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Interlaminar shear strength (ILSS) and compressive strength are two of the most critical properties of carbon fiber-reinforced polymer (CFRP). In this report, three types of epoxy resins—4,4'-diaminodiphenylmethane epoxy resin (AG-80), bisphenol A epoxy resin (E-1NT), and novolac epoxy (EPN)—were studied. E-1NT is characterized by low viscosity and low cost but exhibits poor mechanical properties, while AG-80 offers better wetting with carbon fiber. These two epoxy resins were mixed in various mass ratios. The study revealed that as the AG-80 content increased, the ILSS of the composite also increased, reaching a maximum of 94.04 MPa when the AG-80 content reached 60%. Beyond this point, further increases in AG-80 did not enhance the ILSS. Conversely, the compressive strength initially increased but then declined sharply as the AG-80 ratio increased. The maximum compressive strength was recorded at 748.52 MPa when the AG-80 content reached 60%, which was 21% higher than pure AG-80 and 32% higher than pure E-1NT. Additionally, the study examined three different types of ionic sizing agents and four different resin matrices (E-1NT/DDS, AG-80/DDS, AG-80/E-1NT/DDS, EPN/DDS). Among them, the 60% AG-80/40% E-1NT/DDS/CF formulation demonstrated the best balance in both ILSS and compressive strength. [ABSTRACT FROM AUTHOR]

This article provides an in-depth exploration of the current state of research in microwave-absorbing composite materials, juxtaposing the status quo of coating type and structurally reinforced resin-based composites, with a particular emphasis on the latter's structural and performance superiority. It succinctly elucidates the mechanisms of electromagnetic shielding, as well as the conditions and underlying principles that govern the absorption of microwaves by composite materials. The review continues by dissecting the strategies for enhancing the microwave-absorption capabilities of resin-based composites, including the classification of absorbents, absorbent selection, and an overview of structural design innovations in microwave-absorbing materials. Structural wave-absorbing composites are manufactured by combining different types of resin matrices, absorbers, reinforcing fibers and construction methods. The interactions between these components are scrutinized to reveal how each contributes to the overall performance of the composite. We spotlight the unique construction methods and the intricate relationship between structure and performance in structurally reinforced composites, offering insights into the optimization strategies for composite-material absorption characteristics. Concluding with a forward-looking perspective, the article contemplates the burgeoning potential and future applications of fiber-reinforced resin-based microwave-absorbing composites, setting the stage for a new era in material science and technology. [ABSTRACT FROM AUTHOR]

Resin materials feature exceptional physical properties and inexpensive cost, but unfavorable surface characteristics, such as low wear resistance and poor erosion wear performance, render them tough to satisfy greater demands. The potential option is to prepare supersonic plasma sprayed Al 2 O 3 -13 wt%TiO 2 /Al 2 O 3 -phenolic resin (AT13/Al 2 O 3 -PF) coating on the surface of the resin matrix. AT13 feedstocks are classified into two types: Al 2 O 3 -13 wt%TiO 2 powder prepared by the agglomeration granulation process (AT13-1) and the mixture of spherical Al 2 O 3 and TiO 2 (approximately 13 wt%) powder (AT13-2). The effect of component dispersion on mechanical and tribological characteristics of coatings was thoroughly investigated, as well as the solid particle erosion wear behavior of coatings. The results illustrated that the evenly dispersed TiO 2 phase in AT13-1 coating was prone to homogenize the coating structure, resulting in better tribological characteristics than AT13-2 coating, although erosion wear performance was inferior to AT13-2 coating. The wear rate of AT13-1 coating was 1.36 × 10−5 mm3 (N m)−1, which was 1/21 times that of AT13-2 coating. At the 60° erosion angle, the high porosity of AT13-1 coating resulted in hard phase cracking or hard phase debonding. The high microhardness of AT13-2 coating reduced erosion wear at the 90° erosion angle. [ABSTRACT FROM AUTHOR]

