| Objective:The purpose of this study is to investigate the effect of low-temperature air plasma at atmospheric pressure on the bonding properties of 30% Carbon Fiber Reinforced Polyetheretherketone(CFR-PEEK)after surface modification and its aging.The effect of air low-temperature plasma treatment on the bonding performance of 30% CFR-PEEK surface was investigated by water contact angle test,surface morphology observation and microtensile test.The timeliness of effects of air low-temperature plasma treatment on the bonding properties of 30% CFR-PEEK surfaces were investigated by water contact angle testing,surface morphology observation,and microtensile testing.Methods:Fifty-six 30% CFR-PEEK specimens with the same length,width and height of3 mm*3 mm*6 mm were made and randomly divided into 7 groups(n=8)for water contact angle test and microtensile bond strength test,including 1 group for water contact angle test and 6 groups for microtensile bond strength test: blank control group,0 h group,4 h group,24 h group,72 h group and 120 h group.All samples were sanded with 800 mesh sandpaper + 80 mesh alumina blasting,and all samples except the blank group were treated with air low-temperature plasma for 30 s.The water contact angle test group samples were tested for water contact angle after sanding,sandblasting,and 30 s plasma treatment 0 h,4 h,8 h,24 h,72 h,96 h,120 h,and 144 h,respectively,to analyze the water contact angle of 30% CFR-PEEK before and after sandblasting and the changing characteristics of the water contact angle after air low-temperature plasma treatment.Each bonding group made a 30%CFR-PEEK-Resin bonding model according to different grouping times,and microtensile experiments were performed after 40 h of 37° saline storage.The loading speed was set to 1 mm/min and the tensile direction was perpendicular to the bonding surface until the bonding interface was broken,the maximum load was recorded,the microtensile strength was calculated and recorded,and the tensile strength results were statistically analyzed by applying statistical software.The surface of the specimen was gold blasted and observed by Scanning Electronmicroscope(SEM)to compare the differences of surface morphology after grinding,sandblasting and plasma treatment.Results:1.Water contact angle experiments: the water contact angle of 30% CFR-PEEK specimens was 64.45 ± 3.23° after sanding with 800 mesh sandpaper and increased significantly to 119.66 ± 4.98° after sandblasting with 80 mesh alumina,and the water contact angle was 15.05 ± 1.75° after 30 s of air low-temperature plasma jet treatment.The water contact angle returned to the pre-treatment level on day 5 after air low-temperature plasma treatment of the specimens and changed the fastest within1 day after the plasma treatment.2.Surface morphology observation: the results show that the surface after 800 mesh silicon carbide sandpaper polishing is relatively smooth,with a small amount of rough surface and polishing scratches;the surface after 80 mesh alumina sandblasting treatment obviously increases in roughness;the surface of the specimen is further etched by air atmospheric pressure low temperature plasma treatment after 30 s,showing micron-level grooves.3.Microtensile strength test: six groups of 30% CFR-PEEK resin bonding models were tested for microtensile strength,including 5.13 ± 0.67 MPa for the blank control group,11.25 ± 0.67 MPa for the 0 h group,10.56 ± 0.52 MPa for the 4 h group,9.97 ± 0.50 MPa for the 24 h group,7.33 ± 1.22 MPa for the 72 h group,and7.33 ± 1.22 MPa for the 120 h group.There was no statistical difference between the4 h and 0 h groups and between the 4 h and 24 h groups.The remaining groups were statistically different in pair-wise comparison(P<0.05).Conclusions:1.The surface modification effect of low-temperature plasma technology is closely related to the plasma device treatment parameters,plasma gas,and the physical and chemical properties of the material itself.The plasma treatment of 30%CFR-PEEK under this experimental condition can obtain a good modification effect.2.Air low-temperature plasma jet treatment of 30% CFR-PEEK surface has some etching effect,but the analysis of the results shows that this slight etching does not contribute significantly to the wettability and adhesion of the 30% CFR-PEEK surface.3.The combined application of alumina blasting and air low-temperature plasma significantly improved the bonding strength between 30% carbon fiber reinforced polyetheretherketone and resin.It should be noted that the modification effect is time-limited,with the best bonding strength still obtained within 4 h after treatment,then reduce linearly and returns to the pre-treatment level after 5 days.It is suggested that the modification of 30% carbon fiber reinforced polyetheretherketone using low-temperature plasma technology should be applied as soon as possible to obtain the best modification effect. |
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