Ordered structures in samples of Bisphenol A polycarbonate (BPAPC) prepared by varying thermal and solvent conditions were investigated by infrared and Raman spectroscopy, wide-angle X-ray scattering (WAXS), and differential scanning calorimetry (DSC). Based on the spectroscopic analysis and ab initio quantum mechanical calculations of diphenyl carbonate as a model compound, an assignment of the bands conformationally sensitive to the trans − trans and cis − trans structures is proposed. Temperature dependences of the vibrational spectra of BPAPC show that cis − trans structure is the energetically preferred conformation in the amorphous state and in solution and its population can be increased with decreasing temperature in amorphous BPAPC even below the glass transition temperature. Differences in the degrees of ordering in semicrystalline BPAPC assessed from the vibrational spectra, WAXS, and DSC indicate partial order in the interfacial region between the crystalline and amorphous phases. In some solvents (toluene, benzene), aggregation of BPAPC occurs, leading to the ordered structure analogous to crystalline BPAPC. The order is preserved in semicrystalline BPAPC obtained by the room-temperature evaporation of the solvent.

The study deals with improvement of poly(E-caprolactone) (PCL) parameters by in situ forming of poly(lactic acid) (PLA) fibrils. This structure is achieved by preparation of the melt-drawn microfibrillar composite (MFC) from the PCL/PLA 80/20 blend containing the organophilized montmorillonite (oMMT) added using various mixing protocols. Improved mechanical behavior corresponds to the micron-sized fibrils formation and reinforcement of both polymer components by oMMT, and to increased crystalline phase content in the fibrillar PLA phase. Effective melt drawing is only possible after the rheological parameters of the polymer components have been modified by oMMT where the clay addition method and content are of primary importance. From the results obtained, it follows that the role of oMMT in MFC is quite complex, numerous clay-induced effects may be contradictory and must be harmonized to achieve PCL-based biodegradable MFCs with improved parameters. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016, 133, 43061.

Microfibrillar composites (MFCs) with reinforcing fibrils formed in situ by melt drawing were modified by the addition of layered silicates using different mixing protocols, viz simultaneous addition of components, application of respective premade nanocomposites and their combinations. The objective was to combine reinforcement with changes in the final structure, especially the fibril dimensions. The presented results indicate good potential of the nanoclay to enhance the MFC based on the melt-drawn HDPE/PA6 system. The best mechanical behavior was achieved with the simultaneous addition of all components. The majority of the nanofiller material was contained inside the PA6 fibrils. Both fibrils dimensions and mechanical behavior were significantly affected by the nanofiller migration to the PA6 phase in the course of mixing and melt drawing. Due to a complex effect of the clay, deterioration of mechanical properties was also found. As a result, numerous, in some cases contradictory, effects of nanofillers must be perfectly harmonized to improve the properties of MFCs.

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ABSTRACT:The only shortcoming of PA6-based nanocomposites is low toughness, which is the same as that of the matrix. This work is focused on optimization of toughening these nanocomposites by introduction of small amounts of finely dispersed elastomers. A comparison of reactively compatibilized and analogous nonreactive elastomer-containing nanocomposites indicates the best-balanced mechanical behavior for polar nonreactive elastomers such as NBR and E-MA. This is explained by a significant compatibilizing effect of clay. Besides the elastomer particle size and its properties, the clay localization and its degree of ordering in the interfacial region also significantly influenced mechanical properties of the system.