Aybroad

Aybroad

According to the economic model forecast released by "Bloomberg" on Monday (17th), the probability of the U.S. economy falling into recession in the next 12 months has reached 100%.

In the long list of everyday products that are getting a ‘green’ makeover, shoes are currently a hot topic in the fashion world. You can now minimize your carbon footprint with your literal footprints wearing shoes made from eco-friendly materials.

The International Monetary Fund (IMF) released its latest World Economic Outlook report on Tuesday, lowering its forecast for global economic growth in 2022 to 3.2%. The report also said that due to the impact of the new crown epidemic and epidemic prevention measures, China's economy has slowed down more than expected, and the International Monetary Fund has therefore lowered its full-year growth forecast to 3.3%.

More and more public places require people to change into slippers when entering the house, but wearing a pair of shoes with others may increase the risk of mold infection, so be careful. Pharmacist Chen Jincai pointed out that the weather in Taiwan is hot and humid, and if the hygiene habits are not good, it is easy to contract tinea pedis, which is the so-called Hong Kong athlete.

Hanoi – Vietnam’s Ministry of Planning and Investment announced on the morning of May 29 that the country’s total import and export volume of goods in May 2022 is expected to reach US$62.69 billion, down 4.7% month-on-month and up 14.5% year-on-year.

Aerogel is a kind of new high tech material which can be used for clothes and boots linners.  After months development and testing work, we are now ready to supply the new aerogel shoe insoles to the worldwide partner.

In the past few months, during the outbreak of the epidemic in China, a large number of manufacturing orders were transferred to Vietnam and Southeast Asia. Many people have come to the conclusion that Vietnam has robbed China of its status as the world's factory. But a closer look at the foreign trade data of China and Vietnam may lead to another conclusion.

2022/08/23(火) 06:10

Polyurethane [material]

Polyurethane (PUR and PU) is a polymer composed of a chain of organic units joined by carbamate (urethane) links. While most polyurethanes are thermosetting polymers that do not melt when heated, thermoplastic polyurethanes are also available.

Polyurethane polymers are traditionally and most commonly formed by reacting a di- or polyisocyanate with a polyol. Both the isocyanates and polyols used to make polyurethanes contain on average two or more functional groups per molecule.

Some noteworthy recent efforts have been dedicated to minimizing the use of isocyanates to synthesize polyurethanes, because the isocyanates raise severe toxicity issues. Non-isocyanate based polyurethanes (NIPUs) have recently been developed as a new class of polyurethane polymers to mitigate health and environmental concerns.

Polyurethane products often are simply called “urethanes”, but should not be confused with ethyl carbamate, which is also called urethane. Polyurethanes neither contain nor are produced from ethyl carbamate.

Polyurethanes are used in the manufacture of flexible, high-resilience foam seating; rigid foam insulation panels; microcellular foam seals and gaskets; durable elastomeric wheels and tires (such as roller coaster and escalator wheels); automotive suspension bushings; electrical potting compounds; high performance adhesives; surface coatings and surface sealants; synthetic fibers (e.g., Spandex); carpet underlay; hard-plastic parts (e.g., for electronic instruments); hoses and skateboard wheels.

Polyurethanes are produced by mixing two or more liquid streams. The polyol stream contains catalysts, surfactants, blowing agents and so on. The two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the 'A-side' or just the 'iso'. The blend of polyols and other additives is commonly referred to as the 'B-side' or as the 'poly'. This mixture might also be called a 'resin' or 'resin blend'. In Europe the meanings for 'A-side' and 'B-side' are reversed. Resin blend additives may include chain extenders, cross linkers, surfactants, flame retardants, blowing agents, pigments, and fillers. Polyurethane can be made in a variety of densities and hardnesses by varying the isocyanate, polyol or additives.

Fully reacted polyurethane polymer is chemically inert. No exposure limits have been established in the U.S. by OSHA (Occupational Safety and Health Administration) or ACGIH (American Conference of Governmental Industrial Hygienists). It is not regulated by OSHA for carcinogenicity. Polyurethane polymer is a combustible solid and can be ignited if exposed to an open flame. Decomposition from fire can produce mainly carbon monoxide, and trace nitrogen oxides and hydrogen cyanide.

Liquid resin blends and isocyanates may contain hazardous or regulated components. Isocyanates are known skin and respiratory sensitizers. Additionally, amines, glycols, and phosphate present in spray polyurethane foams present risks.[32]

In the United States, additional health and safety information can be found through organizations such as the Polyurethane Manufacturers Association (PMA) and the Center for the Polyurethanes Industry (CPI), as well as from polyurethane system and raw material manufacturers. Regulatory information can be found in the Code of Federal Regulations Title 21 (Food and Drugs) and Title 40 (Protection of the Environment). In Europe, health and safety information is available from ISOPA,[33] the European Diisocyanate and Polyol Producers Association.

