Aluminum hydroxide-filled polypropylene composites generally form α-crystal due to the strong heterogenous α-nucleation of filler. In order to utilize β-crystal PP with high toughness to prepare aluminum hydroxide-filled PP composites, the aluminum hydroxide-filled PP composites nucleated by calcium pimelate and PP composites filled by calcium pimelate-supported aluminum hydroxide were fabricated. The crystallization and melting behavior of filled composites were compared by differential scanning calorimetry. The influence of aluminum hydroxide contents on the β-crystal content in the filled PP composites was discussed. It is a novel effective method to prepare aluminum hydroxide-filled β-PP composites with calcium pimelate-nucleated aluminum hydroxide.
A novel composite filler sodium lignosulfonate/nano calcium carbonate (SL/CaCO 3 ) was prepared by dry ball milling. Thermogravimetric analysis revealed that the composite filler SL/CaCO 3 had improved thermal properties. The crystallization and melting behavior of isotactic polypropylene (iPP) modified by the composite filler was studied by differential scanning calorimetry. The best complex ratio (1:3) and optimal addition amount (2 wt%) of iPP nucleated by SL/CaCO 3 were confirmed. The results reflected that a small amount of SL/CaCO 3 into iPP could improve the nucleation ability, and excellent mechanical properties were obtained. The relative contents of β ‐crystals ( K β ) in iPP were above 0.83 after addition of the composite filler. At the same time, nano CaCO 3 played a significant role in crystallizing the iPP nucleated and greatly influenced the content of β -crystals. The elongation at break was increased by 32.27% and the impact strength was increased by 62.38% compared to those of pure iPP.
In this paper, magnesiochromite nanocrystalline powder (MgCr2O4) was synthesized through the coprecipitation method using an eggshell membrane as a template to get the best structural and morphological properties. The as-synthesized MgCr2O4 was blended with polyvinylidene fluoride (PVDF) and electrospun. Finally, a robust piezoelectric nanogenerator using the PVDF–MgCr2O4 nanofiber was fabricated. The ferroelectric β-crystalline phase and the piezoelectric characteristics of PVDF were enhanced by the incorporation of MgCr2O4. The fabricated nanogenerator showed an output voltage of 1.05 V with a power density of 0.51 μW/cm2. The practical applicability of the nanogenerator as an energy harvester was evaluated through tapping motions of humans.
Zhengwei Chen,Honghao Zhang,Zaifu Lin,Youhui Lin,Jan H. van Esch,Xiang Yang Liu
To examine the mechanism of the network formation of silk fibroin (SF), monodispersed colloidal particles (MDCPs) are used as well defined foreign substrates to quantify their effect on the primary nucleation of β-crystallites in molecular networks (silk nanofibrils) and the hierarchical network formation of SF. It follows that MDCPs are capable of accelerating the SF gelation by reducing the multistep nucleation barrier, which gives rise to a high density of silk fibril domain networks due to the increase of primary nucleation sites. Consequently, through governing the change in the hierarchical mesoscopic structure, the macroscopic performance of silk materials (e.g., the rheological properties of SF hydrogels and the tensile stress of fibers) can be controlled directly. As SF hydrogels represent a typical example of weak fibril domain–domain network interactions, the increase of fibril domain density leads to weaker gels. On the other hand, SF fibers correspond to strong fibril domain–domain network interactions, the increase of fibril domain density ends up with much tougher fibers. The knowledge obtained provides a facile strategy in controlling the complex hierarchical structure and macroscopic performance of SF materials, and offers useful routes for general design and functionalization of soft materials.
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