title: Prediction of composite elastic modulus and polymerization shrinkage by computational micromechanics.
abstract: OBJECTIVE
  The objective of this study was to simulate the elastic modulus and polymerization shrinkage of a light activated polymer matrix composite using a generalized method of cells (GMC) micromechanics model. Two hypotheses were tested: (1) the micromechanics model provides estimates of elastic modulus vs filler fraction with greater accuracy than the rule of mixtures, Hashin-Shtrikman and phenomenological models; (2) Micromechanics Analysis Code/Generalized Method of Cells accurately simulates experimental benchmarks of polymerization shrinkage strain.
  
  
  METHODS
  The study applied mathematical algorithms to a representative volume element of a model polymer composite to yield value estimates of the elastic modulus and contraction strain. Mechanical properties of the composite constituents were derived from thermomechanical and dynamic mechanical analysis of BisGMA and TEGDMA filled and unfilled resins. Data from the micromechanics model were compared to results of other analytical methods as well as experimental benchmarks.
  
  
  RESULTS
  Predictions of elastic modulus vs filler fraction from the micromechanics model provided greater accuracy than the rule of mixtures and the Hashin-Shtrikman models. Predictions of polymerization shrinkage strain were within 13% of experimental values.
  
  
  CONCLUSIONS
  The elastic micromechanics model presented accurately predicted elastic modulus and polymerization shrinkage strain as a function of filler fraction, superior to other analytical methods.
authors.affiliation: Department of Restorative Dentistry, Division of Biomaterials and Biomechanics, Oregon Health & Science University School of Dentistry, 611 SW Campus Dr., SD-503, Portland, OR 97239, USA. sakaguch@ohsu.edu
authors.forename: R L
authors.initials: RL
authors.lastname: Sakaguchi
authors.forename: B D
authors.initials: BD
authors.lastname: Wiltbank
authors.forename: C F
authors.initials: CF
authors.lastname: Murchison
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000379:methods*; D004055:Differential Thermal Analysis; D004548:Elasticity; D006801:Humans; D008422:Materials Testing; D008956:Models, Chemical; D015394:Molecular Structure; D010316:Particle Size; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D013314:Stress, Mechanical
chemical_list: D003188:Composite Resins; D011109:Polymethacrylic Acids; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate