Discover Top Posts Tagged with #polyvinyl alcohol

Sustainable, high-performance paper coating material could reduce microplastic pollution

Plastic pollution presents a global challenge that must be solved. In particular, packaging accounts for 30–50% of the total plastic consumption. While paper packaging is eco-friendly, it lacks crucial functionalities like moisture resistance and strength. Traditional coating materials exacerbate plastic pollution, prompting the need for sustainable alternatives. Polyethylene (PE) and ethylene vinyl alcohol (EVOH) are typically used as coating materials to improve the low barrier properties of paper packaging, but these substances do not decompose and worsen microplastic pollution when disposed of in the natural environment. In response to this problem, packaging materials made from bio-based substances and biodegradable plastics have been developed, but in most cases, as the packaging performance improves, the biodegradability diminishes rapidly.

Scientists develop self-healing elastomer for flexible electronics

Scientists in China have fabricated a high-strength elastomer with self-healing properties. The polymer has significant potential in the field of flexible electronic devices. In a study, published in Polymer International, researchers from a consortium of universities across Shanghai, China, have described a new poly(vinyl alcohol) (PVA)-based elastomer that can self-repair after damage, to maintain shape and performance. The flexible polymer is a solution to a longstanding issue with the durability of flexible electronic devices. In recent years, flexible electronics have been attracting a lot of attention across multiple industries, with potential applications including flexible patch sensors to monitor blood glucose concentration, and flexible energy storage devices for wearable electronics. Currently however, the long-term stability of such materials is an issue, as Dr. Zili Li, Associate Professor at Fudan University, China, and corresponding author of the study, explained.

Degradation of plastic waste using newly developed biocatalysts

The plastic materials polyurethane and polyvinyl alcohol can now be degraded under mild conditions with the help of enzymes as biocatalysts.

Scientists from the University of Greifswald have developed corresponding methods together with the German company Covestro and teams from Leipzig and Dublin, as recently published in the journal Angewandte Chemie International Edition in two separate articles. It has thus been possible to establish a sustainable and environmentally-friendly process to recycle these polymers.

This helps to address the worldwide problem of plastic waste based on the example of these two synthetic polymers, which are produced industrially at large scale.

Plastics are currently indispensable for the production of construction materials, electric insulation, drinks and food packaging, textiles and many more applications. Unfortunately, the mass production of synthetic polymers, especially for packaging materials, has led to an enormous waste problem for the environment. The polymers polyurethane and polyvinyl alcohol contribute to approximately 8 percent of the European plastic production.

Multifunctional self-healing liquid metal hydrogel developed for human-computer interaction

Recently, researchers from the Hefei Institutes of Physical Science (HFIPS) of the Chinese Academy of Sciences, led by Prof. Tian Xingyou and Prof. Zhang Xian, along with associate Prof. Yang Yanyu from the College of Materials Science and Engineering at Zhengzhou University, used gallium indium alloy (EGaIn) to initiate the polymerization and serve as flexible fillers to construct liquid metal/polyvinyl alcohol(PVA)/P(AAm-co-SMA) double network hydrogel.

"The resulting material was super-stretchable and self-healing," said Li Xiaofei, first author of the paper, "it will promote the research and practical application of hydrogels and liquid metal in intelligent devices and military fields."

The study was published in Materials Horizons.

Most conductive hydrogels suffer from subpar mechanical qualities and lack desirable self-recovery and self-healing abilities, severely limiting hydrogels' potential uses. Liquid metals like gallium indium alloy (EGaIn) can toughen polymers by conforming to their changing shapes. Also, gallium (Ga) in EGaIn can initiate vinyl monomer's free radical polymerization.

Researchers develop viable, environmentally-friendly alternative to Styrofoam

Washington State University researchers have developed an environmentally-friendly, plant-based material that for the first time works better than Styrofoam for insulation.

The foam is mostly made from nanocrystals of cellulose, the most abundant plant material on earth. The researchers also developed an environmentally friendly and simple manufacturing process to make the foam, using water as a solvent instead of other harmful solvents.

