陕西科技大学：《包装技术基础 Fundamentals of Packaging Technology》课程PPT教学课件（英文版）Lesson 7 Plastics 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

1 Plastic in Packaging Lesson 7 第7课 塑料在包装中的应用

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:

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:

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

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

4 Plasticating Extruder Exit port Gear reducer Variable speed motor Feed throat Feed hopper Hopper throat Cooling jacket Screw Heater bands 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

5 Adjustable Die Lips Extrusion Die Adjustable Pressure (Restrictor) Bar Extruder Cast Film and Sheet Extrusion Fig.10.4

5 Adjustable Die Lips Extrusion Die Adjustable Pressure (Restrictor) Bar Extruder Cast Film and Sheet Extrusion Fig.10.4

6 Extruder #1 Extruder #2 Extruder #3 Material #1 Material #2 Material #3 Three-Layer Coextrusion Fig.10.9

6 Extruder #1 Extruder #2 Extruder #3 Material #1 Material #2 Material #3 Three-Layer Coextrusion Fig.10.9

7 Extrusion Cast Film Line Layout Extruder Extrusion die Chill roll Edge trimmer Material roll Fig.10.5

7 Extrusion Cast Film Line Layout Extruder Extrusion die Chill roll Edge trimmer Material roll Fig.10.5

8 Machine Direction Orientation Rotation x 1 x 2 x 3 X 4 From extruder casting rolls Fig.10.8

8 Machine Direction Orientation Rotation x 1 x 2 x 3 X 4 From extruder casting rolls Fig.10.8

9 Extruder Casting Rolls Annealing Zone Extrusion Die Tenter Clips Cross Direction Orientation Fig.10.8

9 Extruder Casting Rolls Annealing Zone Extrusion Die Tenter Clips Cross Direction Orientation Fig.10.8

10 Bubble Blow-up air inlet Cooling air Cooling air Plastic from extruder Die lip adjusting bolts Die Body Die core Frost line Bubble constantly pulled up Blown-film Die Cross-Section Fig.10.6 The die is often rotated to prevent gauge bands

10 Bubble Blow-up air inlet Cooling air Cooling air Plastic from extruder Die lip adjusting bolts Die Body Die core Frost line Bubble constantly pulled up Blown-film Die Cross-Section Fig.10.6 The die is often rotated to prevent gauge bands