The effect of ethanol on surface of semi-interpenetrating polymer network (IPN) polymer matrix of glass-fibre reinforced composite

Effect of interfacial surface treatment on bond strength of particulate-filled composite to short fiber-reinforced composite

Objective

The aim was to investigate the effect of different interfacial surface treatments on the shear bond strength (SBS) between a short fiber-reinforced flowable composite (SFRC) and a particulate-filled flowable composite (PFC). In addition, SBS between two successive layers of similar materials was evaluated.

Materials and methods

One-hundred and forty-four specimens were prepared having either SFRC (everX Flow) as a substructure composite and PFC (G-aenial Flo X) as a surface composite or having one of the two materials as both substructure and surface layer. Eight groups of specimens were created (n = 18/per group) according to the interfacial surface protocol used. Group 1: no treatment; Group 2: ethanol one wipe; Group 3: ethanol three wipes; Group 4: phosphoric acid etching + bonding agent; Group 5: hydrofluoric acid etching + bonding agent; and Group 6: grinding + phosphoric acid etching. Group 7: only PFC layers and Group 8 (control) only SFRC layers without any surface treatment. After one-day storage (37 °C), SBS between surface and substructure composite layers was measured in a universal testing machine, and failure modes were visually analyzed. SEM was used to examine the bonding surface of the SFRC composite after surface treatment. SBS values were statistically analyzed with a one-way analysis of variance (ANOVA) followed by the Tukey HSD test (α = .05).

Results

The SBS between successive SFRC layers (Group 8) was statistically (p < .05) the highest (43.7 MPa) among tested groups. Surface roughening by grinding followed by phosphoric acid etching (Group 6) resulted in a higher SBS (28.8 MPa) than the remaining surface treatments.

Conclusion

Flowable composite with glass fibers (everX Flow) showed higher interlayer SBS compared to PFC flowable composite. Interfacial surface roughness increases the bonding of PFC to the substructure of SFRC.

Preparation and Characterization of Calcium Cross-Linked Starch Monolithic Cryogels and Their Application as Cost-Effective Green Filters

Monolithic cryogels from starch were successfully synthesized and applied as alternative biodegradable filters for the first time. Rice flour was cross-linked with Ca²⁺ from limewater during gelatinization before being frozen and then thawed for three cycles. The resultant material was then soaked in ethanol for 3 h before incubation at 80 °C for 1 h, yielding monolithic material with interconnected pores in sizes of 51 ± 18 to 52 ± 15 µm without any need of freeze-drying. The cryogels possessed macroporous structure with specific surface areas from 1.1 to 4.3 m²g⁻¹, they could adsorb water from 599 ± 27 to 635 ± 59% of their dry weight with low swelling ratios of 6.0 ± 0.3 to 6.4 ± 0.6 g_water/g_cryogel, and could be applied as biofilters to remove suspended particles and reduce the light absorption of water sample from 25 ± 3 to 96 ± 5%. The prepared biofilters can be re-used up to three times, although they cost only USD 0.0004/piece. Complete weight loss resulted from burial in soil for 30 days, indicating environmentally friendly biodegradation and potential for environmental applications.

Interfacial Adhesion of a Semi-Interpenetrating Polymer Network-Based Fiber-Reinforced Composite with a High and Low-Gradient Poly(methyl methacrylate) Resin Surface

The research aimed to determine the tensile bond strength (TBS) between polymerized intact and ground fiber-reinforced composite (FRC) surfaces. FRC prepregs (a reinforcing fiber pre-impregnated with a semi-interpenetrating polymer network (semi-IPN) resin system; everStick C&B) were divided into two groups: intact FRCs (with a highly PMMA-enriched surface) and ground FRCs (with a low PMMA gradient). Each FRC group was treated with: StickRESIN and G-Multi PRIMER. These groups were further divided into four subgroups based on the application time of the treatment agents: 0.5, 1, 2, and 5 min. Next, a resin luting cement was applied to the FRC substrates on the top of the photo-polymerized treating agent. Thereafter, weight loss, surface microhardness, and TBS were evaluated. Three-factor analysis of variance (p ≤ 0.05) revealed significant differences in the TBS among the FRC groups. The highest TBS was recorded for the intact FRC surface treated with G-Multi PRIMER for 2 min (13.0 ± 1.2 MPa). The monomers and solvents of G-Multi PRIMER showed a time-dependent relationship between treatment time and TBS. They could diffuse into the FRC surface that has a higher PMMA gradient, further resulting in a high TBS between the FRC and resin luting cement.

