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5 natural polymers

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Polymer - Wikipedia, the free encyclopedia

A variety of other natural polymers exist, such as cellulose, which is the ..... that have a different composition or configuration than the main chain.(5) ...


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Polymers, Natural Polymers, Natural

The word "polymer" means "many parts" (from the Greek poly, meaning "many," and meros, meaning "parts"). Polymers are giant molecules with molar masses ranging from thousands to millions. Approximately 80 percent of the organic chemical industry is devoted to the production of synthetic polymers, such as plastics, textiles fibers, and synthetic rubbers. A polymer is synthesized by chemically joining together many small molecules into one giant molecule. The small molecules used to synthesize polymers are called monomers. Synthetic polymers can be classified as addition polymers, formed from monomer units directly joined together, or condensation polymers, formed from monomer units combining such that a small molecule, usually water, is produced during each reaction. Polymers are widely found in nature. The human body contains many natural polymers, such as proteins and nucleic acids. Cellulose, another natural polymer, is the main structural component of plants. Most natural polymers are condensation polymers, and in their formation from monomers water is a by-product. Starch is a condensation polymer made up of hundreds of glucose monomers, which split out water molecules as they chemically combine. Starch is a member of the basic food group carbohydrates and is found in cereal grains and potatoes. It is also referred to as a polysaccharide, because it is a polymer of the monosaccharide glucose. Starch molecules include two types of glucose polymers, amylose and amylopectin, the latter being the major starch component in most plants, making up about three-fourths of the total starch in wheat flour. Amylose is a straight chain polymer with an average of about 200 glucose units per molecule. A typical amylopectin molecule has about 1,000 glucose molecules arranged into branched chains with a branch occurring every 24 to 30 glucose units. Complete hydrolysis of amylopectin yields glucose; partial hydrolysis produces mixtures called dextrins, which are used as food additives and in mucilage, paste, and finishes for paper and fabrics. Glycogen is an energy reserve in animals, just as starch is in plants. Glycogen is similar in structure to amylopectin, but in a glycogen molecule a branch is found every 12 glucose units. Glycogen is stored in the liver and skeletal muscle tissues. Cellulose is the most abundant organic compound on Earth, and its purest natural form is cotton. The woody parts of trees, the paper we make from them, and the supporting material in plants and leaves are also mainly cellulose. Like amylose, it is a polymer made from glucose monomers. The difference between cellulose and amylose lies in the bonding between the glucose units. The bonding angles around the oxygen atoms connecting the glucose rings are each 180° in cellulose, and 120° in amylose. This subtle structural difference is the reason we cannot digest cellulose. Human beings do not have the necessary enzymes to break down cellulose to glucose. On the other hand, termites, a few species of cockroaches, and ruminant mammals such as cows, sheep, goats, and camels, are able to digest cellulose. Chitin, a polysaccharide similar to cellulose, is Earth's second most abundant polysaccharide (after cellulose). It is present in the cell walls of fungi and is the fundamental substance in the exoskeletons of crustaceans, insects, and spiders. The structure of chitin is identical to that of cellulose, except for the replacement of the OH group on the C-2 carbon of each of the glucose units with an –NHCOCH3 group. The principal source of chitin is shellfish waste. Commercial uses of chitin waste include the making of edible plastic food wrap and cleaning up of industrial wastewater. All proteins are condensation polymers of amino acids. An immense number of proteins exists in nature. For example, the human body is estimated to have 100,000 different proteins. What is amazing is that all of these proteins are derived from only twenty amino acids. In the condensation reaction whereby two amino acids become linked, one molecule of water forming from the carboxylic acid of one amino acid and the amine group of the other is eliminated. The result is a peptide bond; hence, proteins are polypeptides containing from approximately fifty to thousands of amino acid residues. The primary structure of a protein is the sequence of the amino acid units in the protein. The secondary structure is the shape that the backbone of the molecule (the chain containing peptide bonds) assumes. The two most common secondary structures are the α -helix and the β -pleated sheet. An α -helix is held together by the intramolecular hydrogen bonds that form between the N-H group of one amino acid and the oxygen atom in the third amino acid down the chain from it. The α -helix is the basic structural unit of hair and wool, which are bundles of polypeptides called α -keratins. The helical structure imparts some elasticity to hair and wool. The polypeptides in silk, on the other hand, are β -keratins with the β -sheet structure, in which several protein chains are joined side-to-side by intermolecular hydrogen bonds. The resulting structure is not elastic. Nucleic acids are condensation polymers. Each monomer unit in these polymers is composed of one of two simple sugars, one phosphoric acid group, and one of a group of heterocyclic nitrogen compounds that behave chemically as bases. Nucleic acids are of two types: deoxyribonucleic acid (DNA ), the storehouse of genetic information, and ribonucleic acid (RNA), which transfers genetic information from cell DNA to cytoplasm, where protein synthesis takes place. The monomers used to make DNA and RNA are called nucleotides. DNA nucleotides are made up of a phosphate group, a deoxyribose sugar, and one of four different bases: adenine , cytosine , guanine , or thymine . The nucleotides that polymerize to produce RNA differ from DNA nucleotides in two ways: they contain ribose sugar in place of deoxyribose sugar and uracil instead of thymine. Natural rubber is an addition polymer made up of thousands of isoprene monomer repeating units. It is obtained from the Hevea brasiliensis tree in the form of latex. The difference between natural rubber and another natural polymer, gutta-percha (the material used to cover golf balls), is the geometric form of the polyisoprene molecules. The CH2 groups joined by double bonds in natural rubber are all on the same sides of the double bonds (the cis configuration), whereas those in gutta-percha are on opposite sides of the double bonds (the trans configuration). This single structural difference changes the elasticity of natural rubber to the brittle hardness of gutta-percha. see also Deoxyribonucleic Acid; Nucleic Acids; Polymers, Synthetic; Proteins. Melvin D. Joesten Atkins, Peter W. (1987). Molecules. New York: W. H. Freeman. Joesten, Melvin D., and Wood, James L. (1996). The World of Chemistry, 2nd edition. Fort Worth, TX: Saunders College.

