Combined thermal analysis of fluid plasticizers
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Combined thermal analysis of fluid plasticizers Chukwuemeka L. Ihemaguba1 · Kálmán Marossy1,2 Received: 27 February 2020 / Accepted: 28 September 2020 © The Author(s) 2020
Abstract The paper deals with the study of plasticizers using different thermal methods. The literature data on the melting points of plasticizers proved uncertain; we intended to gather the data by other methods, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermally stimulated discharge (TSD). Results of ten plasticizers are demonstrated. During this work, we found that most of plasticizers have no well-defined melting point, and the solidification of plasticizer is similar to the glass transition of polymers. Only the di-n-butyl-phthalate showed regular crystallization. Thermally stimulated discharge current (TSD) method revealed that these compounds have several transitions –dispersion ranges assigned to different molecular motions. Keywords Plasticizers · DSC · Dynamic mechanical analysis (DMA) · Thermally stimulated discharge (TSD)
Introduction Melting point is an important property of a pure compound. This value is usually imparted in technical data sheets of plasticizers but without describing the method used. We intended to check the melting points by DSC. The behavior of polymers is determined by relaxation processes; therefore, investigation and understanding these processes are essential. Reverse behavior of polymers makes possible the determination of these processes. Even in homopolymers of simple structure, different relaxation processes running simultaneously make the analysis of experimental results difficult, for example, α relaxation (glass transition) assigned to main-chain segmental motion, the β relaxation assigned to side-chain motion and further short-distance conformational motions. The picture is much more complicated if the material is complex, e.g., a copolymer, a polymer blend or plasticized one. The components might influence each other’s mobility. These processes can be investigated in mechanical field: thermo-mechanical analysis (TMA), dynamic mechanical analysis (DMA), thermally stimulated creep (TSC); in * Kálmán Marossy polkal01@uni‑miskolc.hu 1
University of Miskolc, 3515 Miskolc Egyetemváros, Hungary
Borsodchem Zrt, 3700 Kazincbarcika, Bolyai tér 1, Hungary
2
electric field: dielectric thermal analysis (DETA), thermally stimulated discharge (TSD); and by thermal properties: differential scanning calorimetry (DSC). Tseretely [1] tested gelatins by DSC and stated glass transitions can be found in gelatins. For testing liquid substances, DSC is generally used but DMA and TSD are seldom applied. Low molecular mass glassy solids and liquids like phenyl-salicylate, maltitol and glycerol were investigated by TSD [2], and relaxation processes were resolved by thermal sampling method. Rapeseed oil was tested by AC dielectric method [3] from 10 MHz to 3 GHZ. Even 10 Hz is 4 to 5 orders of magnitude higher frequency than the effective frequency of TSD. [4] The effect of pla
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