Polypropylene Chemische Eigenschaften,Einsatz,Produktion Methoden
Chemische Eigenschaften
Polypropylene is a low-density resin that offers a good balance
of thermal, chemical, and electrical properties, along with
moderate strength. Strength can be significantly increased by
using reinforcing agents such as glass fiber. Polypropylene has
limited heat resistance, but it can be used in applications that
must withstand boiling water or steam sterilization.
Polypropylenes can resist chemical attack and are unaffected
by aqueous solutions of inorganic salts or mineral
acids and bases, even at high temperatures. They are not
attacked by most organic chemicals, and there is no solvent
for these resins at room temperature. The resins are attacked,
however, by halogens, fuming nitric acid, other active oxidizing
agents, and by aromatic and chlorinated hydrocarbons
at high temperatures .
Polypropylene is translucent and autoclavable. Properties
can be improved by compounding with fillers, by blending with synthetic elastomers, and by copolymerizing with small
amounts of other monomers.
Verwenden
Modifier for waxes to reduce blocking, scuffing and abrasion. Improves pigment dispersion in polypropylene films and fibers.
Definition
polypropylene: Anisotactic polymer existing in bothlow and high formula-weight forms.The lower-formula-weight polymer ismade by passing propene at moderatepressure over a heated phosphoricacid catalyst spread on aninert material at 200°C. The reactionyields the trimer and tetramer. Thehigher-formula-weight polymer isproduced by passing propene into aninert solvent, heptane, which containsa trialkyl aluminium and a titaniumcompound. The product is amixture of isotactic and atacticpolypropene, the former being themajor constituent. Polypropene isused as a thermoplastic mouldingmaterial.
Vorbereitung Methode
In PP production, propylene monomer is polymerized to
make the homopolymer by using a Ziegler–Natta type coordination
catalyst. This catalyst results from the reaction and
interaction of a transition metal compound and an organometallic
compound, usually an alkylaluminum compound.
Halide atoms are involved in most such catalyst systems .
Polypropylene can be made by solution, slurry (or solvent),
bulk (or liquid propylene), or gas-phase polymerization, or a
combination of these processes . The most widely used is
the slurry process; however, the current trend is toward the
gas-phase process. In the solution, slurry, and bulk processes,
the catalyst system is mixed with propylene and a hydrocarbon
diluent (usually hexane, heptane, or liquid propylene) in a
reactor. After polymerization, the reaction mixture enters a
flash tank where unreacted propylene is removed and
recycled. Propylene–ethylene copolymers [9010-79-1] can
be manufactured when ethylene is fed along with propylene to
the polymerization reactor or by adding ethylene and propylene
to a postpolymerization reactor that contains PP. This
mixture may then be purified to remove lowmolecular weight
and atactic fractions and washed to remove catalyst residues.
The polypropylene resin is then dried and pelletized. During this time, additivesmay be incorporated in the gas-phase
process; no liquid diluent is used .
Allgemeine Beschreibung
Tan to white odorless solid. Less dense than water and insoluble in water. Hence floats on water.
Air & Water Reaktionen
Insoluble in water.
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Polypropylene reacts with chlorine, fuming nitric acid and other strong oxidizing agents.
Hazard
Questionable carcinogen.
Health Hazard
No apparent toxicity
Industrielle Verwendung
Polypropylene is similar in structure to polyethylene,but every other carbon atom has oneof its H2 atoms replaced by a CH2group.Although electrically similar to polyethylene,polypropylene can be made in thinner films, say 5μm as against about 25 μm for polyethylene.These films replace paper for impregnatedcapacitors, with reduced loss.
Sicherheitsprofil
Moderately toxic by
ingestion and intraperitoneal routes.
Questionable carcinogen. When heated to
decomposition it emits acrid smoke and
irritating fumes. Used in injection molding for auto parts, in bottle caps, and in
container closures.
Carcinogenicity
No data on the carcinogenicity
and mutagenicity of propylene are available for evaluation
by the working group.
Polypropylene Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
