Naslov
An attempt to quantitatively analyse submillimetre microplastics by DSC

Autori
Pucić, Irina ; Rapljenović, Ana ; Kwokal, Željko ; Cuculić, Vlado

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

Izvornik
28HSKIKI : 28th Croatian Meeting of Chemists and Chemical Engineers and 6th Symposium Vladimir Prelog : Book of Abstracts / Rogošić, Marko - Zagreb : Hrvatsko društvo kemijskih inženjera i tehnologa (HDKI), 2023, 237-237

Skup
28th Croatian Meeting of Chemists and Chemical Engineers

Mjesto i datum
Rovinj, Hrvatska, 28.03.2023. - 31.03.2023

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
DSC ; microplastics ; plastic pellets ; marine litter

Sažetak
Microplastics (MP) is already a notorious marine pollutant. Its role as a vehicle that transports bacteria and/or various substances including toxic trace metals is less known ; thus METALPATH project was conceived to address that problem. To understand the transport properties of MP it is necessary to assess qualitative and quantitative composition of each particular microplastic batch. This may be both challenging and time consuming, particularly for submillimetre particles. Since MP is constituted mostly of semicrystalline polymers, thermal analysis in the form of differential scanning calorimetry (DSC) is already proven as a fast and relatively simple method for identification of polymer composition in submillimetre microplastic collections. In an appropriately selected temperature range DSC is nondestructive so further analysis can be performed on the same sample. However, it is challenging to directly determine masses of particles in a collection of submillimetre MP. A method for quantitative analysis of MP by DSC was proposed by Hajo and Lackner. The authors stated that, since specific heat of a transformation like melting is expected to be constant for a particular polymer kind, the unknown sample mass can be calculated from calibrations based on a linear relationship of melting peak area and the sample mass. The problem is that the authors also proposed that a single calibration using virgin polymer should be valid for all MPs of that polymer kind, irrespective of their origin and state of degradation. The goal of this study was to test that concept by calibrating the melting peak area and sample mass relationship using both virgin polymers and real MP. In the case of two most common constituents of MP, high-density polyethylene (HDPE) and isotactic polypropylene (iPP), we found that linear relationship was valid, but the slopes of calibration curves varied. Variations were significant even between virgin samples of the same composition, as checked by ATRFTIR. Thus, we conclude that intrinsic polymer characteristics like molecular mass and its distribution and polymer processing affect specific heats of polymers in such a way that proposed calibration may only provide rough estimates of masses. In MP, oxidation and degradation on exposure to environment complicate the problem further so the approach to mass assessment of submillimetre MP batches needs to be revisited.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Interdisciplinarne prirodne znanosti

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