scholarly journals Self-Assembly of Amphiphilic Linear−Dendritic Carbosilane Block Surfactant for Waterborne Polyurethane Coating

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1318 ◽  
Author(s):  
Ruitao Wang ◽  
Chunxiang Li ◽  
Zhaohua Jiang ◽  
Zhijiang Wang
Keyword(s):  
Self Assembly ◽  
High Speed ◽  
Large Scale ◽  
Side Reaction ◽  
Waterborne Polyurethane ◽  
Technical Solution ◽  
Polyurethane Coating ◽  
Complete Replacement ◽  
Two Component ◽  
Undesirable Side Reaction

The traditional two-component waterborne polyurethane coating system cannot effectively inhibit the undesirable side reaction between polyisocyanate and water during curing hardening. It is difficult to avoid the microbubbles formed by this reaction during the film formation process, which severely degrades the appearance and decreases the performance of the film. Therefore, the addition of an amphiphilic Linear-Dendritic carbosilane Block Surfactant (LDBS) to the hardener can physically separate the polyisocyanate emulsion from water through self-assembly. The bubble-free film thickness (BFFT) of the two-component waterborne polyurethane coating in this study is approximately 1.5-fold greater than commercial waterborne polyurethane coatings in today’s coating industry. Fourier transform infrared spectroscopy (FT-IR) varied the effectiveness of LDBS for inhibition of the undesirable side reaction. The successful application of the waterborne polyurethane coating with LDBS on the 600 km/h high-speed maglev train provides a technical solution for large-scale industrialization of waterborne polyurethane coating and complete replacement of solvent polyurethane coating.

scholarly journals Study of the Effect of PGDA Solvent on Film Formation and Curing Process of Two-Component Waterborne Polyurethane Coatings by FTIR Tracking

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 461 ◽  
Author(s):  
Ruitao Wang ◽  
Chunxiang Li ◽  
Zhigang Liu ◽  
Zhongping Yao ◽  
Zhijiang Wang ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Film Formation ◽  
Waterborne Polyurethane ◽  
Hydroxyl Groups ◽  
Curing Process ◽  
Polyurethane Coating ◽  
Polyurethane Coatings ◽  
Rate Of Reaction ◽  
Two Component

Waterborne polyurethane coatings were prepared using polyhydroxyacrylate dispersion, polyisocyanate, and propylene glycol diacetate (PGDA). The rate of reaction between hydroxyl and NCO groups in film formation and curing processes was studied by FTIR. The influence of PGDA amount on film formation and curing was also studied. Results showed that PGDA content had a significant effect on the curing process. With less than 10% PGDA, the role of PGDA was more to assist diffusion of polyhydroxyacrylate and polyisocyanate resin droplets. This promoted the reaction between hydroxyl groups and NCO. With more than 10% PGDA, its effect as a solvent was more and it inhibited the reaction between hydroxyl and NCO groups. When the amount of PGDA was about 10%, the synergy between both the roles promoted the crosslinking and curing reactions. The extent of the curing reaction of NCO was more than 70% in 4 h, which was significantly higher, compared with that of about 30% without PGDA. The good applicability and appearance of the waterborne polyurethane coating prepared in this study were verified for the application to carbon fiber metro vehicles.

scholarly journals A large-scale image dataset of wood surface defects for automated vision-based quality control processes

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 581
Author(s):  
Pavel Kodytek ◽  
Alexandra Bodzas ◽  
Petr Bilik
Keyword(s):  
Quality Control ◽  
High Speed ◽  
Large Scale ◽  
Surface Defects ◽  
Recognition Rate ◽  
Raw Material ◽  
Technical Solution ◽  
Control Processes ◽  
Wide Range ◽  
Authentic Data

The wood industry is facing many challenges. The high variability of raw material and the complexity of manufacturing processes results in a wide range of visible structure defects, which have to be controlled by trained specialists. These manual processes are not only tedious and biased, but also less effective. To overcome the drawbacks of the manual quality control processes, several automated vision-based systems have been proposed. Even though some conducted studies achieved a higher recognition rate than trained experts, researchers have to deal with a lack of large-scale databases and authentic data in this field. To address this issue, we performed a data acquisition experiment set in the industrial environment, where we were able to acquire an extensive set of authentic data from a production line. For this purpose, we designed and implemented a complex technical solution suitable for high-speed acquisition during harsh manufacturing conditions. In this data note, we present a large-scale dataset of high-resolution sawn timber surface images containing more than 43 000 labelled surface defects and covering 10 types of the most common wood defects. Moreover, with each image record, we provide two types of labels allowing researchers to perform semantic segmentation, as well as defect classification, and localization.

scholarly journals Effect of resins on the salt spray resistance and wet adhesion of two component waterborne polyurethane coating

e-Polymers ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 444-452 ◽  
Author(s):  
Qianwei Xu ◽  
Qingli Lu ◽  
Steven Zhu ◽  
Robin Pang ◽  
Wanwen Shan
Keyword(s):  
Salt Spray ◽  
Waterborne Polyurethane ◽  
Ir Absorption ◽  
Polyurethane Coating ◽  
Crosslinking Degree ◽  
Wet Adhesion ◽  
Two Component ◽  
Ft Ir ◽  
Level 1 ◽  
The Relationship

