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71 Cards in this Set
- Front
- Back
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Name for dimensionally stable synthetic material that is plastic during manufacture, and contains very large molecules?
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plastic
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Name for chemical compound consisting of large organic molecules formed by the joining of many small repeating monomer units?
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polymer
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What is the unit for the temperature at which the CTE increases abruptly, indicating increased moleculr mobility and a change from rigid to rubbery?
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Tg
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What does CTE stand for?
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Coefficient of thermal expansion
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Maxillofacial prosthetics are impression materials used (above, below) their Tg value
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above (so they are flexable)
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Restorative composite resins are used (above, below) their Tg value
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below (so they are solid at oral temperatures)
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What type of resin will soften if it is reheated above its Tg?
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thermoplastic resin
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What type of resin is soluble in organic solvents?
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thermoplastic resin
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What type of resin has good flexural and impact properties?
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thermoplastic resin
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What type of resin is generally not cross linked?
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thermoplastic resin
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What type of resin has secondary bonds between chains?
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thermoplastic resin
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Give 3 examples of a thermoplastic resin
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impression compound, acrylic resins, denture teeth
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What type of resin is resistant to change upon reheating?
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thermosetting resin
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What type of resin is infusible?
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thermosetting resin
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What type of resin is insoluble?
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thermosetting resin
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What type of resin has good abrasion resistance?
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thermosetting resin
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What type of resin is highly cross linked?
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thermosetting resin
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What type of resin has primary bonds between chains?
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thermosetting resin
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What is an example of a thermosetting resin?
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restorative resin
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What type of material has properties similar to rubber?
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elastomers
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True or False, elastomers have extensive reversible elongation under small stresses
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True.
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What are some examples of elastomers?
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ortho bands, impression materials
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How should an ideal dental resin behave, biologically?
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tasteless, odorless, nontoxic, nonirritating, insoluble, impermeable
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How should an ideal dental resin behave, physically?
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strength, resist wear, resist occlusal and impact forces, dimnsionally stable, low specific gravity
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How should an ideal dental resin behave, aesthetically?
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should match appearance of oral tissue, should be easy to add tint/pigment, should not discolor
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How should an ideal dental resin behave, chemically?
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It should be chemically stable
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How should an ideal dental resin behave when being manipulated?
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Should be easy to mix, insert, shape, plymerize (cure) and finish; shuld have short setting time; easy to repair; not effeced by clinical complications; no toixic byproducts
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What is the name for repetative intermolecular reaction where monomers are converted to chains making a polymer?
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polymerization
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What is the underlying mechanism in polymerization?
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break monomer bonds and rejoin them between monomers to create polymer
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What 4 elements are typically present in polymers?
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C, H, O, N
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What are the three types of bonds present in polymers?
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intra-chain, inter-chain, mechanical
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Which bond is mainly covalent bonds?
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intra-chain
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Which bond is mainly hydrogen, except in cross-linked?
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inter-chain
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What bond is present in a mechanical polymer bond?
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IPN (interpenetrating polymer network) e.g., in organosilane coupling
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What are the three chains formed in polymers?
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linear, branched, cross-linked
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Cross-linked chains usually consist of what type of bond?
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interchain
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elastomers are usually of which chain type?
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linear
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Thermosetting resins have what type of chain structure?
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cross-linked
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At similar molecular weight, rank the three chain structures from strongest to weakest
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cross-linked, branched, linear
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What is the name for the amount of monomer available for rection which actually took part in the polymerization reaction?
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degree of monomer coversion
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What is the name for the average number of monomer units which have been incorporated into a polymer chain?
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degree of polymerization
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What is the number average degree of polymerization? (Xn)
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Total # of monomer units/total # of molecules
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What is the weight average degree of polymerization? (Xw)
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weight of sample/number of moles
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What does Mo stand for?
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Molecular weight of structural unit
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What does Mn stand for?
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Number average mol weight
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What does Mw stand for?
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Weight average mol weight
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True or False, polydispersity is usually greater than or equal to 1
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True.
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What is the name for the measure of the range and distribution of chain sizes?
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polydispersity
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What is the equation for polydispersity?
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Mw/Mn
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True or False, step-growth (condensation) polymerization creates no byproduct?
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False, there is a byproduct
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What type of reaction is this? A + B --> AB + C
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step-growth or condensation
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A majority of denal polymers are (step-growth, addition)?
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addition
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What's another name for addition polymerization?
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free radical polymerization
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Step-growth are (faster, slower) than addition reactions
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slower
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What is a disadvantge of having a byproduct in a dental material?
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If it releases water, it will not capture oral tissue properly and will skrink later as the water evaporates away
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Between step-growth and addition, which occurs more in biological polymers?
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step-growth
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What is another name for a step-grown reaction?
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condensation
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Put these 4 stages of free-radical polymerization in correct order. (propogation, chain transfer, initiation, termination)
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initiation, propogation, chain transfer, termination
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True or False, once polymerization begins in a free radical reaction, you should not manipulate the material anymore
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True.
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What is the purpose of the inhibitor in polymerization?
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Allows a small window of working time before a reaction takes place
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What's the chemical name of a commonly used inhibitor? What other common element can be an inhibitor?
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Methyl ether of hydroquinone (< [or = to] .006%). Oxygen.
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What is the use of a plasticizer?
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reduce softening temperature and strength of material
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What are the two types of plasticizers?
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internal (copolymerization), external
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Name the three types of copolymers
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random, block, graft (or branched)
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True or False, polymers will be dissolved by organic solvents
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True.
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Plastics have a (large, small) amount of permanent deformation and (large, small) amount of elastic deformation
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large, small
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Elastomers have a (large, small) amount of plastic deformation
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small
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Longer chain polymers disolve (slowly, quickly)
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slowly
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True or False, cross-linked polymers are very easily dissolved
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False, they are not dissolved easily
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Inter-carbon distance in polymers (increases, decreases) during curing
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increases
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Which is longer, a C-C single bond, or a C=C double bond?
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C-C single bond is longer bc it's not held as tightly as a double bond
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