Banca de DEFESA: GABRIELE POLÉZI

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : GABRIELE POLÉZI
DATE: 31/01/2024
TIME: 14:00
LOCAL: on line
TITLE:

PREPARATION AND CHARACTERIZATION OF HYBRID FOAMS OF FUNCTIONALIZED CELLULOSE AND CARBON BLACK WITH POTENTIAL APPLICATION AS ANTISTATIC PACKAGING

PAGES: 70
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Química de Interfaces
SUMMARY:

Electrically conductive foams are widely used in the electronics industry as antistatic packaging
to protect electrical or electronic components sensitive to electrostatic discharge. These
packages present electrical resistivity low enough (<1011 Ω.cm) to allow the dissipation of
electrostatic charges accumulated on the surface of the product. Commercially, antistatic foams
are composed of conductive agents dispersed in petroleum-derived polymer matrices. These
materials combine high energy demands in the synthesis and molding processes, large
generation of dust during the mixing of components, and extremely low degradation rates,
points that generate occupational risks and have a negative impact on the environment. As a
potential solution, cellulose, a biodegradable and abundant biopolymer, has been explored as
an alternative material to produce more environmentally friendly foams. In this work, cationic
cellulose fibrils (FCC), isolated from sugarcane bagasse, were used to disperse carbon black
(CB) in water and produce electrically conductive foams by freeze-drying method. The FCC
were obtained by cationization reaction with glycidyltrimethylammonium chloride. CB was added
to FCC in an aqueous medium, producing stable colloidal dispersions due to electrostatic
interactions between the positive surface charges (trimethylammonium group, –N(CH3)3
+) of
FCC and the polarized π electrons in the aromatic structure of CB. To manufacture foams with
static-dissipative properties, CB was added, in concentrations of 1, 5, 10, 20, and 30 wt.% (in
relation to cellulose dry mass), to aqueous suspensions of FCC at 3.5 wt.%. The effect of CB
content was studied on the physical, mechanical, and electrical properties of the foams.
Furthermore, the biodegradability in soil and fire resistance of these materials were evaluated.
The foams had specific compression moduli between 11 and 21 MPa.cm3.g-1. An increase of
about 66% in the specific modulus of the foam with 10 wt.% CB was observed compared to
foams with CB concentrations ≤ 5 wt.%. Regarding electrical properties, two ranges of behavior
were observed at low relative humidity (20%): (i) foams containing 1 and 5 wt.% CB presented
electrical resistivity of around 108 Ω.cm, being classified as static-dissipative materials; and (ii)
foams with CB content ≥ 10 wt.% showed lower electrical resistivity values (103 to 101 Ω.cm),
characterizing themselves as conductive materials due to the formation of an interconnected
conductive network. FCC/CB foams showed great resistance to the initiation and spread of fire,
being less flammable compared to commercial conductive foam. In conclusion, the interactions
between FCC and CB favored the formation of stable aqueous dispersions and foams with good
mechanical and electrical properties. The FCC/CB composite foams produced in this study
proved to be new electrically conductive porous materials promising for practical electrical
applications, including antistatic packaging.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 052.991.506-52 - JULIANA DA SILVA BERNARDES - UFABC
Membro Titular - Examinador(a) Interno ao Programa - 035.297.869-42 - RUBIA FIGUEREDO GOUVEIA - UFABC
Membro Titular - Examinador(a) Externo à Instituição - FABIO ROBERTO PASSADOR - UNIFESP
Membro Suplente - Examinador(a) Interno ao Programa - 2347767 - MATHILDE JULIENNE GISELE CHAMPEAU
Membro Suplente - Examinador(a) Externo à Instituição - MARCOS VINICIUS LOREVICE - CNPEM