Page 13 - InnoRenew CoE International Conference 2024

Thermal and acoustic properties of fi breboard insulation made with

bark-based adhesive

Marica Mikuljan *, Jaka Gašper Pečnik , Urban Kavka , Rok Prislan , Matthew Schwarzkopf 1,2
1
1
1,2
1,2
1 InnoRenew CoE, Livade 6a, Izola, Slovenia; marica.mikuljan@innorenew.eu; urban.kavka@innorenew.eu
2 Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Glagoljaška 8, 6000 Koper, Slovenia;
matthew.schwarzkopf@innorenew.eu; rok.prislan@innorenew.eu; jaka.pecnik@innorenew.eu
* Corresponding author

Insulation panels were made entirely from wood-derived products and their acoustic and thermal properties were
determined. As part of the ForestValue, BarkBuild project that funded this study, fibreboards were manufactured

with a bark-based lignin adhesive (L samples) and compared with a conventional MUF adhesive (S samples).
Thermal properties were measured after the samples were exposed to different climatic conditions at 20 °C
(oven dry, 65% RH, 90% RH). The thermal conductivity (λ) test was performed according to SIST EN 12664
at nine test points 10, 20, 23, 30, 40, 45, 35, 25 and 20 °C. Sample L had a lower thermal conductivity at
all temperatures and relative humidities indicating better insulation properties. Specific heat was measured at

seven test set points: 19, 26, 35, 42, 40, 30 and 22 °C. A lower average specific heat capacity was measured
in S samples at 65% RH and 90% RH and in oven dried L samples. Thermal diffusivity α was calculated as the
ratio of conductivity to the product of specific heat and density (Kan et al., 2022). Thermal diffusivity of S and L

samples at 65% RH and 90% RH were similar. For oven dried samples, the thermal diffusivity of L samples was
higher than that of S samples.

Sound absorption measurements were made using two specimen sizes to cover a frequency range of 50 Hz to
6400 Hz. (Cox and Antonio, 2009). Sound absorption for both types of fibreboard were relatively low with L-type

αmax = 0.300 at 630 Hz and for S-type αmax = 0.143 at 6300 Hz. When measuring the sound transmission

coefficient x very large deviations were found in both fibreboard types (typically over 10 dB). This finding,

along with the relatively low sound adsorption values (more reflective behaviour) indicate that this method of

measurement is unsuitable for the fibreboards being tested.

Keywords: Fibreboard, bark-based adhesive, thermal properties, acoustic properties, insulation

Acknowledgment: The authors gratefully acknowledge receiving funding from European Union – ForestValue
Research Programme and Republic of Slovenia’s Ministry of Education, Science and Sport.

REFERENCES

Kan, M. Comparison of Different Insulation Materials with Thermal Conductivity Coefficients Based on Density
and Temperature for Two Climate Zones. Int J Thermophys 43, 174 (2022). https://doi.org/10.1007/s10765-
022-03108-8

T. J. Cox and P. D’Antonio, Acoustic Absorbers and Diffusers: Theory, Design and Application. New York, USA:
Taylor&Francis, 2009.

11–12 SEPTEMBER 2024 I IZOLA, SLOVENIA 13