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oai:www.ideals.illinois.edu:2142/71853 2023-07-11 col_2142_5131 col_2142_47053 com_2142_5130 com_2142_47052 com_2142_234

Wool, Richard P. Willett, Julious Lee 2014-12-16T20:52:18Z 2014-12-16T20:52:18Z 10000-01-01 1988 1988 Mechanical strength of incompatible polymer interfaces welded above T$\sb{\rm g}$ has been investigated as a function of time, temperature, and composition. Three pairs of polymers were used: polystyrene-polymethylmethacrylate, polystyrene-co-acrylonitrile-polymethylmethacrylate, and polystyrene-co-acrylonitrile-polycarbonate. For each pair, the weld strength, as measured by G$\sb{\rm IC}$, attained a constant value which increased with welding temperature. While only five to ten percent of bulk G$\sb{\rm IC}$ values, these plateau values are orders of magnitude greater than the work of adhesion calculated using intermolecular forces. For the copolymer-homopolymer pairs, the maximum plateau strength was reached when the interaction parameter was a minimum. These results are in agreement with a model of the interface based on current molecular theories of incompatible interfaces coupled with a chain pull out microstructural deformation mechanism, which predicts that G$\sb{\rm IC}$ increases inversely with the interaction parameter, X. Microscopic investigation of the fracture surfaces revealed dissimilar fracture surfaces for a given pair, with evidence of stick-slip crack growth. X-ray photoelectron spectroscopy revealed residues of one polymer on the other's surface, indicating cohesive fracture occurred to some extent; in each case, the residue was always from the polymer with the lower entanglement density. Made available in DSpace on 2014-12-16T20:52:18Z (GMT). No. of bitstreams: 1 8823290.pdf: 5113962 bytes, checksum: 87c04810974abd02dc1478a14f973517 (MD5) Previous issue date: 1988 Embargo set by: Seth Robbins for item 72019 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 221 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988. http://hdl.handle.net/2142/71853 (UMI)AAI8823290 Engineering, Materials Science Strength Development at Incompatible Polymer Interfaces text Metallurgy and Mining Engineering Metallurgical Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.