Crystallization of Polypropylene Induced by the Aqueous Dispersion of Isotactic Polypropylene Wax Xin-Yi ZHAO 1,a*, Ke ZHAO 2,b and Pei-Qin SUN 3,c

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1 Applied Mechanics and Materials Submitted: ISSN: , Vol. 692, pp Accepted: doi: / Online: Trans Tech Publications, Switzerland Crystallization of Polypropylene Induced by the Aqueous Dispersion of Isotactic Polypropylene Wax Xin-Yi ZHAO 1,a*, Ke ZHAO 2,b and Pei-Qin SUN 3,c 1,2,3 Zhengzhou University, No.100 Kexue Avenue, Zhengzhou, Henan, China a @126.com, b kzhao2005@126.com, c psun2005@zzu.edu.cn *Corresponding author Keywords: Polypropylene, β-crystal, β-nucleating agent, Crystallization Abstract. The Polarized light microscope and DSC are used to study the influence of the nucleation agents type (The aqueous dispersion of isotactic polypropylene wax and the commercial nucleating agent TMB-5), nucleating agents content on the β-crystal content, melting points of α-crystal and β-crystal are studied in the paper. The difference of their capacities of inducing the crystallization of polypropylene are compared and analyzed. The foundation of the treatment of the aqueous dispersions of isotactic polypropylene wax on the reinforcements to induce crystallization on the surfaces of the reinforcements is laid. Introduction The composition of the raw material of the aqueous dispersion of isotactic polypropylene wax[1 ]is 5-35wt% of the isotactic polypropylene wax with a weight-average molecular weight of , wt% of the non-ionic surfactants, wt% of the carboxylic acid secondary surfactant and some water. The average size of particles in aqueous dispersion is 0.1~50µm. The aqueous dispersion can be used to make pretreatments on reinforced materials such as fibers and mica and improve the bond strength of reinforced material and polypropylene matrix. The aqueous dispersion can improve the hydrophilicity and the antistaticity of the material surface of polypropylene. The commercial nucleating agents (include TMB-5) that can induce crystallization of polypropylene can be seen[2-8] Experiments The Raw Materials (1) The isotactic polypropylene (F401): Lanzhou petrochemical company of Petro China (2) β-nucleating agents (TMB-5): Shanxi chemical industry Research Institute (3) Self-made aqueous dispersion of isotatic polypropylene wax (IPPW) (The process of the aqueous dispersion of isotactic polypropylene wax is sufficiently dried into powder: First, most of the water is removed at room temperature. After that it is heated at 180 ºC for 2 hours to be dried completely and it results in powder). Experimental Instruments (1) Polarized light microscope (PLM): Model: OLYMPUS BX61. It is equipped with a heating stage whose model is Linkam THMS600. (2) Differential scanning calorimeter (DSC): Model MDSC-2920, TA instruments. (3) Double-screw extrusion machines: Model SHJ-20, Nanjing instruments. Sample Preparations (1) First of all, pure isotactic polypropylene is be mixed with homemade aqueous dispersion of isotatic polypropylene wax with the weigh ratio of aqueous dispersion at 10%. Then they are put into double-screw extruder to produce the particles of polypropylene by using the melt granulation method. Then previous steps are repeated but the weigh ratio of aqueous dispersion is changed to 5%, 1% and 0.5%. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-09/04/16,01:23:50)

