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.

An investigation into sealing materials for vacuum glazing

Vacuum glazing is an innovative transparent thermal insulator that has application in high performance window, especially in renewable energy. Different materials as well as sealing methods have been adopted to seal windows with different temperatures. The impact of temperatures on sealing layers has been found to have significant effects on the microstructure of the seal. This paper seeks to investigate the effects of sealing materials specifically glass powder and flux compound (borax) for vacuum glazing. The findings of the experiment conducted show that the sealing material was rigid with some leakage around the edge, and we found that this could be stopped by enhancing the uniformity of the seal within the periphery. Also, we found that due to the intense tensile stress from the oven surface temperature of the seal at 200 °C, a crack was observed at the side of the glass. Based on the above findings, this study concludes that a glass powder with a lower melting temperature of below 250 °C with the addition of an adhesive (borax flux) should be used for future vacuum seals.

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.

Selective laser melting Fe and Fe-35Mn for biodegradable implants

Fe and Fe-based alloys are great candidates for biodegradable metal implants. In order to achieve high density pure Fe and Fe-35Mn structures, the correct implementation of process strategies and parameters needs to be studied to achieve high density parts. In this study, pure Fe and Fe-35Mn were successfully processed via SLM with a relative density over 99.5%. The lower melting temperature of Fe-35Mn introduced porosity, resulting in a lower processability compared to the pure Fe. In terms of process optimization, most of the typical quality indicators (roughness, density and apparent density) could be correlated to the energy density.

Analog modeling of fault asperity kinematics using a modified squeeze-box design and wax media

Fault movement is strongly influenced by the physical characteristics of the fault surfaces. Fault surfaces are generally nonplanar and have a certain amount of roughness to them, which manifests as fault asperities. In order for a fault to continue moving along its preexisting surface, the asperities must either move past each other, which involves moving a large volume of rock around these obstacles, or create new fractures that “decapitate” and pulverize these asperities, ultimately leading to a smoother fault surface. We explore a new way to investigate fault asperity kinematics using a squeeze-box analog deformation rig. The more typical and classic squeeze-box model uses sand and/or clay to demonstrate fault and fold deformations. We have designed and built a new analog modeling rig that uses a dual-wax analog material. One constituent is white spherical wax particles that have been embedded in a lower-melting-temperature black matrix wax. Deformation of the analog material is facilitated by the addition of heating elements lining the underside and exterior walls of the squeeze-box reservoir. An aluminum asperity is secured to the floor of the reservoir. Additional overburden is simulated with lead shot that rests on the top surface of the wax block during deformation. Once the experiment is completed, the wax block can be finely sectioned, polished, and scanned in preparation for analysis. Here, we present the first results from this new deformation rig where we were able to generate realistic looking deformation features at different strain rate conditions. The results of this type of modeling provide unique information about fault localization, the role of fluids, and fault asperity kinematics in a polyphase system for a variety of physical conditions within the earth’s crust. These conditions are difficult to model with other analog or numerical techniques or to derive from field or seismic investigations.

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.

Thermo-mechanical and wetting behavior of modified SnAg3.5eutectic solder alloy

Effects of adding bismuth content on structure, thermo-mechanical and wetting behavior of SnAg3.5 eutectic alloy have been investigated. Matrix structure of SnAg3.5 eutectic alloy, such as crystallinity, crystal size and lattice parameters, changed after adding bismuth content which effect on all measured properties. Melting temperature of SnAg3.5 eutectic alloy decreased after adding bismuth content. Elastic modulus and contact angle of SnAg3.5 eutectic alloy varied after adding bismuth content. The Sn66.5Ag3.5Bi30alloy has the best solder properties for electronic applications such as lower melting temperature, contact angle and elastic modulus.

Composite Rods for Brazing

The paper presents research conducted for the development of precursors and wrapped rods for brazing, that deposit, through melting, two different alloys, with respect to the level of silver alloying and the melting temperature. The alloy with the high silver content is introduced under the form of powder, in the coating of the brazing rods, in a participation proportion that assures a buffer layer, with advance proprieties of diffusion in the base metal and in the core alloy of the coated rod. The participation ratio of the silver rich powder alloy is established within the following limits 8-12%, depending on their melting point, the grinding degree and mixing with the deoxidizer coat. The development of the precursors was made by homogeneous melting and spraying on a oblique plan, the grains obtained were grounded, the grist obtained is considered optimum to be introduced in the coating mixture after it successfully passed through a sieve with a mesh of 0.1 mm. The alloyed precursors with 45% silver, grounded between the above mentioned limits, were introduced in the deoxidizer coat mixture af the bare rods type Ag30 according to SR EN 1044/1999. The resulted mixture was used to manufacture experimental lots of covered rods for brazing, which were used for testing, in order to achieve highly important joints. The melting temperature of the precursors was established through micro-alloying so that it will be 10-15°C higher than that of the deoxidizer coat, which in turn has a lower melting temperature, by 56-60°C, than the melting temperature of the core alloy. The deoxidizer coat is usually fluoroboric type, conforming to SR EN 1045/2001. Representative joints made with the new experimental rods, after testing, presented results consistent with the requirements, which allowed the authors to appreciate this method as appropriate for cost reduction with brazing materials in the use of composite coated rods.