Fungus and fire resistance of insulation mats based on water glass bonded non-textile flax fibres
Materials and methods Field retted flax crop were processed to fine non-textile fibres as specified elsewhere (Grohe 2003) and the material employed for the manufacturing of insulation mats. Water glass was applied as an adhesive and a solution prepared by adding 50 vol.% water to the received viscous water glass (Betol 39T1, 36 wt.% solids in water, Woellner Silikat GmbH, Ludwigshafen, Germany;) leading to 18 wt.% solids in water (pH 11). An aqueous borate solution of 14 wt.% boric acid and 10 wt.% sodium hydroxide (33 wt.% NaOH solution) was mixed, giving 24 wt.% solids in water (ph 13). Thus, the mixture contains a fraction of 21.6 wt.% of the flame retardant and fungicide Borax (Na2B4O7·10 H2O). The B(OH)3-solids and the NaOH-solution were received as technical grade by Zschimmer und Schwarz, Lahnstein, Germany. Insulation mats were fabricated via a pilot plant, as described by Grohe 2003. During the process flax fleeces were sprayed either with (A) water glass or with (B) water glass and subsequently with the boric compound. Some insulation mats were fabricated by primarily spraying them with (C) boron-solution followed by another cycle comprised the spraying of water glass and boric compound. Test-series were carried out (Bundesanstalt für Materialforschung und -prüfung, Berlin, Germany) to investigate the biological resistance of insulation mats fabricated via the production runs (A), (B) and (C) (see Table 1). Thereby, five samples (90 · 90 · 40–55 mm) of each production run were exposed to pure cultures of the wood destroying fungal species Aspergillus niger, Aspergillus terreus, Aureobasidium pullulans, Paecilornyces variotii, Penicillium funiculosum, Penicillium ochro-chloron, Scopulariopsis brevicaulis and Trichoderma viride and the degree of fungal attack verified, according to DIN IEC 68-2-10. To investigate the fire properties of insulation mats five samples of the series (B) were tested according to DIN 4102-1 (FIW—München, München, Germany).
Evaluation and fireproofing treatment of wooden heat-insulating/acoustic absorbing materials
Heat insulating and acoustic absorbing materials were endued with fireproof performance and subjected to quantitative evaluations assuming a variety of uses and situations. Fireproofing was performed by spraying an aqueous solution of flame retardants on raw materials (wood shavings, kenaf bast fibers, and core-sheath-type fibers) during the fiber spreading and mixing step. It was possible to treat the materials homogeneously and without increasing manufacturing workload. Flame retardancy was evaluated using vertical flame testing, horizontal flame testing, the 45° Meckel’s Burner method, and a cone calorimetry method in accordance with UL94, JIS D 1201, JIS L 1091, and JIS A 9521, respectively. It was possible to achieve results that satisfied each of these standards, along with quantifying the relations between treatment conditions and performance.
Measurement of Thermal Conductivity of Nonwovens Using a Dynamic Method
A nonsteady-state cooling method has been used to measure the thermal diffusivity (α) of nonwovens. The method is relatively simple and requires a minimum of spe cialized equipment. The calculations required to obtain α from cooling curves are somewhat involved but can be easily performed on a small computer. The apparatus allows α to be measured at various degrees of sample compression. Thermal conduc tivity can be obtained from α if heat capacity and bulk density are known. The tech nique was used to study the effect of fiber structural parameters on the conductivity of nonwovens. The results indicate that in agreement with established theory, con ductivity decreases if the nonwoven is compressed or is made with finer fabrics or has a reflective coating on the fiber surface. This occurs because of a reduction in the radiative component of heat transfer. Fiber shape has no effect on thermal conductivity. Nonwovens made with experimental hollow fibers have lower thermal conductivity than nonwovens containing solid fibers of the same size; no explanation is currently available for this phenomenon.