The effect of high fiber fraction on some mechanical properties of unidirectional glass fiber-reinforced composite.
OBJECTIVE
This study was designed to evaluate the effect of an increase of fiber-density on some mechanical properties of higher volume fiber-reinforced composite (FRC).


METHODS
Five groups of FRC with increased fiber-density were fabricated and two additional groups were prepared by adding silanated barium-silicate glass fillers (0.7 μm) to the FRC. The unidirectional E-glass fiber rovings were impregnated with light-polymerizable bisGMA-TEGDMA (50-50%) resin. The fibers were pulled through a cylindrical mold with an opening diameter of 4.2mm, light cured for 40s and post-cured at elevated temperature. The cylindrical specimens (n=12) were conditioned at room temperature for 2 days before testing with the three-point bending test (Lloyd Instruments Ltd.) adapted to ISO 10477. Fiber-density was analyzed by combustion and gravimetric analyzes.


RESULTS
ANOVA analysis revealed that by increasing the vol.% fraction of E-glass fibers from 51.7% to 61.7% there was a change of 27% (p<0.05) in the modulus of elasticity, 34% (p<0.05) in the toughness, and 15% (p<0.05) in the load bearing capacity, while there was only 8% (p<0.05) increase in the flexural strength although it was statistically insignificant. The addition of particulate fillers did not improve the mechanical properties.


CONCLUSIONS
This study showed that the properties of FRC could be improved by increasing fibervolume fraction. Modulus of elasticity, toughness, and load bearing capacity seem to follow the law of ratio of quantity of fibers and volume of the polymer matrix more precisely than flexural strength when high fiber-density is used.
Department of Prosthetic Dentistry, Institute of Dentistry, University of Turku, Finland. aoabdu@utu.fi
Aous A
AA
Abdulmajeed
Timo O
TO
Närhi
Pekka K
PK
Vallittu
Lippo V
LV
Lassila
D000538:Aluminum Silicates / Q000737:chemistry; D017609:Barium Compounds / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D055119:Elastic Modulus; D005898:Glass / Q000737:chemistry*; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D055595:Mechanical Phenomena; D008855:Microscopy, Electron, Scanning; D018583:Pliability; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
D000538:Aluminum Silicates; D017609:Barium Compounds; D003188:Composite Resins; D003764:Dental Materials; D011109:Polymethacrylic Acids; D012821:Silanes; C485628:Stick resin; C102738:barium glass filler; C009753:fiberglass; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D019904:Polymethyl Methacrylate