Cerbera odollam oil was extracted from the dried Cerbera odollam seeds by the Soxhlet extraction method. Cerbera odollam seed oil-based alkyd resins were synthesized by the alcoholysis–polyesterification process via reaction of the oil with varying amounts of phthalic and maleic anhydride. Standard evaluation methods were used to analyze the physicochemical features of the resins, including acid value, viscosity, and others. Evaluation tests such as drying times, pencil hardness, adhesion, gloss measurement, and chemical inertness were employed to study the film performance of the produced alkyd resins. Mechanical characteristics such as ultimate tensile strength, strength under impact, elastic modulus, surface hardness, and water absorption were evaluated. Further characterization to study the organic architecture of the oil and alkyd resins was carried out by Fourier transform infrared (FTIR) spectroscopy and gas chromatography–mass spectrometry (1H NMR). The resin with the higher percentage of maleic anhydride showed better surface coating application performance in set-to-touch (88 min), dry-to-touch time (105 min), and pencil hardness (5B) while resin higher in phthalic anhydride shows better results in gloss (92.5) and alkali resistance. On the other hand, the resin with the higher percentage of maleic anhydride showed better mechanical performance in tensile strength, tensile modulus, impact strength, and surface hardness while resin with higher percentage of phthalic anhydride showed better results in water absorption and elongation at break. Overall, the synthesized alkyd resins from the Cerbera odollam seed oil possessed great application potential in both surface coating and polymer composites as matrix. [ABSTRACT FROM AUTHOR]

Abstract Background One of the most common causes of aesthetic failure and restoration replacement is the tooth restorations color mismatch specifically after aging. Methods One hundred and two participants with endodontically treated first molar were selected clinically. The patients were randomly splited into two groups and restored either with Cerasmart hybrid ceramic or Vita Enamic polymer infiltrated ceramic network (PICN) crowns and cemented using dual cure adhesive cement. The color difference (ΔE) values after cementation at 0 (Baseline), 6, and 12 months of use were obtained by quantification of L*, a*, and b* values with a digital spectrophotometer. Mann–Whitney test used to compare between tested groups at each time point and between (α = 0.05). Results At 6 months follow-up intervals, Vita Enamic group showed the highest significant ∆L* (p = 0.035) and ∆a* (p 0.05). Furthermore, all color parameters of both groups showed statistically significant difference at 12 months follow-up intervals. After 12 months, Vita Enamic restorations presented higher color change compared to Cerasmart restorations with a (p-value of 0.0120). When comparing the total color difference ∆Et through-out the follow-up intervals of Vita Enamic & Cerasmart groups, there were insignificant difference (p = 0.263). Conclusion Both hybrid materials demonstrated comparable color stability after 1 year of clinical service within clinical acceptance range. However, Cerasmart demonstrated a better colour stability after 1 year. Trial registration ClinicalTrials.gov (ID: NCT05501808) 15/8/ 2022- ‘retrospectively registered’.

Background: One of the most common causes of aesthetic failure and restoration replacement is the tooth restorations color mismatch specifically after aging. Methods: One hundred and two participants with endodontically treated first molar were selected clinically. The patients were randomly splited into two groups and restored either with Cerasmart hybrid ceramic or Vita Enamic polymer infiltrated ceramic network (PICN) crowns and cemented using dual cure adhesive cement. The color difference (ΔE) values after cementation at 0 (Baseline), 6, and 12 months of use were obtained by quantification of L*, a*, and b* values with a digital spectrophotometer. Mann–Whitney test used to compare between tested groups at each time point and between (α = 0.05). Results: At 6 months follow-up intervals, Vita Enamic group showed the highest significant ∆L* (p = 0.035) and ∆a* (p < 0.001) compared to Cerasmart group. ∆b* and ∆E showed no significant difference between both groups (p > 0.05). Furthermore, all color parameters of both groups showed statistically significant difference at 12 months follow-up intervals. After 12 months, Vita Enamic restorations presented higher color change compared to Cerasmart restorations with a (p-value of 0.0120). When comparing the total color difference ∆Et through-out the follow-up intervals of Vita Enamic & Cerasmart groups, there were insignificant difference (p = 0.263). Conclusion: Both hybrid materials demonstrated comparable color stability after 1 year of clinical service within clinical acceptance range. However, Cerasmart demonstrated a better colour stability after 1 year. Trial registration: ClinicalTrials.gov (ID: NCT05501808) 15/8/ 2022- 'retrospectively registered'. [ABSTRACT FROM AUTHOR]

