Papers by Keyword: Resin

Abstract: Injection molding tools are characterized by high costs, due to the use of expensive materials such as aluminum or tool steel, and the lengthy production process involving machining. This greatly limits the economic viability of using metal molds for producing small series, and even more so for rapid prototyping. Additive manufacturing processes, such as masked stereolithography (mSLA), enable the production of molds from polymers providing short production time and good accuracy. However, injection molds manufactured using mSLA using conventional resins suffer from long cooling times and lower strength. This contribution presents a new approach that significantly overcomes these disadvantages by developing and characterizing a novel composite material. To this end, aluminum oxide ceramic particles will be incorporated into a photopolymer resin. Various additives will also be employed to optimize the processability and printability of the newly developed material. This should enhance the thermal and mechanical properties of additively manufactured molds. A series of simple test specimens were produced using mSLA. Sedimentation and printability were analyzed by varying the aluminum oxide mixing ratio. The effect of various additives was also investigated. The composite materials were tested for processability, heat flow and mechanical properties. Scanning electron microscopy (SEM) was used to evaluate the particle size, quantity, distribution and homogeneity of the composite material. To demonstrate the application of the new material in additive tooling, a typical set of tool inserts for injection molding was manufactured.

Abstract: Nowadays, the application of protective coatings based on polymer materials is a widespread method of protecting products and parts of water transport from the effects of various environments and is used to increase their service life after repair and restoration work. Application as a base for polymer composite materials based on epoxy resins is considered relevant. To improve the adhesive and mechanical characteristics of polymer composites, their physical and chemical modification was carried out. In particular, it is promising from a practical point of view to introduce into the epoxy resin a microdispersed filler of synthesized aluminum-copper charge (SACC) with a negligible content. It was established that in order to obtain protective coatings or products for increasing the resource of water transport with increased indicators of adhesive and cohesive characteristics, it is necessary to form a composite with the following number of ingredients: epoxy oligomer – 100% by mass; hardener PEPA – 10% by mass; microdisperse filler synthesized aluminum-copper charge – 2 % by mass. The mechanism of activation of interphase interaction during crosslinking of materials due to the formation of chemical bonds between side groups and segments of the epoxy oligomer and active centers on the surface of particles, such as Al+, Cu+, CuAl2 and Al4C3 is substantiated. It is shown that the adhesive-cohesive properties of materials depend mainly on the volume of the boundary surface layers that are formed around the filler particles during the polymerization of composites. The density of such layers differs from the density of the initial ingredients - polymer and filler and is determined by the following criteria: the level of wetting of the dispersed particles with a low-viscosity Newtonian oligomer, their dispersion and specific surface area, the presence of active centers on the surface. A model of the formation of epoxy composites in the presence of a dispersed filler is proposed. The model assumes the gradual formation of boundary surface layers around filler particles. In particular, it is shown the possibility of forming a network structure of a polymer with supramolecular globular inclusions in a polymer system without a filler, as well as successive stages of structure formation of composites in the presence of a filler.

Abstract: Triply periodic minimal surface (TPMS) represents a class of porous architectures characterized with continuous curved surface and periodic repetition, demonstrating significant potential for industrial applications requiring high specific surface area. In this work, a Gyroid-type TPMS sheet has been designed and manufactured with acrylonitrile butadiene styrene (ABS) resin via stereolithography 3D printing. The printed surface microstructure was characterized by scanning electron microscopy to evaluate the printing accuracy. Both the quasi-static compression test as well as the numeric finite element analysis were performed to study the mechanical response. Compared with the strut-based Re-entrant lattice, the Gyroid TPMS demonstrated a superior combination of high load-bearing and energy-absorption properties. Comparative analysis of compressive load-displacement curves and cracking behaviors elucidated the distinct deformation mechanisms between TPMS and Re-entrant structures. To validate the practical applicability, a prototype helmet liner with Gyroid TPMS structure was successfully manufactured with ABS resin using the studied printing procedures. These findings substantiate the promising implementation potential of TPMS structures in lightweight engineering and impact protection systems requiring synergistic mechanical performance.

