Environmental Engineering Reference
In-Depth Information
Table 3.1
Glass Transition Temperature of Common Plastics
Polymer
Tg (°C) Applications
Low-density polyethylene
(LDPE)
−100
Plastic film, bags, and containers
High-density
polyethylene (HDPE)
−100
Bottles, milk jugs, toys
Polypropylene (PP)
−20
Bottle caps, tape, film, fiber
Poly(ethylene
terephthalate) (PET)
70
Soda bottles, plastic film
Polycarbonate (bisphenol
A polycarbonate) (PC)
144
Bottles, containers, and glazing
Poly(vinyl chloride)
(PVC)
80
Siding, pipes, flooring
Polystyrene (PS)
95
Foam cups and food service items
(EPS), cutlery, containers
Poly(tetrafluoroethylene)
(PTFE)
115
Nonstick surfaces
Poly(vinylidene chloride)
(PVDC)
−35
Saran wrap
Polyacrylonitrile (PAN)
Textile fibers
Poly(methylmethacrylate)
(PMMA)
102-117 Glazing in skylights, windows, and
picture frames. Used also in lighting
fixtures
Poly(vinylacetate) (PVAc) 30
Chewing gum and bubble gum base,
adhesives
Polyamide (nylon 6) (PA) 40
Fishing gear and fiber
Processing generally involves heating the polymer well above the Tg, and on
heating,aplasticmaterialwilltransitionthroughthreephasesdistinguished
by very different moduli (or stiffness; see
Fig. 3.7
). The high modulus of
the polymer in the glassy state changes somewhat abruptly when it reaches
the Tg, and a low-modulus “rubbery” plateau is reached. At even higher
temperatures, the amorphous polymer becomes a “melt” or a viscous liquid