Repairability of a 3D printed denture base polymer: Effects of surface treatment and artificial aging on the shear bond strength

OBJECTIVES

The present study aimed to evaluate the repairability of a 3D printed denture base material. The effects of surface treatments and artificial aging on the shear bond strength (SBS) were investigated.

METHODS

A total of 224 specimens were printed by digital light processing technology (Rapid Shape D30II) using a 3D printing denture base material (FREEPRINT denture). To evaluate the repairability, the SBS and failure modes were measured after surface treatment and artificial aging. Specifically, half of the specimens were further performed with thermocycling (5-55 °C, 5000 cycles) for artificial aging. The aged and non-aged specimens were further divided into four subgroups (n = 28) to simulate a denture base repair with one of the following treatments: control (without surface treatment), monomer (applying methylmethacrylate for 120 s), P600 (grinding with P600 silicon carbide paper) and sandblasting (blasted with 125 μm aluminum oxide with 2 bar), respectively. Surface roughness was measured (n = 6) and surface topography was observed by scanning electron microscopy (n = 2). A test rod was built on the sample surface using the same 3D printing material. Afterward, all specimens further underwent thermocycling (5-55 °C, 10,000 cycles).

RESULTS

For non-aged groups, no significant differences in SBS could be found (p < 0.05), and bondings failed cohesively in the denture base material. Regarding the aged control and monomer group, adhesive failures at the interface were primarily observed, and SBS values were statistically lower than those of the other groups (p < 0.05).

CONCLUSIONS

The 3D printed denture base material exhibited favorable repairability. For the realignment surface, the SBS at the bonding interface is satisfying and additional surface treatments could be not necessary. In contrast, the aged surface could significantly decrease the SBS; hence subtractive surface treatments are highly recommended.

The impact of non-thermal plasma on the adhesion of polyetherketoneketone (PEKK) to a veneering composite system

The PEKK material can be used in prosthodontics for framework manufacturing and is commonly laminated with veneering composites to achieve a better esthetics. Various surface treatment methods including sandblasting, etching, laser and cold plasma treatments were reported to enhance the adhesive properties of dental polymers. Both tensile and shear bond test were employed to quantify the bond strength between PEKK and veneering composites. The present in vitro study aims to evaluate the influence of acetylene, argon, air, nitrogen and oxygen plasma on the shear bond strength between PEKK and one veneering composite. Firstly, to determine which bond test type should be applied, n = 40 PEKK specimens were treated with argon plasma. Both shear and tensile bond tests were performed and compared to the control group (n = 40). In shear bond testing, values were 8.14 ± 1.70 MPa for Argon plasma while 5.83 ± 1.42 MPa for control group. In tensile bond testing, Argon plasma 1.50 ± 0.51 MPa while control group 0.58 ± 0.50 MPa. Afterwards n = 160 PEKK specimens were treated with rocatec sandblasting (n = 20), adhesive (n = 20), acetylene (n = 20), argon (n = 20), air (n = 20), nitrogen (n = 20), oxygen (n = 20) plasma types and compared to the untreated control group (n = 20) using shear bond strength test (SBS). Additionally surface roughness and scanning electron microscopy analyses were performed. The following SBS values were revealed: 10.22 ± 1.06 MPa for rocatec; 9.89 ± 3.08 MPa for acetylene, 9.16 ± 1.48 MPa for adhesive, 7.54 ± 1.52 MPa for argon, 7.09 ± 1.99 MPa for air, 7.03 ± 1.48 MPa for nitrogen, 5.69 ± 1.59 MPa for oxygen plasma types and 4.71 ± 1.54 MPa for the control group. All groups, except control group, showed SBS over 5 MPa, which means that they are suitable for the clinical application, according to ISO 10477. Acetylene showed the highest SBS among all plasma types (p < 0.0001), which was on a level of rocatec sandblasting group. Rocatec and acetylene groups demonstrated Ra values significantly different to the reference group (p < 0.0001). Plasma treatment especially with acetylene gas can be an effective more convenient surface treatment method for strengthening the bond strength between PEKK and veneering composites than traditional sandblasting/adhesive treatment.