Processing, compatibilization and molecular dynamics simulations of immiscible polyolefin/copolyester blends
Translated title
Processering, kompatibilisering og molekylær dynamik simuleringer af ikke blandbare polyolefin/copolyester blandinger
Author
Larsen, Thomas
Term
4. semester
Education
Publication year
2021
Submitted on
2021-06-03
Pages
60
Abstract
Blending dissimilar polymers can create useful materials, but immiscibility and weak interfacial adhesion often limit performance. This thesis examines (i) how the temperature profile during extrusion compounding affects the miscibility and morphology of polypropylene (PP)/poly(ethylene terephthalate glycol) (PETG) blends, (ii) how adding extra maleic anhydride (MAH)–functionalized compatibilizer influences a recycled PP/high‑density polyethylene (HDPE)/poly(ethylene terephthalate) (PET) blend, and (iii) how molecular dynamics (MD) can clarify miscibility in PP/PET systems. Light microscopy on strand surfaces and melts, together with rheology fitted by the Palierne model, showed that dispersed‑phase droplet size increases with PETG content and higher processing temperature; the Palierne model overestimated absolute sizes but captured the same trends. In the recycled blend, extra compatibilizer improved dispersion; FTIR suggested reaction between PET and MAH groups forming PET‑g‑MAH, and thermal/mechanical tests indicated reduced PET mobility and crystallization along with stronger interfacial adhesion, higher toughness and elasticity. MD studies quantified miscibility via Flory–Huggins χ and intermolecular radial distribution functions: most PP/PET blends were immiscible or only slightly miscible, but PP10/PET90 appeared miscible, possibly partly due to slight ordering of PET chains. Dilatometry on PP75/PET25 showed two glass transitions (immiscibility), whereas a reactively compatibilized PP/PP‑g‑PET system exhibited a single Tg between PP and PET. Overall, the work shows that processing conditions and reactive compatibilization can tune morphology and interfacial adhesion in polyolefin/copolyester blends, and that MD provides a useful complement to experiments.
Blanding af forskellige polymerer kan skabe nye materialer, men manglende blandbarhed og svag grænsefladeadhæsion begrænser ofte ydeevnen. Denne afhandling undersøger (i) hvordan temperaturprofilen under ekstrudering og kompoundering påvirker blandbarhed og morfologi i polypropylene (PP)/poly(ethylene terephthalate glycol) (PETG) blandinger, (ii) hvordan ekstra mængder maleinsyreanhydrid (MAH)–funktionaliseret kompatibilisator påvirker en genanvendt PP/high‑density polyethylene (HDPE)/poly(ethylene terephthalate) (PET) blanding, og (iii) hvordan molekylær-dynamik (MD) kan belyse blandbarheden i PP/PET systemer. Lysmikroskopi af strandoverflader og smelter samt reologi med Palierne‑modellering viste, at dråbe-/disperse fase‑størrelser stiger med både PETG‑indhold og højere procestemperatur; Palierne‑modellen overvurderede absolutte størrelser, men fangede de samme tendenser. I den genanvendte blanding forbedrede ekstra kompatibilisator dispersionen; FTIR indikerede reaktion mellem PET og MAH‑grupper med dannelse af PET‑g‑MAH, og termiske/mekaniske tests pegede på reduceret PET‑mobilitet og krystallisering samt stærkere faseadhæsion, højere sejhed og elasticitet. MD‑studier kvantificerede blandbarhed via Flory–Huggins χ og intermolekylære radialfordelingsfunktioner: De fleste PP/PET‑blandinger var ikke eller kun svagt blandbare, men PP10/PET90 fremstod blandbar, muligvis delvist på grund af let orden i PET‑kæder. Dilatometri på PP75/PET25 viste to glasovergange (immiscibilitet), mens et reaktivt kompatibiliseret PP/PP‑g‑PET system udviste en enkelt Tg mellem PP og PET. Samlet viser arbejdet, at procesparametre og reaktiv kompatibilisering målrettet kan styre morfologi og grænsefladeadhæsion i polyolefin/copolyester‑blandinger, og at MD er et nyttigt supplement til eksperimenter.
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Keywords
Blend ; Molecular Dynamics Simulations ; MD ; PP ; PET ; PETG ; Plastix ; Flory-Huggins ; Compatibilizer