Usage and Applications of Polyvinyl Alcohol PVA

Polyvinyl Alcohol ( referred to as PVA) white powder, is a wide range of uses of the water-soluble polymers, performance between the plastic and rubber, its use can be divided into two major fiber and non-fiber applications.

PVA has a unique strength in adhesion, film flexibility, smoothness, oil resistance, solvent resistance, protective colloid property, gas block, and abrasion resistance as well as having a specially treated water resistance. Therefore, in addition to fiber materials for outside, is also used extensively for the production of coatings, adhesives, paper processing agent, emulsifier, dispersant, film and other products. Range of applications throughout the textile, food, medicine, construction, wood processing, paper making, printing, agriculture, steel, polymer and chemical industries.

Performance: Polyvinyl Alcohol Resin products is white solid, good points flocculent, granular, powdery three kinds. It is non-toxic, tasteless, non-polluting, can be dissolved in water 80--90 ℃. Its aqueous solution has good adhesion and film-forming properties; resistance to most organic solvents oils, hydrocarbons, lubricants and the like; polyhydric alcohols with long -chain esterification, etherification, acetalization and other chemical properties.

Usage: Polyvinyl Alcohol PVA is mainly used in the textile industry warp pulp , textile finishing agents, Polyvinyl Alcohol fiber materials. 107 plastic construction and decoration industries, interior and exterior paints, adhesives. In chemical industry as a polymeric emulsifier, dispersant and polyvinyl formal, acetal, butyral resin. In Paper and paper industry as a binder. In Agriculture for soil amendments, pesticides and polyvinyl alcohol film adhesion synergist. Also can be used for cosmetics and induction hardening agent aspects.

The way to test whether this product completely dissolved: Take out a small amount of solution, add 1 ~ 2 drops of iodine solution, if there is a blue granular white body, that has not been completely dissolved, such as color can be evenly spread, has completely dissolved. 

Vanadium Pentoxide Catalyst for Manufacture of Sulfuric Acid

SO3 to SO2 by catalytic (Vanadium Pentoxide) oxidation process was usually not separated it out but directly converted into sulfuric acid. SO3 reacts violently with water, heat to generate H2SO4, but usually no water absorption SO3, because a lot of heat for the evaporation of the water vapor and SO3 formation of acid mist will affect the absorption efficiency, so the use of concentrated sulfuric acid was prepared to absorb SO3 fuming industrial sulfuric acid, diluted sulfuric acid and then can be obtained.

Now the production of sulfuric acid method is contact method, the raw material is still pyrite. The pyrite oxidation of sulfur dioxide in the air, then Vanadium Pentoxide, iron oxide and cuprous oxide as catalyst, the oxidation of sulfur dioxide to sulfur trioxide, sulfur trioxide react with water to form sulfuric acid. The resulting 98% sulfuric acid, known as concentrated sulfuric acid.

sulfuric most important chemical industry is prepared by the contact method. The main raw material for the fuel

contact method Seoul to sulfur or iron sulfide sulfur dioxide and oxygen in the air, oxidation of sulfur dioxide to sulfur trioxide, absorption of the water, any concentration of acid can be obtained. Only then oxidized, there must be some kind of contact with the presence of starting role when; most commonly used in platinum and Vanadium Pentoxide. Spontaneous combustion of sulfur dioxide derived from it may be directly oxidized iron sulfide if spontaneous combustion burner, derived who must first drop of cold, wash them with acid or by filtration method or by the precipitation method to make clean; dust, sulfur vapor, arsenic, phosphorus and other substances were stored in the gas stream must be removed lest they harm and contact agent for impurities lighter than the platinum oxidation alum hazards.

Contact legal sulfuric acid reaction principle: burning sulfur or metal sulfide sulfur dioxide and other raw materials from the system. Sulfur dioxide in the appropriate temperature of the catalyst under the effect of oxidation of sulfur trioxide, sulfur trioxide in the compound with water to form sulfuric acid.

The Properties and Applications of Molybdenum Steel

Properties of Molybdenum and Tungsten are very similar, the boiling point and the conductive performance is outstanding, the linear thermal expansion coefficient is small, easy processing of tungsten. Molybdenum is a kind of chemical element, chemical symbol is Mo, its atomic number is 42, is a kind of gray transition metal. Pure metal molybdenum is silvery white, very hard. Add a small amount of molybdenum to steel, hardened steel. Molybdenum is a very important nutrients to plants, were found in some of the enzyme. And Tungsten is a kind of steel grey or silver white metal, with high hardness and hard melting point. Its atomic number is 74, the atomic weight of it is 183.85. The melting point of it is 3410℃, the boiling point of it is 5900℃, thermal conductivity is 10 to 100 for 174 w/m*k. Slow evaporation at high temperature, the thermal expansion coefficient is very small, the expansion coefficient at 0 to 100 ℃, 4.5 × 10-6 · K-1. The resistance of tungsten is about 3 times larger than the resistance of copper.

lloy steel, stainless steel, tool steel and cast iron is the main field of application of Molybdenum, the Molybdenumproduction determines the demand, the effect of Molybdenum in the steel is as following:

1. To reduce the cooling rate to the appropriate values to obtain a hard martensite, which can improve the strength, hardness and toughness of a large section components.

