ANDRADE, A. L. S.; ANDRADE, ANDRÉ L. SIMÕES.; ANDRADE, ANDRÉ LUÍS SIMÕES.; http://lattes.cnpq.br/9922792912017424; ANDRADE, André Luís Simões.
Resumo:
The objective of this work was to develop a textile finishing based on chitosan/clay
bionanocomposites in cotton fabrics in an attempt to confer antimicrobial and UV
blocking properties. First, two commercial chitosans, coded as Q86 and Q92, were
tested, according to their datasheets they had degrees of deacetylation (GD) of
86.7% and 92.0%. 1% and 2% (w/v) solutions of chitosan in 1% (v/v) acetic acid
were prepared, where 100% cotton tissue samples were immersed (with 150
(T150F) and 200 (T200F) yarns), to promote surface modification. Chitosan was
characterized by spectroscopy in the infrared region (FTIR) for determination of GD
and by capillary viscosimetry for determination of Molecular Weight (Mv). The tissue
samples were impregnated with chitosan and bionanocomposite chitosan/clay
solutions at concentrations of 5, 10 and 50% of Cloisite C20A clay in relation to
chitosan mass. Under the same conditions of preparation, chitosan solutions were
obtained with the addition of the plasticizer Polyethyleneglycol (PEG), to promote
better impregnation of the films and/or Irgacure® crosslinking agent, with
subsequent exposure to a UV source to promote crosslinking. The coated tissues
were characterized by FTIR, Optical Microscopy (OM), Scanning Electron
Microscopy (SEM), Swelling Degree, Contact Angle measurement, and Dispersive
Energy Spectrometry (EDS). In addition to these characterizations, the antimicrobial
activity and sun protection factor were also evaluated. The GD values of the two
chitosans used were differed from those reported by the manufacturers, with both
chitosans being approximately 76%. For molecular weight, it was observed that Q86
had a value near 35 kDa and Q92 of 90 kDa and that immersion of the tissues in
chitosan solutions at any concentration altered the color of the samples. The Q86
was selected for the evaluation of the antimicrobial activity, since it presented lower
molar mass than Q92, potentiating the activity against Gram negative strains. The
T200F tissue was also selected, as it provided a greater useful surface for the
coverage by chitosan films. The Swelling Degree, Contact Angle, MO and MEV tests
showed that there was no contribution of the processing variables or the use of the
PEG to the sample coverage. The SEM showed a superficial alteration of the tissue
samples and the Dispersive Energy Spectrometry (EDS) confirmed the change in
the chemical composition of the same. The FTIR data from the tissue samples
confirm the results of EDS. The results of antimicrobial activity demonstrated only
tenuous activity against E. coli. The Ultraviolet Protection Factor (FPU) results
statistically show that the bionancomposite coatings elevated the FPU of the
crosslinked samples. According to these results it is evidenced that cotton fabrics
coated with chitosan/clay bionanocomposites can be promising as active tissues -
with antimicrobial characteristics and with UV protection.