Synthesis and characterization of melamine–formaldehyde rigid foams for vacuum thermal insulation

Nemanič, Vincenc; Zajec, Bojan; Žumer, Marko; Figar, Nataša; Kavšek, Miha; Mihelič, Igor

doi:10.1016/j.apenergy.2013.09.071

Cited by 56 publications

(31 citation statements)

References 13 publications

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“…3), D) compression test of sponges of different densities, and E) Ashby plot of sponge compressive strength versus density for different materials. 1) Boron nitride, [ 9 ] 2) carbon nanotube, [ 6 ] 3) carbon aerogel, [ 15 ] 4) cellulose fi ber, [ 16 ] 5) cross-linked polystyrene, [ 17 ] 6) polyolefi n (closed cell), [ 18 ] 7) polyethylene (closed cell), [ 19 ] 8) polyimide, [ 20 ] 9) polyethylene (50% strain), [ 19 ] 10) silk fi broin, [ 21 ] 11) melamine-formaldehyde (rigid), [ 22 ] 12) tannin-based (rigid), [ 23 ] 13) PDLLA/Bioglass composite, [ 24 ] 14) latex rubber, [ 19 ] 15) PAN-microspheres and fi bers, [ 25 ] 16) rigid polyurethane, [ 26 ] 17) PVC (cross-linked), [ 27 ] 18) epoxy-boroxine, [ 28 ] 19) bio-based macroporous polymers, [ 29 ] 20) silicon oxycarbide ceramic, [ 30 ] and [ 21 ] ) aluminum foams. [ 31 ] www.afm-journal.de www.MaterialsViews.com…”

Section: Resultsmentioning

confidence: 99%

Ultralight, Soft Polymer Sponges by Self‐Assembly of Short Electrospun Fibers in Colloidal Dispersions

Duan

Jiang

Jérôme

et al. 2015

Adv Funct Materials

168

148

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2850 wileyonlinelibrary.com large amounts of liquids and are excellent fi lters. Sponges with a volume of 1000 cm 3 can process up to 3000 L water h −1 . Furthermore, they can conduct light as discovered recently by Brümmer et al. [ 2 ] In addition, Natalio et al. reported on the formation of sponge skeletons shown to feature great bending strength and on the role of silicatein-α in the biomineralization of silicates in sponges, which accounts for the high reversible compressibility of sponges in spite of low densities. [ 3 ] Aizenberg et al. pointed out on the example of the so-called glass sponges ( Euplectella ) the important role of the hierarchical design from the nanometer to macroscopic length scale for structural materials. [ 4 ] The structural base of sponges are multiarmed spicules of silicate or calcium carbonate, which form highly porous structures of several hierarchical layers as shown in Figure 1 A,B. This leads to highly porous ultralight 3D materials (ultralight is defi ned when the density of material is <10 mg cm −3 ).[ 5 ] In recent literature, a variety of highly porous ultralight 3D materials were reported based on carbon, ceramics, and cellulose, which were characterized by porosities >99% and relatively high compressive strength. [6][7][8][9][10] Carbon and cellulose based sponges show ultralow densities and excellent mechanical properties but soft sponges with similar mechanical integrity are missing.Since spicules of natural sponges conspicuously resemble polymer fi bers, formation of such fi brous structures by electrospinning [ 11 ] could be a promising concept for the preparation of polymer-based biomimetic analogous of natural sponges and would open the huge potential of electrospun materials for 3D sponge-type structures. Indeed, 3D porous structures were prepared by electrospinning which was nicely summarized in comprehensive review in recent literature. [ 7 ] However, previous efforts of making 3D highly porous electrospun materials, for example, via ultrasonic treatment, resulted in higher densities and correspondingly lower porosities of <99%, [ 12 ] as well as relatively poor mechanical performance. Remarkably, Eichhorn et al. claimed that theoretically ultrahigh porosities of electrospun nonwovens >99% could not be achieved. [ 13 ] In contrast to these reports, we present here the formation of ultralight weight highly porous 3D electrospun polymer fi ber-based spongy structures with densities as low as 2.7 mg cm −3 corresponding to a porosity of 99.6%. They were prepared by electrospinning of a photo cross-linkable polymer followed by UV cross-linking, mechanical cutting, suspending cut fi bers in liquid dispersion, and freezedrying. These polymer sponges showed in analogy to natural Ultralight, Soft Polymer Sponges by Self-Assembly of Short Electrospun Fibers in Colloidal DispersionsGaigai Duan , Shaohua Jiang , Valérie Jérôme , Joachim H. Wendorff , Amir Fathi , Jaqueline Uhm , Volker Altstädt , Markus Herling , Josef Breu , Ruth Freitag , Seema Agarwal , and Andreas Gre...

