A Study on the Fatigue Characteristics of Bonded Parts of the Carbon Fiber Reinforced Dental P.M.M.A.

Transcription

1 MEMORS OF THE FACULTY OF ENGNEERNG FUKU UNVERSTY VOL.27 No A Study on the Fatigue Characteristics of Bonded Parts of the Carbon Fiber Reinforced Dental P.M.M.A. Hiroshi KMURA*, Takuji YAMAGUCH*, Tetsuro SHRASH*, Masakazu TSUBOKAWA*, Takashi OGTA* (Received Jul. 5, 1979) n this paper we describe an experimental study. Reported in this article are results of tensile fatigue test under constant stress amplitude applied to bonded section of carbon fiber reinforced dental P.M.M.A., which tensile fatigue test was conducted in comparison with that of the parent material in order to find out fatigue characteristics of the bonded section of the dental P.M.M.A. As a result of the research of test and experiments, it is found that; 1) t is noted that fatigue characteristics of composite material of C.F. 1 wt.%/p.m.m.a. are good. 2) For adhesion of composite material of C.F. 1 wt.%/p.m.m.a., a scarf joint should be adopted. 3) Adhesion by heat-cured type acrylic resin is effective. 1. NTRODUCTON Dental material in cavum oris is always subjected to repeated load and is under stress, thus fatigue characteristics of the dental material itself in cavum oris become a matter of concern. Many of the dental material in cavum oris has combined structures, and the load, when applied repeatedly, produces fatigue. Generally speaking, failure of the dental material in cavum oris under repeated load occurs at the combined structure. Reported in this article are results of tensile fatigue test under constant stress amplitude applied to bonded section of carbon fiber reinforced dental P.M.M.A., which tensile fatigue test was conducted in comparison with that of the parent material in order * Department of Textile Engineering

2 298 to find out fatigue characteristics of the bonded section of the dental P.M.M.A~~ Reported in this article as well are mechanical properties of composite materials which were made by way of trial, b f ' b 'f p 3) ) uslng car on 1 er to reln orce.m.m.a.. 2. EXPERMENTAL MATERAL AND EXPERMENTAL METHOD Series of experiments consisted of tension, bending and fatigue tests of composite materials of P.M.M.A./chopped strands, tension and fatigue tests of bonded materials of such composite materials, tension, bending and fatigue tests of bonded material of the P.M.M.A./prepreg composite material, and observation by S.E.M. of fatigue fracture of composite material of P.M.M.A./chopped strands. Test pieces were made of (i) acrylic resin of heat-cured type (Denture Acrylic, SHOFU "Bio" Resin) heated for 4S minutes in OOoC under OOkg/cm 2 pressure and molded by natural cooling, (ii) the same acrylic resin as above, but at first mixed with chopped strands of carbon fiber (Toreca T300; 3,000 filaments) which was cut into 3mm in length, washed with acetone and dried, thence heat- and pressure-molded, and (iii) prepreg of C.F./ epoxy. Adhesion was by acrylic resin of low temperature cured type and of heat-cured type; but in case of P.M.M.A./prepreg composite material, self-adhesion was adopted. Apparatuses used for experiments were Shimazu's Autograph S-2000 for tension and bending tests and Shimazu's (a) Base material +---f-- t 110 = i Servopet Lab-SP for fatigue test with which tension was applied to prer T3 ~ (b) Adhered material Fig.l Specimens for fatigue test. Table Mechanical properties of C.F./P.M.M.A. composite materials. Mechanical Content ratio of carbon fiber(wt,.) properties Tensile strength (kg/mm 2 ) Young's modu- us (kg mm 2 ) Elongation ( "10) Bending strength (kg/mm 2 ) Bendi ng elastic modulus (kg/mm 2 ) Deflection (mm)

