Epoxy Adhesives

Epoxy adhesives are primarily composed of epoxy resin and curing agent. Epoxy adhesives are supplied in both one-component package and two-component package depending on curing agent used and curing method applied. Two-component epoxy adhesives are prepared by packing epoxy composition and curing agent composition separately. They cure soon after mixing the two components together. Almost all room temperature cure epoxy adhesives are supplied in two-component package. One-component epoxy adhesives are prepared and supplied by mixing all formulated components in advance including epoxy resin and curing agent. One-component epoxy adhesives usually need cure at elevated temperature and store at low temperature in a refrigerator or even freezer. Epoxy adhesives have been widely used as typical reactive adhesives for various applications ranging from general industry, construction, electronics assembly, automobile production to aerospace market. Typical room temperature cure epoxy adhesives, thermal cure epoxy adhesives and UV cure epoxy adhesives are introduced in detail

UV and Thermal Cure Epoxy Adhesives

Typical commercial UV and thermal cure epoxy adhesives have been reviewed and compared. UV cure cationic epoxy adhesives are primarily composed of cycloaliphatic epoxy resin and cationic photoinitiator. UV cationic epoxy adhesives have no surface cure issue and possess low cure shrinkage and good adhesion performance but need post-thermal cure to achieve full adhesion performance in use. Hybrid UV acrylate and thermal cure epoxy adhesives are primarily composed of acrylate monomer, free radical photoinitiator, epoxy resin and curing agent. The hybrid epoxy adhesives combine fast UV curability of acrylate composition and high adhesion performance of thermal cure epoxy composition. A new type initiator free hybrid one-component UV and thermal cure adhesive has been also introduced. It is mainly composed of maleimide compound, acrylic monomer, partially acrylated epoxy resin, epoxy resin and latent curing agent. Its UV cure and thermal cure behaviour have been studied by FT-IR spectroscopy measurement

Computational design of transmembrane pores.

Transmembrane channels and pores have key roles in fundamental biological processes1 and in biotechnological applications such as DNA nanopore sequencing2-4, resulting in considerable interest in the design of pore-containing proteins. Synthetic amphiphilic peptides have been found to form ion channels5,6, and there have been recent advances in de novo membrane protein design7,8 and in redesigning naturally occurring channel-containing proteins9,10. However, the de novo design of stable, well-defined transmembrane protein pores that are capable of conducting ions selectively or are large enough to enable the passage of small-molecule fluorophores remains an outstanding challenge11,12. Here we report the computational design of protein pores formed by two concentric rings of α-helices that are stable and monodisperse in both their water-soluble and their transmembrane forms. Crystal structures of the water-soluble forms of a 12-helical pore and a 16-helical pore closely match the computational design models. Patch-clamp electrophysiology experiments show that, when expressed in insect cells, the transmembrane form of the 12-helix pore enables the passage of ions across the membrane with high selectivity for potassium over sodium; ion passage is blocked by specific chemical modification at the pore entrance. When incorporated into liposomes using in vitro protein synthesis, the transmembrane form of the 16-helix pore-but not the 12-helix pore-enables the passage of biotinylated Alexa Fluor 488. A cryo-electron microscopy structure of the 16-helix transmembrane pore closely matches the design model. The ability to produce structurally and functionally well-defined transmembrane pores opens the door to the creation of designer channels and pores for a wide variety of applications

Development and Evaluation of Porous Pavement Surface Mixtures with Biobased Epoxy Asphalt Binder

Project DescriptionPorous asphalt mixture, designed with a large interconnected air void system, can be placed on pavement to reduce hydroplaning-related traffic accidents, mitigate heat-island effect, and reduce traffic noise. However, due to its thermoplastic and high porosity nature, the material generally has low durability in the field. This research project aimed to improve the durability, strength, and sustainability of porous asphalt mixture by formulating bio-based epoxy asphalt binder (BEAB) and improving its mixture design. In the study, a BEAB formula was firstly developed through a uniform experimental design. Then, the performance of porous asphalt mixture containing BEAB was tested and evaluated along with traditional porous asphalt mixture. Finally, a simple ranking approach was introduced to improve the current mixture design approach. Based on laboratory test results and analysis, the optimum BEAB formula was identified as 7% epoxidized soybean oil (ESBO), 5% maleic anhydride (MA), and 88% base asphalt (PG 67-22). In practice, to achieve balanced pavement performance for water permeability, mixture durability, strength, and cracking resistance, a 4.75-mm nominal maximum aggregate size (NMAS) open gradation with an optimum BEAB content is recommended. The developed BEAB-based porous asphalt mixture may promote the applications of porous asphalt pavement (“green pavement”) and open-graded friction course (OGFC) in more community health related scenarios.U.S. Department of Transportation 69A355174711

Pavement Rehabilitation Policy for Reduced Life-Cycle Cost and Environmental Impact Based on Multiple Pavement Performance Measures

