − − − − − O − − S O C O , , , , , , , Characteristics of Polymers 1 -15 TABLE 1.2 Typical Condensation Polymers Polymerization Reaction a Comments Polyamide (PA) H 2 N R NH 2 C R' C O O Cl Cl H NH R NHC O R' C O Cl HCl + + n n HOC R' COH O O + H 2 N R NH 2 n n H NH R NHC O R' C O OH H 2 O + (2 n –1) n (2 n –1) n H 2 N R COH O n NH R C O H OH + H 2 O ( n –1) n Moldings, fibers, tirecord; poly(hexamethylene adipamide) (Nylon 6,6)e.g., Ultramid A; polycaprolactam (nylon-6), e.g., Ultramid B, Akulon, Perlenka, poly(hexamethylene sebacamide) (Nylon-6,10), e.g., Ultramid S, Zytel. Polyester C R' C O O HO OH HO R OC O R' CO O H + HO R OH n + n (2 n –1) H 2 O n C R' C O O RO OR HO R OC O R' CO O R HO R OH n + + n (2 n –1) ROH n HO R COH O n R CO O O H H + ( n –1) H 2 O n Textile fibers, film, bottles; poly(ethylene terephthalate) (PET) e.g., Terylene, Dacron, Melinex, Mylar. Polyurethane (PU) HO R OH n N R' NCO OC n + H O R OC NH R' O NHC O O R OC NH O R' NCO (n – 1) Rubbers, foams, coatings; e.g., Vulkollan, Adiprene C, Chemigum SL, Desmophen A, Moltopren.
eBook - PDFElements of Polymer Science & Engineering
An Introductory Text and Reference for Engineers and Chemists
- Alfred Rudin(Author)
- 1998(Publication Date)
- Academic Press(Publisher)
This line of reasoning takes us into a more detailed consideration of polymerizations in this and succeeding chapters. 155 156 5 Step-Growth Polymerizations A condensation polymer is one in which the repeating unit lacks certain atoms which were present in the monomer(s) from which the polymer was formed or to which it can be degraded by chemical means. Condensation Polymers are formed from bi- or polyfunctional monomers by reactions which involve elimination of some smaller molecule. Polyesters (e.g., 1-5) and polyamides like 1-6 are exam-ples of such thermoplastic polymers. Phenol-formaldehyde resins (Fig. 5-1) are thermosetting Condensation Polymers. All these polymers are directly synthesized by condensation reactions. Other Condensation Polymers like cellulose (1-11) or starches can be hydrolyzed to glucose units. Their chemical structure indicates that their repeating units consist of linked glucose entities which lack the elements of water. They are also considered to be Condensation Polymers although they have not been synthesized yet in the laboratory. In addition polymers, by contrast, the recurring units have the same structures as the monomer(s) from which the polymer was formed. Examples are polystyrene (1-1), polyethylene (1-3), styrene-maleic anhydride copolymers (1-26), and so on. The difficulty with these definitions is that the same macromolecular structure can be made by different reaction pathways. This situation occurs particularly when cyclic and linear monomers can produce the same polymer. Thus nylon-6 can be made by either of two reactions: H2C ~CH2 / ^CH2 H / I -H,0 HjC C=0 --f N -f C H j -^ C -^ — ^ H ^ N -f C H j -^ ^ C -O H (5-1) / nylon 6 0 0 H 2 C — N -H c-ominohexanoic acid coproloctom The polyamide made from caprolactam is technically an addition polymer by the above definition, while the product made from the amino acid would be a conden-sation polymer.