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Section: Resultsmentioning

confidence: 99%

Ultralight, Soft Polymer Sponges by Self‐Assembly of Short Electrospun Fibers in Colloidal Dispersions

Duan

Jiang

Jérôme

et al. 2015

Adv Funct Materials

168

148

View full text Add to dashboard Cite

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“…A heating cycle of 10 h at 190 • C in vacuum was introduced in our testing schedule with the aim to get rid of the adsorbed water [6].…”

Section: Outgassing Rate Measurementsmentioning

confidence: 99%

“…Various new organic foams are studied as their low density is a very attractive property of a VIP core. Recently, a new type of organic melamineformaldehyde (MF) foam was synthesized and recognized to be appropriate as the core for VIPs due to its low thermal conductivity and extremely low outgassing rate [6]. New nanoporous organic foams, which may simplify production of VIPs, as their tolerable internal pressure could be relatively high, were announced recently [7].…”

Section: Introductionmentioning

confidence: 99%

New organic fiber-based core material for vacuum thermal insulation

Nemanič

Žumer

2015

Energy and Buildings

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“…Being the constituent that incorporates the bulk of the VIP embodied energy, recent research advances have focussed on VIP core innovations, including studies by Nemanic et al [19], Nemanič and Žumer [20], Chen et al [21], Li et al [22][23][24], Chang et al [25], and Choi et al [26]. Albeit comprehensive, the focus of these articles leaned towards the physical impacts of fumed silica based core material innovations.…”

Section: Introductionmentioning

confidence: 99%

Cellulosic-crystals as a fumed-silica substitute in vacuum insulated panel technology used in building construction and retrofit applications

Tetlow

Simon

Liew

et al. 2017

Energy and Buildings

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Cellulosic-crystals as a fumed-silica substitute in vacuum insulated panel technology used in building construction and retrofit applications, Energy and Buildingshttp://dx.doi.org/10. 1016/j.enbuild.2017.08.058 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractThis article investigates impact of substituting fumed silica with a cellulosic-crystal innovation in a commercial Vacuum Insulated Panel (VIP) core. High building performance demands have attracted VIP technology investment to increase production capacity and reduce cost. In building retrofit VIPs resolve practical problems on space saving that conventional insulations are unsuitable for. Three challenges exists in fumed silica: cost, low sustainability properties, and manufacture technical maturity. Cellulosic nano-crystal (CNC) technology is in its infancy and was identified as a possible alternative due to a similar physical nano-structure, and biodegradability. The study aim was to determine a performance starting point and establish how this compares with the current benchmarks. Laboratory cellulosic-crystal samples were produced and supplied for incorporation into commercial VIP manufacture. A selection of cellulosic-panels with core densities ranging 127 -170 kg/m 3 were produced. Thermal conductivities were tested at a pressure of 1 Pa (0.01 mBar), with the results compared against a selection of fumed silica-VIPs with core densities ranging 144 -180 kg/m 3 . Conductivity tests were then done on a cellulosic-VIP with 140 kg/m 3 density, under variable pressures ranging 1 -100,000 Pa (0.01 -1000 mBar). This investigated panel lifespan performance, with comparisons made to a fumed silica-VIP of similar core density. Manufactured cellulosic-samples were found unsuitable as a commercial substitute, with performance below current standards. Areas for cellulosic nano-material technology development were identified that show large scope for improvement. Pursuit could create a new generation of insulation materials that resolve problems associated with current commercial versions. This is most applicable in building retrofit where large ranges of domestic and commercial cases are marginalised from their construction markets due to impracticalities and high upgrade costs. This being a problem in multiple economies globally. Figure 3 with typical layer thicknesses [1,13].VIP thermal conductivities are five to ten times lower than commercial insulations, with the centreof-panel reaching 4 mW/m.K [3,4,14,16]. Albeit excellent performance, the technology is expensive with panel prices multiples of five to ten that of standard insulations [...

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Synthesis and characterization of melamine–formaldehyde rigid foams for vacuum thermal insulation

Cited by 56 publications

References 13 publications

Ultralight, Soft Polymer Sponges by Self‐Assembly of Short Electrospun Fibers in Colloidal Dispersions

Ultralight, Soft Polymer Sponges by Self‐Assembly of Short Electrospun Fibers in Colloidal Dispersions

New organic fiber-based core material for vacuum thermal insulation

Cellulosic-crystals as a fumed-silica substitute in vacuum insulated panel technology used in building construction and retrofit applications

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