Lesson 7 Plastic in Packaging 第7课塑料在包装中的应用
1 Plastic in Packaging Lesson 7 第7课 塑料在包装中的应用
Polymer Properties Depend On 1. What elements are in the molecule? 2. What size(molecular weight) is the molecule? 3. Is the molecule polar or non-polar? 4. What shape is the molecule? 5. What is its thermal history? 6. What is its mechanical history?
2 1. What elements are in the molecule? 2. What size (molecular weight) is the molecule? 3. Is the molecule polar or non-polar? 4. What shape is the molecule? 5. What is its thermal history? 6. What is its mechanical history? Polymer Properties Depend On:
Deformation and Thermal History Room temperature deformation is permanent Plastics stretched at about t and cooled slowly are heat stable Plastics stretched at about Ta and cooled quickly have "memory and will shrink if reheated
3 Deformation and Thermal History Room temperature deformation is permanent. Plastics stretched at about Tg and cooled slowly are heat stable. Plastics stretched at about Tg and cooled quickly have “memory” and will shrink if reheated
Plasticating Extruder 产 Gear reducer Feed hopper Heater bands /Feed throat LF ANSSSYSSSSSSL,Exit port Hopper throat Screw Cooling jacket Variable speed motor Fig.10.2
4 Plasticating Extruder Exit port Gear reducer Variable speed motor Feed throat Feed hopper Hopper throat Cooling jacket Screw Heater bands Fig. 10.2
Cast Film and sheet Extrusion Extruder Eⅹ trusion Die Adjustable Pressure (Restrictor) Bar Adjustable Die Lips Fig 10.4
5 Adjustable Die Lips Extrusion Die Adjustable Pressure (Restrictor) Bar Extruder Cast Film and Sheet Extrusion Fig.10.4