eBook - PDF- George Odian(Author)
- 2004(Publication Date)
- Wiley-Interscience(Publisher)
It should not be taken for granted that all polymers that are defined as condensation poly- mers by Carothers’ classification will also be so defined by a consideration of the polymer chain structure. Some Condensation Polymers do not contain functional groups such as ester or amide in the polymer chain. An example is the phenol–formaldehyde polymers produced by the reaction of phenol (or substituted phenols) with formaldehyde (n − 1) + (n − 1)H 2 O OH n + nCH 2 O OH CH 2 CH 2 OH OH ð1-7Þ These polymers do not contain a functional group within the polymer chain but are classified as Condensation Polymers, since water is split out during the polymerization process. Another example is poly( p-xylene), which is produced by the oxidative coupling (dehydrogenation) of p-xylene: CH 3 nCH 3 n (n − 1)H 2 + CH 2 CH 2 H H ð1-8Þ In summary, a polymer is classified as a condensation polymer if its synthesis involves the elimination of small molecules, or it contains functional groups as part of the polymer chain, or its repeating unit lacks certain atoms that are present in the (hypothetical) monomer to which it can be degraded. If a polymer does not fulfill any of these requirements, it is clas- sified as an addition polymer. 1-1b Polymerization Mechanism In addition to the structural and compositional differences between polymers, Flory [1953] stressed the very significant difference in the mechanism by which polymer molecules are built up. Although Flory continued to use the terms condensation and addition in his discus- sions of polymerization mechanism, the more recent terminology classifies polymerizations into step and chain polymerizations. Chain and step polymerizations differ in several features, but the most important differ- ence is in the identities of the species that can react with each other. Another difference is the manner in which polymer molecular size depends on the extent of conversion.
eBook - PDF- Sami Matar Ph.D., Lewis F. Hatch Ph.D., Sami Matar, Ph.D., Lewis F. Hatch, Ph.D.(Authors)
- 2001(Publication Date)
- Gulf Professional Publishing(Publisher)
CHAPTER ELEVEN Polymerization INTRODUCTION Polymerization is a reaction in which chain-like macromolecules are formed by combining small molecules (monomers). Monomers are the building blocks of these large molecules called polymers. One natural polymer is cellulose (the most abundant organic compound on earth), a molecule made of many simple glucose units (monomers) joined together through a glycoside linkage. ~ Proteins, the material of life, are polypeptides made of ~-amino acids attached by an amide 0 II --(- CNH-)-- linkage. The polymer industry dates back to the 19th century, when natural polymers, such as cotton, were modified by chemical treatment to pro- duce artificial silk (rayon). Work on synthetic polymers did not start until the beginning of the 20th century. In 1909, L. H. Baekeland prepared the first synthetic polymeric material using a condensation reaction between formaldehyde and phenol. Currently, these polymers serve as important thermosetting plastics (phenol formaldehyde resins). Since Baekeland's discovery, many polymers have been synthesized and marketed. Many modern commercial products (plastics, fibers, rubber) derive from poly- mers. The huge polymer market directly results from extensive work in synthetic organic compounds and catalysts. Ziegler's discovery of a coordination catalyst in the titanium family paved the road for synthe- sizing many stereoregular polymers with improved properties. This chapter reviews the chemistry involved in the synthesis of polymers. 301 302 Chemistry of Petrochemical Processes MONOMERS, POLYMERS, AND COPOLYMERS A monomer is a reactive molecule that has at least one functional group (e.g.-OH,-COOH,-NH2,-C=C-). Monomers may add to them- selves as in the case of ethylene or may react with other monomers hav- ing different functionalities. A monomer initiated or catalyzed with a specific catalyst polymerizes and forms a macromolecule~a polymer.
