Tensile and Flexural Properties of β-Nucleated Polypropylenes

Abstract

Tensile and Flexural Properties of b-Nucleated PolypropylenesResuming our previous work on b-nucleated polypropylenes, namely on their impact strength, our present work directs attention towards a flexural and tensile behavior of b-nucleated polypropylenes (b-iPP). For the purposes of this work, commercially available isotactic polypropylene was modified using various amounts of a specific nucleating agent based on N, N 'dicyclohexylnaphtalene-2,6-dicarboxamide (NU100). From the prepared blends test specimens were prepared by injection molding. Structural characterization (crystallinity and the content of b-phase) was carried out by X-ray diffractometry. A multipurpose mechanical property tester was used for determination of tensile and flexural properties. It was found that b-phase content decreased both tensile and flexural strength; on the other hand, the presence of b-phase dramatically raised cold drawability of the injection-molded specimens; addition of 0.03 wt.% of NU100 in the injection-molded parts led to a more than 800 % increase of the draw ratio of specimens tested at the testing speed of 100 mm/min. Furthermore, tensile testing carried out using various strain speeds (10 and 100 mm/ min) revealed that higher ductility of the material containing b-phase is particularly pronounced by faster deformation processes, such as fast drawing or impact load.International Polymer Processing downloaded from www.hanser-elibrary.com by Kungliga Tekniska on August 18, 2015For personal use only.

Competition between α and β Crystallization in Isotactic Polypropylene: Effect of Nucleating Agents Composition

“…Furthermore, the a crystallization can be enhanced by addition of an a nucleating agent (NA), which can significantly improve the stiffness and yield strength of iPP (Fillon et al, 1993;Gahleitner et al, 2011). The NA can also easily shorten the induction time of the crystal nucleation and enhance the overall rate of transformation from molten polymer to crystalline (Chen et al, 2013;Obadal et al, 2004). However, if in a NA, the toughness will be reduced because of the compact structure formed in the a crystals (Li et al, 2012;Zamani et al, 2012).…”

A X-ray study of β-phase and molecular orientation in nucleated and non-nucleated injection molded polypropylene resins

“…The first resin, named HPP, was a homopolymer without nucleating agent. The second resin, named NPP, had sodium benzoate as nucleating agent in the concentration up to the critical concentration at which the β-form content reaches the saturation level 19,20,39 . Properties of both resins are shown in Table 1.…”

“…In the literature [17][18][19][20][21] was revealed the promising mechanical properties of β-form in i-PP articles and it was also exposed that when special crystallization procedures are used or, in particular, specific nucleators as N,N'-dicyclohexylnaphthalene-2,6-dicarboxamide and sodium benzoate are added, the β-form can become as predominant crystalline form in common i-PP articles. Dong and cowokers 17 demonstrated that the sodium benzoate shows apparently versatile nucleating characteristic on the crystallization behavior of i-PP and that this nucleating activity is highly dependent on processing parameters.…”

Effect of Solubility and Nucleating Duality of N,N‘-Dicyclohexyl-2,6-naphthalenedicarboxamide on the Supermolecular Structure of Isotactic Polypropylene

“…The nucleation efficiency of NJS was proved by X-ray diffraction measurements and detailed calorimetric studies. ,− NJS proved to be an efficient nucleating agent also in production under industrial conditions. The β-phase content, or k value, of compression-molded, , extruded, and injection-molded − parts produced with NJS is relatively high. The mechanical and other properties of the processed parts were determined as well.…”

“…In microsections, cut from processed samples, the occurrence of βα-recrystallization cannot be avoided. Thus, a smaller or larger melting peak of the α-iPP can be practically always observed on the melting traces of such samples. − Consequently, conclusions drawn from calorimetric measurements done on samples cooled below must be treated with the utmost caution. , This note holds for those contributions which consider the melting peaks to estimate the amount of β-phase and its melting temperature. The critical evaluation of these results is again beyond the scope of this article.…”