Projects / Programmes
Mineral wool composite with improved insulation properties
| Code |
Science |
Field |
Subfield |
| 2.04.00 |
Engineering sciences and technologies |
Materials science and technology |
|
| Code |
Science |
Field |
| T152 |
Technological sciences |
Composite materials |
| Code |
Science |
Field |
| 2.05 |
Engineering and Technology |
Materials engineering |
mineral wool, aerogel, fumed silica, composite, thermal conductivity, thermal insulation
Researchers (10)
Organisations (2)
Abstract
Improved energy performance of the building, construction and industrial sector is the main focus of the energy efficiency directive. In the energy balance of buildings envelope plays a crucial role. A better insulation is achieved either by increased insulation thickness or by improved insulation performance of the insulation material. Thermal insulation market is ruled by conventional insulation materials with thermal conductivity in the range of 30–40 mW/(m∙K). Increase in the thickness of conventional insulation materials is not sustainable due to larger consumption of materials and related higher energy consumption, as well as higher space requirements for their installation. Today, novel superinsulation materials with thermal conductivity below 20 mW/(m∙K) are not competitive due to poor mechanical performance and low production capacities. For these reasons superinsulation is used only in niche applications. The large gap between both groups of materials could be covered by a composite material. Such composite insulation product should exhibit improved insulation capability and good mechanical properties. The latter can be assured by conventional mineral wool, while the former by a porous nano-structured material, like fumed silica or silica aerogel.
The aim of the project is to prepare a composite product of mineral wool and nano-structured material (NSM), which will exhibit mechanical properties and fire resistance equivalent to the mineral wool and will have improved insulation performance. The goal is to reach a thermal conductivity of 26–30 mW/(m∙K), which is a 20 % improvement in comparison to conventional mineral wool products. In order to reach the 20 % improvement in the thermal conductivity, the specific objectives of the proposed project are (i) to calculate and experimentally validate the required content of NSM in the wool–NSM–air composite, (ii) to develop a preparation procedure for the composite by a wet and/or dry application of NSM, and (iii) to design an industrially feasible process for the composite production.
The proposed project exploits a combination of the mineral fibers, NSM and air voids in the composite, which will result in a unique product with superior properties at a low density. A suitable NSM with optimal thermal and surface properties will be selected from the available commercial products. High requirements were set for the mechanical properties of the composite, which will be achieved by maintaining the original aspect ratio of the fibers and by effective binding of the components in the composite. In this respect we anticipate the development of novel wet and dry application methods. The investigation of the wet method will focus on formulation of suspension and possibility to apply a large amount of NSM onto the fibers. The dry method will concentrate on the selection of the optimal particle size of NSM and its entrapment into the voids between fibers. For both application methods the adjustment of the content and distribution of the binder(s), is the key for achieving a stable composite.
Based on a comprehensive literature review, preliminary studies and market requirements, the innovative approach aims to reach the following parameters of the composite: maintain the original fibers aspect ratio, provide a conventional fiber content (50–80 kg/m3), use a moderate amount of NSM (approx. 40 vol.%), partly maintain air void fraction (approx. 60 vol.%), and exhibit a density in the range of 80–120 kg/m3.
The key for a feasible production of the composite is to integrate its preparation into conventional process of mineral wool production and to use unmodified commercial NSMs. The developed composite has immediate market potential due to unique features in comparison to other products. The results of the project will provide knowledge needed for future upscale as well as background for development of composites with even better insulation and mechanical performance.
Significance for science
The proposed research is beyond the state of the art in the field of wool insulation materials and will result in a unique composite material with superior insulation and mechanical properties at low densities. Preparation of composites has been studied by many research groups, but the produced composites suffer from poor mechanical properties thus making their good insulation properties weakly exploitable; the main reasons being low fiber aspect ratio, high density and high NSM content (i.e. high price).
In order to reach the projects goal several scientifically important issues will be addressed. Modeling of thermal conductivity of fiber–NSM composite will be extended to a third phase represented by macroscopic pores filled with air. The air phase is the key for achieving a low density of the composite, and, consequently, for a lower NSM content. Composites described in the literature have low content of air-filled macro-pores in the volume of the product, resulting in high density which is undesired.
The low aspect ratio of fibers or low fibers content for in-situ prepared composites are related to poor mechanical behavior of the reported composites. The results of our project will demonstrate the feasibility of preparing a composite with outstanding mechanical behavior and improved insulation properties. For this purpose we will develop preparation processes for the dry and the wet application of NSMs not considered by others. The investigation will be focused on formulations of suspensions with required properties, methods for dry application of fine NSM particulates and tuning of the binder formulation and application.
The new knowledge gained through accomplishment of the project will provide background for a future research on novel insulation materials with superior mechanical and insulation properties, the final target being a composite with mechanical stability, superinsulation properties and low environmental impact.
Significance for the country
The development of new insulation materials is important not only for the participating groups (JSI and Knauf Insulation d.o.o.), but also for the whole Knauf Group. Knauf Insulation division is the largest producer of mineral wool in Europe, and second largest in both separate classifications for glass and stone wool. The turnover of Knauf Insulation division in 2016 was 1.6 billion €. Energy efficiency, related to the environmental issues, is driving the development of new, better and greener insulation products. The leading role in this development is of major importance for Knauf Insulation d.o.o., which will secure growth of production and commercialization thus opening possibilities for new working places and future benefits for the owners, workers and society. The market of the green products is growing at a much higher rate than the conventional market. The development of a new generation of insulation materials is the crucial background for future growth of the company and will strengthen the mineral wool industry in Slovenia. From the market perspective a wool–NSM composite with reasonable pricing (mainly dependent on the price of NSMs, which is steadily decreasing) could reach 5 % share or 180 M€ turnover in the next 5–7 years. The intellectual property will be protected by patents and trademarks, which will secure inventor's and company's interests and benefits.
The project fits into the Slovenian Smart Specialization Strategy (S4) in the domain Factories of Future (FoF), where it integrates into key enabling technology (KET) “Advanced manufacturing and processing” and value chain “New materials”.
Direct benefit of the project realization for the society is therefore summarized in three key findings:
-Energy saving products for construction and industrial applications with emphasis on green products,
-Growth of industrial capacities (i.e. new working places) for the insulating materials production in Slovenia and EU, and
-Use of human and environment friendly, non-hazardous raw materials for the composite production.
Most important scientific results
Most important socioeconomically and culturally relevant results
Interim report
