SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Composite materials

27

Wood pulp fibres are an important component of environmentally sound and renewable fibre-reinforced composite materials. The high aspect ratio of pulp fibres is an essential property with respect to the mechanical properties a given composite material can achieve. The length of pulp fibres is affected by composite processing operations. This thus emphasizes the importance of assessing the pulp fibre length and how this may be affected by a given process for manufacturing composites. In this work a new method for measuring the length distribution of fibres and fibre fragments has been developed. The method is based on; (i) dissolving the composites, (ii) preparing the fibres for image acquisition and (iii) image analysis of the resulting fibre structures. The image analysis part is relatively simple to implement and is based on images acquired with a desktop scanner and a new ImageJ plugin. The quantification of fibre length has demonstrated the fibre shortening effect because of an extrusion process and subsequent injection moulding. Fibres with original lengths of >1 mm where shortened to fibre fragments with length of <200 μm. The shortening seems to be affected by the number of times the fibres have passed through the extruder, the amount of chain extender and the fraction of fibres in the polymer matrix.

Concepts: Composite material, Paper, Wood, Boeing 787, Carbon fiber, Fiberglass, Aramid, Composite materials

26

In this study, new dimethacrylate monomer SiMA without Bisphenol A (BPA) structure was synthesized and used as base resin of dental composite materials with the aim of reducing human exposure to BPA derivatives.

Concepts: Bisphenol A, Chemical synthesis, Materials science, Synthesis, Composite material, Epoxy, Dental composite, Composite materials

26

The restoration of endodontically treated teeth involves a difficult decision-making process, especially when it comes to more complex prosthetic rehabilitations. Regarding singletooth restoration, there are high-level requirements for the restorative components and the application of all necessary treatment steps to achieve the final restoration. So when is there a need for a single-crown restoration or when might a composite resin restoration also be sufficient? For the assessment of endodontically treated teeth as abutment teeth for prosthetic restorations, there are no clear guidelines beyond single-tooth restorations. The aim of this article is to compile important aspects of the restoration of endodontically treated single teeth, including more complex prosthetic reconstructions, based on the scientific literature.

Concepts: Composite material, Crown, Dental composite, Composite materials

6

Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignment within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Furthermore, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response.

Concepts: Polymer, Temperature, Materials science, Composite material, Materials, Carbon fiber, Composite materials, Metal matrix composite

3

By incorporating 3D microvascular networks containing a two-part reactive chemistry within a fiber-reinforced composite, continuous cycles of self-healing after interlaminar delamination are achieved. An interpenetrating vasculature shows improved in situ fluid mixing over segregated microchannels, resulting in full recovery (>100%) of mode-I fracture resistance.

Concepts: Bone, Composite material, Cycle, Composite materials, Delamination

2

Resin-based dental materials may intraorally release their chemical components and bisphenol A. The New England Children’s Amalgam Trial found that children randomized to amalgam had better psychosocial outcomes than those assigned to composites for posterior tooth restorations. The objective of this study was to examine whether greater exposure to dental composites is associated with psychosocial problems in children.

Concepts: Composite material, Epoxy, Crown, Dental restoration, Dental composite, Dental materials, Composite materials, Amalgam

0

This study was performed to evaluate the comparative radiopacity of adhesive/resin composite materials in cylindrical cavities using micro-computed X-ray tomography (μCT). The two-step self-etch adhesive systems, Clearfil SE Bond (SE) and FL-Bond II (FL), and flowable resin composites, Beautifil Flow F10 (BF) and Clearfil Majesty ES Flow High (MJ), were used. The radiopacity of bovine tooth structures and restorative materials was measured by μCT. In addition, cylindrical cavities prepared in bovine teeth were restored with the following adhesive/composite combinations: SE-BF, SE-MJ, FL-BF, and FL-MJ. The mean gray values of the composite restorations were calculated. The threshold values of the μCT images were evaluated using the Otsu’s thresholding method. The current results show that the comparative radiopacity of the materials and tooth structure varied, which affected distinguishing the μCT images of the composite restorations in the cylindrical cavity. The proper combination of restorative materials should be considered when conducting in vitro μCT assessments of composite restorations.

Concepts: Medical imaging, Composite material, Epoxy, Boeing 787, Dental composite, Composite materials

0

Synthesize a new BPA-free monomer for use in methacrylate-based materials and evaluate critical properties of resin and composite materials based on the monomer.

Concepts: Composite material, Boeing 787, Dental composite, Composite materials

0

This study aims to compare the ex vivo fracture resistance of root canal treated (RCT) teeth restored with four different types of fibers under composite resin.

Concepts: In vivo, Fiber, Composite material, Dietary fiber, Fiberglass, Aramid, Composite materials

0

Materials with strong magnetic property that can provide excellent microwave absorption performance are highly desirable, especially if their dielectric and magnetic properties can be easily modulated, which make minimal thickness and ultra-wide bandwidth become achievable. The magnetic property of ferromagnetic (FM) and antiferromagnetic (AFM) composite materials are closely related to their ratio of composition, size, morphology and structure. AFM-FM composites become a popular alternative for microwave absorption, however, the controllable design and preparation need urgently optimized. Here, we have successfully prepared a series of plate-like NiO-Ni composites and demonstrated the potential of such composites for microwave absorption. Strong magnetic coupling was found from NiO-Ni nanoparticles by electron holography, which makes NiO-Ni composite a highly efficient microwave absorber (strong reflection loss: -61.5 dB and broad bandwidth: 11.2 GHz, RL < -10 dB). Our findings are helpful to develop strong microwave absorber based on magnetic coupling.

Concepts: Magnetism, Ferromagnetism, Composite material, Antiferromagnetism, Boeing 787, Composite materials, Baseband