Naslov
Modification of polyacrylate material properties used for 3D printing

Autori
Cingesar, Ivan Karlo ; Marković, Marijan-Pere ; Vrsaljko, Domagoj

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, ostalo, znanstveni

Izvornik
CHISA 2022 Scientific programme – table of contents / - Prag, 2022, P542-P542

Skup
25th International Congress of Chemical and Process Engineering (CHISA 2022)

Mjesto i datum
Prag, Češka Republika, 21.08.2022. - 25.08.2022

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
additive manufacturing ; polyacrylate ; material properties

Sažetak
Additive manufacturing (AM) is a technology that enables simple and cost-effective production of customizable 3D components. One of the most interesting additive manufacturing technologies is stereolithography (SLA). SLA offers the ability to 3D print custom reactionware on micro and millimetre scale with transparent materials. As AM became more affordable, 3D printers became go-to tool for manufacturing of flow reactors and other various reaction devices [1, 2]. Transparent materials, dimensional stability, and accuracy are the advantages of SLA, while the limitation to only a few base materials is its disadvantage. Figure 1 shows a possible application of 3D printing for the production of flow reactionware for synthesis, separation and similar processes. Usually, the materials used in SLA need to be post-processed to obtain better application properties. 3D printing was performed using a Form 2 3D printer from Formlabs Inc. The test specimens complied with ISO 527-2. Specimen types 1BA and 5B were selected to see if the thickness and size of the specimen had any effect on the mechanical properties. Two of the materials were characterized: Clear (CLR) resin and High Temperature (HT) resin, manufactured by Formlabs Inc. Post-curing of polyacrylate materials is usually done with a 405 nm light source and a heat source. By exposing the model to light and heat, the degree of cure of the material changes. Curing includes both the degree of polymerization and the crosslinking of the polymer chains. By affecting the degree of cure of the material, mechanical, thermal and physico-chemical properties change. Post-processing was carried out in several different regimes: In a 405 nm light illuminated chamber heated to 60 °C for 15, 30, 45, 60 and 90 minutes, heated at 100 °C for 30 minutes in an Instrumentaria ST-05-S laboratory oven, in a SunTest CPS Heraeus Industrietechnik chamber for 5, 15 and 30 minutes and in direct sunlight for 5, 15 and 30 minutes. After post-curing process, a tensile test was performed to determine the mechanical properties. The tensile test showed that the tensile strength and Young’s modulus increased with increasing duration of post-curing. The sample of Clear material that was post-cured for 90 minutes, had the value of tensile strength and Young's modulus doubled compared to the sample of Clear that was post-cured for 15 minutes. The influence of sample thickness was not confirmed, i.e. there is no influence of sample thickness on the mechanical properties. Thermal properties were analysed by differential scanning calorimetry (DSC). The shift in glass transition temperature (Tg) and post-cure enthalpy (ΔH) were two major parameters used to determine the degree of post- cure. The same heating programme was used for both materials. For both materials, the post-cure enthalpy decreases as the duration of post-cure increases (figure 2). Clear material has lower enthalpy of curing in liquid state so the values overall are lower compared to the High Temperature material. There is a shift in the glass transition temperature for the Clear material, but it does not follow a trend. High Temperature shows a trend in shift of the glass transition temperature to higher values the longer the material is exposed to the post-cure process. Swelling and surface contact angle were two methods for testing physicochemical properties. For the swelling test, small plates of both materials were 3D printed and then immersed in three solvents. Distilled water, ethanol, and acetone were selected as solvents because they are among the most commonly used solvents in chemical laboratories. Both materials showed high resistance to water penetration. Clear material showed lower resistance to ethanol than the High Temperature material, but both materials showed almost no resistance to acetone penetration. The results of the surface contact angle tests showed no trend. This is consistent with the post-cure process, as the post-cure process generally affects the mass below the surface and not so much the surface. Stereolithography can be used to successfully 3D print reactionware. By post-curing the material mechanical and thermal properties of material are affected, and we can choose to which degree material should be cured depending on application of the manufactured model.

Izvorni jezik
Engleski

Znanstvena područja
Kemijsko inženjerstvo, Temeljne tehničke znanosti, Interdisciplinarne tehničke znanosti

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