Browse > Article
http://dx.doi.org/10.12989/amr.2013.2.2.111

A study of plastic plateau disappearance in stress-strain curve of annealed polypropylene films during stretching  

Lei, Caihong (School of Materials and Energy, Guangdong University of Technology)
Wu, Shuqiu (School of Materials and Energy, Guangdong University of Technology)
Xu, Ruijie (School of Materials and Energy, Guangdong University of Technology)
Xu, Yunqi (School of Materials and Energy, Guangdong University of Technology)
Peng, Xinlong (School of Materials and Energy, Guangdong University of Technology)
Publication Information
Advances in materials Research / v.2, no.2, 2013 , pp. 111-118 More about this Journal
Abstract
The changes of plastic plateau in the stress-strain curves of annealed polypropylene (PP) films during stretching under room temperature were followed and the corresponding melting properties and microstructure were characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). It was found that during stretching the plastic plateau disappeared progressively with the increase of drawing ratio. At the same time, the endotherm plateau in DSC curves also disappeared progressively. The presence of the plastic plateau was attributed to the stretching of unstable crystalline part which was formed by tie chains around initial row-nucleated lamellae structure during annealing. During stretching, the unstable part was stretched and converted to bridges connecting separated lamellae. There was direct relationship between the disappearance of plastic plateau and pore formation.
Keywords
polypropylene; row-nucleated lamellae structure; melt-stretching mechanism; micropores; hard elastomer;
Citations & Related Records
연도 인용수 순위
  • Reference
1 Nitta, K.H. and Takayanagi, M. (2000), "Tensile yield of isotactic polypropylene in terms of a lamellar-cluster model", J. Polym. Sci. Part B: Polym. Phys., 38(8), 1037-1044.   DOI   ScienceOn
2 Feng, Z, Keum, J.K. and Chen, X.M. (2007), "The role of interlamellar chain entanglement in deformation-induced structure changes during uniaxial stretching of isotactic polypropylene", Polym. J.,48(27), 6867-6880.   DOI   ScienceOn
3 Lei, C.H., Huang, W.L., Xu, R.J. and Xu, Y.Q. (2012), "The correlation between the lower temperature melting plateau endotherm and the stretching-induced pore formation in annealed polypropylene films", J. Plast Film Sheet., 28(2), 151-164.   DOI   ScienceOn
4 Noether, H.D. and Hay, I.L. (1978), "Small-angle X-ray diffraction studies and morphology of microporous materials and their 'hard' elastic precursors", J. Appl. Cryst., 11, 546-547.   DOI
5 Rastogi, S., Lippits, D.R., Peters, G.W.M., Graf, R., Yao, Y. and Spiess, H.W. (2005), "Heterogeneity in polymer melts from melting of polymer crystals", Nat. Mater., 4, 635- 641.   DOI   ScienceOn
6 Sadeghi, F., Ajji, A. and Carreau, P.J. (2007b), "Analysis of row nucleated lamellar structure of polypropylene obtained from cast film: Effect of melt rheology and process conditions", Polym. Eng. Sci., 47(7), 1170-1178.   DOI   ScienceOn
7 Tabatabaei, S.H., Carreau, P.J. and Ajji, A. (2009), "Effect of processing on the crystalline orientation morphology and mechanical properties of polypropylene cast films and microporous membrane formation", Polym. J., 50(17), 4228-4240.   DOI   ScienceOn
8 Sadeghi, F., Ajji, A. and Carreau, P.J. (2007a), "Analysis of microporous membranes obtained from polypropylene films by stretching", J. Membr. Sci., 292(1-2), 62-71.   DOI   ScienceOn