The supermolecular morphology of injection-molded SiO 2 /polypropylene (PP) nanocomposites was investigated via thin sections analyzed under polarized light and the systematic development of an appropriate etching technique, which allowed the study of the supermolecular morphologies with light microscopy (LM) and high-resolution field emission scanning electron microscopy (FESEM). In parallel, information regarding the dispersion, distribution state, and morphology of SiO 2 particles was investigated via transmission electron microscopy (TEM) and scanning electron microscopy (SEM) of the ion-polished and fractured surfaces of SiO 2 -filled PP. The TEM/SEM results demonstrated an almost homogeneous dispersion and distribution of SiO 2 particle agglomerates in the PP matrix. With polarized transmitting LM, reflecting LM, and FESEM, the spherulitic structure of the nanocomposites could be visualized to obtain information on the nanoparticle influence on the crystallization and structural behavior. The size and size distribution of the spherulites analyzed with transmitting light (thin sections) and reflecting light (etched specimens) showed an excellent correlation. With increasing filler loading, the mean size of the spherulites decrease as did the degree of crystallinity. This was a clear indication that the particles acted as nucleation agents and, on the other hand, hindered the arrangement of the molecules during the crystallization. As a result, the particles were most likely located in three areas: the center of the spherulites, the areas between the highly crystalline branches, and the spherulite boundaries. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39655.

Alloying polybenzoxazine with liquid rubber was studied in order to overcome its brittleness. We used three kinds of liquid rubber having different functional groups at the chain-end, which are amino, carboxyl and methoxyl groups, namely ATBN, CTBN and ETBN, respectively, to examine the effect of liquid rubber terminal groups on the polymerization of a typical benzoxazine monomer, F-a, and the compatibility with the polybenzoxazine, PF-a. DSC analysis revealed that ATBN and CTBN were effective modifier for lowering the onset temperature of the ring-opening polymerization of F-a. PFa/ATBN hybrid films exhibited high homogeneity throughout wide range of weight ratios of ATBN due to acid-base interaction between the phenolic groups of PF-a and the amino terminal groups of ATBN as confirmed by SEM. Viscoelastic measurement of the hybrids revealed improvement in toughness for the hybrids having low content of ATBN. Moreover, increase of the glass transition temperature of the polybenzoxazine was observed by the hybridization with ATBN. Thermogravimetric analyses revealed that the addition of liquid rubber also enhanced the thermal stability of the polybenzoxazine.

Although the research and development of nanocomposites for almost a decade focused on structural properties, these properties remained until today far below expectations, which were forecast at the beginning of the new millennium. However, even if it is well known that the processing history has a major impact on the structure and properties of final components, this aspect was not subject of intensive research in the past. The talk focuses on the role of the manufacturing sequence on the morphology and properties of polypropylene based nanocomposites. In general it can be stated that the incorporation of nano-sized TiO 2-fillers improves the some mechanical properties of the resulting nanocomposites as long as the production enables a good dispersion and distribution of the nanofiller agglomerates. However, with increasing filler loading, the morphology of injection molded parts changes: The size of the spherulites and the degree of crystallinity decreases while the crystallization/solidification proceeds faster. Simultaneously a slight improvement in the mechanical performance up to a certain filler loading can be found. However, improved mechanical properties of the nanocomposites in the final component cannot be exploited if its production in a subsequent welding step is required. The reason for the decrease in the mechanical properties is the decrease in the viscosity by the addition of the fillers, and thereby caused extreme flow processes and subsequent orientation of the fillers as well as the weakening of the filler/matrix-interphase in the welding zone. In summary, it can be observed that nanocomposites increasingly offer great opportunities for applications where single-component materials reach their limits. The key to success is the processing. Therefore it is of crucial importance that the total manufacturing history is understood and controlled. Only then it is possible to sustainably exploit the potential of polymer nanocomposites in the application.