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Flow Induced Polymer Degradation During Ink-JetPrinting
[Thesis]. Manchester, UK: The University of Manchester; 2010.
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Abstract
The effect of hydrogen bonding interactions on the drop generation of both acid and hydroxylcontainingpolymer solutions is reported showing that polymer chain relaxation can beinfluenced through the use of appropriate polymer co-solvent interactions for polymers havingweight average molecular weight (Mw) < 100 kDa.Reported for the first time is evidence of flow-induced polymer degradation during inkjetprinting for both poly(methylmethacrylate) and polystyrene in good solvent. Polymers havingMw either less than 100 kDa or greater than approximately 1,000 kDa show no evidence ofmolecular weight degradation. The lower boundary condition is a consequence of low Deborahnumber imposed by the printhead geometry and the upper boundary condition due to viscoelasticdamping. For intermediate molecular weights the effect is greatest at high elongationalstrain rate and low solution concentration with higher polydispersity polymers being mostsensitive to molecular weight degradation. For low polydispersity samples, PDi £ 1.3 chainbreakage is essentially centro-symmetric induced either by overstretching when the strain rateincreases well beyond a critical value, that is the stretching rate is high enough to exceed the rateof relaxation or by turbulence. For higher polydispersity samples, PDi chain breakage isconsistent with almost random scission along the chain inferring that the forces required to breakthe chain are additionally transmitted either by valence bonds, i.e. network chains and junctionsor discrete entanglements rather than solely by hydrodynamic interaction.Preliminary results are presented on the degradation of molecular structure in water of twogalactomannan’s in water after inkjet printing. Galactommann’s are known to form complex Hbondedstructures in water and the results are consistent with breaking of the H-bonding structureat low reduced concentration with evidence of main chain breakage at higher reducedconcentration , c/c* = 0.25
Layman's Abstract
The effect of hydrogen bonding interactions on the drop generation of both acid and hydroxylcontainingpolymer solutions is reported showing that polymer chain relaxation can beinfluenced through the use of appropriate polymer co-solvent interactions for polymers havingweight average molecular weight (Mw) < 100 kDa.Reported for the first time is evidence of flow-induced polymer degradation during inkjetprinting for both poly(methylmethacrylate) and polystyrene in good solvent. Polymers havingMw either less than 100 kDa or greater than approximately 1,000 kDa show no evidence ofmolecular weight degradation. The lower boundary condition is a consequence of low Deborahnumber imposed by the printhead geometry and the upper boundary condition due to viscoelasticdamping. For intermediate molecular weights the effect is greatest at high elongationalstrain rate and low solution concentration with higher polydispersity polymers being mostsensitive to molecular weight degradation. For low polydispersity samples, PDi £ 1.3 chainbreakage is essentially centro-symmetric induced either by overstretching when the strain rateincreases well beyond a critical value, that is the stretching rate is high enough to exceed the rateof relaxation or by turbulence. For higher polydispersity samples, PDi chain breakage isconsistent with almost random scission along the chain inferring that the forces required to breakthe chain are additionally transmitted either by valence bonds, i.e. network chains and junctionsor discrete entanglements rather than solely by hydrodynamic interaction.Preliminary results are presented on the degradation of molecular structure in water of twogalactomannan’s in water after inkjet printing. Galactommann’s are known to form complex Hbondedstructures in water and the results are consistent with breaking of the H-bonding structureat low reduced concentration with evidence of main chain breakage at higher reducedconcentration , c/c* = 0.25
Keyword(s)
Inkjet printing, DOD, Polysacchride degradation,Overlap concentration, Microfab,High Mwt PMMA