Spumă

Spumă formată de un săpun

Spuma este un sistem dispers format într-un lichid în care sunt răspândite bule de gaz, separate între ele de lichidul respectiv.[1] Termenul mai poate face referire și la materiale asemănătoare spumei, precum spuma poliuretanică, polistiren, etc.

Formare

Sunt necesare câteva condiții pentru ca spuma să se formeze: este nevoie de lucru mecanic, prezența unor surfactanți care să reducă tensiunea superficială, iar formarea spumei trebuie să fie mai rapidă decât distrugerea sa.[2]

Lucrul mecanic (L) este necesar pentru formarea spumei, deoarece avem nevoie de o creștere a suprafeței (ΔS):

unde γ este tensiunea superficială.

Vezi și

Referințe

  1. ^ Spumă” la DEX online; accesat pe 19 iulie 2017
  2. ^ Bikerman, J.J. "Formation and Structure" din Foams; New York, Springer-Verlag, 1973. ch 2. sec 24–25

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