AbstractEffects of the type, chemical structure and NCO/OH of resins on wet adhesion and salt spray resistance of two component waterborne polyurethane coating were studied in this paper. The content of functional groups in resins and films were analysed by areas of their FT-IR absorption peak to study the relationship with anticorrosive performance of coatings. Coatings based on resins with more -OH tend to have stronger wet adhesion and salt spray resistance because resins with more -OH have more possibilities to react with -NCO to form a compact film with a higher crosslinking degree. The wet adhesion of coatings after 8 h of immersion deteriorated from level 1 to level 5 with the increase of NCO/OH due to the decrease of -OH in coatings to link with substrates. And excess -NCO tend to react with H2O to generate CO2 to form cracked physical bubbles, which would weaken the wet adhesion.

scholarly journals Study of the catalytic selectivity of an aqueous two-component polyurethane system by ftir spectroscopy

2003 ◽  
Vol 57 (11) ◽  
pp. 559-562 ◽  
Author(s):  
Jakov Stamenkovic ◽  
Suzana Cakic ◽  
Goran Nikolic
Keyword(s):  
Aquatic Toxicity ◽  
General Rule ◽  
Side Reaction ◽  
Waterborne Polyurethane ◽  
Organotin Compounds ◽  
Dibutyltin Dilaurate ◽  
Hydroxyl Groups ◽  
Tin Compounds ◽  
Water Side ◽  
Two Component

The difficulty in formulating a two component waterborne polyurethane, is the isocyanate-water side reaction, which can lead to gassing/foaming, loss of isocyanate functionality, low gloss and a reduced pot life. To compensate for this side reaction, these formulations usually contain a large excess of isocyanate. Tin compounds, especially dibutyltin dilaurate, are widely used in coatings as catalysts for the isocyanate/hydroxyl reaction. Because of the high aquatic toxicity of some organotin compounds, there has been an attempt to ban organotin compounds from all coating applications. As a general rule, organotin catalysts are not selective, they catalyze the reaction of isocyanates with both hydroxyl groups and water and also catalyze the hydrolysis of ester groups. One novel approach to control the water side reaction is the use of catalysts which selectively catalyze the isocyanate-polyol reaction and not the isocyanate-water reaction. The selectivity of a variety of metal catalysts (metal octoates, metal acetylacetonates and mangan chelates with mixed ligands) to catalyze the preferred reaction was measured using the FTIR method.

Growing Large Nanostructured Superlattices by Sequential Activation of Self-Assembly

2011 ◽  
Author(s):  
Zhouzhou Zhao ◽  
Wei Lu
Keyword(s):  
Self Assembly ◽  
High Speed ◽  
Large Scale ◽  
Average Concentration ◽  
Two Dimensional ◽  
Scanning Velocity ◽  
Bistable State ◽  
Sequential Activation ◽  
Dimensional Growth ◽  
Previous Step

We propose a mechanism to grow a large superlattice of phase domains from a continuum homogenous binary film by sequential activation of self-assembly. Self-assembly was initiated in a small mobile region, where atoms could diffuse, to form a seed pattern, Then the mobile region was shifted gradually. This process led to the formation of a long-rang ordered superlattice, regardless whether the seed was perfect or not. The pattern quickly improved to a perfect superlattice along with the sequential activation. We found that the scanning velocity can effectively control the domain pattern when the system is in a bistable state, which refers to a window of average concentration where two different superlattices can both stabilize. We demonstrated two schemes for large-scale high speed fabrication: alternation between scanning directions, using the superlattice created in each previous step as a large seed; and two dimensional growth.

Do elite soccer players cover longer distance when losing? Differences between attackers and defenders

2020 ◽  
pp. 174795412098227
Author(s):  
Carlos Lago-Peñas ◽  
Anton Kalén ◽  
Miguel Lorenzo-Martinez ◽  
Roberto López-Del Campo ◽  
Ricardo Resta ◽  
...  
Keyword(s):  
New York ◽  
High Speed ◽  
Large Scale ◽  
Tracking System ◽  
Soccer Players ◽  
Running Performance ◽  
Situational Variables ◽  
Total Distance ◽  
Professional Soccer ◽  
Score Line

This study aimed to evaluate the effects playing position, match location (home or away), quality of opposition (strong or weak), effective playing time (total time minus stoppages), and score-line on physical match performance in professional soccer players using a large-scale analysis. A total of 10,739 individual match observations of outfield players competing in the Spanish La Liga during the 2018–2019 season were recorded using a computerized tracking system (TRACAB, Chyronhego, New York, USA). The players were classified into five positions (central defenders, players = 94; external defenders, players = 82; central midfielders, players = 101; external midfielders, players = 72; and forwards, players = 67) and the following match running performance categories were considered: total distance covered, low-speed running (LSR) distance (0–14 km · h−1), medium-speed running (MSR) distance (14–21 km · h−1), high-speed running (HSR) distance (>21 km · h−1), very HSR (VHSR) distance (21–24 km · h−1), sprint distance (>24 km · h−1) Overall, match running performance was highly dependent on situational variables, especially the score-line condition (winning, drawing, losing). Moreover, the score-line affected players running performance differently depending on their playing position. Losing status increased the total distance and the distance covered at MSR, HSR, VHSR and Sprint by defenders, while attacking players showed the opposite trend. These findings may help coaches and managers to better understand the effects of situational variables on physical performance in La Liga and could be used to develop a model for predicting the physical activity profile in competition.

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