Rubber, Heat and Molds: teacher key

How Plastic Toy Bricks Are Made, grade 10 edition, written for 10th grade. A closer look at why one small plastic part holds so well, how molten plastic becomes a brick in seconds, and what happens to the plastic that is left over.

Read the book. Print this page for the key.

Questions and answers

1. Which part of ABS gives it toughness?
   • Styrene
   • Polybutadiene (answer)
   • Pigment
2. When was the patent for the brick filed?
   • January 28, 1958 (answer)
   • January 23, 1958
   • 1947
3. Why do thermoplastics suit injection molding better than thermosets?
   • They are always cheaper
   • A thermoset left in the barrel too long can seize the screw (answer)
   • They need no heat
4. What does the 2011 weighing example show about quality checks?
   • Bags were never weighed
   • Bags outside the weight range are caught so an operator can re-sort them (answer)
   • Only the heaviest bags are kept
5. In this book, what does amorphous mean?
   • Very hard
   • Having no definite melting point (answer)
   • Transparent
6. What did a 2008 report say happens to most LEGO manufacturing plastic waste?
   • It is buried
   • All but about 1 percent is recycled (answer)
   • It is burned in the factory

Words

• amorphous: without fixed shape
• thermoplastic: plastic that melts
• prototypes: first test models
• polybutadiene: rubbery ingredient
• silos: storage tanks