The effect of hydrogen bonding interactions on the drop generation of both acid and hydroxyl-containing polymer solutions is reported showing that polymer chain relaxation can be influenced through the use of appropriate polymer co-solvent interactions for polymers having weight average molecular weight (Mw) < 100 kDa. Reported for the first time is evidence of flow-induced polymer degradation during inkjet printing for both poly(methylmethacrylate) and polystyrene in good solvent. Polymers having Mw either less than 100 kDa or greater than approximately 1,000 kDa show no evidence of molecular weight degradation. The lower boundary condition is a consequence of low Deborah number imposed by the printhead geometry and the upper boundary condition due to viscoelastic damping. For intermediate molecular weights the effect is greatest at high elongational strain rate and low solution concentration with higher polydispersity polymers being most sensitive to molecular weight degradation. For low polydispersity samples, PDi £ 1.3 chain breakage is essentially centro-symmetric induced either by overstretching when the strain rate increases well beyond a critical value, that is the stretching rate is high enough to exceed the rate of relaxation or by turbulence. For higher polydispersity samples, PDi chain breakage is consistent with almost random scission along the chain inferring that the forces required to break the chain are additionally transmitted either by valence bonds, i.e. network chains and junctions or discrete entanglements rather than solely by hydrodynamic interaction. Preliminary results are presented on the degradation of molecular structure in water of two galactomannan’s in water after inkjet printing. Galactommann’s are known to form complex H-bonded structures in water and the results are consistent with breaking of the H-bonding structure at low reduced concentration with evidence of main chain breakage at higher reduced concentration, c/c* = 0.25.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:525670 |
| Date | January 2010 |
| Creators | Alamry, Khalid Ahmad Abet |
| Contributors | Yeates, Stephen |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.research.manchester.ac.uk/portal/en/theses/flow-induced-polymer-degradation-during-inkjetprinting(88d2394a-d6be-4291-ba64-9544932e5279).html |
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