Ny forskning visar sätt att bygga effektiva material för överlägsen termisk hantering

Vi identifierar ofta material baserat på deras egenskaper. Men de framsteg som uppnåtts inom materialvetenskap och ingenjörskonst har gjort det möjligt att producera material som kombinerar ovanliga egenskaper, vilka ofta står i stark kontrast till varandra. 

I ett nyligt exempel demonstrerade ett forskarlag möjligheten att konstruerade material både är styva och kan erbjuda isoleringsegenskaper när de utsätts för värme. både styva och kapabla att erbjuda isolering. 

Enligt Jun Liu, medförfattare till en artikel om arbetet och docent i maskin- och rymdteknik vid North Carolina State University, hade han följande att säga om upptäcktsens unikhet och materialet:

“Vi har nu upptäckt en rad material som både är styva och utmärkta termiska isolatorer. Dessutom kan vi konstruera materialen efter behov för att kontrollera hur styva och termiskt ledande de är.”

Vanligtvis finner man att material med hög elasticitetsmodul, en egenskap som manifesteras genom ökad styvhet, inte är isolerande. De är snarare mycket termiskt ledande. 

Men vad händer om vi behöver material som fungerar som bra isolatorer utan att förlora sin styvhet? Dessa material kommer att vara användbara i situationer där man skapar termiska isoleringsbeläggningar för att skydda elektronik mot höga temperaturer.

En djupare undersökning av materialet och mer information om forskningen visar att de material forskarna arbetade med är en undergrupp av de tvådimensionella hybridorganisk-oinorganiska perovskiterna (2D HOIP). Dessa material består av tunna filmer med ‘växlande organiska och oorganiska lager i en mycket ordnad kristallstruktur.’ Vad som ökar deras värde är att det är möjligt att justera sammansättningen av antingen det oorganiska eller det organiska lagret.

Processen innebär att ersätta kol‑kol‑kedjorna i de organiska lagren av dessa material med bensenringar. Detta leder till ett scenario där det är möjligt att kontrollera eller reglera elasticitetsmodulen och den termiska ledningsförmågan. 

Forskningen hjälpte teamet att ta fram minst tre distinkta 2D HOIP‑material som blev mindre termiskt ledande ju styvare de blev.

Förutom att skapa styva men isolerande material bidrog forskningen också till att införa kiralitet i de organiska lagren, vilket innebär att samma styvhet och termiska ledningsförmåga kan upprätthållas utan att göra omfattande förändringar i sammansättningen av de organiska lagren. Ytterligare framsteg på detta område kan säkerställa möjligheten att optimera andra egenskaper hos dessa material utan att oroa sig för hur dessa förändringar påverkar materialets styvhet eller termiska ledningsförmåga.

När det gäller att bedöma den praktiska tillämpningspotentialen för dessa material kan många företag dra nytta av forskningen. Dessa företag har FoU‑resurserna för att föra forskningen vidare, testa den i större skala och integrera dess fördelar i sin befintliga produktlinje eller skapa en helt ny produktlinje. I de följande avsnitten diskuterar vi ett par sådana företag och undersöker hur de kan anta denna innovation.

#1. Owens Corning

Owens Corning’s (OC ) Foamular‑sortiment består av högpresterande extruderad polystyrenisolering. Extruderad polystyrenfoam består av slutna celler och erbjuder förbättrad ytstruktur, högre styvhet och minskad termisk ledningsförmåga. 

Dess högpresterande extruderade polystyren erbjuder isolering genom en produkt som är hållbar, mångsidig och motståndskraftig och är praktisk för en rad användningsområden inom arkitektur, ingenjörskonst och byggnation. Förutom sina isoleringsegenskaper är materialen också fuktresistenta. 

Owens Corning has a proprietary manufacturing process named Hydrovac that manufactures these solutions. The process offers a consistent closed-cell structure, free of voids, which keeps moisture out while delivering an R-value of 5 per inch of thickness. In the context of insulation, the R-value is a measure of how well a building’s insulation can prevent the flow of heat in and out of the home. The higher the R-value, the greater the performance of the insulation product. 

The product has compressive strengths ranging from 15 to 100 psi and is manufactured in compliance with ASTM C5781. It could be the ideal choice in Protected Roof Membrane Assemblies (PRMA) for vegetative roofs, which can withstand wet soils and loads. Additionally, it is lightweight, easy to handle, and compatible with common exterior claddings and finishes. Not only does the product offer up to 13 times more resistance to water than conventional EPS insulation, but it also retains a minimum of 90% of R-value over 20 years.

The research on hybrid organic-inorganic perovskites (2D HOIP) we discussed in the earlier segment could offer Owens Corning new avenues to augment its leadership in this space. 

Founded in 1938 and based in Toledo, Ohio, Owens Corning recorded net sales of $9.7 billion in 2023.

#2. Gore

While discussing the research on 2D HOIP, we saw that the materials had the potential to offer thermal insulation to electronic materials. Gore, a company specializing in thermal insulation for mobile devices, will benefit from these materials and the research.

Gore Thermal Insulation is an advanced thermal management solution that has conductivity lower than air. It can increase design flexibility and the designer’s ability to direct heat through greater control of z-axis thermal conductivity. Improved control of the z-axis means superior spreading options that help components perform at higher levels for longer periods, accommodate shrinking form factors, and meet surface temperature requirements. 

