Polymethyl methacrylate creep

Figure 4.34 Influence of the degree of stretching on aging behavior Left in polymethyl methacrylate (creep behavior) [585]...

There are two types of maxillofacial implants extraoral and intraoral. The former deals with the use of artificial substitutes for reconstructing defective regions in the maxilla, mandible, and face. Useful polymeric materials for extraoral implants require (1) match of color and texture with those of the patient (2) mechanical and chemical stability (i.e., material should not creep or change color or irritate skin) and (3) ease of fabrication. Copolymers of vinyl chloride and vinyl acetate (with 5 to 20% acetate), polymethyl methacrylate, silicones, and polyurethane rubbers are currently used. Intraoral implants are used for repairing maxilla, mandibular, and facial bone defects. Material requirements for the intraoral... 

Fig. 6.6. Compressive creep strains in repair mortars, (a) Polymethyl methacrylate mortar, (ft) Polyvinyl acetate modihed mortar, (c) Magnesium phosphate modified mortar, d) Flowing concrete.

Figure 11.12 Creep rates as a function of total creep strain for polymethyl methacrylate at indicated temperatures for a stress level of 56 MPa. (Reproduced from Sherby, O.D. and Dorn, ].B. (1958) Anelastic creep of polymethyl methacrylate. ]. Mech. Phys. Solids, 6, 145. Copyright (1958) Elsevier Ltd.)...

Sherby, O.D. and Dorn, J.B. (1958) Anelastic creep of polymethyl methacrylate. 

As discussed in Section 11.3.1, Eyring and collaborators had already considered the application of activated rate theory to the creep of polymers. For polymethyl methacrylate, Sherby and Dorn [68] showed that the creep rate could be fitted to an equation of the form... 

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