NASCIMENTO, C. C. F.; http://lattes.cnpq.br/4878629467021604; NASCIMENTO, Carmem Célia Francisco.
Resumo:
There is considerable interest on the use of organic as well as inorganic nucleating
agents for semi-crystalline thermoplastics. The use of mineral fillers as inorganic nucleating
agents has been largely studied, even though these agents are not quite as efficient are the
organic ones. The addition of mineral fillers onto polymers often improve mechanical and
physical properties, lower costs as well as increase the degree of crystallinity, melt and
crystallization temperatures of semi-crystalline polymers.
In this work the efficiency of conventional (talc, calcium carbonate) and nonconventional
(attapulgite and bentonite) mineral fillers as nucleating agents for isotactic
polypropylene were evaluated by differential scanning calorimetry (DSC). The results
showed that attapulgite and talc to exhibit the highest nucleating efficiency (61,22 % at 2
% attapulgite content and 41,59 at 5 % talc content) among the fillers under study.
The Ozawa method was used to determine the kinetics of non-isothermal
crystallization of PP nucleated by attapulgite and talc. Three filler concentrations (1,2 and
5 % w/w) and three cooling rales (2, 5 and 10 °C/min) were used in this study. It was
shoron that Ozawa's " n ' 1 expoent increased with Tc, varying from 0,3-3,8 which taken as
an indication o f morphological changes from fibrillar to spherulilic structures.