title: Short fiber reinforced composite: the effect of fiber length and volume fraction.
abstract: OBJECTIVE
  The aim of this study was to determine the effect of short fiber volume fraction and fiber length on some mechanical properties of short fiber-reinforced composite (FRC).
  
  
  METHODS
  Test specimens (2 x 2 x 25 mm3) and (9.5 x 5.5 x 3 mm3) were made from short random FRC and prepared with different fiber volumes (0%-22%) and fiber lengths (1-6 mm). Control specimens did not contain fiber reinforcement. The test specimens (n=6) were either dry stored or thermocycled in water (x10.000, 5-55 degrees C) before loading (three-point bending test) according to ISO 10477 or statically loaded with a steel ball (Ø 3.0 mm) with a speed of 1.0 mm/min until fracture. A universal testing machine was used to determine the flexural properties and the load-bearing capacity. Data were analyzed using analysis of variance (ANOVA) (p=0.05) and a linear regression model.
  
  
  RESULTS
  The highest flexural strength and fracture load values were registered for specimens with 22 vol% of fibers (330 MPa and 2308 N) and with 5 mm fiber length (281 MPa and 2222 N) in dry conditions. Mechanical properties of all test specimens decreased after thermocycling. ANOVA analysis revealed all factors were affected significantly on the mechanical properties (p<0.001).
  
  
  CONCLUSIONS
  By increasing the volume fraction and length of short fibers up to 5 mm, which was the optimum length, the mechanical properties of short FRC were improved.
authors.affiliation: Prosthodontics and Biomaterials, Institute of Dentistry, University of Turku, Finland. sufgar@utu.fl
authors.forename: Sufyan K
authors.initials: SK
authors.lastname: Garoushi
authors.forename: Lippo V J
authors.initials: LV
authors.lastname: Lassila
authors.forename: Pekka K
authors.initials: PK
authors.lastname: Vallittu
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins / Q000737:chemistry*; D019245:Compressive Strength; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis; D005898:Glass; D016014:Linear Models; D008422:Materials Testing; D018583:Pliability; D011092:Polyethylene Glycols; D011109:Polymethacrylic Acids
chemical_list: D003188:Composite Resins; D011109:Polymethacrylic Acids; C009753:fiberglass; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate