Annemarie Puri

Thermoanalytical and infrared spectroscopy investigations of some mineral pastes containing organic polymers

Abstract The interaction in the presence of water between organic polymers [two polyvinyl alcohol acetate (PVA1 and PVA2)-, one polyvinyl acetate (PVAc)-, and one acryloethyl–metacrylomethyl (R)-type copolymers] and inorganic materials (3CaO·Al 2 O 3 +CaSO 4 ·2H 2 O, 12CaO·7Al 2 O 3 , and CaO·Al 2 O 3 ) was investigated using complex thermal analyses and infrared (IR) spectroscopy. The DTA curves of the 1-to 28-day-hydrated organo-mineral composite samples showed some significant differences in comparison with those of the hydrated inorganic materials. The most important differences consist in the presence of some exothermic peaks that are not attributable to the pure organic polymers. More than that, none of the specific effects of the pure organic polymers are evidenced on the DTA curves of the hydrated organo-mineral composite materials. This, in connection with their IR spectra, which clearly evidence the disappearance of some investigated polymers specific IR bands, can be considered as an indirect evidence of the cross-linking of polymer chains via metal ions.

THE STUDY OF 'DSP' BINDING SYSTEMS BY THERMOGRAVIMETRY AND DIFFERENTIAL THERMAL ANALYSIS

The so-called DSP (Densified Systems containing homogenously arranged Particles) systems represent a high-performance class of inorganic binders. The hydration and hardening processes of some DSP systems, based on calcium silicates (C3S and C2S) or Portland cement/clinker with silica fume additions, were assessed, in this paper, using the thermogravimetry (TG) and differential thermal analysis (DTA). These data permit a qualitative and quantitative study of the formed hydrates as well as the estimation of hydration process kinetics.

ESCA, MIP and Mechanical Characterization of some Portland Cement – Methyl-Cellulose Composites

The paper brings information concerning the influence of methyl-cellulose (MC) – an organic polymer with oxygen rings – on the electron configuration and characteristics of some high strength Portland cement pastes. Electron Spectroscopy for Chemical Analysis (ESCA) investigations suggest a chemical interaction between the MC polymer and the Portland cement. Mercury Intrusion Porosimetry (MIP) results reveal a close packed arrangement of cement particles. The MC polymer network reduces the porosity both in the large and finer pore regions. The weight and length variations – swelling in wet conditions and contraction in dry conditions – are as important as the polymer proportion increases in the samples. The MC added cements can develop higher strength than the polymer-free samples, even after 360 and 720 days of hardening time; they are attributed not only to the porosity reduction but also to the chemical reactions of the polymer with the inorganic ions/free valences on the solid surface to form complex microstructural interphase regions.