Abstract: PMMA resin has been commonly used for fabricating surgical obturators. However, the surface roughness and porosity of the resin can cause microbial aggregation and biofilm formation, leading to potential complications for the patients. Recent progress in antimicrobial strategies for PMMA resin has been reported. It was shown that incorporating vanillin into PMMA resin inhibited biofilm formation by bacteria and yeasts. However, the effect on other properties of the resin has not been studied. The aim of this study was to evaluate the mechanical properties of PMMA resin with 0.1% and 0.5% vanillin incorporation, including flexural strength, flexural modulus, and surface hardness, compared to a control group. All tests were performed according to ISO 20795-2:2013. For flexural strength and modulus, specimens are tested using a three-point bending machine. A Vickers hardness apparatus was used for the surface hardness test. Data on both surface hardness and flexural modulus were statistically analyzed by one-way ANOVA and Turkey’s multiple comparison test. Those of flexural strength were statistically analyzed by the Welch and Dunnett T3 Test with a significance level of 0.05. Results indicated that increasing the amount of vanillin incorporation decreased flexural strength, modulus, and surface hardness. Nevertheless, flexural strength and modulus were still within ISO standards. In conclusion, the incorporation of vanillin into PMMA resin could affect its mechanical properties. However, the application of this resin in a clinical setting could possibly be done due to its standardized flexural strength and modulus.

Abstract: Resin is a compounding ingredient that can be used in tire treads to improve (wet) grip resistance. Increasing tan delta in the temperature range between 0°C and 20°C is important to improve (wet) grip resistance. To understand the behavior of resins and determine which resin is best suitable to improve traction in SBR/BR blends, the solubility of polyterpene and α-methyl styrene resin in SBR-BR blends is investigated. The method for measuring the solubility of resin in SBR/BR blends at a 70/30 weight ratio was developed. The solubility parameters (δ) were calculated based on the group contribution method, and the Δδ values between resins and rubbers were correlated with the weight increase of lightly crosslinked SBR/BR blends at different temperatures. A smaller Δδ means higher solubility of the resin in the rubber, which is confirmed by the high level of resin uptake in the rubber. Based on the research, it was found that molecular weight, polarity, and temperature, are factors, which influence the solubility of resins into the rubber. In addition, based on the DMA measurements, SBR/BR (Ni-cat) containing polyterpene shows a higher tan delta at 0 – 20°C compared to SBR/BR (Nd-cat) containing polyterpene. This fact indicates that a correct selection between the type of rubber and resin is important depending on the requirement needed.

Abstract: Space traveling, extra-planetary exploration and even colonization requires to replicate our capabilities of manufacturing under non-entirely known environments and conditions. With the recent, yet always present, interest on colonizing spaces like the Moon or even Mars, space-based Additive Manufacturing (AM) has been considered for enabling space inhabitants to build their own tools. However, the same manufacturing techniques that are commonly used on Earth are not entirely applicable in space, especially during the considerably long traveling stage. Thus, several works have reported the study of how AM could be used in microgravity or near-zero g conditions by using the International Space Station as a laboratory. Unfortunately, the costs for doing such experiments are prohibitive, which is why experimentation in microgravity conditions on Earth is promising. In this paper, we explore the possibility of applying light-sensitive resin under Microgravity conditions using a Drop Tower facility and we propose a microgravity liquid printing technique. Our preliminary experiments focused on studying movement and extrusion velocities, extrusion nozzle diameter, UV light power, extrusion, and solidification times. The experimental runs (one catapult launch and four drops) let us find promising, although not entirely conclusive, data and practices to be considered in future works using this methodology. As expected, there is a similarity to liquid extrusion on Earth given that the initial shape and speed of extrusion influences the liquid material. Our findings also suggest that an initial contact point would help to increase the contact force due to surface tension and that the extrusion and solidification times are less than 5 seconds, which implies faster printing processes than in earth gravity conditions because the microgravity provides us less layer mixing during extrusion. The hardware, material and Microgravity drop tests used confirm the feasibility of this technique and they become an initial step for this printing process and liquid materials.

