Polymer film as starch azure container for the easy diastase activity determination in honey

A new original application for a polyacrylic film based on the monomers 2-(dimethylamino)ethyl methacrylate (NNDA), 2-hydroxyethyl acrylate (2HEA) and methylmethacrylate (MMA) as a starch azure container has been set up for a simple determination of honey diastase activity. The proposed method is based on the correlation of reducing sugars generated during the enzymatic process with the Schade reference assay. The polyacrylic film is charged with starch azure acting as a container for this substance; thus, the starch does not interfere in the measurement of reducing sugars, so that the diastase activity is easily calculated. The method has been contrasted with Schade method, showing good correlation and differences under 0.4% between methods in some honey samples. The polyacrylic film has great potential for the routine honey diastase activity assessment in small laboratories, dramatically reducing analysis time and cost.

Foaming Behaviour and Compressive Properties of Microcellular Nanostructured Polystyrene

A batch foaming process has been employed to obtain microcellular materials from polystyrene plus a SBM copolymer (polystyrene-co-1,4-polybutadiene-co-poly(methyl methacrylate). In the first part of the process, raw materials were mixed and extruded in a proportion 90:10 to obtain the precursor materials, leading to a nanostructured assembly in which SBM self-organizes in the polystyrene matrix. In a second stage, foaming was carried out by means of supercritical CO2 in a single step-process. Foamed samples were produced using a technique based on the saturation of the polymer under scCO2, and final properties were controlled by varying the temperature. The swelling in scCO2 was performed at 300 bar during 16 h, and subsequently releasing the gas with a fixed depressurization rate of 60 bar/min. Temperature was varied from 30 °C to 80 °C, leading to densities from 1.0 g/cm3 to 0.5 g/cm3 and cell sizes from 2 micron to 100 micron. In this part of the work, a comparison between foaming behaviour of neat PS and a nanostructured PS+SBM blend is reported, investigating the role of the nanostructured phase as nucleating agents for microcellular foaming. Finally, low rate compression tests were carried out, analyzing the dependence of mechanical parameters such as elastic modulus, yield stress and densification strain with density.