- Shashanka Rajendrachari, Orhan Uzun(Authors)
- 2021(Publication Date)
- Bentham Science Publishers(Publisher)
Polymers R. Shashanka , Orhan UzunAbstract
In the present chapter, we have discussed the classification of polymers, structure, properties, fabrication process, and polymerization mechanism. Generally, polymers are made up of a series of molecules joining together and the average molecular weight of chains ranges from 10,000 to more than one million. The process of chemically joining the monomers together to create giant molecules is called polymerization. In polymers, atoms are joined together by a strong bond called covalent bonding. Many of the polymers are organic (carbon-based polymers) and inorganic (non-carbon based polymers like polysiloxanes, polyphosphazene, polysilanes, etc.).Keywords: Addition and condensation polymerization, Bakelite, Branched and cross-linking polymers, Classification, Homo and co-polymers, Linear, Mechanisms, Molding techniques, Natural polymers, Nylon, Polymers, Properties of polymers, Polyethylene, PVC, Poly propylene, Synthetic polymers, Tacticity, Thermosetting and thermoplastics.Fig. (1)) Polymers [1 ].1. INTRODUCTION
The word polymer comes from the Greek language “poly” meaning many and “mers” means units. A polymer is defined as a group of many units or it is a combination of a large number of monomers together to form a giant structure. Most of the time the word polymer is used for “plastic” also; but, all plastics are polymers, but not all polymers are plastics [2 ]. Fig. () shows the polymers [1 ].1Polyvinyl chloride (PVC), polyethylene, polymethyl methacrylate (PMMA), nylons, bakelite, etc. are some of the examples of polymers. Polymers are very popular due to their wide range of applications as mentioned below [1 ]:- Automobile industries
- Constructional purposes
- Aerospace applications
- Medical applications
- Packaging applications
- Electronic goods etc.
2. PROPERTIES OF A POLYMER
eBook - PDF- Robert O. Ebewele(Author)
- 2000(Publication Date)
- CRC Press(Publisher)
Chapter 6 Condensation (Step-Reaction) Polymerization I. INTRODUCTION Condensation polymerization is chemically the same as a condensation reaction that produces a small organic molecule. However, as we sa w in Chapter 2, in condensation polymerization (i.e., production of a macromolecule) the functionality of reactants must be at least 2. Recall that functionality was defined as the average number of reacting groups per reacting molecule. To derive expressions that describe the physical phenomena occurring during condensation polymerization (polycondensation) — a tool vital to process design and product control — three approaches have been traditionally adopted: kinetic, stoichiometric, and statistical. Various degrees of success have been achieved by each approach. We treat each approach in the succeeding sections. Before then, we briefly discuss the overall mechanism of polycondensation reactions. II. MECHANISM OF CONDENSATION POLYMERIZATION The mechanism of polycondensation reactions is thought to parallel that of the low-molecular-weight analogs. As a result of their macromolecular nature, polymers would be expected to have retarded mobility. It was therefore predicted, purely on theoretical arguments, that the chemical reactivity of polymers should be low. • The collision rate of polymer molecules should be small due to their low kinetic velocity. This should be accentuated by the high viscosity of the liquid medium consisting of polymer molecules. • Shielding of the reactive group within the coiling chain of its molecule should impose steric restrictions on the functional group. This would lead to a reduction in the reactivity of the reactants. Flory 1 has shown from empirical data that for a homologous series the velocity constant measured under comparable conditions approaches an asymptotic limit as the chain length increases.
eBook - PDF- John J. McKetta Jr(Author)
- 1993(Publication Date)
- CRC Press(Publisher)
892 Polymerization Polymerization Introduction Polymerization conditions and processes often differ greatly for the pro-duction of different high polymers or even in some cases the same polymers. Careful control of the operating conditions is needed in all cases to obtain high-quality products in an economical manner. The high polymers consid-ered here are those that have high molecular weights and that find uses as plastics, elastomers (or synthetic rubbers), synthetic fibers, adhesives, and surface coatings, such as paints or varnishes. The operating conditions for the production of a polymer affect the rates of polymerization and also at least some of the following structural features of the polymer molecules: molecular weight, cross-linking, linearity of the molecule, branching, and stereospecificity. These features have a major effect on the morphology or packing abilities of the molecules and hence on the physical properties of the polymers. The relationship between struc-tural features of the molecules and physical properties is considered in more detail later. Chemistry of Polymerization Based on the reactants used to produce the polymers, polymerizations are divided into two broad categories: polycondensations and addition polym-erizations. Polycondensation Polyesters, polyamides (or nylons), polyurethanes, phenolics, urea resins, and epoxies are important examples of polycondensations. Often but not always, two or more reactants are employed, and the average functionality of the reactants must be at least two. A functionality of one is defined as the ability of a molecule to form a single chemical bond with another mol-ecule. With a functionality of two, chemical bonds can be obtained with two other molecules. In the latter case, polymerization can occur and the polymer chain can increase in length (and molecular weight), forming so-called linear molecules.
