Applied Physics A

, Volume 101, Issue 1, pp 215–224

Model properties relevant to laser ablation of moderately absorbing polymers

  • S. Lazare
  • I. Elaboudi
  • M. Castillejo
  • A. Sionkowska
Article

DOI: 10.1007/s00339-010-5754-5

Cite this article as:
Lazare, S., Elaboudi, I., Castillejo, M. et al. Appl. Phys. A (2010) 101: 215. doi:10.1007/s00339-010-5754-5

Abstract

A set of polymers including biopolymers and polymers from renewable resources are studied, with attention paid to their capability to form a foamy surface layer by laser irradiation. A model of laser-induced pressure wave is discussed, with its tensile tail giving rise to a fast and dense nucleation of cavities that can expand to microbubbles when filled with ablation gas. The intensity of the pressure wave has a maximum for an absorption coefficient of ∼1000 cm−1. Polyvinyl acetate, studied as a prototype polymer experimentally and by modeling, allows discussing the role of the viscosity drop in the dynamics of the laser-induced cavitations. In the Zeldovich frequency factor, a T (temperature) and P (pressure) dependent model of viscosity, and a T-dependent model of surface tension are introduced. It is further suggested that the well-known free-volume nanoholes existing in the material before the irradiation can constitute the nuclei of importance and that their concentration is one of the factors controlling the pre-exponential factor in the nucleation rate law.

Nomenclature

α

absorption coefficient

la=α−1

laser absorption depth

cs

speed of sound in the polymer

Cp

heat capacity of the polymer

ρ

density of the polymer

F(t)

instantaneous fluence

g(t)

normalized time profile of laser pulse

τ

pulse width

τ0

pulse width parameter in g(t)

F0

total fluence for a ns pulse

f0

fluence of a “Dirac” or fs laser pulse

αcsτ<1

pressure confinement condition

t

time

z

depth

J(t,z)

nucleation rate

σ

surface tension of the material

Z

Zeldovich frequency factor

n0

molecular density factor

v

volume of a free volume hole in PVAc

J0=Zn0

pre-exponential factor

Pi

pressure inside

Po

pressure outside the nucleating bubbles

Pv

vapor pressure inside bubbles

T(z,t)

temperature at depth z and time t

Tc

critical temperature of the polymer

T0

ambient temperature

Tmax 

maximum surface temperature

A0

target absorptivity

Γ

Grüneisen constant

Rs=−1

surface reflection coefficient of sound

po(z,t)

pressure for a fs pulse (ultrashort)

Po(z,t)

pressure for a ns pulse (long)

p1(z,t),p2(z,t) and p3(z,t)

pressure of the 3 superimposed subwaves

δT,δP,TR,PR

parameters of the Avramov model

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • S. Lazare
    • 1
  • I. Elaboudi
    • 1
  • M. Castillejo
    • 2
  • A. Sionkowska
    • 3
  1. 1.Institut des Sciences Moléculaires (ISM) UMR 5255Université Bordeaux 1TalenceFrance
  2. 2.Instituto de Química Física Rocasolano, CSICMadridSpain
  3. 3.Faculty of ChemistryNicolaus Copernicus UniversityToruńPoland