聚-4-乙基苯酚抗氧剂对聚丙烯结晶行为的影响

doi:10.11944/j.issn.1000-0518.2019.05.180286

摘要/Abstract

摘要：

通过差示扫描量热仪(DSC)和X射线粉末衍射仪(XRD)研究了聚-4-乙基苯酚抗氧剂对聚丙烯结晶行为的影响。分别用Jeziorny法和Mo法处理非等温结晶动力学。同时用Friedman法和Kissinger法计算其结晶活化能。最后由结晶活化能与结晶温度的变化曲线求得Hoffman-Lauritzen参数成核速率常数(K_g)和迁移活化能(U^*)值,进而求得折叠链端表面自由能(σ_e)和分子链段折叠功(q)。结果表明,抗氧剂的加入,使聚丙烯的结晶峰温度向低温区移动,结晶半峰宽变大,半结晶时间(t_1/2)增大,Jeziorny法所得的结晶速率常数(Z)降低,Mo法所得反映结晶速率快慢的参数F(T)提高,在相同结晶转化率下,结晶活化能负值变小。 Hoffman-Lauritzen参数K_g、U^*、σ_e和q值均增大。所有变化均表明聚-4-乙基苯酚抗氧剂对PP的结晶有抑制作用。

关键词: 聚丙烯, 抗氧剂, 非等温结晶

Abstract:

The effect of poly(4-ethylphenol) antioxidant on the non-isothermal crystallization behavior of polypropylene(PP) was studied by differential scanning calorimetry(DSC) and X-ray powder diffractometry(XRD), respectively. The non-isothermal crystallization kinetics was studied by the Jeziorny method and the Mo method, and the activation energy was calculated by the Friedman method and the Kissinger method at the same time. The Hoffman-Lauritzen parameters of nucleation rate constant(K_g) and molecular diffusion activation energy(U^*) are obtained from the relation of crystallization activity energy and average crystallization temperatures for PP and PP with (4-ethylphenol) antioxidant(PP-A) samples, and the fold surface free energy(σ_e) and the work of chain folding per molecule(q) are then calculated. The results show that the crystallization peak of PP-A moves to a lower temperature with the addition of antioxidant, and the crystallization half-peak width becomes broader, the semi-crystallization(t_1/2) and the parameter F(T) reflecting the value of cooling rate chosen at unit crystallization time obtained by Mo method increase while the crystallization rate(Z) decreases. The negative crystallization activity energy becomes smaller at the same crystallization conversion rate, and the Hoffman-Lauritzen parameters of K_g, U^*, σ_e and q increase. All the results indicate that poly(4-ethylphenol) antioxidant inhibits the crystallization of PP.

Key words: polypropylene, antioxidant, non-isothermal crystallization

张予东,高芸,张磊,李庆华. 聚-4-乙基苯酚抗氧剂对聚丙烯结晶行为的影响[J]. 应用化学, 2019, 36(5): 539-547.

ZHANG Yudong,GAO Yun,ZHANG Lei,LI Qinghua. Effect of Poly(4-ethylphenol) Antioxidant on Non-isothermal Crystallization Behavior of Polypropylene[J]. Chinese Journal of Applied Chemistry, 2019, 36(5): 539-547.