Abstract: Today the prepreg technology for the manufacture of products from polymer composite materials is widely used in the global industry. This technology involves the use of prepregs obtained by preliminary impregnation of the reinforcing materials with binder solutions, which contain up to 50% environmentally sensitive and fire hazardous solvents. However, in many cases no systematic approach is used to solve the issues of choosing the optimal values of the solvent content in the binder solution to ensure its specified viscosity according, as well as the issues of safety of the industrial activity; instead, these issues are solved independently. It results in the unreasonable expense, loss of quality of the composite products and insufficient level of safety of production activity at the relevant workplaces. This study deals with the systematic prediction of the process parameters, taking into consideration the safety of operational procedures during the impregnation of prepregs and permissible range of deviations from their regulated value. The method and the relevant implementing technique for the prediction of optimal process parameters of the binder solutions for impregnation of prepregs in view of safety of the production activity have been developed. Dependences of the viscosity of the binder on its temperature and volume content of one-component, binary and three-component solvents have been obtained, with the tolerance band specified for the volume and weight contents of the solvent in the binder, which provides an acceptable deviation in the solution viscosity for the effective impregnation of prepreg. The paper proposes and substantiates the criterion of content of the binary solvent in the binder being optimal one in terms of process conditions. This criterion provides both the specified quality of impregnation of the reinforcing material and requirements for the safety of production activity. The actual hands-on examples are considered as related to the determination of optimal content of the binary solvent with the components for the specific binder and alcohol-acetone solvent. It is shown that the optimal weight concentration of acetone in the solvent is 0.085, with the solvent weight content in the mixture of 0.279. These parameters provide the maximum allowable concentration of solvent vapors, ensuring the safety of production activity. It should also be noted, that the solvent weight content differs by maximum 5% from the value required when using alcohol only, which provides high safety margin of the production activity.

Abstract: Orthodontic appliance made of resin is one of the main factors involving the shift of oral microbial community towards the source of pathogens by providing an extra site for adhesion and attachment of microorganisms to form biofilm associated with infections of multiple organs including respiratory tract. As a result, there is a demand for seeking of oral appliances with antimicrobial properties to reduce the risk of these infections. Here, vanillin (a principal flavoring agent with its antimicrobial property) has been incorporated to orthodontic resin and investigated the effect on biofilm formation of respiratory pathogens. The self-curing PMMA orthodontic resin samples (Siam Cement Group, Thailand) were fabricated depending on the percentage of vanillin adding (0.1% and 0.5% w/w vanillin). Resin without vanillin was used as a control. All samples were coated with sterile saliva collected from healthy volunteers. The bacterial biofilm formation assay was done by adding suspension (10⁷ colony forming unit/mL) of Staphylococcus aureus ATCC 5638, Staphylococcus epidermidis ATCC 14990, Streptococcus pneumoniae ATCC 49619, and Pseudomonas aeruginosa ATCC 27853 to the samples and incubated in shaking incubator (120 r/min) for 120 min at 37 °C to allow the adhesion of the bacteria. Afterwards, non-adherent bacterial cells were washed out and Brain Heart Infusion broth was added and further incubated for 24 h to enable the biofilm formation. The amount of vital biofilm was quantified by Cell Counting Kit WST-8 (Dojindo Molecular Technologies, USA). It was found that the inclusion of vanillin to resin decreased the biofilm formation of S. aureus, S. epidermidis, and P. aeruginosa whereas no effect was observed on S. pneumoniae. Both the 0.1% and 0.5% vanillin concentrations could significantly inhibit the biofilm of S. aureus and P. aeruginosa whereas only 0.5% vanillin showed the inhibitory effect on S. epidermidis. Up to 40% biofilm reduction was noticed with S. epidermidis and P. aeruginosa while that of S. aureus was about 30%. In conclusion, the present data demonstrate that the development of orthodontic PMMA resin incorporated with vanillin may be a possible candidate for fabricating of oral appliance with antimicrobial property against respiratory pathogens. This suggests that it could be useful for the prevention or management of respiratory infection related to bacterial biofilm formed on oral appliances.

Abstract: Now a days environment is getting polluted due to different types of manmade reasons than ever for extreme use of synthetic materials. Various kinds of waste materials from numerous industries are also enhancing this. So, Utilization of waste materials and reduction of synthetic materials will definitely subside the environmental pollution. In this research, waste jute fabric and leather waste (cow hides) were used as reinforcing agent and unsaturated polyester resin (UPR) as matrix to prepare environmental friendly composite materials. Hand-lay up method was conducted to fabricate composite materials. Different percentages of waste leather and used jute fabrics were used with the UPR. Improved mechanical properties, tensile strength (TS), tensile modulus (TM), and percentage elongation at break (EB) were observed with the certain percentage of waste materials. Composites were also characterised by the scanning electron microscope (SEM) and fourier transform infrared (FTIR).

Abstract: In the present work, composite materials with a two wastes - waste goose feather as a filler and resinous waste from HMF production as a binder - have been developed. The mechanical properties and water sorption in dependence with feather/HMF resin composite content were studied. The composites containing 50% of feather have high strength properties up to 46 N/mm² and low water sorption (lower 1%), which results in high water resistance. Due to these properties, they can become an excellent alternative to urea-formaldehyde resins and plastics based on them.