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- Langer, Sarka, 1960, et al.
(författare)
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Indoor air quality in passive and conventional new houses in Sweden
- 2015
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Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 93:P1, s. 92-100
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Tidskriftsartikel (refereegranskat)abstract
- The indoor environment was evaluated in 20 new passive houses and 21 new conventionally built houses during the 2012/2013 and 2013/2014 heating seasons. Temperature, relative humidity (RH), the concentrations of NO2, ozone, formaldehyde, volatile organic compounds (VOC) and viable microbiological flora were measured. Air exchange rates (AER) were estimated from the CO2 concentrations measured in the bedrooms. The median AER was slightly higher in the passive houses than in the conventional ones (0.68 h-1 vs. 0.60 h-1). The median concentrations in the passive and the conventional buildings were 10 and 12μg/m3 for NO2, 9.7 and 11 μg/m3 for ozone, 11 and 16μg/m3 for formaldehyde, and 270 and 150 μg/m3 for TVOC, respectively. Significant differences in the TVOC and formaldehyde concentrations between the two groups of buildings indicated substantial sources of TVOC present in the passive houses, while sources of formaldehyde may have been more pronounced in the conventional houses. In contrast to the passive houses, the indoor microbiological flora indicated possible mould or moisture problems in six (29%) of the conventionally built houses. When compared with the results previously reported for the Swedish housing stock, AERs and NO2 concentrations were significantly higher in both groups of newly built buildings, while formaldehyde concentrations were significantly lower in the passive houses. TVOC concentrations were not significantly different from those reported for the housing stock, although the most abundant individual VOCs were present mostly at higher concentrations in the new buildings.
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- Martinez-Hermosilla, G. A., et al.
(författare)
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Relative permeability of barrier dispersion coatings applied on paper-based materials mathematical modeling and experimental validation : Mathematical modeling and experimental validation
- 2022
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Ingår i: JCT Research. - : Springer. - 1547-0091 .- 2168-8028. ; 19:2, s. 543-558
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Tidskriftsartikel (refereegranskat)abstract
- Barrier dispersion coatings have been used to improve barrier properties of paper-based materials. Like other technologies such as thermoplastic composites, dispersion coatings include fillers to create obstacles that complicate the pathways for permeants through coatings. The development of these technologies has received significant attention where even predictive barrier performance models have been created. However, to the best of our knowledge, none of them are applicable to barrier dispersion coatings. This research proposed a mathematical model to predict the relative permeability of barrier dispersion coatings applied on paper-based materials based on Fick’s law. The uncertainty of the barrier properties due to variation in filler orientation and spatial location was included through Monte Carlo simulation. Model validation against four models previously published by other authors, and water vapor transmission rate measured on three coating formations and two coating thicknesses was also conducted. The model predictions and experimental results showed that the increase in the amount of fillers reduces the relative permeability, and this reduction can be higher if the size of the fillers is larger. The predictions agreed with experimental results particularly at volume fractions below 10%. In most of the cases, the proposed model achieved better prediction in comparison with those already published. The model is useful to predict relative barrier performance of different coating formulations and can be used as a tool for future developments.
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- Mesic, Beko, et al.
(författare)
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Effect of pressure and time on water absorption of coated paperboard based on a modified Cobb test method
- 2024
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Ingår i: TAPPI Journal. - : TAPPI Press. - 0734-1415. ; 23:4, s. 221-230
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Tidskriftsartikel (refereegranskat)abstract
- This manuscript presents the study of water absorption by paperboard subjected to water at high hydrostatic pressure based on a modified Cobb tester. The new tester is based on TAPPI Standard Test Method T 441; however, the water column can reach up to 550 mm. The evaluation consisted of measurements of water absorption for coated and uncoated paperboard at different exposure times from 5 s to 45 s and water column heights from 10 mm to 500 mm (corresponding to hydrostatic pressures 98 Pa and 4.9 kPa, respectively). The coatings were formulated as a combination of styrene acrylate (SA; two binder levels) and two types of ground calcium carbonates (differing particle sizes) to form the two pre -coating structures: open and closed. The coating weight was 6 g/m2 applied on 210 g/m2 solid bleached board (SBB). In addition, 210 g/m2 uncoated boards were studied. Characterization of the coatings was performed with scanning electron microscopy (SEM), mercury intrusion, and roughness. It was found that the new device properly mimics the conditions of the current Cobb tester. The characterization of the coating also confirmed the presence of more open/larger pores of open coatings, confirming the desired coating structure. The absorption of boards was mainly driven by exposure pressure by comparing with exposure time. This was already evident after shorter periods of exposure time at 5 s and also 15 s exposure time. Paperboards with open coatings showed slightly higher absorption than other boards.
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