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The effect of branch density polyoxymethylene copolymersIlg, Andrea Diane 15 May 2009 (has links)
Today, there is a great need for polymers made from biorenewable resources
due to the increasing price and diminishing supplies of petroleum and the
overabundance of plastic waste in landfills. Polyoxymethylene can be produced
from biorenewable feedstocks, depolymerized to formaldehyde through chemical
recycling, and may be a viable alternative to many polyolefins. However, there has
been limited research on varying the thermomechanical properties of
polyoxymethylene so that it can be used in a wider variety of applications. Our
approach employs the cationic copolymerization of trioxane with various amounts of
1,2-epoxyalkanes and 4-alkyl-1,3-dioxolanes to arrive at polyoxymethylene
derivatives with controlled branching and morphology.
Branching content has been measured by nuclear magnetic resonance (NMR)
spectroscopy and correlates well with the comonomer feed fraction. The melting
temperatures of the copolymers, determined from differential scanning calorimetry
(DSC), are depressed predictably with increasing amounts of comonomer
incorporation. The copolymerizations behaved the same regardless of whether the
comonomer was an alkyldioxolane or epoxyalkane. 1,2-Epoxybutane/trioxane
copolymers and 4-ethyl-1,3-dioxolane/trioxane copolymers gave the best melting point and % crystallinity results using boron trifluoride diethyl etherate as the
cationic initiator.
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