Katharina Resch

ALL POLYMERIC FLAT-PLATE COLLECTOR - POTENTIAL OF THERMOTROPIC LAYERS TO PREVENT OVERHEATING

The investigations showed that the maximum absorber temperatures can be limited by thermotropic glazings. In general the impact of the thermotropic layer on collector efficiency is insignificant, as long as the solar transmission is above 85% in the clear state. Collectors with twin-wall sheet covers were found to be best suited in combination with thermotropic layers. As to thermotropic layer design for this collector configuration a residual hemispherical solar transmittance ranging from 25 to 60% in opaque state is effectual to control the stagnation temperatures in the range from 80 to 130°C. For maximum working efficiency a rapid and steep switching process and switching temperatures between 50 and 60°C are required.

Interface conditions of two-shot molded parts

The focus of this work is on interfaces of two-shot molded parts. It is well known that e.g. material combination, process parameters and contact area structures show significant effects on the bond strength of multi-component injection molded parts. To get information about the bond strength at various process parameter settings and material combinations a test mold with core back technology was used to produce two-component injection molded tensile test specimens. At the core back process the different materials are injected consecutively, so each component runs through the whole injection molding cycle (two-shot process). Due to this consecutive injection molding processes, a cold interface is generated. This is defined as overmolding of a second melt to a solidified polymer preform. Strong interest lies in the way the interface conditions change during the adhesion formation between the individual components. Hence the interface conditions were investigated by computed tomography and Raman spectroscopy. By analyzing these conditions the understanding of the adhesion development during the multi-component injection molding was improved.The focus of this work is on interfaces of two-shot molded parts. It is well known that e.g. material combination, process parameters and contact area structures show significant effects on the bond strength of multi-component injection molded parts. To get information about the bond strength at various process parameter settings and material combinations a test mold with core back technology was used to produce two-component injection molded tensile test specimens. At the core back process the different materials are injected consecutively, so each component runs through the whole injection molding cycle (two-shot process). Due to this consecutive injection molding processes, a cold interface is generated. This is defined as overmolding of a second melt to a solidified polymer preform. Strong interest lies in the way the interface conditions change during the adhesion formation between the individual components. Hence the interface conditions were investigated by computed tomography and Raman spectrosco...

Thermotropic overheating protection glazings: effect of functional additives and processing conditions on the overheating protection performance

Abstract Within this study, the effect of functional additives and processing conditions on the overheating protection performance of thermotropic systems with fixed domains (TSFD) for overheating protection purposes was evaluated. The focus was on improving the overheating protection performance of a prototype TSFD based on a UV curable acrylate resin by optimization of the material constitution (addition of functional additives like surfactants and nucleating agents) and the processing conditions (temperature conditions during manufacturing, annealing). For the evaluated system, an effect of the nucleating agent on the overheating protection performance was ascertained. Furthermore, omission of an annealing step improved the overheating protection performance slightly.