Flashcards in Questions from class - Lecture 12 Deck (6)
How does the force needed to stretch a rubber vary with the elongation?
Scales with (lambda - 1/lambda^2), that is approximately linearly with lambda.
How is the plateau modulus related to the molar mass between crosslinks?
The plateau modulus scales with 1/M_c.
Which structures are observed in crystalline polymers on different length scales?
At small length scales: lamellae
At bigger length scales: spherulites
In which temperature range is crystallization possible?
From approx. T_g + 30K - T_m - 10K
Which molecular characteristics favor crystallization?
Highly packed arrangement of chains must be possible in 3D. Energy loss upon crystallization.
Symmetric, linear chains crystallize best.
vdW forces between chains. Polar groups can result in rigid and well-oriented arrangement. Isotacticity. Low degree of branching. High molar mass.