[PARALOID™ B-60 Solid Grade Thermoplastic Acrylic Resin - Palmer Holland](^2^)

Choosing the right solvent to use with acrylic resins in the restoration of ceramics is important because of its long-term effect on the properties of the resin: depending on the nature of the solvent, varying residual amounts will remain present for over a year. Literature has described the plasticizing effect of residual solvent in Paraloid resins: the use of low volatile solvents favors the presence of residual solvent in acrylic resins [3], and the plasticization effect of residual solvent leads to decreased Tg [1, 21, 33]. Schilling et al. [22] point out that it is difficult to establish a reliable Tg value for Paraloid B72. The presence of acetone in Paraloid B72 resins can decrease Tg by several degrees; toluene can lead to a 15 C reduction, and trichloroethane can cause a decrease in Tg of as much as 25 C [33]. Our measurements presented in Figs. 1 and 3 correlate Tg values with the quantity of residual solvent and room temperature drying time, the residual solvent has a significant impact on the Tg values, even several months after the application. According to Bellenger et al. [32], the quantity of solvent in the resin depends on the absorption capacity of the latter. This property varies with hydrogen bonded solvents. The plasticizing role of solvents is essentially dependent on this criterion of solvent absorption. A poorly hydrogen bonded solvent, such as toluene, has thus greater plasticizing efficiency than ethanol, which is a strongly hydrogen bonded solvent. Plasticizers influence the adhesive properties of acrylic resin [34]. They also cause a weakening of intermolecular attractions between polymer chains, with a consequent decrease in tensile strength, a lowering of Tg and an increase in the elongation and flexibility of films. Residual solvents can therefore modify the adhesive properties of Paraloid by acting as plasticizers, as well as by creating internal stresses (induced by shrinkage) during their evaporation [35]. In our study, we focused on the impact of solvent on Paraloid films, while the effect of water was not specifically studied. However, a loss of adhesion may lead to an increase of moisture at the film/ceramic interface [34]. The relative humidity parameter should probably be more accurately evaluated and integrated into future studies. To improve the performance of Paraloid resins, micro-cellulose may be added to increase Tg value [15]. The stabilizing effect of micro-cellulose is probably due to its interaction with the residual solvent.

Rohm & Haas, Technical Leaflet C-379, 1975 also lists heptane, isobutanol, and ethylene glycol as insoluble. A solvent selection table with viscosity values in cps. at 25C for a 40% solids solution is also given.

Top Rated 82a114 Paraloid Solid Grade Resins Solvent Selection C

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Solutions of PiBMA, as well as other acrylics, may turn yellow over time, even if stored in darkened cabinets. This problem may be exacerbated if xylenes or if a less pure grade solvent are used to solubilize the resin. The only precaution put forth by the manufacturers is a warning about the generation of static electricity in handling the resins in the presence of flammable solvents (technical literature supplied by ICI Acrylics, 32). 2ff7e9595c