Polishing Performance of a Recycled Grinding Wheel Using Grinding Wheel Scraps for the Wet Polishing of Stainless-Steel Sheets

The surfaces of large austenitic stainless-steel sheets, which have side lengths of at least 1 m a sheet thickness of at least 6 mm, used for food tanks and sliding plates in seismic isolation devices, must be finished to a mirror surface. Polishing is performed to improve the surface quality of such sheets and dry machining is typically applied. The problems associated with dry machining are the exhaust heat of machining and treatment of chips. A transition to wet machining is required to solve these problems. In our laboratory, we have developed a wet polishing machine and researched the selection of grinding wheels to develop wet polishing technology for large stainless-steel sheets. In this study, to reduce tool cost and reuse resources, we attempted to manufacture a recycled grinding wheel using snippets of grinding wheel scraps. A polyvinyl alcohol (PVA) aqueous solution was used as the bonding agent for the recycled grinding wheel to reduce environmental load. To overcome the ease of dissolution of PVA in water, we attempted to improve the water resistance of the PVA aqueous solution by incorporating an organic titanium compound. This is one of our efforts to contribute to sustainable development goals. The results are summarized below. (1) A recycled grinding wheel was fabricated by kneading crushed pieces of grinding wheel scrap with a bonding agent. (2) The maintenance of the shape of the recycled grinding wheel was controlled by the concentration of the bonding agent. (3) The recycled grinding wheel with a PVA bonding agent was vulnerable to water. In contrast, the recycled grinding wheel to which the organic titanium compound was added exhibited improved water resistance. (4) The polishing of stainless-steel sheets using the plain PVA recycled wheel was relatively ineffective, but polishing using the recycled wheel with the titanium additive was comparable to polishing with a new grinding wheel.

Research on the Synthesis and Performance of a New Type of Neutral Polymer Bonding Agent

In order to improve the mechanical properties of nitrate ester plasticized polyether (NEPE) propellants, 3-allylic hydantoin was synthesized by hydantoin, potassium hydroxide and 3-bromopropene, and then a new type of intermediate polymer bonding agent (NPBA) was synthesized by 3-allylic hydantoin, acrylonitrile, hydroxyethyl acrylate and dimethylaminoethyl methacrylate. At the same time, two traditional neutral polymer bonding agents were synthesized for comparative study. Through the contact angle test, the bond performance prediction shows that: compared with the two traditional bond agents, the bond work between the new bond agent and oxidant (ammonium nitrate, ammonium perchlorate) is greater, indicating that the bond between the new bond agent and oxidant is stronger.

Evaluation of Polymer Modified Mortar and Bonding Agent for Structural Repair

Polymer modified mortar is found to be suitable for structural repair and strengthening of damage structural elements. Conventional mortar is not preferred in repair of concrete since it has inferior mechanical property and durability performance. Polymer based mortar is an alternative to conventional mortar with enhanced mechanical properties. However, there are limited specifications and guidelines available for specifying PMM mixes for structural repair work. The research work aims to evaluate the mechanical performance of polymer based mortar with varying concentration of styrene butadiene rubber latex at laboratory scale. Another aspect in repair of corrosion damage structures is the bond between the substrate concrete and repair mortar. In order to study the effectiveness of bonding agents, the performance evaluation of bonding agents has been evaluated using slant shear test and pull-off test as per ASTM C 882 and EN 1542 respectively. Findings of study indicates that at 8-10 percent concentration of dry polymer solid by cement mass in polymer based mortar is the optimum dosage. Styrene-butadiene rubber based polymer mortar showed improvement in flow in comparison to normal mortar however, mixes with crushed sand shows decrease in flow which is due to presence of more fines. Slant shear and pull-off test method shows epoxy bonding agent give better bond strength as compared to SBR latex.

