Whey-based resins

Figure 2. Proposed reaction pathways for the synthesis of whey-based resins. Ammonia gas may be used in a two-step reaction scheme. Structures of polymers shown here are hypothetical.

Table III shows the properties of particleboards prepared with Phase I whey permeate-based resin. Table IV shows the properties of rice-hull-reinforced building boards using Phase II resin. Low-quality boards are prepared with rice hulls, but their qualities may be improved by using ground hulls or adding sawdust to the formulation. Although whey-based resins have been found to be excellent adhesives for binding solid lignocellulosic materials, these resins tend to require higher cure temperatures and longer cure times as compared to formaldehyde-based resins.

This chapter describes preliminary investigation into the thermosetting process of one whey-based resin preparation using differential scanning calorimetry (DSC). 

A Mettler TA 3000 system consisting of a TC 10A TA processor and a DSC 20 measuring cell was used to investigate the curing reaction of the whey-based resin prepared as follows. A mixture of 171-g whey permeate, 73.2-g NH4NO3, 2.85-g CuCl2, and 200-mL H20 was placed into a Parr pressure reactor and heated with stirring at 125 °C for 90 min. The pH of the final preparation was 3.6. 

The complexity of the whey-based resin thermosetting process can be illustrated by considering several isothermal investigations. Samples of the resin... 

However, when a fresh sample of the resin was heated isothermally at 185 °C, there was an exothermic process evident that peaked within the first minute and reached completion within approximately 4 to 5 min. Thus, it is evident that the cure mechanism may change with change in reaction conditions, revealing the complexity of the whey-based resin thermosetting process. 

It is clear from the results obtained that the core temperature rises above the platen temperature in the presence of phthalic anhydride. Since no unusual differences in the DSC thermogram of whey-based resin in the presence and in the absence of phthalic anhydride were seen, the exothermic phenomenon being observed under conditions of board preparation deserves further investigation. 

The use of formaldehyde-free adhesive resins from whey and whey byproducts for manufacturing construction-quality boards could resolve these problems simultaneously. The demand for formaldehyde-based thermosetting adhesive resins in the United States was estimated to be 1.9 billion pounds in 1983 (5). The anticipated requirement for resins and the potential availability of raw materials from whey are a fortuitous combination. 

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