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Current conservation approaches are shifting toward small, tailored, and less invasive interventions. Therefore the problems and best practices for conservators are becoming increasingly mobile. The future of art preservation heating systems will be with “intelligent” devices that are portable, flexible, reliable, and cost-effective. In this scenario, flexible heaters are becoming the preferred device for the application of heat in restoration since they can be shaped in different geometries and sizes, are easy to be transported and can be applied in the most versatile way with other treatment devices. Moreover, such devices can be applied also for in situ treatments, for instance, in emergency interventions. The development of these flexible devices comes from the past and, therefore, has a long history. To provide the reader with a comprehensive description of most innovative heating devices for art conservation, this chapter provides a brief history on how such devices evolved from the beginning to now, with the final aim of understanding the technological challenges and issues that allowed to continuously improve traditional heat tables and wound wire–based blankets toward the creation of innovative carbon nanotubes (CNTs)-based devices. After an historical investigation of heating devices, mostly based on heat tables, the chapter focuses on current technologies where nanomaterials are increasingly being used to boost the heating performance in several fields of application. Finally this work describes the main outcomes of a recent European Project, which applied CNTs-based coating on flexible substrates to create the first prototypes of intelligent mobile heaters to be adopted extensively by conservators. A number of applications of this new kind of device are eventually proposed and discussed.

In this work, the elastic properties of melts of polycarbonate (PC)/multi-wall carbon nanotubes (MWCNT) composites were studied by means of rotational and capillary rheometry. Linear viscoelastic shear oscillations combined with simultaneous electrical measurements, creep recovery experiments in shear and extrudate swell measurements were performed. The application of the fractional Zener model for the phenomenological description of the viscoelastic properties of PC/MWCNT composites in the linear regime is discussed. The modulus of the spring of the fractional Zener model is a measure of elasticity and increases with carbon nanotubes concentration. The results of creep recovery experiments reveal that the microstructure strongly influenced the viscosity and the reversible deformation of the nanocomposites. Below the rheological percolation threshold, agglomeration of carbon nanotubes generally led to an increase of the reversible deformation up to a maximum value. Above the rheological percolation threshold, a larger concentration of carbon nanotubes caused a decrease of the recoverable deformation. As revealed by capillary rheometry, the extrudate swell of the PC/MWCNT composites at shear rates above 100 s − 1 was lower than the extrudate swell of neat polycarbonate which indicates the decrease of reversible deformation caused by the addition of MWCNT in capillary flows (large stress regime). The experimental data are discussed in the context of the current understanding of the rheological properties and the microstructure of polymer composites with carbon nanotubes.

A method of carbon nanotubes (CNTs) oxidation at room temperature using ozone with added water vapor is described. The resulting CNTs were characterized by Fourier transform infrared, X-ray photoelectron spectroscopy, and scanning and transmission electron microscopy. These show that more oxygenated functional groups could be grafted onto the CNT surfaces due to the addition of water vapor, compared to traditional approaches in which high density of ozone is required. The existed hydroxyl radicals in the water vapor/ozone mixture is considered to be responsible for the increased CNT oxidizing degree.

The influence of molar mass and temperature on the formation of networks of multiwalled carbon nanotubes (MWCNT) in oscillatory shear flows was investigated. Combined rheological and electrical investigations were performed using composites with 0.5–5.0 wt% MWCNT in a low- and a high-viscosity polycarbonate (PC) at 190 °C and 250 °C. The objective of this work was to study the dynamics of the simultaneous formation of electrical and rheological networks by taking into account the superposition of (i) network breakup by the applied shear field and (ii) the diffusion-controlled clustering of carbon nanotubes. The formation (i.e. the buildup) of electrical and rheological networks proceeds more rapidly for a lower-viscosity matrix and at higher temperatures, whereas breakup of the electrical network is more pronounced at lower temperatures because of a larger stress-transfer between polymer matrix and MWCNT network. Sinusoidal shear deformation results in an oscillatory electrical conductivity with decreasing average value at large shear amplitudes, indicating that the electrical nanotubes network consists of weakly bonded carbon nanotube clusters which can be easily released and reformed. These data also show that MWCNT–MWCNT bonds can be reversibly deformed up to a maximum deformation. The latter experimental result precises the current understanding of electrical carbon nanotubes networks.

Mild heating devices currently available to conservators are still limited in terms of precision, versatility, mobility, accessibility and cost. Moreover, they lack a range of operational features, such as low power requirements, efficient power use, temperature stability and uniform heat distribution. Carbon nanotubes-based technologies can provide a wide range of technical solutions for overcoming these limitations, thereby allowing the development of more precise, flexible and portable heating devices. This work describes the design of an innovative carbon nanotube-based intelligent mobile accurate thermo-electrical mild heating device, to be used in the art conservation field. The device consists of three different types of flexible heating mats with different designs (opaque and ultra-thin/woven and breathable/transparent) and different operational and physical properties. The entire heating system is completed by a control unit that controls, monitors and registers the heating and by a power supply unit. First tests performed on a series of prototypes of the designed heaters showed that the device was able to convey uniform heating on different working materials, thus proving to be effective for thermal consolidation.