Surface Energies of Polymers:

Many plastics are hydrophobic and are not naturally "wettable". As a general rule, acceptable adhesion is achieved when the surface energy of the solid substrate (measured in dynes/cm) is approximately 8-10 dynes/cm greater than the surface tension of the liquid. Table 1.0 shows typical surface energies for untreated polymer substrates. Due to the vast differences between resin formulations, the values listed below should be used for general benchmark purposes.

Table 1.0 -- Surface Energies of Untreated Polymers

Surface energy (dynes/cm)
Polypropylene, OPP, BOPP 29-31
Polyethylene 30-31
Polyvinyl Acetate (PVA) Copolymer 33-44
Polystyrene 38
Polystyrene (low ionomer) 33
ABS 35-42
Polyamide <36
Epoxy <36
Polyester 41-44
Rigid PVC 39
Plasticized PVC 33-38
Engineering Thermoplastics
PET 41-44
Polycarbonate 46
Polyimide 40
Polyacetal <36
Polyphenylene oxide (PPO) 47
PBT 32
Polysulfone 41
Polyethersulfone 50
Polyphenylene sulfide (PPS) 38
Nylon 33-46
Polyethylene copolymer 20-24
Fluorinated ethylene propylene 18-22
Polyvinyl fluoride 28
Silicone 24
Natural rubber 24
Styrene butadiene rubber 48