The work, led by Amir Ameli, assistant professor in the School of Mechanical and Materials Engineering, and Xiao Zhang, associate professor in the Gene and Linda School of Chemical Engineering and Bioengineering, is published in the journal Carbohydrate Polymers.

Researchers have been working to develop an environmentally friendly replacement for polystyrene foam, or Styrofoam. The popular material, made from petroleum, is used in everything from coffee cups to materials for building and construction, transportation, and packaging industries. But, it is made from toxic ingredients, depends on petroleum, doesn't degrade naturally, and creates pollution when it burns.

Weak hydrogen bonds key to strong, tough infrastructure

The right mix of hydrogen bonds in polymer and cement composites is critical to making strong, tough and ductile infrastructure material, according to Rice University scientists who want to mimic the mechanics of mother-of-pearl and similar natural composites with synthetic materials.

Seashells made of mother-of-pearl, aka nacre, get their remarkable properties from overlapping micron-sized, mineralized plates held together by a soft matrix. This structure can be approached by cement and polymer composites that may, for instance, make better earthquake-resistant concrete, according to Rouzbeh Shahsavari, an assistant professor of civil and environmental engineering.

The Rice lab ran more than 20 computer simulations of how polymers and cement molecules come together at the nanoscale and what drives their adhesion. The researchers showed that the proximity of oxygen and hydrogen atoms is the critical factor in forming a network of weak hydrogen bonds that connects soft and hard layers. Common polyacrylic acid (PAA) proved best at binding the overlapping layers of cement crystals with an optimal overlap of about 15 nanometers.

"This information is important to make the best synthetic composites," said Shahsavari, who ran the project with Rice graduate student Navid Sakhavand. "A modern engineering approach to these materials will have a large impact on society, especially as we build new and replace aging infrastructure."

Kevlar-based artificial cartilage mimics the magic of the real thing

The unparalleled liquid strength of cartilage, which is about 80 percent water, withstands some of the toughest forces on our bodies.

Synthetic materials couldn't match it -- until "Kevlartilage" was developed by researchers at the University of Michigan and Jiangnan University.

"We know that we consist mostly of water -- all life does -- and yet our bodies have a lot of structural stability," said Nicholas Kotov, the Joseph B. and Florence V. Cejka Professor of Engineering at U-M, who led the study. "Understanding cartilage is understanding how life .forms can combine properties that are sometimes unthinkable together."

Many people with joint injuries would benefit from a good replacement for cartilage, such as the 850,000 patients in the U.S. who undergo surgeries removing or replacing cartilage in the knee.

While other varieties of synthetic cartilage are already undergoing clinical trials, these materials fall into two camps that choose between cartilage attributes, unable to achieve that unlikely combination of strength and water content.

Making products more biodegradable with starch

A new starch-based film, or coating, developed by Agricultural Research Service (ARS) scientists, can make paper and other materials more water resistant and biodegradable. The film can potentially be used in food packaging, plastic bags, and other products, reducing the amount of synthetic products clogging landfills.

Starch, which is 100-percent biodegradable, is used in some plastics and films because it is inexpensive and biodegrades rapidly. But existing starch-containing materials do not have the strength, flexibility, and ease of processing required for many other uses.

Polyvinyl alcohol (PVOH), a petroleum-based synthetic polymer, is widely used for film applications, but it has limited biodegradability. Scientists at the ARS National Center for Agricultural Utilization Research (NCAUR) in Peoria, Illinois, recently developed starch complexes that can be blended with PVOH to improve the properties of films and make them more biodegradable. The team included chemist George Fanta, plant physiologist Frederick Felker, chemist Gordon Selling, and research associate William Hay.

Says Fanta, "At our lab, we look for new value-added products from starch that benefit U.S agriculture and consumers. Products we develop can help replace totally synthetic products like plastic polyethylene bags and polystyrene foam packing materials."

Weak hydrogen bonds key to strong, tough infrastructure

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