polymer

polymer , chemical compound with high molecular weight consisting of a number of structural units linked together by covalent bonds (see chemical bond ). The simple molecules that may become structural units are themselves called monomers; two monomers combine to form a dimer, and three monomers, a trimer. A structural unit is a group having two or more bonding sites. A bonding site may be created by the loss of an atom or group, such as H or OH, or by the breaking up of a double or triple bond, as when ethylene, H 2 C[symbol]CH 2 , is converted into a structural unit for polyethylene , -H 2 C-CH 2 -. In a linear polymer, the structural units are connected in a chain arrangement and thus need only be bifunctional, i.e., have two bonding sites. When the structural unit is trifunctional (has three bonding sites), a nonlinear, or branched, polymer results. Ethylene, styrene, and ethylene glycol are examples of bifunctional monomers, while glycerin and divinyl benzene are both polyfunctional. Polymers containing a single repeating unit, such as polyethylene, are called homopolymers. Polymers containing two or more different structural units, such as phenol-formaldehyde, are called copolymers. All polymers can be classified as either addition polymers or condensation polymers. An addition polymer is one in which the molecular formula of the repeating structural unit is identical to that of the monomer, e.g., polyethylene and polystyrene . A condensation polymer is one in which the repeating structural unit contains fewer atoms than that of the monomer or monomers because of the splitting off of water or some other substance, e.g., polyesters and polycarbonates (see illustration) . Many polymers occur in nature, such as silk, cellulose , natural rubber , and proteins . In addition, a large number of polymers have been synthesized in the laboratory, leading to such commercially important products as plastics, synthetic fibers, and synthetic rubber. Polymerization, the chemical process of forming polymers from their component monomers, is often a complex process that may be initiated or sustained by heat, pressure, or the presence of one or more catalysts.