Apart from its sophisticated thermal insulation properties, Gore’s solution has other performance benefits, including being easy to integrate and having the backing of a team of engineers that supports design guidance and modeling integration from the early design cycle through commercialization. 

Founded by Bill and Vieve Gore in 1959 and headquartered in Newark, Delaware, United States, Gore has an annual revenue of US$4.8 billion. 

Further Research on the Dynamics Between the Nature of Materials and their Thermal Conductivity

Insulation has a wide range of application potential. Eventually, most of the spaces and materials in our everyday lives require protection from heat. It is quite natural that not all sorts of materials fit every type of application scenario. 

Research on thermal insulation performance and its impact on indoor air quality of cellulose-based thermal insulation materials investigated various factors influencing thermal conductivity. These factors included the type of raw material used, manufacturing processes, density, moisture content, and the temperature of the test environment.

The research also pointed out some correlations that would prove necessary in developing materials of superior and unique insulating properties. For instance, the research noted that moisture negatively impacted thermal performance. Conversely, an increase in density, achieved through material compression, tended to reduce thermal conductivity, particularly for materials with uniformly distributed air gaps.

The research delved deeper to list specific product compositions whose thermal performance was the best at their natural densities. One product comprised cellulose acetate, waste cigarette filters, waste cigarette paper, and waste aluminized paper. Another comprised waste papers only. 

When it came to sorption capacity, the most obvious intensification of sorption could be found in the case of the thermal insulation material made from wood fibers and the one made from cellulose that came from waste cardboard, poor processing, and inhomogeneous products. 

The research was deemed useful as it analyzed thermal insulation materials made from recycled agro-industrial waste. These materials, often present in construction materials, remained underdeveloped.

The research that sparked our current discussion aimed to protect electronic goods from heat. There are also examples of research conducted in this space. A team of researchers from Xi’an Jiaotong University, Xi’an, China, for instance, conducted an experimental study on active thermal protection for electronic devices used in deep-downhole environment exploration. In the next segment, we will go deeper into that research and its findings.

Click here to learn about the self-heating concrete that could help our roads, aquifers, and wallets.

Active Thermal Protection for Electronic Devices Used in Deep−Downhole−Environment Exploration

Let us begin with what deep-downhole-environment exploration is. It is one of the most critical application areas of electronic devices wherein devices are used to exploit and extract shale oil. The challenge arises from the fact that it is a zone of high temperature combined with high pressure. The thermal conditions in these spaces could be so severe that they could jeopardize the safe operation of electronic components. The researchers, in this case, studied an active thermal−insulation system consisting of a spiral annular cooling plate (ACP), a thermal storage container with a phase−change material (PCM), and an aerogel mat (AM). 

The team experimentally measured the impact of the ACP’s structure, layout, and working−medium flow rate on heat−protection performance. Performance implied two parameters: temperature−control capability and system−operating time. 

The research found that an aerogel mat layer was necessary and that the inner ACP case displayed better thermal protection performance. The study also proposed an annular cooling plate (ACP) with spiral flow for hybrid thermal protection with insulation material for use in deep downhole environments.

Another study, conducted in 2022 and published in the journal Nature, investigated soft, stretchable thermal protective substrates for wearable electronics. 

Soft, Stretchable Thermal Protective Substrates for Wearable Electronics

Many medical applications today are based on the effective use of wearable electronics. In that sense, these products require careful handling. However, during operations, these devices might get overheated, causing thermal discomfort or damage to the skin. A team of researchers searched for materials and structures that could provide advanced thermal protection. 

They reported a soft, stretchable thermal protective substrate featuring a composite design. It comprises the highly popular polymeric material polydimethylsiloxane with embedded heat-absorbing microspheres, consisting of phase change materials encapsulated inside the resin shell.

The results were promising as the substrate could be subjected to complex deformations over 150% and could reduce the peak skin temperature increase by 82% or higher under optimizations. 

Material Improving Steady-State System Performance in a Thermally Stressed Google Pixel 3XL

Another interesting example of selecting the appropriate thermal insulating material involved the use of graphite foils with ultra-high spreading capacity and insulation sheets with ultra-low thermal conductivity. These were deployed on modified Google Pixel 3XL to reduce surface touch (skin) temperatures.

The deployment was carried out to minimize the impact of the device junction temperature compared to standalone insulating solutions like air or graphite while also enhancing the device’s steady-state system performance. Four unique thermal solutions of comparable thickness (~350 µm) were fabricated for the experiment. Afterward, these solutions were subjected to thermal stress testing in the Pixel via 3DMark—Sling Shot Extreme.

The results were promising. The steady-state touch temperatures came down by up to 3.2°C with a <1°C increase in max junction temperature (TJ) when compared with single-component thermal solutions of graphite, insulation, and air.

The research concluded that high-performance insulation-graphite composites could offer significant utility in empowering high-powered, thin architectures of mobile electronics. However, the optimal design configuration might vary, as each mobile electronic system could present unique thermal challenges owing to its diversity of system power and available space.

Overall, heat conservation is a practice that has immense potential to help us achieve the models of sustainability we want for a greener future. Any research on effective insulation or thermal management is essentially research on materials, looking into their unique properties and optimizing them as needed. Current research trends show that enough work is already being done in that direction. The efforts will only intensify in the days to come. 

Click here to learn about the adaptive roof tiles that may be key to reducing heating and cooling energy consumption.