Impact of Various Cross Linking Agents on Dentin Adhesive Systems - an In-vitro Study

Aims and Objectives: The main aim of this study is to compare and evaluate the shear bond strength of composite resin using a total etch adhesive and self-etch adhesive after treatment with different collagen cross-linking agents. Materials and Methods: Forty freshly extracted human maxillary central incisors were taken. The proximal dentin was exposed, cavities were prepared on mesial and distal of each tooth. The specimens were randomly divided into two groups based on bonding agent applied-Group A and Group B i.e universal bonding agent and all in one bonding agent respectively and are subdivided into four groups based on the surface treatment of dentin. Group I A (n=10) Control-total etch(CTE); Group II A (n=10) Sodium Ascorbate-total etch (STE); Group III A (n=10)- Proanthocyanidin total etch(PTE); Group IV A (n=10)- Chitosan total etch (CHTE); Group I B (n=10) Control-self etch (CSE); Group II B (n=10) Sodium Ascorbate-self etch(SSE); Group III B (n=10)- Proanthocyanidin self-etch (PSE); and Group IV B (n=10) - Chitosan self-etch (CHSE). Shear bond strength of the specimens are tested with universal testing machine, and the data was statistically analysed with one way ANOVA. Results: Significantly higher shear bond strength to dentin was observed in teeth treated with 6.5% Proanthocyanidin Total etch, 10% Sodium Ascorbate Total etch and 1% Chitosan acetate compared to the control group. No significant difference was seen with self-etch treated groups. Conclusion: Dentin surface pretreatment with 6.5% Proanthocyanidin, 10% Sodium Ascorbate and 1% Chitosan acetate results in significant enhancement in bond strength of composite resin to deep dentin.

Facile fabrication of low-cost activated carbon bonded polyethersulfone membrane for efficient bacteria and turbidity removal

The current research aimed to fabricate a cost-effective activated carbon disc for the bacteria and turbidity removal in contaminated water using polyethersulfone membrane solution as a bonding agent. The mixing compatibility and bonding stability of the blend activated carbon disc were studied with a bonding strength test. The morphology of activated carbon discs was studied by a microscope. The activated carbon discs had a thick dense layer between the powder. Activated carbon discs significantly removed the total coliforms populations (99%) when evaluated against river water whilst removal by the powder was only up to 90%. The turbidity removal efficiency for the activated carbon increased from 29%-79% with the utilization of membrane as the bonding agent in forming the disc. However, the pH of water treated by the activated carbon powder and disc did not change significantly, yet it lied within the pH range of safe drinking water (6.5–7.7). It revealed the important role of PES membranes for the activated carbon discs to improve coliform and turbidity removal in the water, ensuring the quality of water resources.

Assessment of Wettability and Contact Angle of Bonding Agent with Enamel Surface Etched by Five Commercially Available Etchants: An In Vitro Study

Background. The quantity and quality of the etching pattern produced by acids play a significant role in the wettability and contact angle of the adhesive with the enamel surface in orthodontics. The better the etch pattern, the more the surface energy of the enamel, better the penetration of the adhesive, which ultimately results in better bond strength. The present study aimed to evaluate the contact angle of the bonding agent with the enamel surface etched by five commercially available etchants and check if any difference existed between the five. Materials and Methods. Twenty-five human maxillary and mandibular central incisors and premolars extracted for orthodontic or dental purposes were used in this study as samples. The teeth were allocated into five groups based upon the etchant used to etch the enamel surface. After the samples were etched, a hard tissue microtome was used to create thin slices of the enamel surface. The samples were then exposed to bonding agent Ormco Enlight. The bonding agent was released in the form of droplets onto the enamel slices mounted on a contact angle goniometer. The contact angle values were tabulated, and statistical analysis using the one-way ANOVA test was carried out. Results. The contact angle measurements of the etchant group, DPI, were the lowest, while D-tech has the highest contact angle values. However, statistical analysis revealed no statistically significant difference between the contact angle measurements of the five groups included in the study. Conclusion. No statistically significant difference existed between the five etchant groups included in the study. However, commercially available etchant DPI showed lesser contact angle and thus better wettability in comparison to other groups. Further elemental analysis and surface analysis are required to validate these results.