From Yahoo Answers

Question:Hey friends! Well actually I have a chemistry project to do and it would be really great if you all could give me some information on 5 natural polymers or any link which has information on 5 natural polymers. Thanks!

Answers:Carbohydrates and Starches Cellulose Chitins and Chitosans Lignins chk these links http://pslc.ws/mactest/natupoly.htm http://en.wikipedia.org/wiki/Polymer http://www.sigmaaldrich.com/materials-science/material-science-products.html?TablePage=16371327 http://www.elmhurst.edu/~chm/vchembook/400polymers.html http://www.scienceclarified.com/Ph-Py/Polymer.html

Question:just 5 at least! or what ever you can give me.=]

Answers:polyester in clothes, polystyrene in foam packaging polycarbonate like in Nalgene bottles proteins are polypeptides, a polymer of amino acids. DNA is a polymer of nucleic acids.

Question:Could you help me answer these questions in detail. 1.List 3 examples for the uses of plastics. 2.What element is the main building block for plastics? 3.What is a monomer? Give an example. 4.What is a polymer? Give an example. 5.Explain what polymerisation is. 6.List two natural polymers that are not plastic. 7.Plastics are categorised under two types thermoplastic and thermoset. What happens to thermoplastics and thermoset plastic when they are heated? 8.What are the differences in structure and bonding of the polymers, between thermoplastic and thermoset? 9.Which type of plastic is easier to recycle and why? 10.Design a leaflet about the differences of the two types of plastics. Give examples of at least two uses in your home of each type of plastic. For each use, describe how the properties of the plastic make it suitable for its use. You can also use your own search and the links below to help.

Answers:1.List 3 examples for the uses of plastics, carrier bags, toys and sporting goods e.g footballs 3. A monomer is a single alkene 4. a polymer is a chain of monomers 5. polymerisation is where monomer crack he double bonds and join together. 7. Thermosetting keep thier original form, they stay hard and solid. Thermoplastics begin to soften and bend. 8. Thermoplastics have weak intermolecular bonds where thermoset have strong connections. 9. Thermoplastic is easier to recycle because it breaks down easier when heated

Question:What is a synthetic polymer? I just need the definitions not examples.

Answers:Natural polymers are polymers that occur in nature like silk or cellulose. Synthetic polymers are made in chemical plants by polymerizing monomers such as esters into polyester.

From Youtube

Ku-ki Shop Jewelry - Polymer clay :Find these at ku-ki-shop.com Thanks for watching and commenting! Some facts - MOST IMPORTANT: thank you so much for all your comments, sorry for not replying to each one! - i use polymer clay - everything is handmade but i also add some little plastic beads to my creations. - i do not use any molds, except for oreo cookies. -i do not make tutorials, sorry - but there are GREAT tutorials here on youtube to help you make this kind of crafts. MUSIC from Core of Soul(natural beauty)

Polymer road stabilization chemical :Although normal soil and sand are abundant global natural resources, many types cannot be used for construction purposes due to the lack of suitable and affordable stabilization technology. While in developed countries the normal high cost of road and construction materials can be accepted and tolerated, other less fortunate or third world countries are forced to defer or abandon their countries road and construction development until a cost effective method of construction is devised. In many global regions, the locally available (insitu) soil, gravels and sands are unsuitable for construction purposes and up until now cannot be stabilized with conventional agents or cement. Natural gravels suitable for the construction and maintenance programs of roads etc, are also becoming less scarce and in some locations not available at all.!! So the need and transportation of borrowed pit materials to site are costly and have a high transport and time implication in most cases. In consequence, National and Regional infrastructure developments of most kinds are therefore severely inhibited and so therefore innovative and cost effective solutions to these growing problems are urgently required