2 256 Proceedings of 2014 International Conference on Material Engineering and Environment Science (2) Pure isotactic polypropylene is mixed with commercial nucleating agent TMB-5 with the weigh ratio of TMB-5 at 0.5%. Then they are put into double-screw extruder to produce the particles of polypropylene by using the melt granulation method. Then previous steps are repeated but the weigh ratio of TMB-5 is changed to 0.3%, 0.2%, 0.15%, 0.1%, 0.05% and 0.02%. (3) Pure isotactic polypropylene is put into double-screw extruder to produce the particles of polypropylene by using the melt granulation method. Sample Tests Polarized Light Microscope (1) A prepared PP particle sample is chosen and polarized light microscopy (OLYMPUSBX61) equipped with a heating stage whose model is Linkam THMS600 is heated at 50 ºC /min to 220 ºC. After 5mins, it is cooled to 134 ºC at 10 ºC /min. Then it is crystallized isothermally while the crystallization process is observed and photographed. (2) A prepared PP particle sample is chosen and polarized light microscopy (OLYMPUSBX61) equipped with a heating stage whose model is Linkam THMS600 is heated at 50 ºC /min to 220 ºC. After 5mins, it is cooled at the cooling rate of 5 ºC /min while the crystallization process is observed and photographed. (3) The other PP particle samples go through the above steps. (4)The obtained polaroid photos are analyzed and discussed. DSC (1) The DSC MDSC-2920, TA instruments is used to put about 6.5mg of a prepared PP particle sample into the testing aluminum pan. The DSC is heated at 10 ºC /min from room temperature to 250 ºC and the protective gas is helium. Then the DSC is naturally cooled to about 50 ºC. The above steps are repeated except that another prepared PP particle sample is chosen. (2) The obtained DSC curves are analyzed and discussed. Results and Discussion The Results of Polarized Light Microscopy Fig. 1 Polarized photos of pure PP Polarized Photos of Pure PP. It can be seen from Fig. 1 that pure PP cannot produce β-crystal when it is isothermally crystallized at 134 ºCnor when it is crystallized at the cooling ratio of 5 ºC /min.

3 Applied Mechanics and Materials Vol Fig. 2 Polarized photos of the mixture of IPPW and PP when content of IPPW is 10% Polarized Photos of the Mixture of IPPW and PP. It can be seen from Fig. 2 that the mixture of IPPW and PP when content of IPPW is 10% can produce β-crystal when it is isothermally crystallized at 134 ºC, but it cannot produce β-crystal when it is crystallized at the cooling ratio of 5 ºC /min. Fig. 3 Polarized photos of the mixture of IPPW and PP when content of IPPW is 5% It can be seen from Fig. 3 that the mixture of IPPW and PP when content of IPPW is 5%can produce β-crystal when it is isothermally crystallized at 134 ºC, but it cannot produce β-crystal when it is crystallized at the cooling ratio of 5 ºC /min. Fig. 4 Polarized photos of the mixture of TMB-5 and PP when content of TMB-5 is 0.5% Polarized Photos of the Mixture of Commercial β-nucleating Agent TMB-5 and PP. It can be seen from Fig. 4 that the mixture of TMB-5 and PP when content of TMB-5 is 0.5% can produce β-crystal when it is isothermally crystallized at 134 ºC or it is crystallized at the cooling ratio of 5 ºC /min.

4 258 Proceedings of 2014 International Conference on Material Engineering and Environment Science Fig. 5 Polarized photos of the mixture of TMB-5 and PP when content of TMB-5 is 0.3% It can be seen from Fig. 5 that the mixture of TMB-5 and PP when content of TMB-5 is 0.3% cannot produce β-crystal when it is isothermally crystallized at 134 ºC or it is crystallized at the cooling ratio of 5 ºC /min. In conclusion, IPPW can induce β-crystal to grow in PP under the condition of isothermal crystallization at 134 ºC. Pure PP cannot produce β-crystal at anytime.tmb-5 can induce β-crystal to grow in PP under the condition of isothermal crystallization at 134 ºC or the cooling crystallization at the cooling ratio of 5 ºC /min. But polarized light microscopy can only qualitatively analyze whether there is any β-crystal preliminarily, not measure content of β-crystal accurately. The Results of DSC Tests The Influence of Homemade IPPW on the β-crystal Grows on PP Fig. 6 The DSC curve of the mixture of IPPW and PP Table 1 The crystallization of each sample of the mixture of IPPW and PP Sample name Content of The melting point The melting point of β-crystal (%) of β-crystal(ºc) α-crystal(ºc) Pure IPPW IPPW0.5% IPPW1% IPPW5% IPPW10% Pure PP