3 299 stressed test pieces at 22Hz. 3. EXPERMENTAL RESULTS AND CONSDERATON Table 1 shows summary of results of tension and bending tests conducted with trial-manufactured carbon fiber reinforced P.M.M.A. having 0-3 wt.% carbon content. t is k~own from Table 1 that strength and elastic modulus increased, while elongation and deflection decreased, as C.F. content became bigger, and effectiveness of reinforcement of P.M.M.A. is proved. Fig.l shows shape and size of test piece for fatigue test, which applied correspondingly to fatigue test piece for Baldwin SF-Ole S-N curves of P.M.M.A. parent material and of bonded materials of P.M.M.A. bonded with acrylic resins of heat-cured type and low temperature type are shown in Fig.2. t is known from this figure that fatigue strength was 2.0, 1.8 and 1.4kg/mm 2 respectively, which means that fatigue strength of the specimen bonded with heatcured type acrylic resin was 90% and the specimen bonded with low temperature type acrylic resin was 70% against that of the parent material respectively. Fatigue limit with repeated stress with any of the specimens was 10 6 Fig.3 is the comparison of S-N curve of selfadhered material of C.F./P.M.M.A. sandwich material and fluid acrylic resin with that of bonded material of P.M.M.A.. Fatigue strength of self-adhered material of composite material and fluid acrylic resin Fig.2 Relation between stress amplitude and number of cycles to failure for adhered P.M.M.A.!30\N-{ o---pmma base'malenal --Adhered matenal of PMMA.--Adheslon by heat-cured acrylic rt'sin.--adht'slon by low temperature acrylic resin :...' "'-': 0 ~20r--\ ~-'?=:-+--== ~_o :.~. ~._ -..-_ ~. Vl t------t-----i 10 5 log 10 7 Number of cycles to failure' (N)

4 300 was 0.7kg/mm 2, which was only 35% of that of P.M.M.A. parent material and 39% of that of P.M.M.A. bonded material. Fig.4 is the comparison of S-N curves of composite materials having 0.5 and 1.0 wt.% of C.F. mixed in acrylic resin and the S-N curve of P.M.M.A. parent material. Fatigue strength of the C.F. 0.5 wt.%/p.m.m.a. material was 2.2kg/mm 2, while that of C.F. 1.0 wt.%/p.m.m.a. material was 2.3kg/mm 2, which corresponded to 110 and 115% of that of the parent material respectively. S-N curves of P.M.M.A. material reinforced with 1 wt.% of C.F. and two kinds of bonded materials bonded with heat-cured type acrylic resin are shown in Fig.5. Fatigue strength was 2.3, 2.1 and 1.7kg/mm 2, while Fig.3 Relation between stress amplitude and number of cycles to failure for self adhered C.F. prepreg/ P.M.M.A. sandwich and fluid acrylic resin. C U :J ~20 -zr. E o ~ ViJ.O.. ~ '" ~.. Adhered material of PMMA (Adhe>5on by heal-cured acrylic resin).--aclhe'red matenalof CFprE'prE'g/PMMA sandwch and flud acrylic fe'sln.-.--e los log 10 7 Number of cycles to 'failure (N) Fig.4 Relation between stress amplitude and number of cycles to failure for C.F./P.M.M.A. composite materials..--pmma base' male'nal.-cf conte'nt O.5wlo',/PMMA. composte mate'nal.--cf content 10 wl'l, PMMA. composite material los log Number of cycles to failure (N)

5 301 Fig.S Relation between stress amplitude and number of cycles to failure for adhered C.F./ P.M.M.A. composite materials.... f E Jl' C!J -g ~ ,,--- CF low!"'.' PMMA. composite matenal ".--Adhered CF 10wt"t. PMMA. ~_\ composite material with same fluid composite re-sin \ Vlffdlw//,@ \f Wd4-WiWA ~~-----=--.. o ~ C!J "- Vi. 2o ~.... _-; ~ ~ ~1~0r ~ ~~ 10 NUmber of cycles to ( N ) Table 2 Tension test results of adhered P.M.M.A. and C.F./P.M.M.A. composite materials. Joint type. PMMA -... ~u.'-=t+ Fluid acrylic resin ~~.PMMA Fluid acrylic resin Tensi e stren~ Young's modu- Elongation th (kg/mlt'f) us (kgrmm2) (.,.) W'ilm C.Fl.Owt,.1 ~~ ~.. PMMA. tat1 i poste material Fluid C.F lont~/.1 PM.MA. ot~ -j._-- ~ C.F 10Nt~/.1 PMMAcom poste matenal F uid C.F ldwl /o PM.M.A. Table 3 Tension test results of self adhered C.F. prepreg and C.F. prepreg/p.m.m.a. sandwich structure. Joint type ~l~lt~pmma Fluid a~rylic resin Tensile streng- Young's modu- Elongation th (kg/mm 2 ) us (kg mm2 ) ( 0,.) ,self-adhesion ~Fluidacry. lie resin C.F prep reg Self- adhesion o~~auidacry. -. he re51n c.f. prepregl PMMA. sandwich structure

6 302 (a) P.M.M.A.; cr=2.3kg/mm 2 (b) P.M.M.A.; cr=3.0kg/mm 2 (c) Adhesion with C.F. 1.0 wt.%/p.m.m.a.; cr=1.8kg/mm 2 (d) Adhesion with C.F. 1.0 wt.%/p.m.m.a.; cr=1.8kg/mm 2 (e) Adhesion with C.F. 1.0 wt.%/p.m.m.a.; cr=3.0kg/mm 2 (f) Adhesion with C.F. 1.0 wt.%/p.m.m.a.; cr=3.0kg/mm 2 Photo.l The appearances of fatigue fracture of P.M.M.A. and C.F./P.M.M.A. composite material by S.E.M. (Hitachi HSM-2A).

