Rigid Amorphous Fraction as an Indicator for Polymer-Polymer Interactions in Highly Filled Plastics

Above a percolation threshold a flow restriction has to be overcome by higher pressure in plastic processing. Besides amount and geometry of fillers, the interactions of polymer and filler are important. By differing the amorphous phase of polymers into a rigid amorphous and a mobile amorphous fraction, predictions about interactions are possible. The objective is the generation of a flow restriction and the combined investigation of polymer–particle interaction. SiO2 was used up to 50 vol.% in different spherical sizes in PLA and PP. A capillary-rheometer was used as a tool to create a yield point and by that investigations into the state of the flow restriction were possible. All produced compounds showed, in plate-plate rheometry, an increase in viscosity for lower shear rates and a significant change in the storage modulus. In DSC, hardly any specific rigid amorphous fraction was detectable, which suggests that there is a minor interaction between macromolecules and filler. This leads to the conclusion that the change in flow behavior is mainly caused by a direct interaction between the particles, even though they are theoretically too far away from each other. First images in the state of the yield point show a displacement of the particles against each other.

A case study of zeolitization process: “Tufo Rosso a Scorie Nere” (Vico volcano, Italy): inferences for a general model

This paper focuses on the authigenic mineralization processes acting on “Tufo Rosso a Scorie Nere” (TRS), i.e. one of the main pyroclastic units of the Vico stratovolcano (Latium, Italy). The pyroclastic deposits appear in general massive and made of “black vitreous vesiculated juvenile scoriae”, immersed in an ashy matrix lithified after zeolitization processes. The main minerals are chabazite and phillipsite, and the zeolitic content is locally variable, reaching 68 % wt. Zeolites grow replacing both amorphous fraction and pre-existing phases, occurring inside both matrix and scoriae. Concerning scoriae, zeolitization moves from the rim to the core of the scoriaceous fragment as a function of (a) temperature of the fluids and (b) permeability (primary or secondary). Composition of parental fresh glass and that of zeolitized rocks is compatible with trachyte chemistry, lightly undersaturated in SiO2, and the alteration processes modified the parental rock chemical features. Zeolites genesis is ascribed to a “geoautoclave-like system”, and zeolites display a Si/Al ratio similar to that of the parental glasses. TRS presents promising mineralogical characteristics as supplementary cementitious material in the production of mixed cements.

Enhanced piezoelectricity from highly polarizable oriented amorphous fractions in biaxially oriented poly(vinylidene fluoride) with pure β crystals

Piezoelectric polymers hold great potential for various electromechanical applications, but only show low performance, with |d33 | < 30 pC/N. We prepare a highly piezoelectric polymer (d33 = −62 pC/N) based on a biaxially oriented poly(vinylidene fluoride) (BOPVDF, crystallinity = 0.52). After unidirectional poling, macroscopically aligned samples with pure β crystals are achieved, which show a high spontaneous polarization (Ps) of 140 mC/m2. Given the theoretical limit of Ps,β = 188 mC/m2 for the neat β crystal, the high Ps cannot be explained by the crystalline-amorphous two-phase model (i.e., Ps,β = 270 mC/m2). Instead, we deduce that a significant amount (at least 0.25) of an oriented amorphous fraction (OAF) must be present between these two phases. Experimental data suggest that the mobile OAF resulted in the negative and high d33 for the poled BOPVDF. The plausibility of this conclusion is supported by molecular dynamics simulations.

Temperature dependence of the rigid amorphous fraction of poly(butylene succinate)

At room temperature and at the human body temperature, all the amorphous fraction is mobile in poly(butylene succinate).

Giant spontaneous polarization for enhanced ferroelectric properties of biaxially oriented poly(vinylidene fluoride) by mobile oriented amorphous fractions

Oriented amorphous fraction in biaxially oriented poly(vinylidene fluoride) gives it significantly enhanced dielectric and ferroelectric properties.