PS material (polystyrene) (General Purpose
Polystyrene GPPS, commonly known as: PS; high impact polystyrene HIPS, commonly
known as: super glue is not broken) for the production of insulating
transparent pieces, decorative pieces, and chemical equipment, optical
instruments, etc. ʱ??
Forming characteristics: 1. amorphous
material, moisture absorption is small, without fully dry, difficult to break
down, but the thermal expansion coefficient, easy to produce internal stress,
good mobility, can bolt or plunger-type injection molding machine.
2. to use high melt temperature, high mold
temperature, low injection pressure, injection time extend help to reduce
stress. Prevent shrinkage and deformation. Chemical and physical properties:
Most commercial use of PS are transparent, non-crystalline material. PS has
very good geometric stability, thermal stability, the optical transmission
characteristic, electrical insulating properties and a very slight hygroscopic
tendency. It is resistant to water, dilute mineral acids, but can be strong
oxidizing acids such as concentrated sulfuric acid corrosion and can be
expanded and deformed in some organic solvent. Typical shrinkage between 0.4 to
0.7%.
POM (POM, commonly known as: steel)
heat-crystalline plastic, melting point of 165 to 175 degrees, the nature of
the nearest metal.
Advantages: 1 has high mechanical strength
and rigidity.
2. The highest fatigue strength.
3. High environmental resistance,
resistance to organic solvents.
4. Resistance to repeated impact
resistance.
5. wide temperature range (-40 to 120
degrees).
6. good electrical properties.
7. good recovery.
8. The self-lubricating properties, good
wear resistance.
9. excellent dimensional stability.
Disadvantages: 1. process if prolonged high
temperatures can lead to thermal decomposition.
2. No self-extinguishing.
3. antacid poor.
4. forming a large shrinkage.
Chemical and physical properties: POM is a
tough elastic material, even at low temperatures are still very good creep
properties, geometric stability and impact resistance. POM homopolymer
materials have both copolymer material. Homopolymer material has a very good
extension strength, fatigue strength, but not easy to process. Copolymers have
good thermal stability, chemical stability and ease of processing. Both
homopolymer material or copolymer materials are crystalline materials and are
not easily absorb moisture. The high crystallinity of POM cause it has a fairly
high shrinkage, can be high up to 2% to 3.5%. For a variety of enhanced
materials have different shrinkage.
PVC (polyvinyl chloride) Chemical and
physical properties: Rigid PVC is one of the most widely used plastic
materials. PVC material is a non-crystalline materials. PVC material in actual
use, often by adding stabilizers, lubricants, auxiliary processing agent,
pigment, impact agents and other additives. PVC material is not easily
flammable, high strength, resistance to climate variability and excellent
geometric stability. PVC of oxidants, reducing agents and strong acids have a
very strong resistance. However, it can be concentrated oxidizing acids such as
concentrated sulfuric acid, concentrated nitric acid corrosion and does not
apply to contact with aromatic hydrocarbons, chlorinated hydrocarbons
occasions. PVC melt temperature during processing is a very important process
parameters, if this parameter incorrectly will cause the material to decompose
problems. PVC is rather poor flow characteristics, the process is very narrow
range. Especially high molecular weight PVC material more difficult to process
(this material is usually added to lubricants to improve the flow
characteristics), so commonly used are low molecular weight PVC material. PVC
contraction rate is very low, typically 0.2 to 0.6%.
PE (polyethylene)
A. is the largest output, the most should
be the plastic in the world, with its output accounting for 30% of world
plastics production.
B. The structure of long chain-like
structure or a branched structure, a crystalline polymer type song.
C. odorless and tasteless flammable white
powder, the appearance of floating white.
D. excellent electrical insulation
properties, high frequency cable insulation should be made.
E. having high chemical stability.
F. good low temperature properties, good
air permeability, can make agricultural films, bags.
PP (polypropylene, commonly known as the
pleated plastic) is the most common plastic produce a heat-resistant, high
yield strength, high bending labor life. Shrinkage greater resistance to impact
strength with temperature changes. Insufficient rigidity. Flammable Chemical
properties of stability, good dielectric properties, better engage in chemical
erosion resistance, the ability to soak 80 degrees below the inorganic acid,
lye, salts, and many organic solvents, water absorption is also minimal. At the
melting point has good mobility, good molding properties Chemical and physical
properties:. PP is a semi-crystalline materials. To be more rigid than PE and
has a higher melting point. Since the type of PP homopolymer temperature is
higher than the above 0 ℃ very brittle, so many commercial PP material is added 1-4% ethylene
random copolymer or a higher ratio of clamp-stage ethylene content copolymer.
PP copolymer-based material has a lower heat distortion temperature (100 ℃), low
transparency, low gloss, low rigidity, but have a stronger impact strength. PP
ethylene content increases strength increases. PP Vicat softening temperature
of 150 ℃. Due to the high degree of crystallinity, the surface rigidity and
scratch resistance properties of this material is very good. PP environmental
stress cracking problem does not exist. Generally, the use of glass fiber,
metal additives or thermoplastic rubber modified PP. MFR PP turnover ranges
from 1 to 40. Low MFR PP material better impact properties but extend lower
strength. MFR for the same material, copolymer-based homopolymer type intensity
ratio is higher. Since the crystal, PP contraction rate is very high, typically
1.8 to 2.5%. And shrinkage direction uniformity than PE-HD material is much
better. 30% of glass additive can shrink rate fell to 0.7%. Homopolymer and copolymer
PP material has excellent resistance to moisture absorption, resistance to acid
corrosion, anti-solubility. However, it aromatic hydrocarbons (such as benzene)
solvents, chlorinated hydrocarbons (carbon tetrachloride) solvents is not
resistance. PP did not like PE still has oxidation resistance at elevated
temperatures.
PPE ethylene polypropylene chemical and
physical properties: In general, PPE or PPO, commercially available materials
generally mixed with other thermoplastic materials such as PS, PA and so on.
These hybrid materials are generally still call it PPE or PPO. PPE or PPO
hybrid has better processing characteristics than the pure material. Change
characteristics depending on the mixture as a ratio of PPO and PS. Mixed with
PA 66 of the mixed material has a stronger chemical stability at high
temperatures. Moisture absorption of this material is very small, its products
have excellent geometric stability. PS material mixed with non-crystalline, and
mixed with the PA of the material is crystalline. Glass fiber additives can
make the shrinkage rate decreased to 0.2%. This material also has excellent
electrical insulating properties and low coefficient of thermal expansion. The
viscosity depends on the mixture ratio of the material, PPO rate increase will
result in increased viscosity.
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