7 303 joint efficiencies of butt joint and 45 scarf joint were 74% and 91% respectively, which were in proportion to adhesion area. Tensile strength, elastic modulus and elongation of various bonded materials of P.M.M.A. and C.F.R.P.M.M.A. are shown in Tables 2 and 3. t is known that tensile strength and elongation of C.F. prepreg are low, but this is considered to be due to resin content ratio (40%). t is also found that a scarf joint is superior with regard to adhesion strength and elongation, and is correlative with adhesion area. Photo.l shows S.E.M. pictures of fatigue fracture of bonded section of P.M.M.A. and C.F.R. P.M.M.A. bonded with C.F.R. acrylic resin. Stress concentration on account of existence of reinforcement was little, and the fracture on the contrary looked like fatigue failure on adhesion interface. 4. CONCLUSON The following summary can be made from the results of the present research. } t is noted that fatigue characteristics of composite material of C.F. 1 wt.%/p.m.m.a. are good. 2} For adhesion of composite material of C.F. 1 wt.%/p.m.m.a., a scarf joint should be adopted. 3) Adhesion by heat-cured type acrylic resin is effective. ACKNOWLEDGMENTS The authors wish to express his sincere thanks to Prof. Dr. Y.Kawamura, Prof. Dr. S.Kawai, Prof. Dr. R.Yamaga, Prof. Dr. Y.Tsuchiya, Dr. Y.Okuno, Dr. Y.Moriwaki and Dr. H.Matsushiro of Osaka University for their encouragements and valuable discussions. The work is supported by the Grant-in-Aid from the Ministry of Education of Japan. REFERENCES 1) Tore: Technical Sheet of Carbon Fiber Toreca, CF-08Rl, 1972; CF-06R1, ) The Society for the Study of Standard Testing Method of Plastics: Plastics Testing Handbook, Publication of Nikkan Kogyo Press Co. Ltd., p.117, ) H.Maki, etc.: Collection of Composite Material Technology, ndustrial Technology Center, p.709, ) T.Hayashi, etc.: Composite Material Engineering, Nikkagiren, p.900, 1971.

8 304 5) The Society of Dental Science and Engineering: Dental Science and Engineering, shiyaku Press Co. Ltd., p.362, ) H.Kimura, etc.: A Study on the Self Adhesion of Carbon Fiber Prepreg and Dental Acrylic Resin on the Hybrid Composites of Thin Plate, The Journal of the Japan Research Society of Dental Materials & Appliances, Vol.34, No.2, p.l68-l77, ) H.Kimura, etc.: A Study on the Fiber Orientation Effects of Carbon Fiber Reinforced Anisotropy Dental Polymer Hybrid Composites on the Extreme Thin Plate, The Journal of the Japan Research Society of Dental Materials & Appliances, Vol.35, No.2, p.115-l22, ) H.Kimura, etc.: A Study on the Adhesion of the Composite Artificial Teeth, The Journal of the Japan Research Society of Dental Materials & Appliances, Vol.35, No.2, p.177-l83, ) H.Kimura, etc.: A Study on the Denture Base with Carbon Fiber Reinforced Hybrid Composite, The Journal of the Japan Research Society of Dental Materials & Appliances, Vol.33, No.3, p , ) H.Kimura, etc.: A Study on the Welding of Dental Acrylic Resin, The Journal of the Japan Research Society of Dental Materials & Appliances, Vol.34, No.4, p , ) H.Kimura, etc.: A Study on the Carbon Fiber Reinforced Denture Resin Base, The Journal of the Japan Research Society of Dental Materials & Appliances, Vol.34, No.2, p.ll6-125, ) H.Kimura, etc.: A Study on the Carbon Fiber Reinforced Dental P.M.M.A. Composites of Thin Plate with Brush on Technical Method, The Journal of the Japan Research Society of Dental Materials & Appliances, Vol.35, No.2, p.l23-l29, 1978.