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Polymers: Strength Variation with Additives. Ariunaa Bayarbat, Scott Steffin, and Travis Yaeger. SRJC Engr 45 12/05/05 Instructor: Younes Ataiiyan.
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Polymers:Strength Variation with Additives Ariunaa Bayarbat, Scott Steffin, and Travis Yaeger SRJC Engr 45 12/05/05 Instructor: Younes Ataiiyan
How do different additions to a polyester polymer affect its strength?
Polymers • Monomer • The basic building block of a polymer • The smallest repeating unit in a polymer chain • A polymer has a linear, branched, or network structure of chained monomers
Polymerization Initiation: Creation of the free radical, giving instability to a monomer Propagation: Monomer additions to the chain, passing along instability Termination: Removal of instability (free radical) through combination with another unstable chain or impurity, or passage of instability to another monomer
Polymers form a network of interconnected branches, like knots, held together by hydrogen bonding and weak forces • Resin • “Any of numerous physically similar polymerized synthetics or chemically modified natural resins including thermoplastic materials such as polyvinyl, polystyrene, and polyethylene and thermosetting materials such as polyesters, epoxies, and silicones that are used with fillers, stabilizers, pigments, and other components to form plastics.”
Polymer Categories • Thermoplastic • Thermoset • Thermoset polymers get hard and rigid upon heating • They retain their shape once they are cooled • They have network molecular structures • The polymerization process is enhanced by higher temperatures and it is not reversible
Polyester Thermoset Casting Resin • Reasons for choosing • Inexpensive • Clear • Easy to make samples • Thick enough for tests
Experiment • Base sample • We mixed 100 g of the resin with 28 drops of the catalyst MEKP (Methyl Ethyl Ketone Peroxide) • We poured it into a mold of 5”x 4.5” • Samples were about 0.25” thick • Four different samples with additions • 2.5 g of sawdust • 2 g of vitamin C (from vitamin C tablets) • 5 g of cornstarch • 28 more drops of the catalyst
We let the samples set for a week • We cut them into small pieces and uniform thickness • We performed a compression test on the samples
Analysis • Theoretically, the base sample was supposed to have the lowest strength because the additives caused more strength • The data show the base sample having the greatest strength • Real conclusions cannot be drawn from the data because of the many variables besides just the additions
Conclusions • The result was different from what we expected • The reasons for inconclusive results • Different sample areas • Different sample thicknesses • The uneven testing surface • Things we would do differently • Uniform size for all samples • Much greater percentage of additions in each sample • Use better testing surface
Resources • Shackelford, James F. Introduction to Materials Science for Engineers. Upper Saddle River, NJ: Pearson Education Inc., 2005. • http://members.tripod.com/sunfh/chem13.htm • http://en.wikipedia.org/wiki/Main_Page • http://dictionary.reference.com/search?q=resin • http://www.deutsches-kunststoff-museum.de/optimal/eplast01.htm • http://wwwcp.tphys.uni-heidelberg.de/Polymer/day1/p4.htm • http://www.franklinparrasch.com/index.htm