Page 354 - Carrahers_Polymer_Chemistry,_Eighth_Edition

Naturally Occurring Polymers—Plants 317

Cellulose xanthate: Product of soda cellulose and carbon disulfi de.
Chitin: Polymer of acetylated glucosamine present in the exoskeletons of shellfi sh.
Collagen: Protein present in connective tissue.
Compounding: Processing of adding essential ingredients to a polymer such as rubber.
Cyclodextrins: Oligomeric cyclic products formed from the reaction of starch treated with a
certain enzyme.
Degree of substitution (DS): Number that designates the average number of reacted hydroxyl
groups in each anhydroglucose unit in cellulose or starch.
Dextran: Branched polysaccharide synthesized from sucrose by bacteria.
Drying: Jargon used to describe the cross-linking of unsaturated polymers in the presence of
air and a heavy metal catalyst (drier).
Ester gum: Ester of rosin and glycerol.
Ethylhydroxyethylcellulose (EHEC): Nonionic mixed ether formed form HEC and ethyl
chloride.
Fibrils: Thread-like strands or bundles of fi bers.
Fossil resins: Resins obtained from the exudate of prehistoric trees.
Galalith: Commercial casein plastics.
γ-Cellulose: Cellulose soluble in 8% caustic solution.
Glycogen: Highly branched polysaccharide that serves as the reserve carbohydrate in animals.
Guayule: Shrub that produces cis-1,4-polyisoprene rubber.
Gutta percha: Naturally occurring trans-1,4-polyisoprene.
Hevea Brasiliensis: Natural rubber, NR.
Humic acid: Polymeric aromatic carboxylic acid found in lignite.
Hydrocellulose: Cellulose degraded by hydrolysis.
Hydroxyethylcellulose (HEC): Produced from alkaline cellulose and ethylene oxide.
Hydroxypropylcellulose: Thermoplastic cellulose ether formed from alkaline cellulose and
propylene oxide.
Latex: Stable dispersion of polymer particles in water.
Lignin: Noncellulosic resinous component of wood.

Mercerized cotton: Cotton fiber that has been immersed in caustic solution, usually under
tension, and washed with water removing the excess caustic.
Methylcellulose (MC): Formed from alkaline cellulose and chloromethane.
Native cellulose: Naturally occurring cellulose; like cotton.
Oligosaccharide: Low molecular weight polysaccharide.
Racked rubber: Stretched rubber cooled below its T .
g

Rayon: Cellulose regenerated by acidification of a cellulose xanthate (viscose) solution.
Recent resins: Resins obtained from exudates of living trees.
Regenerated cellulose: Cellulose obtained by precipitation from solution.
Retrogradation: Process whereby irreversible gel is produced by the aging of aqueous solu-
tions of amylose starch.
Shellac: Natural polymer obtained from the excreta of insects in Southeast Asia.
Starch: Linear or branched polysaccharides of many anhydroglucose units joined by an alpha
linkage; amylose is the linear fraction and amylopectin is the branched fraction.
Tenacity: Term used for the tensile strength of a polymer.
Terpene: Class of hydrocarbons having the empirical formula C H .
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Viscose: Alkaline solution of cellulose xanthate.
EXERCISES

1. Why is starch digestible by humans? Why is cellulose not digestible by humans?
2. How does cellobiose differ from maltose?

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