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 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Non-Isothermal Crystallization and Thermal Degradation Kinetics of Biodegradable Poly(butylene adipate-co-terephthalate)/Starch Blends) ผู้เขียน: ดร.สุรศักดิ์ เชียงกา, รองศาสตราจารย์ ,  Satayu Suwannasopon, Nutnarun (Supreya) Trivijitkasem สื่อสิ่งพิมพ์:pdf AbstractThe non-isothermal crystallization behavior of biodegradable poly (butylene adipate-coterephthalate)/ starch (PBAT/S) blends was studied using differential scanning calorimetry under a nitrogen atmosphere from 25 to 225 ?C at four constant cooling rates of 5, 10, 15 and 20 ?C.min-1. There was only one crystallization peak in the exothermic curve which shifted to a lower temperature as the cooling rate was increased. The crystallization temperature decreased from 98 to 84 ?C, but the crystallization enthalpy increased from 11 to 12 J.g-1 as the heating rate was increased. The thermal degradation(TG) of the PBAT/S blends was studied using thermogravimetric analysis under a nitrogen atmosphere from 100 to 800 ?C at five constant heating rates of 1, 2, 5, 10, and 15 ?C.min-1. The TG curves showed two degradation stages occurring at 309–342 ?C and 375–420 ?C, which were the degradation of corn starch and PBAT, respectively. The thermal degradation kinetics of the PBAT/S were analyzed using the isoconversion Flynn- Wall-Ozawa model-free method. The results showed that both the apparent activation energy and the logarithm pre-exponent factor increased with increasing conversion ?. The average apparent activation energy and the average logarithm apparent pre-exponent factor for ? = 0.1 – 0.9 were 266 kJ.mol-1 and 37 min-1, respectively. The reaction model g(?) determined from the master plot method for PBAT/S was a phase-boundary controlled reaction, where g(?) = [1– (1– ?)1/2] |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Thermal Degradation of Biodegradable Poly(butylene adipate-co-terephthalate)/Starch Blends) ผู้เขียน:ดร.สุรศักดิ์ เชียงกา, รองศาสตราจารย์, Satayu Suwannasopon, Nutnarun (Supreya) Trivijitkasem สื่อสิ่งพิมพ์:pdf AbstractThermal degradation of biodegradable poly(butylene adipate-co-terephthalate) /starch (PBAT/S) blends of 15 ?m thickness was investigated by thermogravimetric analysis in a nitrogen atmosphere and in an air atmosphere at a flow rate of 20 mL.min-1. The non-isothermal experiments were conducted at five constant heating rates (? = 1, 2, 5, 10 and 15 oC.min-1) from 100 to 800 oC. The thermogravimetric curves showed two degradation stages in a nitrogen atmosphere and three degradation stages in an air atmosphere. The second stage occurred at temperatures from 366 to 418 and 369 to 421 oC respectively. Three models—namely, the model-free isoconversion methods of Kissinger-Akahira-Sunose (KAS), Ozawa-Flynn-Wall (OFW) and Friedman (FR) were used to determine the dependence of the apparent activation energy E?. The results showed higher E? values on conversion ? in the nitrogen atmosphere. The average E? levels were 172, 174 and 173 kJ.mol-1 in the nitrogen atmosphere and 159, 159 and 160 kJ. mol-1 in the air atmosphere for the KAS, OFW and FR methods, respectively. This confirmed that thermal degradation in an air atmosphere is faster than in a nitrogen atmosphere. |
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