Currently the advances in the field of 3D printing are causing a revolution in the (bio-)medical field. With applications ranging from patient-specific anatomical models for surgical preparation to prosthetic limbs and even scaffolds for tissue engineering, the possibilities seem endless. Today, the most widely used method is FDM printing. However, there is still a limited range of biodegradable and biocompatible materials available. Moreover, printed implants like for instance cardiovascular stents require higher resolution than is possible to reach with FDM. High resolution is crucial to avoid e.g. bacterial growth and aid to mechanical strength of the implant. For this reason, it would be interesting to consider stereolithography as alternative to FDM for applications in the (bio-) medical field. Stereolithography uses photopolymerizable resins to make high resolution prints. Because the amount of commercially available resins is limited and hardly biocompatible, here we investigate the possibility of using acrylates and vinylesters in an effort to expand the existing arsenal of biocompatible resins. Mechanical properties are tailorable by varying the crosslink density and by varying the spacer length. To facilitate rapid production of high-resolution prints we use masked SLA (mSLA) as an alternative to conventional SLA. mSLA cures an entire layer at a time and therefore uses less time to complete a print than conventional SLA. Additionally, with mSLA it takes the same time to make 10 prints as it would to make only one. Several formulations were prepared and tested for printability and mechanical strength.
MULTIFILE
PURPOSE: Limited information is available on the effect of Immediate Dentin Sealing (IDS) on the fracture strength of indirect partial posterior restorations. This study evaluated the effect of IDS on the fracture strength and failure types of two indirect restorative materials.MATERIALS AND METHODS: Standard MOD inlay preparations were made on sound molars (N=40, n=10 per group) and randomly divided into four groups to receive the inlay materials with and without the application of IDS: Group L-IDS-: Li2Si2O5 (Lithium disilicate, IPS e.max) without IDS; Group L-IDS+: Li2Si2O5 with IDS; Group MR-IDS-: Multiphase resin composite (MR, Lava Ultimate) without IDS; MR-IDS+: MR with IDS. Inlays made of L were etched with 5% hydrofluoric acid, and MR inlays were silica coated. After silanization, they were cemented using adhesive resin cement (Variolink Esthetic DC). The specimens were thermo-mechanically aged (1.2×106 cycles, 1.7Hz, 8000 cycles, 5-55°C) and then subjected to load to failure (1 mm/min). Failure types and locations of debondings were classified. Data were statistically analyzed using ANOVA, Mann Whitney U-test and Chi-square tests (α=0.05). Two-parameter Weibull distribution values including the Weibull modulus, scale (m) and shape (0), values were calculated.RESULTS: After aging conditions, no apparent changes were observed in marginal integrity but occlusal wear facets were more common with MR than with L (p<0.001). Material type and the application of IDS significantly affected the results (p=0.013). While group L-IDS- showed the lowest mean fracture strength (1358±506N) among all groups (p<0.05), application of IDS significantly increased the results significantly (L-IDS+: 2035±403N) (p=0.006). MR groups with and without IDS, did not show significant difference (MR-IDS-: 1861±423, MR-IDS+: 1702±596 N) (p=0.498). When materials without IDS are compared, L showed significantly lower results than that of MR (p=0.035). With the application of IDS, no significant difference was noted between L and MR materials (p=0.160). Weibull distribution presented the highest shape (0) for L-IDS+ (5.66) compared to those of other groups (3.01-4.76). Neither the material type (p=0.830), nor the application of IDS (p=0.54) affected the severity of the failure types. In 95% of the cases, the IDS layer left adhered on the tooth surface after fracture tests. In groups where no IDS was used, resin cement remained on the tooth surface in 44% of the cases (p=0.001). No significant differences were observed between the materials with respect to cement remnants or IDS after fracture (p=0.880). The incidence of repairable failure types (83%) was more common with L than with MR (75%) material (p>0.05).CONCLUSION: Immediate dentin sealing improves adhesion, and thereby the fracture strength of inlays made of lithium disilicate but not that multiphase resin composite.