5 Applied Mechanics and Materials Vol It can be seen from Fig. 6 and Table 1 that IPPW can be a good β-nucleating agent for polypropylene. The β-crystal content of the mixture of IPPW and PP is nearly 30% when the content of IPPW is 1%. And Fig. 6 and Table 1 show that the melting point of β-crystal is lower in the sample with high β-crystal content. Pure IPPW can produce β-crystal, but its content of β-crystal and its melting point of α- Crystal and β-crystal are lower than the mixture of IPPW and PP with the content IPPW between 1-10%. With the increase of the content of IPPW, the melting point of α-crystal decreases and the peak of α-crystal is also more and more steep. The Influence of TMB-5 on the β-crystal Grows on PP Fig. 7 The DSC curve of the mixture of TMB-5 and PP Table 2 The crystallization of each sample of the mixture of TMB-5 and PP Sample name Content of The melting point of The melting point of β-crystal (%) β-crystal(ºc) α-crystal(ºc) Pure TMB TMB % TMB % TMB-5 0.1% TMB-5 0.2% TMB-5 0.3% TMB-5 0.5% Pure PP It can be seen from the above images and tables that the commercial β-nucleating agent TMB-5 has a good effect. To begin with, the content of β-crystal increases with the increase of the content of TMB-5 and it reaches its peak of more than 40% when the content of TMB-5 is 0.05%. After that, with the increase of the content of TMB-5, the content of β crystal rises and falls and it is about 30% when the content of TMB-5 is 0.5%. The content of the commercial β-nucleating agent TMB-5 can not be too high otherwise its capability of inducing β-crystal is lower and it has the best effect when the content of TMB-5 is 0.05%. Pure TMB-5 cannot produce β-crystal. In addition with the increase of TMB-5 content, the DSC curve moves down. Summary (1) The aqueous dispersions of isotactic polypropylene wax can be used as polypropylene nucleating agent, although its efficiency of inducing β-crystal still need to be improved. (2) The commercial polypropylene nucleating agent TMB-5 has a most appropriate content. (3) The results of the content of β-crystal which are obtained by PLM and DSC are different about the same set of samples.

6 260 Proceedings of 2014 International Conference on Material Engineering and Environment Science Acknowledgement This research was financially supported by Zhengzhou University. References [1]Zhao Ke, Sun Peiqin, Zhao Xinyi, et al. The Aqueous Dispersion of Maleic Anhydride Grafted Polypropylene with its Preparation Method and Application [P]. China Patent: CN , [2]Gabarczyk J, Paukzta D. Infuence of additives on the structure and properties of polymorphic transition of isotactic polypropylene eaused by amninosulphur compounds [J]. Polymer, 1981, 22: [3]Kilwon Cho, D Nabi Saheb, Hoiehang Yang, et al. Memory effect of locally ordered α-phase melting and phase transformation behavior of β-isotactic polypropylene [J]. Polymer, 2003, 44(14): [4]Shi Guanyi, Zhang Jingyun. Research on the β-crystalline polypropylene. Chinese Science Bulletin, 1981, 12: [5]Shi Guanyi, Zhang Jingyun, Jin Hesheng, et al. China patent. CN B, 1986 [6]Dou Qiang, Qian Yunhe, Wen Bin et al. β-nucleation don't toughening modification of polypropylene. Modern plastics processing and applications of 2001, 12 (6): 11 [7]Dou Qiang, Wang Bin. Polypropylene β-crystal nucleating agent development and application of modern plastics processing and applications, 2001, 13(5)4 [8]Wang Kezhi, new functional additives for plastics [M]. Shen Beijing: Chemical Industry Press, 2003:75

7 Proceedings of 2014 International Conference on Material Engineering and Environment Science / Crystallization of Polypropylene Induced by the Aqueous Dispersion of Isotactic Polypropylene Wax / DOI References [3] Kilwon Cho, D Nabi Saheb, Hoiehang Yang, et al. Memory effect of locally ordered α-phase melting and phase transformation behavior of β-isotactic polypropylene [J]. Polymer, 2003, 44(14): /S (03)