Final ReportHighway pavement is a critical component of the highway transportation infrastructure. After the construction of a pavement system, pavement condition will deteriorate over time due to a combination effect of material aging, traffic loading, and environmental factors. As pavement condition deteriorates, vehicle operating costs and their corresponding environmental impacts would increase significantly. To restore the pavement performance and to reduce its adverse effects on public users and environment, asphalt overlay activities are conducted frequently during the service life of a pavement. Meanwhile, asphalt overlay itself consumes large amounts of energy and natural resources. The purpose of this research is to guide highway agencies to optimize flexible pavement overlay strategies using the integrated cycle assessment (LCA) - life cycle cost analysis (LCCA) approach. In the study, a post-overlay pavement roughness progression model in terms of international roughness index (IRI) is firstly developed to evaluate the effect of asphalt overlay design factors on pavement roughness progression. Then, by incorporating the proposed post-overlay IRI model in the integrated LCA-LCCA framework, the life cycle environmental and economic impacts of different overlay strategies are evaluated. Finally, a multi-objective optimization framework is proposed for identifying the eco-friendly and cost-effective asphalt overlay strategy. Based on the comparative analysis results, the inclusion of 30% reclaimed asphalt pavement (RAP) in asphalt overlay is found to reduce life cycle energy consumption, greenhouse gas (GHG) emissions, criteria air pollutants, and life cycle costs. For asphalt overlay projects, pavement surface roughness effects, construction activity, and material production are three major contributors to life cycle energy consumption and GHG emissions. The usage phase vehicle operating costs and agency costs are two dominant factors in the LCCA of different asphalt overlay strategies. Based on a sensitivity analysis, traffic level and IRI trigger value for asphalt overlay have a significant effect on the life cycle environmental and economic sustainability of overlaid pavements.U.S. Department of Transportation 69A355174711

Development and Evaluation of Porous Pavement Surface Mixtures with Bio-based Epoxy Asphalt Binder

Final ReportPorous asphalt mixture, as one type of pavement surface materials, is designed intentionally to leave a large interconnected airvoid system in the mixture. It can be placed on pavement to reduce hydroplaning-related traffic accidents, mitigate heat-islandeffect, and reduce traffic noise. However, due to its thermoplastic and high porosity nature, porous asphalt mixture generallyhas low durability in the field. This study aims to improve the durability, strength, and sustainability of porous asphalt mixtureby formulating bio-based epoxy asphalt binder (BEAB) and improving its mixture design. In the study, a BEAB formula wasfirstly developed through a uniform experimental design. Then, the performance of porous asphalt mixture containing BEABwas tested and evaluated along with traditional porous asphalt mixture. Finally, a simple ranking approach was introduced toimprove the current mixture design approach. Based on laboratory test results and analysis, the optimum BEAB formula wasidentified as 7% epoxidized soybean oil (ESBO), 5% maleic anhydride (MA), and 88% base asphalt (PG 67-22). Compared tothe base asphalt, the formulated BEAB may improve the strength, durability, and environmental sustainability of porousasphalt mixture without reducing its permeability and cracking resistance. In practice, to achieve balanced pavementperformance for water permeability, mixture durability, strength, and cracking resistance, a 4.75-mm nominal maximumaggregate size (NMAS) open gradation with an optimum BEAB content is recommended. The developed BEAB-based porousasphalt mixture would promote the applications of porous asphalt pavement (“green pavement”) and open-graded frictioncourse (OGFC) in more community health related scenarios.U.S. Department of Transportation 69A355174711

A Study on the Design of Vision Protection Products Based on Children’s Visual Fatigue under Online Learning Scenarios

The rate of myopia in children is increasing rapidly under online learning scenarios. One of the important reasons for this is incorrect reading and writing posture. Three screen view parameters (viewing angle, viewing height, and viewing distance) are selected as significant influencing factors and blink rating is used as a sign of visual fatigue through literature analysis to study the influence factors of myopia in children, and their correlation. Children’s visual fatigue is evaluated by subjective evaluation and is recording using an eye tracker for changes in the three factors through online learning scenario simulation experiment. An optimal regression model is constructed that illustrates the relationship between the three variables and the visual fatigue levels. The aim of this study is to confirm the quantitative relationship between the screen view parameters and visual fatigue, and to design a child vision protection product on this basis. The test results show there is a linear positive correlation between the viewing angle, viewing height, and viewing distance. A vision protection device has been designed based on this model and was verified through function prototype testing. The result of this study quantified the relationship among screen view parameters and children’s visual fatigue, which provides a theoretical basis for the design of a children’s visual protection device

A Study on the Design of Vision Protection Products Based on Children’s Visual Fatigue under Online Learning Scenarios

The rate of myopia in children is increasing rapidly under online learning scenarios. One of the important reasons for this is incorrect reading and writing posture. Three screen view parameters (viewing angle, viewing height, and viewing distance) are selected as significant influencing factors and blink rating is used as a sign of visual fatigue through literature analysis to study the influence factors of myopia in children, and their correlation. Children’s visual fatigue is evaluated by subjective evaluation and is recording using an eye tracker for changes in the three factors through online learning scenario simulation experiment. An optimal regression model is constructed that illustrates the relationship between the three variables and the visual fatigue levels. The aim of this study is to confirm the quantitative relationship between the screen view parameters and visual fatigue, and to design a child vision protection product on this basis. The test results show there is a linear positive correlation between the viewing angle, viewing height, and viewing distance. A vision protection device has been designed based on this model and was verified through function prototype testing. The result of this study quantified the relationship among screen view parameters and children’s visual fatigue, which provides a theoretical basis for the design of a children’s visual protection device