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Abstract

The free volume and the mechanical properties of Palacos R bone cement were determined from positron annihilation lifetime spectroscopy (PALS) and from dynamic mechanical thermal analysis (DMA) in the temperature ranges 24-220 degrees C and 30-120 degrees C, respectively. The heating of bone cement caused an appreciable reduction of the free volume, measured as a decrease in the ortho-positronium lifetime tau(3) from 2.04 to 1.91 ns, as well as a clear increase in the storage modulus from 2.3 to 3.0 GPa. The changes in free volume and storage modulus after the heat treatment were interpreted as an effect of elimination of residual monomer from the bone cement. The free volume of the bulk-polymerized phase of bone cement was estimated from a simple difference method, suggesting that the residual monomer was eliminated from the bone cement between 60 and 90 degrees C, thus implying a glass transition temperature of only 60 degrees C for the bulk-polymerized phase. The spherical free volume cavity size estimated from the ortho-positronium lifetime V(tau(3)), and the storage modulus E'(storage) from DMA measurements were found to correlate by a linear relationship throughout the studied temperature range, and the correlation appeared to be independent of the presence of residual monomer.

Beyond the Spherical Approximation: Elongated Free Volume Holes in Rubbers: A Positron Annihilation Study

“…Positron annihilation lifetime spectroscopy (PALS) 1 is one of the few experimental techniques able to supply information on the free volume, an important concept in designing polymers with desired performance. Indeed, relevant characteristics of polymers, such as mechanical and thermal properties, 2 as well as permeability, 3 are related to the free volume. 4 In addition, the size and the shape of the holes forming the free volume may play a role, for example, in gas separation membranes.…”

Layered double hydroxide induced advancement in joint prosthesis using bone cement: the effect of metal substitution

“…1 The space between the bone and implant can be lled with bone cement for stronger mechanical bonding to prevent destabilization during stress distribution between the bone-implant interface from everyday activities and the strength of the bone cement is somehow proportional to the joint's life/durability. 2 All commercial PMMA based bone cements are cold cured powder-liquid combined systems, and for clinical applications, powder and liquid components are combined and the mixture is inserted into bone where the polymerization reaction takes place. PMMA bone cement has the ability to resist fatigue related cracking to a certain extent.…”

Positron Annihilation Lifetime Spectroscopy as a Special Technique for the Solid-State Characterization of Pharmaceutical Excipients, Drug Delivery Systems, and Medical Devices—A Systematic Review

“…The free volume and mechanical properties of Palacos ® R bone cement were investigated by PALS. The free volume hole size was reduced in the matrix due to the elimination of residual monomers at temperatures higher than 60 °C [ 114 ].…”