An important step towards improving performance while reducing weight and maintenance needs is the integration of composite materials into mechanical and aerospace engineering. This subject explores the many aspects of composite application, from basic material characterization to state-of-the-art advances in manufacturing and design processes. The major goal is to present the most recent developments in composite science and technology while highlighting their critical significance in the industrial sector—most notably in the wind energy, automotive, aerospace, and marine domains. The foundation of this investigation is material characterization, which offers insights into the mechanical, chemical, and physical characteristics that determine composite performance. The papers in this collection discuss the difficulties of gaining an in-depth understanding of composites, which is necessary to maximize their overall performance and design. The collection of articles within this topic addresses the challenges of achieving a profound understanding of composites, which is essential for optimizing design and overall functionality. This includes the application of complicated material modeling together with cutting-edge simulation tools that integrate multiscale methods and multiphysics, the creation of novel characterization techniques, and the integration of nanotechnology and additive manufacturing. This topic offers a detailed overview of the current state and future directions of composite research, covering experimental studies, theoretical evaluations, and numerical simulations. This subject provides a platform for interdisciplinary cooperation and creativity in everything from the processing and testing of innovative composite structures to the inspection and repair procedures. In order to support the development of more effective, durable, and sustainable materials for the mechanical and aerospace engineering industries, we seek to promote a greater understanding of composites.
Microbes like bacteria and fungi can grow on almost everything, including e.g. on a music CD made of aluminum and polycarbonate. How? By producing an optimal mixture of effective enzymes that degrade the material on which the microbes thrive. In this project we want to find and characterize microbes that have the ability to digest one of the most commercially successful but at the same time hard-to-degrade materials: furan-based bio-composite resin. To help the microbes to degrade this recalcitrant material, we first must open up the complex resin structure by using (mild) acidification, grinding, and/or UV light. Thus, with this project we aim to find an effective and sustainable way to safely and effectively dispose and recycle used bio-composite resins. Our findings will help to increase the circularity of bio-composite materials and as such decrease the environmental waste pressure.
A transition to a circular economy is needed to revolutionize the construction sector and make it more sustainable for present and future generations. While the construction industry and the production of construction materials contribute to environmental pollution, they also offer great potential for addressing many environmental problems. Sheet materials are engineered wood boards that are produced from recycled or solid wood where an adhesive is used to bind the particles together, predominantly used in: Furniture manufacturing, Flooring application, Roofing, Wall sheathing. The most common binder for boards is urea-formaldehyde. Other binders may be used depending on the grade of board and its intended end-use. For example, melamine urea-formaldehyde, phenolic resins and polymeric diphenylmethane diisocyanate (PMDI) are generally used in boards that require improved moisture resistance. Formaldehyde is classified in the in the European Union as a carcinogen and it carries the hazard statement 'suspected of causing cancer'. In this project mycelium composites are developed as a formaldehyde-free, fully natural and biodegradable material with high potential to substitute these hazardous materials. The heat-press process, the feasibility of which was evaluated in a previous Kiem HBO project, is to be further developed towards a process where mycelium sheets with different thicknesses will be obtained. This is considered as a fundamental step to increase the material approachability to the market. Different Material manufacturing techniques are also considered to enable the increase of sample thicknesses and volume. Moreover, a business study will be incorporated to allow further understanding of the material market potential. The consortium composition of V8 Architects, QbiQ, Fairm, Verbruggen Paddestoelen BV, and CoEBBE merges different expertise and guarantees the consideration of the whole material production chain. The research will contribute to bring mycelium composites a step closer to the market, giving them visibility and increasing the possibility to a commercial breakthrough.
The recycling of high-quality polymer-based materials, such as composites, is currently predominantly done through coarse mechanical recycling, pyrolysis (thermal recycling), or solvolysis (chemical recycling). Due to technical, economic, and ecological limitations, there is relatively little industrial-scale recycling of these materials (7), resulting in a significant portion ending up in landfills or incinerators. This leads to the main question: How can knowledge and implementation of chemical recycling contribute to the design and material transition for thermosetting composite materials used in the energy transition? After preliminary scoping, subsequent focusing on commonly used epoxy resins for wind turbine blades and hydrogen pressure vessels, and scaling up from lab-scale resin products to post-consumer materials, the following results are anticipated: Clear end-of-life strategies for newly developed and existing thermosetting composites used for the energy transition. High-quality recycling of thermosetting composites materials based on chemical recycling.