The methods of manufacturing polyurethane finished goods range from small, hand pour piece-part operations to large, high-volume bunstock and boardstock production lines. Regardless of the end-product, the manufacturing principle is the same: to meter the liquid isocyanate and resin blend at a specified stoichiometric ratio, mix them together until a homogeneous blend is obtained, dispense the reacting liquid into a mold or on to a surface, wait until it cures, then demold the finished part.

2022/08/23(火) 06:10

EVA [material]

Ethylene vinyl acetate (also known as EVA) is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene.

It is a polymer that approaches elastomeric materials in softness and flexibility, yet can be processed like other thermoplastics. The material has good clarity and gloss, low-temperature toughness, stress-crack resistance, hot-melt adhesive waterproof properties, and resistance to UV radiation. EVA has a distinctive "vinegar" odor and is competitive with rubber and vinyl products in many electrical applications.

Hot melt adhesives, hot glue sticks, and top of the line soccer cleats are usually made from EVA, usually with additives like wax and resin. EVA is also used as a clinginess-enhancing additive in plastic wraps. Craft foam sheets are made of EVA and these foam sheets are popularly used for children's foam stickers.

EVA is also used in biomedical engineering applications as a drug delivery device. The polymer is dissolved in an organic solvent (e.g., dichloromethane). Powdered drug and filler (typically an inert sugar) are added to the liquid solution and rapidly mixed to obtain a homogeneous mixture. The drug-filler-polymer mixture is then cast into a mold at −80 °C and freeze dried until solid. These devices are used in drug delivery research to slowly release a compound. While the polymer is not biodegradable within the body, it is quite inert and causes little or no reaction following implantation.

EVA is one of the materials popularly known as expanded rubber or foam rubber. EVA foam is used as padding in equipment for various sports such as ski boots, bicycle saddles, hockey pads, boxing and mixed martial arts gloves and helmets, wakeboard boots, waterski boots, fishing rods and fishing reel handles. It is typically used as a shock absorber in sports shoes, for example. It is used for the manufacture of floats for commercial fishing gear such as purse seine (seine fishing) and gillnets. In addition, because of its buoyancy, EVA has made its way into non-traditional products such as floating eyewear. It is also used in the photovoltaics industry as an encapsulation material for silicon cells in the manufacture of photovoltaic modules. EVA slippers and sandals are currently very popular because of their properties like light weight, easy to form, odorless, glossy finish, and cheaper compared to natural rubber. In fishing rods, it is used to construct handles on the rod-butt end. EVA can be used as a substitute for cork in many applications.

EVA emulsions are polyvinyl acetate (PVAc) copolymers based on vinyl acetate (VAM) internally plastized with vinyl acetate ethylene (VAE). PVAc copolymer are adhesives used in packaging, textile, bookbinding for bonding plastic films, metal surfaces, coated paper, as redispersible powder in plasters and cement renders

Vinyl acetate ethylene copolymer(VAE), is also used in coatings formulation of good quality interior water-borne paints at 53% Primary dispersant

Hydrolysis of EVA gives ethylene vinyl alcohol (EVOH) copolymer.

EVA is used in orthotics, fire safe cigarettes (FSC), surfboard and skimboard traction pads, and for the manufacturing of some artificial flowers. It is used as a cold flow improver for diesel fuel and a separater in HEPA filters. EVA can easily be cut from sheets and molded to shape. It is also used to make thermoplastic mouthguards that soften in boiling water for a user specific fit. It is also used for impregnation of leather. Additional uses are in the making of nicotine transdermal patches since the copolymer binds well with other agents to form gel like substances. EVA is also sometimes used for making body bags.

2022/08/23(火) 06:10

GEL [material]

A gel (coined by 19th-century Scottish chemist Thomas Graham, by clipping from gelatine) is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state. By weight, gels are mostly liquid, yet they behave like solids due to a three-dimensional cross-linked network within the liquid. It is the crosslinking within the fluid that give a gel its structure (hardness) and contribute to the adhesive stick (tack). In this way gels are a dispersion of molecules of a liquid within a solid in which the solid is the continuous phase and the liquid is the discontinuous phase.

Many gels display thixotropy – they become fluid when agitated, but resolidify when resting. In general, gels are apparently solid, jelly-like materials. By replacing the liquid with gas it is possible to prepare aerogels, materials with exceptional properties including very low density, high specific surface areas, and excellent thermal insulation properties.

Many substances can form gels when a suitable thickener or gelling agent is added to their formula. This approach is common in manufacture of wide range of products, from foods to paints and adhesives.

In fiber optics communications, a soft gel resembling "hair gel" in viscosity is used to fill the plastic tubes containing the fibers. The main purpose of the gel is to prevent water intrusion if the buffer tube is breached, but the gel also buffers the fibers against mechanical damage when the tube is bent around corners during installation, or flexed. Additionally, the gel acts as a processing aid when the cable is being constructed, keeping the fibers central whilst the tube material is extruded around it.

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