#threadsofpolymers Etiketinde En Popüler Paylaşımlar
#threadsofpolymers
For uncrosslinked polymer chains, the entanglement molecular weight is a thermodynamic property.
One can easily achieve an “underentangled” state, in which the polymer chains entangle less than the thermodynamic entanglement density. Just deform the polymer.
🧵1/5 An uncrosslinked, high-molecular-weight, amorphous polymer is glassy at low temperatures, rubbery at intermediate temperatures, and liquid at high temperatures.
This behavior is characterized by modulus as a function of temperature.
Modulus is measured at small stress.
#threadsofpolymers
Wear and tear of tires emit particles
Particles are of sizes 10 nm - 0.1 mm.
Globally on average one person emits 0.8 kg/year.
Wear and tear of tires contribute 5-10% polymers in oceans, and 3-7% particles in air.
https://t.co/Tv5eDhTQDj
In discussing with colleagues and teaching, it helps to have facts in mind, sharply.
I’ll gather threads on such facts, keeping each fact basic, and each thread short.
#threadsofpolymers, polymer
#thermofact, thermodynamics
#fractofact, fracture
#beinglinear, linear algebra
#threadsofpolymers
Entropy of mixing in condensed phases
1/5 When a pure substance of molecule A mixes with a pure substance of molecule B, the entropy of the mixture exceeds the sum of the entropies of the two pure substances.
The excess is called the entropy of mixing.
#threadsofpolymers Arrested Phase Separation (APS)
https://t.co/wEMwc84EJY
🧵1/10 Arrested Phase Separation (APS)
Two species of polymers often separate into phases.
Under certain conditions, the sizes of the phases arrest at the nanoscale.
Why?
@GuogaoZhang @Junsoo_twit @jasongsteck @Christine_h_ahn @sammyhassan180
#threadsofpolymers Ductile-to-Brittle Transition in a Polymer Glass
https://t.co/Gwtaep5mP9
🧵1/6 Monomers form polymer chains by chemical bonds. Polymer chains aggregate by physical interactions.
The chemical bonds are much stronger than the physical interactions. A factor ~ 100 is representative.
A figure from a 2014 paper @ShiQingWang4
#threadsofpolymers Entanglement Molecular Weight
https://t.co/UQzGiGqU4B
🧵1/5 An uncrosslinked, high-molecular-weight, amorphous polymer is glassy at low temperatures, rubbery at intermediate temperatures, and liquid at high temperatures.
This behavior is characterized by modulus as a function of temperature.
Modulus is measured at small stress.
In discussing with colleagues and giving lectures, it helps to keep certain basic facts in mind.
Let's gather threads on such facts for polymers. I'll keep each fact basic, and each thread short.
I'll call them Threads of Polymers, and use #threadsofpolymers.
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