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.
PACKING
Different types of Plyers are packed in a 25-Kgs. Bags
Type of Polymers:
Polyethylene is a thermoplastic polymer with a variable crystalline structure and a vast range of applications depending on the particular type. It is one of the most widely produced plastics in the world.
- Low-Density Polyethylene (LDPE):
- Application: shopping bags and other plastic film applications.
- Packing: Different types of Plyers are packed in a 25-Kgs. Bags
- Linear Low-Density Polyethylene (LLDPE)
- Application: shopping bags and other plastic film applications.
- Packing: Different types of Plyers are packed in a 25-Kgs. Bags
- High Density Polyethylene (HDPE):
- Application: milk cartons, laundry detergent, garbage bins, and cutting boards.
- Packing: Different types of Plyers are packed in a 25-Kgs. Bags
| 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) is a thermoplastic “addition polymer” made from the combination of propylene monomers 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
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) is one of the most commonly used thermoplastic polymers worldwide (next to only a few more widely used plastics like PET and P.P.). It is naturally white and very brittle (before the additions of plasticizers) plastic. PVC has been around longer than most plastics. 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 | 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 is a synthetic aromatic hydrocarbon polymer made from the monomer known as styrene Polystyrene can be solid or foamed.
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.