PKG 825-FS22 Polymer Packaging Materials Homework I
Homework I: to complete HW I, you will need to read chapters 1 to 3, the lab, and the lecture material. You must provide a complete answer to each question to receive all the points. The HW I report must be typed and submitted to the assignment folder. Total points: 100 pts.
Due date: Firday, 9/16/22 at 11:55 PM EDT.
Questions
1. The figure below shows the glass transition and melting temperatures of the main packaging polymers (i.e., PEs, PET, PS, Nylon, PVDC) and some biodegradable polymers (i.e., PLA, PCL, PHB/V, PHA). Based on the information acquired in the class, explain the main reason for this difference based on the polymer constitutional units. Make sure to discuss the influence of each type of chemical bond in the structure. 20 pts
Figure 1. Melting vs glass transition temperature for different polymers.
2. LLDPE is considered a regular branched polymer, LDPE is considered a branched polymer, and HDPE is considered a linear polymer. Explain how the linearity and branching of the different PEs are obtained and the main effects on their properties and final performance. Provide concrete differences and the effect of these differences on the polymer final properties. 20 pts.
2. Discuss the properties (Tg, Tm, crystallinity, tensile strength, barrier, water sensitivity) you would expect from the polymer shown below, based on considerations of regularity, conformational flexibility, and intermolecular forces. Explain your reasoning.
Comparison with better-known polymers is a good way to proceed. I do NOT want you to research this polymer (and it may well not exist, anyway). I want, instead, for you to draw some logical conclusions based on the concepts we have discussed in class. 20 pts
3. After reading the report Breaking the Plastic Wave, PEW Charitable Trusts, (https://www.systemiq.earth/wp-content/uploads/2020/07/BreakingThePlasticWave_MainReport.pdf), explain what are the main proposed waste management techniques to reduce the amount of plastic leaking into the ocean? 20 pts .
5. In the last decade, we acquired significant knowledge about the semicrystalline structure of polymers. What are the main consequences of non-crystalline (i.e., mobile (MAF) and the rigid (RAF) amorphous fractions) and crystalline phases (Xc-crystalline fraction) on the properties of glassy polymers (make sure to discuss mechanical and barrier properties)? Furthermore, what are the differences between a glassy and rubbery polymer? What are the implications for packaging applications? 20 pts