- James A. Newell(Author)
- 2012(Publication Date)
- Wiley(Publisher)
Also called chain growth polymerization and free-radical polymerization. | Condensation Polymerization | Formation of a polymer that occurs when two potentially reactive end groups on a polymer react to form a new covalent bond between the polymer chains. This reaction also forms a by-product, which is typically water. 5.2 | Types of Polymers 161 Table 5-1 Physical Properties of Commercial Polymers Polymer Category T m (°C) T g (°C) Density (g/cm 3 ) Tensile Strength (MPa) Tensile Modulus (MPa) PMMA Acrylic 265–285 105 1.19 55–76 2400–3400 PBO Aramid n/a n/a 1.54 5800 180,000 Nylon 6,6 Nylon 255 n/a 1.14 90 3400 PET Polyester 245–265 80 1.4 172 4275 LDPE Polyolefin 110 n/a 0.92 10.3 166 HDPE Polyolefin 130–137 n/a 0.94–0.97 19–30 800–1400 PP Polyolefin 164 220 0.903 35.5 1380 Viscose Rayon n/a n/a 1.5 28–47 9.7 PVDC HVTP 160 24 1.17 34.5 517 PS HVTP 180 74–110 1.04 46 2890 PVC HVTP 175 81 1.39 55 2800 Polyisoprene Elastomer 40 263 0.970 17–25 1.3 Polybutadiene Elastomer n/a 2110 to 295 1.01 18–30 1.3 Polychloroprene Elastomer n/a 245 1.32 25–38 0.52 Values from Polymer Handbook, 4th edition, J. Brandrup, E. Immergut, and E. Grulke, eds. (Hoboken, NJ: John Wiley & Sons, 1999). | Cracking | Process of breaking large organic hydrocarbons into smaller molecules. 162 Chapter 5 | Polymers 5.3 ADDITION POLYMERIZATION A ddition polymerization, which is also known as free-radical polymerization or chain growth polymerization, begins with a vinyl monomer, like the one shown in Figure 5-21. The groups that surround the double-bonded carbon can be different, and the identity of the monomer changes accordingly. If all four atoms are hydrogen, the vinyl monomer is ethylene. If one hydrogen atom is replaced by a benzene ring, the monomer is styrene. More than one hydrogen atom can be replaced with other atoms. A vinyl monomer with one chlorine atom would be vinyl chloride; two chlorine atoms would make the monomer vinylidene.
eBook - PDFCompositional Analysis of Polymers
An Engineering Approach
- Aleksandr M. Kochnev, Oleg V. Stoyanov, Gennady E. Zaikov, Renat M. Akhmetkhanov, Aleksandr M. Kochnev, Oleg V. Stoyanov, Gennady E. Zaikov, Renat M. Akhmetkhanov(Authors)
- 2016(Publication Date)
- Apple Academic Press(Publisher)
Condensation Polymers: A REVIEW G. E. ZAIKOV Russian Academy of Sciences, Moscow, Russia CHAPTER 6 CONTENTS 6.1 Phenoplasts ................................................................................................. 134 6.2 Aminoplasts (Carbamide Resin) ................................................................. 136 6.3 Polyesters .................................................................................................... 137 6.4 Polycarbonates ............................................................................................ 139 6.5 Poly(Ether-Ketones) (Peek) ........................................................................ 141 6.6 Polyamides .................................................................................................. 142 6.7 Aromatic Polyamides ................................................................................. 143 6.8 Polyimides ................................................................................................... 144 6.9 Polysulfones ................................................................................................ 145 6.10 Polysulfides ................................................................................................. 146 6.11 Polyselenides ............................................................................................... 148 6.12 Silicones ...................................................................................................... 149 References ............................................................................................................. 149 134 Compositional Analysis of Polymers: An Engineering Approach 6. 1 PHENOPLASTS Phenoplasts (phenolics) are synthetic resins formed by the condensation polym-erization reaction of phenol or its derivatives with aldehydes. The most com-monly used are phenol formaldehyde resins (PF).
