Bio-based composites made of poly(L-lactic acid) (PLLA) and β-cyclodextrin/d-limonene inclusion complex (CD-Lim) were prepared by melt extrusion. Encapsulation of volatile d-limonene molecules within β-cyclodextrin cages was proven to be a successful strategy to prevent evaporation during high-temperature processing. However, small amounts of limonene were released upon processing, resulting in the plasticization of the polymeric matrix. Morphological analysis revealed good dispersion of the filler, which acted as a nucleating agent, favoring the growth of PLLA crystals. The composites′ lowered glass transition temperature upon the addition of CD-Lim was also proved by thermomechanical analysis (DMA). Moreover, DMA revealed constant stiffness of modified materials at room temperature, which is crucial in PLLA-based formulations.
This article investigates the effect of modifying the polypropylene (iPP) a-phase nucleating agent 1,3:2,4-bis(3,4-dimethylbenzylidene) sorbitol (DMDBS) with tetrasilanolphenyl silsesquioxane (phPOSS). It has been proven that an increasing amount of silsesquioxane leads to differences in the crystallization behavior. What is more, it has been observed that the nucleation effect that results from the addition of sorbitol derivatives is suppressed by phPOSS activity. To understand the influence of phPOSS addition on the crystallization kinetics of PP/DMDBS/phPOSS composites that have been prepared by melt processing in a twin screw extruder, differential scanning calorimetry, rotational rheometry and Fourier transform infrared spectroscopy are performed.
Composites based on isotactic polypropylene (iPP) modified with a sorbitol derivative (NX8000) and siloxane-silsesquioxane resin containing reactive phenyl groups (SiOPh) were prepared by melt extrusion. These iPP-based formulations were investigated to evaluate the influence of such additives on the crystallization behavior and morphology, as well as on thermal and mechanical properties. The addition of sorbitol fastens crystallization kinetics of iPP and leads to higher transparency of iPP films. Upon the incorporation of siloxane-silsesquioxane resin, no further effect on iPP crystallization kinetics is evidenced by calorimetry, optical microscopy, and X-ray diffraction analysis. Transparency of iPP-based composites is improved upon the addition of sorbitol, but decreased when SiOPh is added to the formulation. The composites are also stiffer, compared to neat polypropylene with a decreased elongation at break and increased Young's modulus values, with increasing amounts of fillers. The effect of the siloxane-silsesquioxane resin on properties of iPP/NX8000/ SiOPh composites was explained taking into account compatibility of the components and morphology of the composites. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43476.
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