Polypropylene filled nucleated

Grein, G Toughness of Neat, Rubber Modified and Filled -Nucleated Polypropylene From Fundamentals to Applications. Vol. 188, pp. 43-104. 

Toughness of Neat, Rubber Modified and Filled -Nucleated Polypropylene... 

Causin, V., Yang, B. X., Marega, C., Goh, S. H., and Marigo, A. 2009. Nucleation, structure and lamellar morphology of isotactic polypropylene filled with polypropylene-grafted multiwalled carbon nanotubes. European Polymer Journal 45 2155-2163. 

Interesting results were reported by Mi et al. [19]. They analyzed polypropylene filled with bamboo fibers with the addition of polypropylene grafted with maleic anhydride. The use of the agent promoting the adhesion was aimed at improving interactions between the components. In case of systems polypropylene/bamboo fibers/compatibilizer, the TCL has been formed. This was explained by higher ability to nucleation of bamboo fibers in relation to MAPP-grafted polypropylene as compared to pure polymeric matrix. 

The structure of crystalline polymers may be significantly modified by the introduction of fillers. All aspects of the structure change on filling, crystallite and spherulite size, as well as crystallinity, are altered as an effect of nucleation [9]. A typical example is the extremely strong nucleation effect of talc in polypropylene [10,11], which is demonstrated also in Fig. 2. Nucleating effect is characterized by the peak temperature of crystallization, which increases significantly on the addition of the filler. Elastomer modified PP blends are shown as a comparison crystallization temperature decreases in this case. Talc also nucleates polyamides. Increasing crystallization temperature leads to an increase in lamella thickness and crystallinity, while the size of the spherulites decreases on... 

Grein, C. Toughness of Neat, Ruhher Modified and Filled fJ-Nucleated Polypropylene From... 

It apparently depends on the amount of the fillers (hence, amount of the plastic) and ability of the fillers to interfere with crystallization of the plastic. The less the crystallites in the filled plastic, the less the shrinkage. The less the plastic in the filler composite, the less the shrinkage. At the same filler loading, fillers with nucleation effects lead to lesser mold shrinkage. For example, when polypropylene, showing mold shrinkage of 1.91%, was fllled with some mineral and cellulosic fillers, its mold shrinkage was as follows [2] ... 

Studies on a similar group of materials - polymeric composites reinforced with sisal fibers - were conducted by Manchado et al. [35]. They analyzed the presence of different fibers, such as sisal, on crystallization of polypropylene. The composites were prepared in special chamber for mixing where the matrix was plastified at 190°C. Obtained materials were subjected to thermal analysis by DSC. The analysis of thermograms allowed for a similar finding like in Joseph s studies [34], The presence of sisal fibers, as well as other fibers used in the study, accelerated crystallization of polypropylene. This was explained by the nucleating effect of sisal filler. Also, the half-time crystallization (ti/2) decrease was observed for polypropylene with the addition of sisal fibers in comparison with unfilled polypropylene. The analysis of nonisothermal crystallization showed that the degree of polypropylene crystallinity is higher for the composites filled with sisal fibers than for unfilled polymer. 

The nucleating effect of lignocellulosic fiUer was also investigated by Yang et al. [36]. They used thermal analysis to test polypropylene composites filled with... 

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