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.
This study focuses on the structure, morphology, and properties of linear polyethylene (PE) profiles manufactured by continuous extrusion. High level of chain orientation was achieved using specific flow and processing conditions. An extrusion die with semihyperbolic convergency was used to generate high percentage of elongational flow and chain extension. Simultaneously, high extrusion pressure and relatively low melt temperature led to flow-induced crystallization of PE extended chains. The structure of PE tapes consists of crystal aggregates with different level of orientation and crystallinity.
Abstract. Synergistic effect was observed between two types of flame retardant and two types of polyhedral oligomeric silsesquioxanes (POSS). The polymer matrix was represented by low density polyethylene Bralen RB 2-62 (Slovnaft).
with conventionally extruded rods, self-reinforced polyethylene rods were continuously prepared using a conventional extruder equipped with a converging extrusion die. From the work, it is apparent that the self-reinforced rods showed elastic moduli nearly four times higher than that of conventionally extruded rods. Scanning electron microscopy revealed that the morphology of the self-reinforced rod was fibrous and that the fibrils extended straight along the extrusion direction. Moreover, the self-reinforced rods melted at a higher temperature than the rods which had been prepared conventionally. The extrusion line as designed in this work seems to be suitable for self-reinforcement of polymers.
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