The FTIR infrared spectroscopy method was used to analyze the changes of the PP group and the modified PP at the time of aging(the most important is the infrared absorption peak of the carbonyl compound).The change of...The FTIR infrared spectroscopy method was used to analyze the changes of the PP group and the modified PP at the time of aging(the most important is the infrared absorption peak of the carbonyl compound).The change of the PP carbonyl index was also known.We can understand the process of light and oxygen aging and the mechanism of light stabilizer on PP.After accelerated aging,it was found that the carbonyl index of pure PP increased with the increasing of aging time.The carbonyl index of modified PP after adding HALS was relatively small,and the change range was small,and the anti-aging effect was obvious.展开更多
The effect of a novel active nucleating agent(TBC8-eb) on the isothermal crystallization of poly(L-lactic acid) (PLLA) was studied by differential scanning calorimetry(DSC) and Fourier transform infrared spectroscopy(...The effect of a novel active nucleating agent(TBC8-eb) on the isothermal crystallization of poly(L-lactic acid) (PLLA) was studied by differential scanning calorimetry(DSC) and Fourier transform infrared spectroscopy(FTIR) . The analysis on kinetics demonstrates that TBC8-eb can not only accelerate the crystallization rate but also transform most of the original spherulite crystals of PLLA into sheaf-like crystals. Furthermore,the free energy of folding(σe) of PLLA and PLLA with TBC8-eb is 0.15 and 0.06 J·m-2,respectively,which suggests that the addition of TBC8-eb favors the regular folding of molecule chains in the crystallization of PLLA,improv-ing its crystallization rate. The FTIR results show that TBC8-eb can accelerate the conformational ordering of PLLA in the isothermal crystallization. The conformational ordering of PLLA nucleated with TBC8-eb begins with the interchain interaction of CH3,and then a short helix emerges where a couple of CH3 groups interact.展开更多
The red seaweed Melanothamnus somalensis was investigated as potential economic source of agar. The effect of different conditions of alkali pre-treatment on chemical properties of agar was evaluated. Agar was extract...The red seaweed Melanothamnus somalensis was investigated as potential economic source of agar. The effect of different conditions of alkali pre-treatment on chemical properties of agar was evaluated. Agar was extracted by various concentrations of NaOH （4%, 6% and 8%） and heated at different temperatures （70 ℃, 75 ℃ and 80 ℃） for different durations （2 h, 2.75 h and 3.5 h）. The yields-molecular weight （Mw） and sulfate contents of extracted agar were analysed and characterized by FTIR spectroscopy. The yield was significantly increased at these treatments from 23.29% to 30.86%. Mw studied by HPLC ranged from （.12.45 ± 0.21） × 10^5 to （8.60 ± 2.40） × 10^5 Da. FTIR bands show sulfate groups in C4 and C6 ofgalactose and no sulfate group were found on both C2 of galactose and C2 of 3,6-anhydrogalactose. All treatments showed a high sulfate content that ranged from 5.4% to 10.1%. These properties were found to be significantly affected by the alkali pre-treatment concentration （p 〈 0.05）. In conclusion, agar extracted in this study was considered acceptable for industrial application and the optimal conditions for extraction were found to be at 6% NaOH at 70 ℃ for 2 hours.展开更多
文摘The FTIR infrared spectroscopy method was used to analyze the changes of the PP group and the modified PP at the time of aging(the most important is the infrared absorption peak of the carbonyl compound).The change of the PP carbonyl index was also known.We can understand the process of light and oxygen aging and the mechanism of light stabilizer on PP.After accelerated aging,it was found that the carbonyl index of pure PP increased with the increasing of aging time.The carbonyl index of modified PP after adding HALS was relatively small,and the change range was small,and the anti-aging effect was obvious.
基金Supported by the National Natural Science Foundation of China （20876042） Program of Shanghai Subject Chief Scientist （10XD1401500） Research Fund for the Doctoral Program of Higher Education of China
文摘The effect of a novel active nucleating agent(TBC8-eb) on the isothermal crystallization of poly(L-lactic acid) (PLLA) was studied by differential scanning calorimetry(DSC) and Fourier transform infrared spectroscopy(FTIR) . The analysis on kinetics demonstrates that TBC8-eb can not only accelerate the crystallization rate but also transform most of the original spherulite crystals of PLLA into sheaf-like crystals. Furthermore,the free energy of folding(σe) of PLLA and PLLA with TBC8-eb is 0.15 and 0.06 J·m-2,respectively,which suggests that the addition of TBC8-eb favors the regular folding of molecule chains in the crystallization of PLLA,improv-ing its crystallization rate. The FTIR results show that TBC8-eb can accelerate the conformational ordering of PLLA in the isothermal crystallization. The conformational ordering of PLLA nucleated with TBC8-eb begins with the interchain interaction of CH3,and then a short helix emerges where a couple of CH3 groups interact.
文摘The red seaweed Melanothamnus somalensis was investigated as potential economic source of agar. The effect of different conditions of alkali pre-treatment on chemical properties of agar was evaluated. Agar was extracted by various concentrations of NaOH （4%, 6% and 8%） and heated at different temperatures （70 ℃, 75 ℃ and 80 ℃） for different durations （2 h, 2.75 h and 3.5 h）. The yields-molecular weight （Mw） and sulfate contents of extracted agar were analysed and characterized by FTIR spectroscopy. The yield was significantly increased at these treatments from 23.29% to 30.86%. Mw studied by HPLC ranged from （.12.45 ± 0.21） × 10^5 to （8.60 ± 2.40） × 10^5 Da. FTIR bands show sulfate groups in C4 and C6 ofgalactose and no sulfate group were found on both C2 of galactose and C2 of 3,6-anhydrogalactose. All treatments showed a high sulfate content that ranged from 5.4% to 10.1%. These properties were found to be significantly affected by the alkali pre-treatment concentration （p 〈 0.05）. In conclusion, agar extracted in this study was considered acceptable for industrial application and the optimal conditions for extraction were found to be at 6% NaOH at 70 ℃ for 2 hours.
