Succinic acid

Sodium alginate (Brookfield viscosity 350–550 mPa × s, c = 1%, w/w at 20 °C) was supplied by Across Organics (Geel, Belgium). Chestnut extract Farmatan (≥ 76% tannins) was provided by Tanin Sevnica (Sevnica, Slovenia). Calcium chloride (purity ≥ 96%) and acetic acid (99.5–99.9%) were purchased from Avantor Performance Materials (Gliwice, Poland). Glycerol was supplied by Merck (Darmstadt, Germany), while epoxidized soybean oil and epoxidized palm oil were from Inbra Indústrias Químicas LTDA (Sao Paulo, Brasil) and Malaysian Palm Oil Board (Kajang, Malaysia), respectively. Propylene glycol, cyclohexene and toluene (both pure p.a.), formic acid (85.0%), hydrogen peroxide (30.0%), disodium hydrogen phosphate dihydrate and sodium hydrogen carbonate (pure p.a.) were purchased from Chempur (Piekary Śląskie, Poland). Oleic acid (90.0%) was supplied by Alfa Aesar (Ward Hill, MA, USA), and succinic acid (≥ 99.5%) by POL-AURA (Zabrze, Poland). Methanesulfonic acid (> 99.0%) was provided by TCI (Zwijndrecht, Belgium).

Oleic acid tech. 90.0% (Alfa Aesar, Ward Hill, MA, USA), propylene glycol pure p.a. (Chempur, Piekary Śląskie, Poland), succinic acid ≥ 99.5% (Pol-Aura, Zabrze, Poland), toluene pure p.a. (Chempur, Piekary Śląskie, Poland), and methanesulfonic acid > 99.0% (TCI, Zwijndrecht, Belgium), were used in this study to synthesize mixed esters. Formic acid 85.0% (Chempur, Piekary Śląskie, Poland), hydrogen peroxide 30.0% (Chempur, Piekary Śląskie, Poland), and di-sodium hydrogen phosphate dihydrate pure p.a. (Chempur, Piekary Śląskie, Poland) were used for epoxidation reaction and purification of epoxidized mixed esters.
Suspension PVC with a K value of 70 and a bulk density of 0.495 g/cm³ (Polanvil S-70, Anwil S.A., Włocławek, Poland) was used in this study. Calcium carbonate filler (Extra 1, Piotrowice II, Tarnobrzeg, Poland) and Ca/Zn thermal stabilizer (Baeropan R8890KA/2, Baerlocher GmbH, Unterschleißheim, Germany) were used as additives. PVC blends were plasticized with commercially available plasticizers, i.e., DINP (Jayflex, ExxonMobil, Machelen, Belgium), DEHP (Oxoplast O30, Grupa Azoty ZAK S.A., Kędzierzyn-Koźle, Poland), and with plasticizers synthesized (Samples 1, 2, 3, and 4) in this work.