2. Reduce the temper brittleness.

3. The resistance to hydrogen embrittlement.

4. The resistance to sulfide stress cracking.

5. Improve the high strength.

6. To improve the corrosion resistance of stainless steel, especially the anti chloride pitting.

7. To improve the high strength low alloy steel welding performance.

As steel Molybdenum alloy additives are the most important uses , according to statistics of 1986, which accounts for the total world consumption of 83% of Molybdenum. And where a steel containing Molybdenum World crude steel production has accounted for 1/10. Therefore, Molybdenum steel than is often used as an industrially developed country or one of the signs. 

Types of Silicone Rubber and Basic Features

Silicone Rubber products can run a large amount of electric power system, and this should thanks largely to its excellent water repellency, water repellency and stain-resistant flash capability. Current products on the market, mainly as the following three categories:

Room Temperature Vulacanized Silicone Rubber (RTV Silicone Rubber):

This kind of Silicone Rubber has excellent hydrophobic properties and contamination resistance properties, hardness is low, but because of the RTV, and various aspects of mechanical properties and resistance erosion ability is poor, aging is worse.

Room Temperature Vulacanized Silicone Rubber is with room temperature curing, good mobility, forming process is simple and can operate on the spot.

High Temperature Vulcanized Silicone Rubber (HTV Silicone Rubber):

This kind of Silicone Rubber has the resistance to aging, resistance to tracking and erosion, water repellent, stain proof, fire retardant, ozone resistant, UV resistant, dampness resistant, resistant to high and low temperature and tearing strength of character.

High Temperature Vulcanized Silicone Rubber is with 140 to 180℃ high temperature curing, poor mobility, special shapes or large equipment moulding process complex. Oxidant gas production and retained in the product, and mold corrosion.

Liquid Silicone Rubber (LSR):

This kind of Silicone Rubber is with all the advantages of High Temperature Vulcanized Silicone Rubber, it has excellent properties on technological properties of the proof tracking, high and low temperature resistance and hydrophobic properties and so on.

Liquid Silicone Rubber is with 90 to 140℃ curing, good flowability, components directly in the Silicone Rubber of Platinum catalysts, two-component mixed crosslinked, forming process is simple. Particularly suitable for external insulation of large equipment, and no damage to mould.

Molybdenum Dioxide And Molybdenum Trioxide

Molybdenum Dioxide, is a kind of brown-black powder with steel shiny purple. The density of Molybdenum Dioxide is 6.44 g/cm3, we can get Molybdenum when heat the Molybdenum Dioxide  with hydrogen the temperature is above 500℃. And generate Molybdenum Oxychloride reaction with chlorine, and hydrogen chloride, alkaline,acid reaction. And it is very slightly soluble in Sulfuric Acid, Nitric Acid and Silver Nitrate. Oxidation of Molybdenum Dioxide can get Molybdenum Trioxide. Can be made of metal Molybdenum in steam heating, or heating to 470 ℃ MoO3 in hydrogen reduction of. Used in producing Molybdenum and other Molybdenum compounds.

Molybdenum is a silver-white metallic powdered Molybdenum gloss black, the melting point of it is 2610℃, the boiling point of it is 5560℃, the density of it is 10.2g/cm3. Molybdenum is very stable at room temperature in air, when the temperature was raised to 600℃, quickly react with oxygen to produce the more volatile Molybdenum Trioxide. At 500 to 1150 ℃ reduction with hydrogen trioxide or Ammonium Molybdate , Molybdenum can be available. MoO3 molecular weight of 143.94. White transparent rhombic crystals, to yellow when heated, cooled and restore the original color. Density 4.692g/cm3, melting point 795 ℃, boiling point 1155 ℃, easy sublimation. Insoluble in water, can be melted in a solution of ammonia and alkali generated Molybdate. Dissolved in acid, Molybdenum Dioxide generated root (MoO22 +) and Molybdenum Oxide root (MoO4 +) complex cation to form a soluble complex with the acid group. Oxidizing very weak at high temperature may be hydrogen, carbon, aluminum reduction. Reagents for the analysis, Molybdenum and Molybdenum alloy salt preparation. Ignition or Molybdenum or Molybdenum Disulfide to obtain calcined in air Molybdate.

