It Takes Only 2 Minutes To Dissolve Cellulose At Low Temperature.

Using urea, sodium hydroxide and water as solvent, it will be very difficult to dissolve before precooling to -12 C.

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Zhang Lina, who has been committed to the research and application of the natural polymer materials science and application of biomass resources, has led her team to break through the traditional method of heating and dissolving with organic solvents, and put forward a "green" method and a new concept of water system to dissolve polymers at low temperature. The new agricultural materials such as cotton lint, bagasse, shrimp shell and crab shell have been pformed into practical materials.

In this way, waste can be pformed into comfortable fabrics, degradable films, daily necessities and biomedical materials.

Compared with traditional dissolving technology, what is the "green" nature of cellulose's low temperature dissolving theory and the impact on the textile industry? This reporter gave an exclusive interview with Professor Zhang Lina.

The fastest dissolution rate is -12 2 minutes.

"The viscose method used to produce rayon and cellophane in China needs a large amount of carbon disulfide, which causes serious pollution to the environment.

We have invented a new cellulose solvent -7% sodium hydroxide (NaOH) /12% urea aqueous solution.

When the solvent is cooled to -12 C, it can rapidly dissolve cellulose (its molecular weight is below 1.2 * 105), and the dissolution time takes only 2 minutes to reach the fastest dissolution rate in the history of cellulose.

We have studied the mechanism of cellulose dissolution and low temperature dissolution by means of variable temperature FT-IR spectroscopy, dynamic and static light scattering (LLS), pmission electron microscopy (TEM), X- ray diffraction (XRD), 15N- and 13C-NMR.

Zhang Lina said.

They have shown that NaOH hydrate can easily form hydrogen bonds with cellulose and directly link to cellulose molecular chains, forming a vermicular inclusion complex containing urea -NaOH as the main body.

The complex formed by hydrogen bonding between macromolecules and solvents is highly stable at low temperatures.

It is concluded that the dissolution of cellulose at low temperature is caused by the dynamic self-assembly of small solvent molecules (sodium hydroxide, urea, water) and cellulose macromolecules, which not only widens the theory of polymer dissolution, but also puts forward a new concept of low temperature dissolving.

In the water system, no chemicals are volatilized at low temperature, so this is a clean production process.

A variety of cellulose products can be prepared.

How to get better application of cellulose solution after low temperature? This is probably the most concerned topic for enterprises.

Zhang Lina and her team have done in-depth research on their usability. The research and development of new fiber, cellulose membrane, cellulose magnetic material and cellulose hydrogel have laid a solid foundation for the basic research of Cellulose Science.

"Using this cellulose solution, we successfully spin out new regenerated cellulose fibers through a small pilot plant.

It has a circular cross-section (similar to Tencel), smooth surface and excellent mechanical properties, and its tensile strength is close to commercial viscose filament. After industrial production, the strength of the wire can be greatly improved after optimizing the equipment.

Zhang Lina told reporters that this new method of producing regenerated cellulose fibers without pollution, low cost and short production cycle is expected to replace the currently polluted viscose method.

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Similarly, Zhang Lina's team used this cellulose solution to prepare pparent membranes, fluorescent films and light-emitting films.

According to the affinity of cellulose water system, luminescent inorganic particles such as alkaline earth aluminum salts can be dispersed uniformly in cellulose aqueous solution.

At the same time, the inorganic nanoparticles can be firmly embedded in the cellulose substrate to form a luminous film. After 10 minutes of sunlight exposure, it can shine 10 hours in the dark. It is a promising information material.

These pparent membranes and fluorescent films can be completely biodegraded in the soil. In the future, they can also be used as environmental protection packaging and special packaging materials.

"Based on the dependence of cellulose solubility on molecular weight and temperature, we also prepared a regenerated cellulose membrane reinforced by nanoscale cellulose whiskers.

The strength of the membrane is as high as 157MPa and has good biodegradability. "

Zhang Lina added.

Using the porous structure of cellulose filaments or membranes in wet state, Zhang Lina's team has created a new way for in-situ synthesis of inorganic magnetic nanomaterials by micro nano holes.

Magnetic fibers containing iron oxide nanoparticles were prepared by in-situ synthesis in wet cellulose fibers.

The magnetic cellulose filament has excellent mechanical properties, ultraviolet absorption and superparamagnetic properties.

Especially when the magnetic cellulose filament is calcined at 600 degrees Celsius, pure iron oxide fibrous nanomaterials can be made. Because of its excellent electrochemical activity and high power release capacity, ferric oxide fibrous nanomaterials can play a role in the field of electric and magnetic functional materials.

In addition, the cellulose chain has a semi-rigid feature. "We use it as the wall of the gel hole to construct cellulose gel with high strength and large pore size.

Macroporous hydrogels prepared from cellulose and carboxymethyl cellulose can absorb 1000 times of water and maintain good shape. This hydrogel shows different swelling ratios in different solutions, and also has intelligent behavior.

Zhang Lina introduced these new types of cellulose products in detail.

Market promotion after industrialization

Regarding the wide application of cryogenic dissolving technology, S.Kuga, chairman of the second international cellulose conference and professor of University of Tokyo in Japan, evaluated it as "the most easily industrialized technology".

According to Zhang Lina, cellulosic low temperature dissolving technology is being industrialized. Among them, Hubei Chemical Fiber Group Ltd has already spun cellulose solution into filament. Then they worked with Jiangsu Haian Shing Ling electric appliance company to get the preliminary industrialization test result of this project.

Under the suggestion of the academician of the Chinese Academy of engineering, Zhang Lina's team is currently working with Tangshan Sanyou chemical fiber Limited by Share Ltd to look forward to bringing this advanced technology to the market.

In terms of the application cost of the technology, "its price is slightly lower than the cost of viscose yarn, and there is not much demand for textile enterprises in the new technology and cost input."

Zhang Lina gave such an answer, "in the NaOH/ urea water solvent, the application cost of the cellulose low temperature dissolution technology itself should be relatively low, and how to control the cost in different textile enterprises in the future depends on the specific circumstances of the enterprise."

The technology of low temperature dissolution of cellulose is low carbon, environmental protection and affordable. For its market prospect, Zhang Lina is very optimistic. "China's textile industry is so huge. If we can dissolve biomass resources and spin weave, we will have to save resources for the country."

It seems that this is not only a new technology to promote the technological revolution of the textile industry, but also a stepping stone to China's textile industry to achieve energy saving and emission reduction and enhance industrial development during the "12th Five-Year" period.