Annex 65, Long-Term Performance of Super-Insulating-Materials in Building Components and Systems. Report of Subtask II: Scientific Information for Standardization Bodies dealing with Hygro-Thermo-Mechanical Properties and Ageing

This subtask is divided in two actions:Action 2A: Materials Assessment & Ageing Procedures (Experiments & Simulation)Action 2B: Components & Systems Assessment (Experiments & Simulation)As their structures and microstructures are completely different, Super-Insulating Materials (SIMs) cannot be compared directly to traditional insulating materials. Worldwide acceptance of these materials will be improved if the hygro-thermal and mechanical properties of SIM can be clearly articulated and reproduced. In particular, nano-structured materials used to manufacture a SIM are characterized by a high specific area (m\ub2/g) and narrow pores (smaller than 1 μm) which make them very sensitive to gas adsorption and condensation, especially in contact with water molecules.Therefore, methods of characterization must be adapted, or new methods developed to measure the microstructural, hygro-thermal and mechanical properties of these materials and their barrier films.In parallel, modelling methods to describe heat, moisture and air transfer through nano-structured materials and films will have to be developed (adsorption and desorption models, diffusion models, freeze-thawing …).Of course, a few methods will be common to all SIMs, but due to their structural differences some specific modelling methods have to be developed.SIMs can offer considerable advantages (low thickness, low Uvalue) ; however potential drawback effects should be considered in the planning process in order to optimise the development of these extraordinary properties (very low thermal conductivity) and to prevent negative publicity which could be detrimental to this sector of emerging products. This is why ageing tests will be set according to realistic conditions (temperature, moisture, pressure, load …) as set out in SubTask 3A. One objective of artificial ageing is to understand potential degradation processes that could occur. The durability of hydrophobic treatment is one of these processes and will also be subject to discussion and investigation.At the component scale, additional characterizations are needed as panels or rolls are sold by manufacturers. In particular, thermal bridges will be carefully investigated, as the extraordinary thermal performance of SIMs are sensitive to the influence of thermal bridges

Effect of different biopolymers and polymers on the mechanical and permeation properties of extruded PHBV cast films

The biopolymer poly‐3‐hydroxybutyrate‐co‐3‐hydroxyvalerate (PHBV) is a promising material for packaging applications but its high brittleness is challenging. To address this issue, PHBV was blended with nine different biopolymers and polymers in order to improve the processing and mechanical properties of the films. Those biopolymers were TPS, PBAT, a blend of PBAT + PLA, a blend of PBAT + PLA + filler, PCL and PBS, and the polymers TPU, PVAc, and EVA. The extruded cast films were analyzed in detail (melting temperature, crystallinity, mechanical properties, permeation properties, and surface topography). A decrease in crystallinity and Young's modulus and an increase in elongation at break and permeability were observed with increasing biopolymer/polymer concentration. In PHBV‐rich blends (≥70 wt % PHBV), the biopolymers/polymers PCL, PBAT, and TPU increased the elongation at break while only slightly increasing the permeability. Larger increases in the permeability were found for the films with PBS, PVAc, and EVA. The films of biopolymer/polymer‐rich blends (with PBAT, TPU, and EVA) had significantly different properties than pure PHBV. A strong effect on the properties was measured assuming that at certain biopolymer/polymer concentrations the coherent PHBV network is disrupted. The interpretation of the permeation values by the Maxwell–Garnett theory confirms the assumption of a phase separation

Environmental Microplastic Particles vs. Engineered Plastic Microparticles—A Comparative Review

Microplastic particles (MPs) pose a novel threat to nature. Despite being first noticed in the 1970s, research on this topic has only surged in recent years. Researchers have mainly focused on environmental plastic particles; however, studies with defined microplastic particles as the sample input are scarce. Furthermore, comparison of those studies indicates a discrepancy between the particles found (e.g., in the environment) and those used for further research (e.g., exposure studies). Obviously, it is important to use particles that resemble those found in the environment to conduct appropriate research. In this review, different categories of microplastic particles are addressed, before covering an overview of the most common separation and analysis methods for environmental MPs is covered. After showing that the particles found in the environment are mostly irregular and polydisperse, while those used in studies with plastic microparticles as samples are often not, different particle production techniques are investigated and suggestions for preparing realistic plastic particles are given

