Insulation materials, thermal phenolic foam

Mineral fillers and mineral fibers also increase temperature resistance. Phenolic resin-bound textile non-wovens exhibit excellent properties regarding changing climatic conditions, aging behavior, and thermal resistance compared to other insulation materials (PUR, PS foams, crosslinked PE). 

Phenol—formaldehyde resins are used as mol ding compounds (see Phenolic resins). Their thermal and electrical properties allow use in electrical, automotive, and kitchen parts. Other uses for phenol—formaldehyde resins include phenoHc foam insulation, foundry mold binders, decorative and industrial laminates, and binders for insulating materials. 

The test methods mostly follow British Standards, but some are more closely related to the ISO tests. Care must be taken to ensure that the correct sample size is u.sed. The determination of water absorption by diffusion is based on the Swiss Standard SIA 279 Part 5.07 [13] (see Section 2.6 below). Similarly the properties of extruded board are specified in BS 3837, Part 2, 1990 [14]. BS 3927, 1986 [15], specifies rigid phenolic foam for thermal insulation in the form of slabs and profiled sections. The material is classified as types A. B. and C. which differ principally in thermal conductivity, water vapor permeability and apparent water absorption. Thermal conductivity is measured by methods described in BS 4370, Part 2, Method 7 [16] or Appendix B of BS 874 [17]. ... 

Phenolic resin foam is an interesting material for the cellular insulation industry because of its high temperature resistance, fire resistance, and very low smoke generation [16]. The aqueous resole is crosslinked in the presence of a surfactant and a low boiling liquid, that volatizes during the increase ofviscosity or plasticity of the mixture. The surfectant is necessary to develop a uniform fine cellular foam stracture [1,6], Carbonization of phenolic foams yields carbon foams with an excellent thermal resistance, that are applied as high temperature insulation materials for the production of filters for corrosive agents and catalyst supports [1]. 

Table 26.1. Overview of insulation materials sorted by their ambient condition thermal conductivities conventional (red) and superinsulation materials and components (turquoise) can be classified by their respective thermal conductivity values. Phenolic and polyurethane foams mark a transition area between those two families (pink)...

Polyphenols. Another increasingly important example of the chemical stabilization process is the production of phenolic foams (54-57) by cross-linking polyphenols (resoles and novolacs) (see Phenolic Resins). The principal features of phenolic foams are low flammability, solvent resistance, and excellent dimensional stability over a wide temperature range (54), so that they are good thermal-insulating materials. 

To prepare thermal insulating materials, Carvalho et al. (2003) prepared phenolic and lignophenolic (lignin-phenol-formaldehyde) foams and determined their thermal conductivities 0.057 W m K (density of 0.12 g cm ) for phenolic foam and 0.072 W m" K" (density of 0.45 g cm ) for lignophenolic foam. Tondi et al. (2009) prepared tannin-based rigid foams with thermal conductivity values between 0.024 and 0.030 W m K" for densities between 0.08 and 0.12 g cm", respectively. 

A variety of cellular plastics exists for use as thermal insulation as basic materials and products, or as thermal insulation systems in combination with other materials (see Foamed PLASTICS). Polystyrenes, polyisocyanurates (which include polyurethanes), and phenolics are most commonly available for general use, however, there is increasing use of other types including p olye thylene s, polyimides, melamines, and poly (vinyl chlorides) for specific applications. 

Phenol-formaldehyde (PF) was the first fully synthetic macromolecular material ( Bakelite , 1907). In a slightly precured condition and provided with fillers, it is, as a moulding powder, available for processing into end-use articles such as bulb fittings, switch housings, coils, laminated wood and foam for thermal insulation. 

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