Plastics

Material

Plastics

Plastics are polymers with plastic behaviour (see glossary).

Polymers are organic materials characterized by long chain-like molecules built up from many units (monomers), generally repeated hundreds or thousands of times. All atoms in a chain are bonded by covalent bond to each other, while Van der Waals bonding keeps the chains together. All plastics are polymers but not all polymers are plastics (e.g. starch and cellulose).

Plastics generally have low density, low strength, are electrical and thermal insulators and have good resistance to chemicals. They can usually be recycled as raw materials (thermoplastics) or as inert fillers (thermosetting).

Listing

Plastic type	Price (DKK/kg)	Density (kg/liter)
ABS	12	1.05
EP (epoxy)
EP GF (epoxy)	38	1.5
PA	29	1.10-1.15
PC	36	1.2
PE	8-9	0.9-0.96
PE-HD	9	0.96
PE-LD	8	0.9
PEEK	-	-
PET (polyester)	-	-
PH (Bakelite)	10	-
PMMA (acrylic)	19	1.18
POM (acetal)	26	1.41
PP	8	0.9
PS	11	1.05
PTFE		2,12-2,25
PUR	35	1,11-1,25
PUR for foaming	20	0,01-0,24
PVC	11	1.38
UP (polyester)	20	1.5
UP GF (polyester)	20	1.5
Vinylester	30	-

Price Price level July 1997. GF means glass filled. The prices are only meant as guiding figures. Prices vary significantly for different material purity and for different types of raw material (plate, wire, granulate, etc.).

Plastics News supply a frequently updated resin price list (US prices) on the web.

When comparing prices of different materials, it should furthermore be noted that a number of factors influence the amount of material used in a product, e.g. material stiffness, production waste, etc.

In the detailed description of plastic materials, cost is indicated as either low (less than 10 DKK pr. kg), medium (10-20 DKK pr. kg) or high (more than 20 DKK pr. kg).

References

Index of trade names:
Matweb (look under help)

Links:
Endura Plastics
Modern Plastics
Injection Moulding Cost Estimator
The Danish Plastics Federation

Books:
Plast og gummi ståbi
Design with plastic

For materials in general see also the following links:
Machine Design On-line
Materials by Design

Photo Thomas Nissen (Computer graphics)