Bimodal architecture and rheological and foaming properties for gamma-irradiated long-chain branched polylactides

被引:52
作者
Fang, Huagao [1 ]
Zhang, Yaqiong [1 ]
Bai, Jing [1 ]
Wang, Zhongkai [1 ]
Wang, Zhigang [1 ]
机构
[1] Univ Sci & Technol China, Hefei Natl Lab Phys Sci Microscale, Dept Polymer Sci & Engn, CAS Key Lab Soft Matter Chem, Hefei 230026, Anhui, Peoples R China
基金
美国国家科学基金会;
关键词
ELECTRON-BEAM IRRADIATION; GURP-PALMEN-PLOT; POLY(LACTIC ACID); MELT RHEOLOGY; THERMORHEOLOGICAL BEHAVIOR; MOLECULAR-STRUCTURE; MECHANICAL-PROPERTIES; POLY(L-LACTIC ACID); THERMAL-PROPERTIES; CROSS-LINKING;
D O I
10.1039/c3ra40879e
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
A series of long-chain branched polylactides (LCB-PLAs) were prepared from a linear PLA precursor by applying gamma radiation with addition of the trifunctional monomer, trimethylolpropane triacrylate (TMPTA) and their topological structures were investigated by size-exclusion chromatography coupled with a multiangle light scattering detector (SEC-MALLS) and rheology. SEC-MALLS measurements show that LCB-PLAs exhibit not only the increased weight-average molecular mass but also a bimodal architecture with a short linear chain fraction and a LCB fraction, as compared with LCB-PLA samples generated by electron-beam radiation, which only show the monomodal macromolecular structure. The introduction of LCB structure contributes to the enhancement of complex viscosity, shear-thinning and storage modulus, and the deviations of phase angle, delta from the "universal'' curve of linear PLA in delta(vertical bar G(star)vertical bar) plots (van Gurp-Palmen plot). By the analysis of the thermorheological behaviors and determination of activation energies, the bimodal architecture is confirmed. Activation energies around 77 kJ mol(-1) lead to an expectation that some linear macromolecules are still present in LCB-PLAs, while the higher activation energies at large phase angles are associated with the existence of the LCB ones. A conclusion with respect to the tree-like topography for LCB-PLAs is drawn from the molecular mass dependences of zero-shear viscosity (eta(0)-M-w plot). An explanation to these findings is provided under the consideration of the radiation dose rate for the gamma radiation. The remarkable modification of PLA topological chain structure contributes to the improvement of the foaming properties of LCB-PLAs.
引用
收藏
页码:8783 / 8795
页数:13
相关论文
共 69 条
[1]  
[Anonymous], 1998, Rheol. Bull
[2]   Molecular characterization of semi-fluorinated copolymers with a controlled amount of long-chain branching [J].
Auhl, D ;
Kaschta, J ;
Münstedt, H ;
Kaspar, H ;
Hintzer, K .
MACROMOLECULES, 2006, 39 (06) :2316-2324
[3]   Long-chain branched polypropylenes by electron beam irradiation and their rheological properties [J].
Auhl, D ;
Stange, J ;
Münstedt, H ;
Krause, B ;
Voigt, D ;
Lederer, A ;
Lappan, U ;
Lunkwitz, K .
MACROMOLECULES, 2004, 37 (25) :9465-9472
[4]   Comparison of Molecular Structure and Rheological Properties of Electron-Beam- and Gamma-Irradiated Polypropylene [J].
Auhl, Dietmar ;
Stadler, Florian J. ;
Muenstedt, Helmut .
MACROMOLECULES, 2012, 45 (04) :2057-2065
[5]   An overview of polylactides as packaging materials [J].
Auras, R ;
Harte, B ;
Selke, S .
MACROMOLECULAR BIOSCIENCE, 2004, 4 (09) :835-864
[6]   Volatile products and new polymer structures formed on 60Co γ-radiolysis of poly(lactic acid) and poly(glycolic acid) [J].
Babanalbandi, A ;
Hill, DJT ;
Whittaker, AK .
POLYMER DEGRADATION AND STABILITY, 1997, 58 (1-2) :203-214
[7]   An electron spin resonance study on gamma-irradiated poly(L-lactic acid) and poly(D,L-lactic acid) [J].
Babanalbandi, A ;
Hill, DJT ;
ODonnell, JH ;
Pomery, PJ ;
Whittaker, A .
POLYMER DEGRADATION AND STABILITY, 1995, 50 (03) :297-304
[8]  
Burchard W, 1999, ADV POLYM SCI, V143, P113
[9]   Electron-beam treatment of poly(lactic acid) to control degradation profiles [J].
Cairns, Marie-Louise ;
Dickson, Glenn R. ;
Orr, John F. ;
Farrar, David ;
Hawkins, Klaus ;
Buchanan, Fraser J. .
POLYMER DEGRADATION AND STABILITY, 2011, 96 (01) :76-83
[10]   THERMORHEOLOGICAL EFFECTS OF LONG-CHAIN BRANCHING IN ENTANGLED POLYMER MELTS [J].
CARELLA, JM ;
GOTRO, JT ;
GRAESSLEY, WW .
MACROMOLECULES, 1986, 19 (03) :659-667