Modelling and numerical simulation of water vapour sorption kinetics in humidity regulating polypropylene films containing sodium chloride

This study proposes a mathematical time-dependent model to examine the humidity sorption kinetics and the storage capacity of a porous packaging polymer material (PP) containing NaCl as hygroscopic substance. Water vapour pressure gradient was chosen as the principal driving force for the transport of water vapour in the film. Solving the diffusion equation numerically by the finite element method resulted in the evolution of water vapour contents calculated inside humidity regulating film specimens. The influence of the diffusion and the sorption coefficients of the polymer, and of the thickness and the NaCl content of the film on kinetics and capacity of the humidity regulating films could be determined. By comparison of the calculated amount of absorbed water vapour with experimental data, a good agreement between the predicted tendencies of the numerical and experimental results was found. The model was validated in a region of the salt's sorption isotherm above the deliquescence point of NaCl and significantly below the humidity at which the holes in PP are completely filled with water. The results permit to develop optimized humidity regulating films for individual food requirements. Application of this model could facilitate the development of these active films using different polymers and hygroscopic substances

Process control for thin organic coatings using fluorescence dyes

The fluorescence dyes rhodamine B and auramine O were added to a coating material based on hybrid polymers (ORMOCER®s) in concentrations of 10 ppm each. The fluorescence intensity of the auramine depends on the curing state of the lacquer while rhodamine is almost insensitive to this variation of the molecular environment. With the combination of both these dyes, the curing state as well as the thickness of the coating can be measured. Due to the low concentration the dyes do not degrade the properties of the lacquer coating

A systematic approach for the accurate and rapid measurement of water vapor transmission through ultra-high barrier films

Flexible organic electronic devices are often protected from degradation by encapsulation in multilayered films with very high barrier properties against moisture and oxygen. However, metrology must be improved to detect such low quantities of permeants. We therefore developed a modified ultra-low permeation measurement device based on a constant-flow carrier-gas system to measure both the transient and stationary water vapor permeation through high-performance barrier films. The accumulation of permeated water vapor before its transport to the detector allows the measurement of very low water vapor transmission rates (WVTRs) down to 2 × 10−5 g m−2 d−1. The measurement cells are stored in a temperature-controlled chamber, allowing WVTR measurements within the temperature range 23–80 °C. Differences in relative humidity can be controlled within the range 15%–90%. The WVTR values determined using the novel measurement device agree with those measured using a commercially available carrier-gas device from MOCON®. Depending on the structure and quality of the barrier film, it may take a long time for the WVTR to reach a steady-state value. However, by using a combination of the time-dependent measurement and the finite element method, we were able to estimate the steady-state WVTR accurately with significantly shorter measurement times

Common Trends and Differences in Antioxidant Activity Analysis of Phenolic Substances Using Single Electron Transfer Based Assays

Numerous assays were developed to measure the antioxidant activity, but each has limitations and the results obtained by different methods are not always comparable. Popular examples are the DPPH and ABTS assay. Our aim was to study similarities and differences of these two assay regarding the measured antioxidant potentials of 24 phenolic compounds using the same measurement and evaluation methods. This should allow conclusions to be drawn as to whether one of the assays is more suitable for measuring specific subgroups like phenolic acids, flavonols, flavanones, dihydrochalcones or flavanols. The assays showed common trends for the mean values of most of the subgroups. Some dihydrochalcones and flavanones did not react with the DPPH radical in contrast to the ABTS radical, leading to significant differences. Therefore, to determine the antioxidant potential of dihydrochalcone or flavanone-rich extracts, the ABTS assay should be preferred. We found that the results of the flavonoids in the DPPH assay were dependent on the Bors criteria, whereas the structure–activity relationship in the ABTS assay was not clear. For the phenolic acids, the results in the ABTS assay were only high for pyrogallol structures, while the DPPH assay was mainly determined by the number of OH groups