polyvinyl alcohol (PVA)
Open classification: chemistry, natural science, industry
Directory? Basic information
Combination/combination information
Overview of hazards
fire fighting
Emergency treatment of leakage
Operation, disposal and storage
Contact control/personal protection
Physical and chemical characteristics
Main applications
Main applications
Basic information
Chinese name: polyvinyl alcohol
English name 2: polyvinyl alcohol (viny) polymer, referred to as poval, PVA.
CAS number: 9002-89-5
Molecular formula: [C2H4O]n
Composition/composition information
Content of harmful substances, CAS number
Polyvinyl alcohol 9002-89-5
Overview of hazards
Health hazards: Inhalation, ingestion or absorption through the skin are harmful to the body and irritate the eyes and skin.
Danger of explosion: This product is flammable and irritating.
Part IV: First aid measures
Skin contact: Take off contaminated clothes and rinse with running water.
Eye contact: Lift eyelids and rinse with running water or normal saline. See a doctor.
Inhalation: Leave the site and go to a place with fresh air. If you have difficulty breathing, give oxygen. See a doctor.
Intake: Drink enough warm water to induce vomiting. See a doctor.
fire fighting
Hazard characteristics: Powder and air can form explosive mixture. When it reaches a certain concentration, it will explode when it meets Mars. Combustible gas is produced by thermal decomposition.
Harmful combustion products: carbon monoxide and carbon dioxide.
Fire extinguishing method: Firefighters must wear gas masks and full-body fire protection suits to extinguish the fire in the upwind direction. Extinguishing agent: atomized water, foam, dry powder, carbon dioxide, sand.
Emergency treatment of leakage
Emergency treatment: isolate the leaked contaminated area and restrict access. Cut off the fire. It is recommended that emergency personnel wear dust masks (full face masks) and protective clothing. Avoid dust, carefully sweep it up, put it in a bag and move it to a safe place. It can also be washed with plenty of water, diluted and put into the wastewater system. If there is a large amount of leakage, cover it with plastic sheets and canvas. Collect and recycle or transport to the waste disposal site for treatment.
Operation, disposal and storage
Precautions for operation: closed operation. Closed operation to provide good natural ventilation. Operators must be specially trained and strictly abide by the operating procedures. It is recommended that the operator wear a self-priming filter dust mask, chemical safety glasses, gas-proof overalls and rubber gloves. Stay away from kindling and heat sources, and smoking is strictly prohibited in the workplace. Use explosion-proof ventilation system and equipment. Avoid dust. Avoid contact with oxidants. When handling, handle with care to prevent the packaging and containers from being damaged. Equipped with corresponding varieties and quantities of fire fighting equipment and leakage emergency treatment equipment. Empty containers may leave harmful substances behind.
Precautions for storage: Store in a cool and ventilated warehouse. Stay away from fire and heat sources. Should be stored separately from oxidant, and should not be mixed. Equipped with corresponding varieties and quantities of fire fighting equipment. The storage area should be equipped with suitable materials to control leakage.
Contact control/personal protection
occupational exposure limits
China MAC (mg/m3): 10.
Maximum allowable concentration in the former Soviet Union (mg/m3): 10
TLVTN: No standards have been established.
TLVWN: No standard has been established.
Engineering control: closed operation. Provide good natural ventilation conditions.
Respiratory system protection: when the dust concentration in the air exceeds the standard, you must wear a self-priming filter dust mask. Air respirator should be worn during emergency rescue or evacuation.
Eye protection: Wear chemical safety glasses.
Physical protection: wear anti-virus infiltration overalls.
Hand protection: wear rubber gloves.
Other protection: Smoking is strictly prohibited in the workplace. Maintain good hygiene habits.
Physical and chemical characteristics
Appearance and properties: milky white powder.
Melting point (℃): No data available.
Boiling point (℃): No data available.
Relative density (water =1):1.31-1.34 (crystal)
Relative steam density (air = 1): No data available.
Saturated vapor pressure (kPa): No data available.
Combustion heat (kJ/mol): no data available.
Critical temperature (℃): No data available.
Critical pressure (MPa): No data available.
Logarithmic value of octanol/water partition coefficient: no data.
Flash point (℃): No data available.
Ignition temperature (℃): 4 10 (powder cloud)
Upper explosion limit %(V/V): No data available.
Lower explosive limit% (volume ratio): 125 (g/m3)
Solubility: insoluble in petroleum ether, soluble in water.
Main applications
Used for manufacturing polyvinyl acetal, gasoline-resistant pipeline and vinylon synthetic fiber, fabric treating agent, emulsifier, paper coating, adhesive, etc.
A water-soluble polyvinyl alcohol fiber and its preparation method are characterized in that 100 part of polyvinyl alcohol with polymerization degree of 500-2000 and alcoholysis degree of 75-99mo 1% is added into a stainless steel dissolving kettle filled with 200-400 parts of mixed solvent, and the ratio of dimethyl sulfoxide to water is 90-70:/kloc-0. The pressure is -0.0 1 ~-0.08 MPa, and it is dissolved for 3 ~ 4 hours to prepare spinning solution. After filtration, defoaming, dry-wet spinning and post-treatment, water-soluble polyvinyl alcohol fiber was obtained. The water-soluble temperature of the fiber is 10 ~ 90℃, the strength is ≥3.5cN/dtex, and the fineness of single fiber is 65438+. Its filaments are processed into tops, blended with tops, cotton slivers, hemp and chemical fibers to make high count yarns or hollow yarns, or cut into short fibers for non-woven fabrics, embroidered base fabrics and paper making.
It has the following excellent characteristics:
Soluble PVA is soluble in water, and the higher the water temperature, the greater the solubility, but it is almost insoluble in organic solvents. The solubility of PVA varies with alcoholysis degree and polymerization degree. PVA with partial alcoholysis and low polymerization degree dissolves very quickly, while PVA with complete alcoholysis and high polymerization degree dissolves slowly. Generally speaking, the degree of alcoholysis is greater than the degree of polymerization, which affects the solubility of PVA. The dissolution process of PVA is staged, that is, affinity wetting-swelling-infinite swelling-dissolution.
Film-forming PVA is easy to form film and has excellent mechanical properties. The tensile strength of the film increases with the increase of polymerization degree and alcoholysis degree.
Adhesive PVA has good adhesion with hydrophilic cellulose. Generally speaking, the higher the degree of polymerization and alcoholysis, the stronger the adhesive strength.
When the heat-stable PVA powder is heated to about 100℃, its appearance changes gradually. Partially alcoholized PVA began to melt at about 190℃ and decomposed at 200℃. Fully alcoholized PVA began to melt at about 230℃ and decomposed at 240℃. Thermal cracking experiments show that the lower the degree of polymerization, the faster the weight loss; The higher the alcoholysis degree, the shorter the decomposition time.
At present, medical PVA has specifications such as PVA05-88, PVAl7-88 and PVA- 124. The alcoholysis degree of the first two specifications is (88 2) (m 01)%, and the average polymerization degree (n) is 500-600 and 1700 respectively. Degree of alcoholysis of polyvinyl alcohol. 124 is 98-99 (m01)%, and the average degree of polymerization (n) is n) 2 400-2 500.
It is one of the strategic tasks for China's traditional Chinese medicine to develop new pharmaceutical excipients and promote the optimization of dosage forms. PVA has the characteristics of convenient synthesis, safety and low toxicity, easy control of product quality, low price and convenient use. Therefore, PVA is an excellent pharmaceutical excipient with redevelopment potential.