On the Effect of Recycled Polyolefins on the Thermorheological Performance of Polymer-Modified Bitumen Used for Roofing-Applications

In order to meet the technical specifications in roofing applications, the bitumen used for this purpose is standardly modified by polymers. This, in general, allows the re-use of recycled polymer during the production of polymer-modified bitumen (PmB), simultaneously reducing the amount of polymeric waste. Recycling processes, however, may degrade or contaminate polymers, leading to reduced crystallinity and lower melting temperature. Six different recycled polyolefins (high crystallinity: iPP, HDPE; reduced crystallinity: APP, PP Copolymer; waxy polyolefins: Wax 105, Wax 115) were assessed on their suitability for roofing applications. Mixing characteristics, polymer distribution and thermo-mechanical properties of the PmB samples were determined, employing fluorescence microscopy, modulated temperature differential scanning calorimetry (MTDSC) and dynamic shear rheometry (DSR). Depending on mixing properties, two levels of polymer content (5 and 16 wt% or 16 and 30 wt%) were considered. High crystallinity polymers exhibited the biggest increase in |G*| and lowest phase angle. Reduced crystallinity polymers were more easily dispersed and showed improved |G*| and phase angle. Waxy polyolefins improved bitumen similarly to reduced crystallinity polymers and are easily dispersed. The results suggest, that a reduced crystallinity or lower melting temperature of the recycled polymers resulting from degradation or contamination may be beneficial, resulting in improved mixing behavior and a more homogeneous distribution of the polymer within the bitumen.

Effects of fructose and stevia on the rheological, technological and sensory characteristics of ice cream

This study investigated the potential use of fructose and stevia to improve the technological parameters of ice cream. Ice cream was made of 2 different mixtures. Low-fat ice cream mixtures (0.4% fat) were made with: sweet buttermilk, 5% fructose, 20% banana puree, and sweet buttermilk, 5% fructose, 20% pear puree. The ice cream with stevia was made with cream (13% fat), milk, skim milk powder and whey powder, cherry puree (16%) and 0.48% stevia solution (20% concentration). The ice cream with banana showed rapid melting rate and the highest acidity. On the contrary, the ice cream with pear showed lower melting rate, but caused to increase the hardness and resulted with less overall acceptability. The enrichment of the ice cream with stevia and cherry showed the same coherence of hardness and overall acceptability.

Impurity effects in thermal regelation

When a particle is placed in a material with a lower bulk melting temperature, intermolecular forces can lead to the existence of a “premelted” liquid film of the lower melting temperature material.

Characterization of Irradiation Crosslinked Polyamides for Solar Thermal Applications—Basic Thermo-Analytical and Mechanical Properties

Polyamide 66 (PA 66) and short glass fiber reinforced versions of PA 66 are widely used for solar-thermal applications, in which thermal and environmental loading of components is from high importance. In this study, the influence of crosslinking via electronic beam irradiation on the morphology and mechanical behavior of unreinforced PA 66 and two types of short glass fiber reinforced PA 66 (30 wt % glass fiber content, 35 wt % glass fiber content) was investigated. In total, five different electronic beam irradiation doses in the range of 0 and 200 kGy were applied. Besides experiments with unconditioned specimens, also preconditioned specimens saturated with water at 80 °C for seven days were investigated. It was found that irradiation causes a shift to lower melting temperatures and lower melting enthalpies, while simultaneously leading to higher glass transition temperatures (TG), increasing small strain modulus values and higher tensile strengths. Also, as expected, preconditioning samples in water at 80 °C to water uptake saturation leads to a shift to lower TG values (‘plasticization’ effect). In terms of tensile behavior at room temperature, water saturated specimens (being above TG at room temperature) exhibited lower modulus and tensile strength values compared to quasi-dry specimens (being below TG at room temperature).

Thermal decomposition of sodium amide, NaNH2, and sodium amide hydroxide composites, NaNH2–NaOH

Composites of NaNH2 and the omnipresent NaOH have a lower melting temperature and form a non-stoichiometric solid solution, Na(OH)1−x(NH2)x, during heating.