Polypropylene (PP) features and applications.
A polypropylene characteristics
( 1 ) Physical properties: polyolefin is nontoxic , odorless, tasteless milky highly crystalline polymer density of only
0.90 ~ 0.91g/cm3, is one of the lightest of all the plastic variety . It particularly stable water . 24h, the water
absorption of only 0.01% , from about 8 to 150,000 molecular weight. Good formability , but shrinkage ,
thick jade products easy to sag . Product surface gloss, easy coloring .
( 2)mechanical properties : high crystallinity polypropylene , regular structure , which has excellent mechanical
properties .Its strength and hardness, flexibility than HDPE , but at room temperature and low temperatures ,
high molecular structure itself is structured so poor impact strength , the molecular weight increases, the
impact strength increases, but the molding processability deteriorates the most outstanding performance PP is
bending fatigue resistance , such as injection molding with integral hinges PP can withstand 7 × 107 times opening
and closing of folding bending without signs of damage , dry friction coefficient and nylon similar. But in
the oil lubrication , as nylon. ( 3 ) , thermal properties : PP has good heat resistance ,
melting point 164 ~ 170 ℃, products can be sterilized at temperatures above 100 ℃ , in the case without outside ,
150 ℃ not deformed . Brittle transition temperature of -35 ℃, -35 ℃ will happen in less than crisp , cold resistance
than polyethylene.
( 4) Chemical resistance: good chemical stability of polypropylene , in addition to sulfuric acid can be concentrated ,
the variety of other chemical reagents are relatively stable, low molecular weight aliphatic hydrocarbons, aromatic
hydrocarbons and chlorinated hydrocarbons can make PP soften and swell , while its chemical stability as well as
improved with increasing degree of crystallinity , making it suitable for a variety of chemical polypropylene pipes and
fittings , anti -corrosive to good effect.
( 5) Electrical properties: Polypropylene frequency insulation performance, since it absorbs almost no water , so the
insulation performance is not affected by humidity. It has a high dielectric constant , and with the rise in temperature ,
the heat can be used to produce electrical insulation products, it is also very high breakdown voltage , suitable for electrical
accessories , anti- voltage , arc resistance , but electrostatic high, with copper contacts easy to aging .
( 6 )weather resistance : Poly Propylene was very sensitive to ultraviolet light . Zinc oxide , dilaurylthiopropionate ester ,
carbon black or similar milky fillers can improve its resistance properties.
Second, the use of polypropylene
( 1 )film products : polypropylene film is not transparent and glossy products , small water vapor and air permeability ,
it is blown into film. Cast film (CPP), biaxially oriented film (BOPP) , etc.
( 2)injection molding products : can be used in the automotive, electrical，mechanical , instrumentation, radio , textile,
medical fabric,defense and other engineering accessories , agricluture fabric, table clothes, pp spunbond nonwoven fabric daily necessities, turnover box . Health care equipment, building materials
( 3 )extruded products: do pipes, profiles, monofilament fish with a rope , packing tape, tied belay , woven belt , fiber,
composite coating, sheet, plate , etc., blow molding products, a variety
of small containers.
( 4 ) Other : low foaming , Gaisu board . Synthetic wood , laminate , synthetic , high foam can be used for structural foam .