eBook - PDF- Ferdinand Rodriguez, Claude Cohen, Christopher K. Ober, Lynden Archer(Authors)
- 2014(Publication Date)
- CRC Press(Publisher)
107 Polymer Formation 4.1 POLYMERIZATION REACTIONS Polymerization is the process of joining together small molecules by covalent bonds to produce high-molecular-weight polymers. Both natural and synthetic polymers are built from these simple small molecular units known as monomers. However, the range of properties that can be achieved depends on the strategy used to assemble these units. This chapter covers many of the synthetic strategies used to build poly-mers and provides examples of several of the commercial polymers made with these techniques. There are basically two approaches to polymer formation: chain-growth and step-growth polymerization. Chain-growth polymerization involves combining monomers with similar reactive functions starting from a single reactive site and growing the polymer chain from that site. The reactive chain site can be a cation, an anion, or a radical. The type of chain-growth polymerization selected depends on the monomer to be used and the requirements of the target polymer. Among the recent inventions in polymerization chemistry has been living polymerization that permits the growth of polymer chains with identical molecular weights and enables the creation of block copolymers or other polymers with well-controlled structures. Certain transition metals will also catalyze polymer formation with hydrocar-bon vinyl monomers. This work resulted in the Nobel Prize in Chemistry in 1955. Such polymers include polyethylene and polypropylene and are among the largest volume polymers produced. More recently the 2000 Nobel Prize in Chemistry has been awarded for the discovery of conducting polymers, also first made by metal-catalyzed chain-growth polymerization. More recently again, the 2005 Nobel Prize in Chemistry has been awarded for work on ring-opening metathesis polymerization and the development of new functional group-tolerant catalysts for this polymeriza-tion reaction.
eBook - ePub- Charles E. Carraher Jr.(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
vinyl polymers .
The atoms in the backbone of addition polymers are almost always only carbon.H 2C = CXH → −( −nCH 2− CXH − )(4.1) Condensation Polymers generally contain fewer atoms in the polymer backbone than in the reactants because of the formation of by-products during the polymerization process and the backbone contains noncarbon atoms.(4.2) where A–X can be most Lewis bases such as –NH2 , –SH, and –OH, and B–Y can be the Lewis acids such asThe corresponding polymerizations to form these polymers are typically chain polymerizations to form addition polymers and stepwise polymerizations to form condensation polymerizations.The term stepwise kinetics , or step-growth kinetics, refers to polymerizations in which the polymer’s molecular weight increases in a slow, stepwise manner as the reaction time increases. Figure 4.1 contains a depiction of the stepwise polymerization process. Initially, there is only monomer R and R1 present (far left). After some time, all the monomer has reacted, yet no high-molecular-weight chains are found with the greatest DP being 2.5 (middle). As polymerization continues, longer chains grow with a high DP of 10 (far right) for this depiction. Eventually, all of the chains will connect finally giving the polymer. Figure 4.2 contains a representative plot of DP as a function of time for this process.Figure 4.1 Depiction of stepwise chain growth for monomers R and R1 as the polymerization begins (far left) and progresses toward the right.Figure 4.2 System molecular weight for stepwise kinetics as a function of reaction time and reaction temperature, T .The formation of polyesters from a dialcohol (diol) and a dicarboxylic acid (diacid) will be used to illustrate the stepwise kinetic process. Polymer formation begins with one diol molecule reacting with one diacid, forming one repeat unit of the eventual polyester (Equation 4.3
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
