Reološko ponašanje polikaprolakton (PCL)/termoplastični škrob (TPS) mješavina

undergraduate thesis

• Title (english): Rheological behaviour of polycaprolactone (PCL)/thermoplastic starch (TPS) blends
• Author: Ana Pracaić
• Mentor: Elvira Vidović (mentor)
• Committee member: Elvira Vidović (predsjednik povjerenstva)
• Committee member: Vesna Ocelić Bulatović (član povjerenstva)
• Committee member: Domagoj Vrsaljko (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2024-09-05, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

U današnje vrijeme, sve veća pažnja usmjerava se prema očuvanju okoliša i biorazgradivosti materijala. Zbog toga se sve više primjenjuju biorazgradivi polimeri poput škroba. Škrob je prah kojeg je potrebno plastificirati da bi se dobro iskoristila njegova svojstva: mekoća, niska cijena i visoki postotak biorazgradivosti. On prelazi u termoplastični škrob (TPS) djelovanjem mehaničke i toplinske energije u prisustvu plastifikatora. Pripravom TPS-a dolazi do potpunog narušavanja kristalne strukture te se dobije potpuno amorfni polimer. Umješavanjem TPS-a s drugim polimerima pokušava se dobiti ekološki prihvatljivije polimere zbog njihove biorazgradivosti. Miješanje TPS-a sa polikaprolaktonom (PCL) daje sustav
TPS/PCL poboljšanih nekih svojstava i moguće šire primjene. Primjer upotrebe TPS/PCL sustava je za proizvodnju vrećica za pakiranje hrane, čija primjena raste zahvaljujući porastu ekološke osviještenosti, a sve u cilju povećanja uporabe biorazgradivih polimera. Dodatno, sve se više rabi u medicinske svrhe. Kod priređenih TPS/PCL mješavina ispitano je njihovo reološko ponašanje te su uz pomoć dinamičko-mehaničke (toplinske) analize (DMTA) istražena mehanička svojstva. Mjerenja na oscilacijskom reometru provedena su ispitivanjem u frekvencijskom području od 0,1 do 100 rad/s pri amplitudi deformacije 0,5% te pri stalnoj temperaturi od 120 °C. Određeno je područje linearne viskoelastičnosti s obzirom na ovisnost modula pohrane o amplitudi deformacije koja je mjerena na 120 °C pri frekvenciji od 1 Hz. Kod DMTA metode se torzijski djelovalo na uzorke u temperaturnom rasponu od -80 °C do 160 °C. Djelovanjem torzije dolazilo je do deformacije ili loma uzorka ovisno o omjeru TPS-a i PCL-a u mješavini. Analiza uzoraka pokazala je da porastom udjela PCL-a dolazi do smanjenja viskoznosti sustava. Najveća viskoznost zabilježena je u sustavu TPS/PCL (80/20). Zbog toga se sustavi udjela TPS-a većeg od 30 mas.% ponašaju kao gelovi te imaju veću otpornost na deformacije, a sustavi manjeg udjela ponašaju se poput tekućina. Dodatkom punila titanijeva dioksida TiO2 mijenjaju se morfološka svojstva i kristalnost mješavina što otvara dodatnu mogućnost kontrole svojstava i utjecaja na njih.

Abstract (english)

In today's world, increasing attention is being directed towards environmental preservation and biodegradability of materials. As a result, biodegradable polymers such as starch are being increasingly applied. Starch is a powder that needs to be plasticized to fully utilize its properties: softness, low cost, and high biodegradability. It transforms into thermoplastic starch (TPS) under the influence of mechanical and thermal energy in the presence of a plasticizer. The preparation of TPS completely disrupts the crystalline structure, resulting in a fully amorphous polymer. By blending TPS with other polymers, efforts are being made to create more environmentally friendly polymers due to their biodegradability. Mixing TPS with polycaprolactone (PCL) produces a TPS/PCL system with improved properties and potentially broader applications. An example of the use of the TPS/PCL system is in the production of food packaging bags, whose application is growing thanks to the rise in environmental awareness, all aimed at increasing the use of biodegradable polymers. Additionally, it is increasingly used for medical purposes. The rheological behavior of prepared TPS/PCL mixtures was examined, and mechanical properties were investigated using dynamic mechanical (thermal) analysis (DMTA). Measurements on an oscillatory rheometer were conducted by testing in a frequency range from 0.1 to 100 rad/s at a deformation amplitude of 0.5% and a constant temperature of 120 °C. The linear viscoelastic region was determined based on the dependence of the storage modulus on the deformation amplitude measured at 120 °C at a frequency of 1 Hz. In the DMTA method, the samples were subjected to torsion in the temperature range from -80 °C to 160 °C. The torsional action caused deformation or fracture of the sample depending on the ratio of TPS to PCL in the mixture. Analysis of the samples showed that increasing the PCL content decreases the viscosity of the system. The highest viscosity was recorded in the TPS/PCL (80/20) system. Therefore, systems with a TPS content greater than 30 wt.% behave like gels and have greater resistance to deformation, while systems with lower content behave like liquids.
The addition of titanium dioxide (TiO2) filler alters the morphological properties and crystallinity of the mixtures, offering an additional possibility to control and influence their properties.

• Keywords: termoplastični škrob; polikaprolakton; titanijev dioksid; DMTA; reologija
• Keywords (english): thermoplastic starch; polycaprolactone; titanium dioxid; DMTA; rheology
• Language: croatian
• URN:NBN: urn:nbn:hr:149:800262
• Study programme: Title: Chemical Engineering - Undergraduate study; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-11-06 09:08:34