PE, PP, PVC, PS

What is polymer?

Polymers are large molecules made by bonding (chemically linking) a series of building blocks. The word polymer comes from the Greek words for “many parts.” Each of those parts is called, monomer.

For more information on the grades and specifications, please do not hesitate to contact us

Packing

  • Different types of Plyers are packed in a 25-Kgs. Bags

Type of RDR Energy Polymers:

Polyethylene (PE)

Polyethylene is a lightweight, durable thermoplastic with variable crystalline structure. It is one of the most widely produced plastics in the world.

1-Polyethylene (PE)

  • Low-density polyethylene (LDPE)
  • High-density polyethylene (HDPE)
  • Linear low-density polyethylene (LLDPE)

Application of polymers

Ranging for films, tubes, plastic parts, laminates, etc. in several markets (packaging, automotive, electrical, etc.).

Comparison between Main Types of Polyethylene

  LDPE LLDPE HDPE
Polymer Full Name Low Density Polyethylene Linear Low Density Polyethylene High Density Polyethylene
Structure High Degree of short chain branching + long chain branching High Degree of short chain branching Linear (or Low degree of short chain branching)
Catalyst and process Using radical polymerization using tubular method or auto clave method Using Ziegler-Natta catalyst or metallocene catalyst Ziegler-Natta catalyst in:
– Single-stage polymerization
– Multi-stage polymerization or a Cr or Phillips-type catalyst
Density 0.910-0.925 g/cm3 0.91-0.94 g/cm3 0.941-0.965 g/cm3
Crystallinity Low crystalline and high amorphous (less than 50-60% crystalline) Semi-crystalline, level between 35 to 60% High crystalline and low amorphous (>90% crystalline)
Characteristics
  • Flexible and good transparency
  • Good moisture barrier properties
  • High impact strength at low temperature
  • Excellent resistance to acids, bases and vegetable oils
 As compared to LDPE, it has:

  • higher tensile strength
  • higher impact and puncture resistance
  • Excellent Chemical Resistance
  • High tensile strength
  • Excellent moisture barrier properties
  • Hard to semi-flexible
Recycling Code
General Applications Shrink wrap, films, squeezable bottles garbage bags, extrusion moldings, and laminates High performance bags, cushioning films, tire separator films, industrial liners, elastic films, ice bags, bags for supplemental packaging and garbage bags
  • Molecular weight distribution is relatively narrow, has applications in injection moldings or flat yarns, and the latter type
  • Molecular weight distribution is wide, is used to make film products, hollow plastic products and pipes

Polypropylene (PP)

It finds uses in the same industries as PE. PP competes in many areas with HDPE. In comparison to HDPE, it has a higher melting point, better crack resistance, a higher heat deflection temperature, and in many cases, higher tensile strength. PP has superior stress crack resistance. It is, however, less stable than HDPE to thermal, light, UV and oxidative degradation.

Polypropylene Processing Conditions

Polypropylene can be processed by virtually all processing methods. Most typical processing methods include Injection Molding, Extrusion Blow Molding and General Purpose Extrusion.

Injection Molding

  • Melt temperature: 200-300°C
  • Mold temperature: 10-80°C
  • Drying is not necessary if stored properly
  • High mold temperature will improve brilliance and appearance of the part
  • Mold shrinkage lies between 1.5 and 3%, depending on processing conditions, rheology of the polymer and thickness of the final piece

Extrusion (tubes, blow and cast films, cables, etc.)

  • Melt temperature: 200-300°C
  • Compression Ratio: 3:1
  • Cylinder Temperatures: 180-205°C
  • Pre-Drying: No, 3 hours at 105-110°C (221-230°F) for regrind
  • Blow molding
  • Compression molding
  • Rotational molding
  • Injection blow molding
  • Extrusion Blow Molding
  • Injection stretch blow molding
  • General Purpose Extrusion

Application

It is used in a variety of applications to include packaging for consumer products, plastic parts for various industries including the automotive industry, special devices like living hinges, and textiles.

Polyvinyl chloride (PVC)

Polyvinyl chloride or PVC is formed from the monomer chloroethene, which is commonly known as vinyl chloride.

PVC TYPES:

The popular methods used to manufacture PVC commercially are Suspension PVC (S-PVC) Process and Bulk or Emulsion (E-PVC) Process

Suspension PVC (S-PVC) Process

In pressure-tight reactor, the monomer is introduced with polymerization initiator and other additives. The content of the reaction vessel are mixed continuously to maintain suspension and ensure uniform particle size of PVC resin.
Typical suspension polymerized PVC has a mean particle size of 100-150 µm with a range of 50-250 µm.
S-PVC grades are formulated to meet an extensive range of requirements such as, high plasticizer absorption for flexible products, or high bulk density and good powder flow required for rigid extrusion

Bulk or Emulsion (E-PVC) Process

In this process, surfactants (soaps) are used to disperse the vinyl chloride monomer in water. The monomer is trapped inside soap micelles are protected by the soap and polymerization takes place using water soluble initiators.
The primary particles are solid, smooth surfaced spheres, which are clustered into irregular shaped aggregates with a typical mean particle size of 40-50 µm with a range of 0.1-100 µm.
E-PVC resins are used in a wide range of specialty applications such as coating, dipping or spreading

Suspension PVC (S-PVC) Process Bulk or Emulsion (E-PVC) Process
  • Lower flexible PVC formula costs
  • PVC particles obtained are mixed with plasticizers & can be extruded in pellets, which are further used for processing via extrusion, calendaring, injection molding…
  • Processing equipment is typically very expensive
  • Higher flexible PVC formula costs
  • PVC powder obtained is mixed with plasticizers to produce a paste which is further used for coatings, dipping, spraying…
  • Processing Equipment may or may not be very expensive
Suspension PVC (S-PVC) Process Bulk or Emulsion (E-PVC) Process
  • Lower flexible PVC formula costs
  • PVC particles obtained are mixed with plasticizers & can be extruded in pellets, which are further used for processing via extrusion, calendaring, injection molding…
  • Processing equipment is typically very expensive
  • Higher flexible PVC formula costs
  • PVC powder obtained is mixed with plasticizers to produce a paste which is further used for coatings, dipping, spraying…
  • Processing Equipment may or may not be very expensive

Application

A collection of products made from polyvinyl chloride: pipes, electrical tape, and car parts.

Polystyrene (PS)

Polystyrene is made from the monomer styrene, which is a liquid petrochemical.

Types

The three most important grades of styrene are:

  • GPPS: General-purpose polystyrene, also known as crystal-clear polystyrene, is a fully transparent, rigid and rather brittle low cost thermoplastic made from styrene monomer. GPPS is a solid product manufactured in the form of 2-5 mm pellets.
  • HIPS: High impact polystyrene contains usually 5 to 10% rubber (butadiene) and is used for parts, which require high(er) impact resistance. HIPS is a graft copolymer having polystyrene sidearm. The grafting occurs when some of the radicals react with the double bonds of the polybutadiene.
  • EPS: Expandable polystyrene consists of micro-pellets or beads containing a blowing agent (usually pentane). The expanded or foamed polystyrene is thermally insulating and has high impact resistance.

Applications:

 

Uses include protective packaging (such as packing peanuts and CD and DVD cases), containers, lids, bottles, trays, tumblers, disposable cutlery  and in the making of models.

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