参考文献

[1]	Zheng K,Duan H,Zhang L,et al. Synthesis of Poly(4-methoxyphenol) by Enzyme-Catalyzed Polymerization and Evaluation of Its Antioxidant Activity[J]. New J Chem,2013,37:4185-4191.
[2]	Zheng K,Tang H,Chen Q M,et al. Enzymatic Synthesis of a Polymeric Antioxidant for Efficient Stabilization of Polypropylene[J]. Polym Degrad Stab,2015,112:27-34.
[3]	Gao Y H,Jiang F,Zhang L,et al. Enzymatic Synthesis of Polyguaiacol and Its Thermal Antioxidant Behavior in Polypropylene[J]. Polym Bull,2016,73:1343-1359.
[4]	JIANG Fan,CHAI Chunxiao,TIAN Qingfeng,et al. Influences of p-Cresol Oligomer on Thermal Oxidation Stability of Polypropylene[J]. Polym Mater Sci Eng,2017,33(12):53-58(in Chinese). 江帆,柴春晓,田庆丰,等. 4-甲基苯酚低聚物对聚丙烯热氧稳定性的影响[J]. 高分子材料科学与工程,2017,33(12):53-58.
[5]	Papageorgiou G Z,Achilias D S,Bikiaris D N,et al. Crystallization Kinetics and Nucleation Activity of Filler in Polypropylene/Surface-Treated SiO2 Nanocomposites[J]. Thermochim Acta,2005,427:117-128.
[6]	Jiang J,Li G,Tan N S.Crystallization and Melting Behavior of Isotactic Polypropylene Composites Filled by Zeolite Supported β-Nucleator[J]. Thermo Acta,2012,546:127-133.
[7]	Nattapon U,Methakarn J,Zheng P,et al. Effects of Cooling Rates on Crystallization Behavior and Melting Characteristics of Isotactic Polypropylene as Neat and in the TPVs EPDM/PP and EOC/PP[J]. Polym Test,2015,44:101-111.
[8]	Durmus A,Yalcinyuva T.Effects of Additives on Non-isothermal Crystallization Kinetics and Morphology of Isotactic Polypropylene[J]. J Polym Res,2009,16:489-498.
[9]	Klemens G,Susanne B,Gernot M,et al. Characterization of the Influence of Specimen Thickness on the Aging Behavior of a Polypropylene Based Model Compound[J]. Polym Degrad Stab,2015,111:185-193.
[10]	Xin M L,Ma Y J,Lin W H,et al. Use of Dihydromyricetin as Antioxidant for Polypropylene Stabilization[J]. J Therm Anal Calorim,2015,120:1741-1747.
[11]	LIU Xianlong,LI Juan,WU Yujiao,et al. Effect of Different Antioxidants on Properties of PP/NA-11 by Non-isothermal Crystallization Kinetic[J]. China Plast Ind,2015,43(2):81-85 (in Chinese). 刘先龙,李娟,伍玉娇,等. 非等温结晶动力学研究不同抗氧剂对PP/NA-11性能的影响[J]. 塑料工业,2015,43(2):81-85.
[12]	CHAI Chunxiao,JIANG Fan,ZHENG Ke,et al. Enzymatic Synthesis of 4-Ethylphenol Oligomer and Investigation of Its Antioxidant Performance[J]. Chem Res,2017,28(4):487-492 (in Chinese). 柴春晓,江帆,郑轲,等. 4-乙基苯酚低聚物的酶催化合成及抗氧化性能研究[J]. 化学研究,2017,28(4):487-492.
[13]	Weng W G,Chen G H,Wu D J.Crystallization Kinetics and Melting Behaviors of Nylon 6/Foliated Graphite Nanocomposites[J]. Polymer,2003,44(26):8119-8132.
[14]	ZHANG Yudong,GUO Liping,XU Xiangmin,et al. Non-Isothermal Crystallization Kinetics and Dynamic Mechanical Properties of Polyoxymethylene/Reactable nano-SiO2 Composites[J]. China Plast,2013,27(2):44-50(in Chinese). 张予东,郭莉萍,徐翔民,等. 聚甲醛-可反应性纳米SiO2的非等温结晶动力学及动态力学性能[J]. 中国塑料,2013,27(2):44-50.
[15]	MO Zhishen.A Method for the Non-isothermal Crystallization Kinetics of Polymers[J]. Acta Polym Sin,2008,7:656-661(in Chinese). 莫志深. 一种研究聚合物非等温结晶动力学的方法[J]. 高分子学报,2008,7:656-661.
[16]	Vyazovkin S.A Time to Search:Finding the Meaning of Variable Activation Energy[J]. Phys Chem Chem Phys,2016,18:18643-18656.
[17]	Vyazovkin S.Isoconversional Kinetics of Polymers:The Decade Past[J]. Macromol Rapid Commun,2017,38:1600615-1600636.
[18]	Kissinger H E.Variation of Peak Temperature with Heating Rate in Differential Thermal Analysis[J]. J Res Natl Bur Stand,1956,57(4):217-221.
[19]	Friedman H J.Kinetics of Thermal Degradation of Char-Forming Plastics from Thermogravimetry. Application to a Phenolic Plastic[J]. J Polym Sci Part C,1964,6(1):183-195.
[20]	Vyazovkin S,Sbirrazzuoli N.Isoconversional Analysis of Calorimetric Data on Nonisothermal Crystallization of a Polymer Melt[J]. J Phys Chem B,2003,107:882-888
[21]	Vyazovkin S,Sbirrazzuoli N.Isoconversional Approach to Evaluating the Hoffman Lauritzen Parameters(U* and Kg) from the Overall Rates of Nonisothermal Crystallization[J]. Macromol Rapid Commun,2004,25(6):733-738.
[22]	Gupta S,Yuan X P,Chung T C M,et al. Isothermal and Non-isothermal Crystallization Kinetics of Hydroxyl-Functionalized Polypropylene[J]. Polymer,2014,55(3):924-935.
[23]	Wu T M,Hsu S F,Chien C F,et al. Isothermal and Nonisothermal Crystallization Kinetics of Syndiotactic Polystyrene/Clay Nanocomposites[J]. Polym Eng Sci,2004,44(12):2288-2297.
[24]	Mahajan S J,Deopura B L,Yimin W.Structure and Properties of Drawn Tapes of High-Density Polyethylene/Ethylene Copolymer Blends.I[J]. J Appl Polym Sci,1996,60(10):1517-1525.