Modeling the relaxation properties of resin matrix during cure plays an important role in predicting process-induced residual stresses and final distortions of resin-based composites. This paper develops a physical characterization model, which explains the temperature and cure-degree dependence of relaxation behaviors in terms of the size of cooperatively rearranging region, and special emphasis is placed on investigating the general physical mechanism of cure degree affecting the relaxation properties. In this model, the relaxation time is governed by a modified Adam-Gibbs equation, which is extended here to include the cure dependence. In addition, the relaxation modulus is modeled in a chemo-rheologically simple manner (CSM) based on the free volume theory. Material characterization is carried out using experimental data of two typical resins. It is shown that two cure-dependent model parameters, i.e., the smallest size of the cooperatively rearranging region and the glass transition temperature, are sufficient in accounting for the effect of cure on the relaxation modulus, and could provide a physical explanation of the influence of cure on relaxation behaviors. Furthermore, the proposed model is numerically realized by incorporating ABAQUS with UMAT subroutine, and its validity in predicting the residual stresses and final distortion of composites is also numerically verified by comparing with the results available in literature. [Display omitted] • The cure effects on relaxation behaviors are modeled based on polymer physics. • The cure degree effects are represented by the cooperatively rearranging region. • The smallest size of cooperatively rearranging region descends with an increase of cure degree. • Two cure-dependent model parameters are sufficient to include the influence of cure degree. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ultrafast laser processing has recently emerged as a new tool for processing fiber-reinforced polymer (FRP) composites. In the astronautic industry, the modified epoxy resin (named 4211) and the modified cyanate ester resin (known as BS-4) are two of the most widely used polymers for polymer-based composites. To study the removal mechanism and ablation process of different material components during the ultrafast laser processing of FRPs, we isolated the role of the two important polymers from their composites by studying their femtosecond UV laser (260 fs, 343 nm) ablation characteristics for controllable machining and understanding the related mechanisms. Intrinsic properties for the materials' transmission spectrum, the absorption coefficient and the optical bandgap (Eg), were measured, derived, and compared. Key parameters for controllable laser processing, including the ablation threshold (Fth), energy penetration depth (δeff), and absorbed energy density (Eabs) at the ablation threshold, as well as their respective "incubation" effect under multiple pulse excitations, were deduced analytically. The ablation thresholds for the two resins, derived from both the diameter-regression and depth-regression techniques, were compared between resins and between techniques. An optical bandgap of 3.1 eV and 2.8 eV for the 4211 and BS-4 resins, respectively, were obtained. A detectable but insignificant-to-ablation difference in intrinsic properties and ablation characteristics between the two resins was found. A systematic discrepancy, by a factor of 30~50%, between the two techniques for deriving ablation thresholds was shown and discussed. For the 4211 resin ablated by a single UV laser pulse, a Fth of 0.42 J/cm2, a δeff of 219 nm, and an Eabs of 18.4 kJ/cm3 was suggested, and they are 0.45 J/cm2, 183 nm, and 23.2 kJ/cm3, respectively, for the BS-4 resin. The study may shed light on the materials' UV laser processing, further the theoretical modeling of ultrafast laser ablation, and provide a reference for the femtosecond UV laser processing characteristics of FRPs for the future. [ABSTRACT FROM AUTHOR]

Copyright of Cotton Textile Technology is the property of Cotton Textile Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aimed to compare the monomer elution, microhardness, and roughness of experimental resin‐based composites (RBCs) prepared from a novel monomer system derived from 9,9‐Bis[4‐(2‐hydroxyethoxy)phenyl]fluorene) (Bis‐EFMA), bisphenol A‐glycidyl methacrylate (Bis‐GMA), and urethane dimethacrylate (UDMA) with each other, also with a commercial RBC, 3 M ESPE FiltekTM Z250 (FZ). Experimental Bis‐EFMA (ET), Bis‐GMA (BT), and UDMA (UT) based composites were prepared (20% Bis‐EFMA or 20% Bis‐GMA or 20% UDMA, and 20% triethylene glycol dimethacrylate [TEGDMA], and 60% glass filler). 60 specimens were produced (n = 5) and exposed to ethanol solution for 7 days. Then specimens were tested at baseline (T0), first (T1), third (T2), and seventh (T3) days. ET and FZ released significantly lower TEGDMA than other RBCs did (p < 0.05). BT released significantly higher TEGDMA than other RBCs did at T1 (p < 0.05). However, no significant difference was found between FZ and ET at T1 (p > 0.05). FZ exhibited the highest microhardness at all‐time points; besides, the microhardness of BT was lowest at T0, while the microhardness of BT and UT was lower than that of FZ and ET at T1, T2, and T3 (p < 0.05). BT exhibited higher roughness at T2 than the UT did at T0 and T1, significantly (p < 0.05). However, no significant difference was found between the other RBCs (p > 0.05). Bis‐EFMA, a novel bisphenol A‐free monomer system, has the potential to be used in commercial RBCs as a substitute for Bis‐GMA in terms of lower monomer elution and higher microhardness. [ABSTRACT FROM AUTHOR]