While the Molybdenum Dioxide is different from Molybdenum Trioxide, it has two oxygen atoms, Molybdenum Dioxide, brown black powder, with steel shiny purple. Oxidation of it is very weak, at high temperature can be hydrogen, carbon, aluminum reduction. Used as an analytical reagent, preparation of Molybdenum and Molybdenum salt. Burning Molybdenum or Molybdenum Disulfide in air or roasting Molybdenum prepared.

Polyvinyl Alchol PVA 1788 and PVA 1799

Architectural coatings commonly use Polyvinyl Alcohol PVA 1788 and PVA 1799. Polyvinyl Alcohol is derived from the hydrolysis of Polyvinyl Acetate, and can not derived by the polymerization of Vinyl Alcohol. Because Vinyl Alcohol is very unstable, there can be no free Vinyl Alcohol Monomer. The formula of Polyvinyl Alcohol is (CH2CH)OH, wherein the degree of hydrolysis and degree of polymerization has a great influence on the physical properties of Polyvinyl Alcohol. The polymerization degree of the Polyvinyl Alcohol can be divided into a high polymerization degree, medium polymerization degree and low degree of oligomerization, and recently, the development of an ultra-high degree of polymerization products.

There are three typically kinds of alcoholysis, namely, 78 %, 88 % and 98 %. The complete alcoholysis of Polyvinyl Alcohol is 98 % to 100 %, partial alcoholysis of alcoholysis typically is 87 % to 89 %. For convenience, we often fetching thousands of polymerization degree, rounded at the front, percentages in the back alcoholysis. Therefore, PVA 1788 means that polymerization is 1700, with diethylene glycol 88 %, PVA 1799 means that polymerization is 1700, with diethylene glycol 99 %.

PVA 1788 is with good water solubility, whether in cold water, was quickly dissolved in hot water, but PVA 1799 only dissolves in hot water at 95 ℃ or above. Due to Polyvinyl Alcohol PVA to neutral, at the time of dissolution does not need special corrosion requirements, but it’s best to use stainless steel or enamel reaction kettle, because these materials will not rust and contamination of the solution.

PolyvinylAlcohol PVA 1788 and PVA 1799 can be used for emulsion polymerization of Vinyl Acetate emulsion stabilizer. Polyvinyl Alcohol can be used in the manufacturing of water-soluble adhesives, and can be used as modification of starch adhesive agents. And also can be used to preparation of photosensitive adhesive and benzene class solvent resistant sealant. Polyvinyl Alcohol also can be used as release agents, dispersants and so on.

What is Sodium Ascorbate?

Sodium Ascorbate is a kind of white to yellowish white crystalline powder or granules, odorless, slightly salty flavor. The decomposition temperature of it is of 218 ℃, in the dry conditions are more stable, light color burn, after moisture absorption and slow oxidation and decomposition in aqueous solution. Sodium Ascorbate can be much easier to be soluble in water than Ascorbic Acid, 10 % aqueous solution PH is about 7.5.

First aid measures:

Ingestion: Do not induce vomiting. If the victim is conscious, instead of convulsions, give 1 or 2 glasses of water to dilute the chemicals, and to make a hospital or poison control center immediately.

Breath in: Leave the contaminated area immediately and take deep breath of fresh air. If the symptoms (such as wheezing, coughing, shortness of breath, or in the mouth, throat, or chest burning), call the doctor, and was prepared to transport victims to hospitals.

Skin: It can cause skin irritation. Symptoms may include redness and burning of the skin and other skin damage. Gently and thoroughly wash all affected skin areas with soap and water. If you develop symptoms such as redness or irritation, immediately call a doctor, and be prepared to transport the victim to a hospital for treatment.

Eyes: First check the victim of contact lenses, if present removed. While calling a hospital or poison control center for 20 to 30 minutes of water or saline solution flush eyes of the victims. Do not put any ointments, oils, or medication in the victim 's eyes, the doctor did not specify. If symptoms ( such as redness or irritation ) development, please transported the victim to a hospital immediately.

The stability of Sodium Ascorbate:

Aqueous solution is unstable, and the air is greater than pH 6.0 by the relative stability when exposed to rapid oxidation of Ascorbic Acid gradually darken light it is exposed to light in the air is gradually dimmed, but not damage, slight coloration therapeutic activity Ascorbic acid injection. Solution of Ascorbic Acid is rapidly oxidized in the air, the drug in an alkaline medium should be protected, air and light. Ascorbic Acid at concentrations greater than 100 mg/ml may undergo decomposition and the production of carbon dioxide. Due to the increased pressure may develop after prolonged storage, carefully open the ampoule containing Ascorbic Acid injection.