This new measurement technique provides a versatile and accurate method to measure material shrinkage for various polymerizations and is expected to guide the processing of photopolymers for improved service life in practices.

PS of different exemplary materials (typical dental resin mixtures) are measured and show good consistency with the results reported previously, indicating the accuracy and reliability of the proposed method. ResultsĪ unified method for the PS measurement is finally established by combining experimental testing, theoretical prediction, and finite element analysis. A theoretical model was developed to establish the relationship between the measured uniaxial shrinkage, the free shrinkage of the material, and the degree of polymerization. As such, uniaxial sample shrinkage and degree of polymerization were measured simultaneously in real-time for the whole photopolymerization process. MethodĪ NIST-developed cantilever beam-based testing system was adapted with an ultra-low beam stiffness (1 × 10 –3 N/μm) to capture the sample deformation under a near-free-of-constraint environment and was coupled with in-situ near-infrared spectroscopy for polymerization kinetics monitoring. The aim of this study is to develop a new, accurate, and convenient measurement method for PS during photopolymerization and establish the exact correlation between PS development and polymerization kinetics. However, existing methods are often limited by tedious operation, low measurement accuracy, and/or high measurement cost.

Many methods have been adopted to measure the PS.

Polymerization shrinkage (PS) and the resulting shrinkage stress are two major reasons causing premature material failures in these applications. Photopolymerized materials have been widely applied in various engineering fields, such as 3D printing, dental restorations, micro/nano fabrications, etc.

Solid converter pdf 7.0