Environmental Engineering Reference
In-Depth Information
Figure 4.8
A diagram of the bottle blow molding process. 1. Heated
parison. 2. Mold closing. 3. Blowing air into mold 4. Cooling and opening
mold. 5. Molded bottle.
Table4.4
comparesthethreepopularprocessingmethodsintermsofenergy
demand by selected aspects of the process and underlines the energy use by
auxiliary (usually downstream) equipment in nearly all the processes.
Table
4.5
summarizes approximately energy demand by different aspects of the
basic process itself. In injection molding, extrusion, and film blowing, the
blending of the viscous mass of plastic takes up most of the energy.
Table 4.4
Relative Energy intensity of Selected Plastic Processing
Techniques
Source: Based on data from the British Plastics Federation (1999).
Processing
method
Blend Mix Expand Heat
mold
Cool
mold
Cure
Injection molding
+++ ++
++
++
Extrusion
++++ ++
++
Film blowing
++++ ++ +++
+++
Compression
molding
+
+
+++
+++++
Thermoforming
+
+
+++
++
Calendaring
+++ +
+
Rotational molding
++
+
+
++
++
Foam blowing
+
+
++
++
Unsaturated
polyester
*
+
+++
