Phenolic mortars

Phenolic mortars have excellent resistance to acids, particularly for dilute nitric acid (up to 50%) and sulfuric acid (60-90%) but can only tolerate very dilute alkaline solutions at low temperatures. 

Phenolic Mortars Phenolics are the oldest resinous mortars used with acid brickwork. The original phenol-formaldehyde materials have an effective pH range of about 0-10. They are very resistant to dilute and concentrated non-oxidizing acids, solvents and dilute alkalies. Modified phenolics further increase this pH range. Such mortars raise the maximum pH well above the normal pH 0-12 range, and are the only resin-based mortars resistant to aniline. Phenolics are useful up to an upper service temperature of 360°F. 

Some mortars are heat sensitive. The speed of set of furan mortars in particular, is much accelerated by heat, so that "open time" can be reduced to 10 minutes at 85° to 90°F. The effects of temperature on setting speeds of other resins are less extreme, but the contractor will have more time to use up his mix at a 60° to 70°F material temperature. Phenolic mortars must be stored prior to use at temperatures of 60°F or lower. If they are left in areas where they may be overheated, they can be ruined in a short time or so badly affected as to be unusable. There is a case on record of phenolic mortars being delivered to a site in Texas late on Friday, and left on the loading dock, resulting in materials which were totally unusable by 7 A.M. on Monday morning when the construction crew arrived. On the other hand, no serious damage will result if the components of resin mortars are subjected to temperatures below freezing. 

The phenolic mortars provide resistance to high concentrations of acids and to sulfuric acid at elevated temperatures. Fillers for the phenolic mortars are 100% carbon, 100% silica, or part carbon and part silica. For high concentration of sulfuric acid, silica is the filler of choice. Carbon fillers are used where resistance to high concentrations of hydrofluoric acid is required. Table 7.10 lists some typical compatibilities of phenolic mortars. 

STERNCHEM Phenolic Mortar is formulated to provide superior service for acid brick constructions requiring the chemical resistance of carbon/resinous phenolic systems. 

Although the use of simple diluents and adulterants almost certainly predates recorded history, the use of fillers to modify the properties of a composition can be traced as far back as eady Roman times, when artisans used ground marble in lime plaster, frescoes, and po22olanic mortar. The use of fillers in paper and paper coatings made its appearance in the mid-nineteenth century. Functional fillers, which introduce new properties into a composition rather than modify pre-existing properties, were commercially developed eady in the twentieth century when Goodrich added carbon black to mbber and Baekeland formulated phenol— formaldehyde plastics with wood dour. 

Sulphonphthaleins. These indicators are usually supplied in the acid form. They are rendered water-soluble by adding sufficient sodium hydroxide to neutralise the sulphonic acid group. One gram of the indicator is triturated in a clean glass mortar with the appropriate quantity of 0.1 M sodium hydroxide solution, and then diluted with water to 1 L. The following volumes of 0.1 M sodium hydroxide are required for 1 g of the indicators bromophenol blue, 15.0 mL bromocresol green, 14.4 mL bromocresol purple, 18.6 mL chlorophenol red, 23.6 mL bromothymol blue, 16.0 mL phenol red, 28.4 mL thymol blue, 21.5 mL cresol red, 26.2 mL metacresol purple, 26.2 mL. 

In a typical experiment, the phenol (1 mol) and freshly crystallized NBS (3 mol) were ground in a mortar. The color of the mixture changed immediately from white to yellow-brown. The solid mixture was treated with CCI4 after an appropriate time (ranging from 1 min to 2 h), the succinimide removed by filtration and the product chromatographed on silica gel (hexane-EtOAc). 

The phenol should be ground in a mortar to eliminate lumps. 

Extraction of Cured, Modified Phenol-Formaldehyde Resins. A sample of the modified resin was spread as a thin coating on a sheet of aluminum foil and cured in an oven at 170 °C for 5 minutes. The cured resin was removed from the aluminum foil, weighed, and broken into small pieces that were placed in water (10 to 15 mL) for extraction at room temperature. After 1 to 2 hours, the water was decanted from the solid resin. The resin was extracted in this manner an additional three to four times. The residue from the water extraction at room temperature was dried and ground using a mortar and pestle. The ground resin was extracted with hot water in a Soxhlet apparatus for 24 hours. The room temperature extract and hot water extract were combined, concentrated, and diluted to a known volume for analysis. The quantity of modifier in the extract was determined by HPLC (77). 

Resin Mortars This group includes the furans, phenolics, polyesters and the epoxies. Some of these mortars are used as thin membrane beds in lieu of asphaltic. Except for the epoxies and polyesters, most of these are acid catalyzed materials. The alkalinity of the concrete will retard the catalyzing reaction. Therefore, the concrete substrate must be neutralized before such a mortar is installed in direct contact with concrete. 

The selection of the resin is made in the same manner as the selection of the brick mortar, covered elsewhere in this volume, with the exception that the binder of the membrane must be a resin-not a silicate or a sulfur-and the order of choice is, first, the lowest possible shrinkage furan, then a phenolic and, finally, only if one of these two is unable to handle the chemical exposure, a vinyl ester or a polyester. 

Figure 45-3 One of the earliest acid-resistant tile floors in a brewery pasteurizer room (1940), laid in a Portland cement bed with a phenolic resin mortar grout.

The classic thermosets, such as ebonite, phenolics, ureas, melamines and polyesters as well as the epoxies, when reinforced with fiberglass or graphite fibers could also be classified as high performance thermosets. While these plastics cannot be readily extruded or injection molded, they are resistant to the effects of moderately high hostile environments. Phenolic resin mortars have been used for over a half century for the construction of chemical resistant vessels and for joining brick and tile used as linings in hot acid environments. (1.)... 

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