Ralph M. Paroli

Comparison of IR Techniques for the Characterization of Construction Cement Minerals and Hydrated Products

The influence of FT-IR sampling techniques on the characterization of cement systems was investigated. Three FT-IR techniques were used to study tricalcium silicate (C3S), hydrated C3S, calcium hydroxide, and calcium silicate hydrate (C–S–H). They include transmission spectroscopy (TS), photoacoustic spectroscopy (PAS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The TS technique (using KBr pellets) was the most labor-intensive but was found to give the simplest spectra with well-defined bands. The PAS technique was found to be the simplest technique but yielded bands at lower wavenumber than TS. DRIFTS was determined to be a good alternative for cement powders since it provided spectra similar to those for the TS technique. DRIFTS required more sample preparation than PAS but less sample preparation than the KBr pellet technique.

Quantitative Analysis of Monomer Composition in Ethylene-Propylene Block Copolymers by FT-IR Spectroscopy:

The quantitative analysis of ethylene (or propylene) in the commercially important ethylene-propylene (EP) copolymers has been the subject of considerable research. Although NMR is the most useful method, it does present certain problems such as solubility and cost. IR is therefore still preferred from the industrial point of view. In IR, most of the work has been done on high-ethylene-content EP copolymers, with the use of conventional grating spectrophotometers. The two IR regions usually employed are at 1460–1380 and 1160–720 cm−1, and these have been studied for blends of homopolymers ranging from 0–100 wt % polyethylene (PE) and for random copolymers containing 42–66.7 wt % PE. The analyses are based on measurements of the ratios of absorbances at 1380–1460 and 1160–720 cm−1, as well as the ratios of peak areas for the two IR regions. Difficulties arise when one is attempting to accurately measure absorbance or peak area ratios at the two extremes of the concentration ranges.

The effect of nitrobenzene and aminobenzoic acids on the hydration of tricalcium silicate: a conduction calorimetric study

Abstract The hydration of tricalcium silicate (C 3 S) in the presence of 0.004, 0.008 and 0.016 mol.% (with respect to 100 g of the silicate) of benzole acid, o -, m - and p -nitrobenzoic and aminobenzoic acids, was followed by conduction calorimetry. Benzoic acid at 0.004 and 0.008 moles behaved as a delayed accelerator of hydration, whereas at a dosage of 0.016 moles it performed as an accelerator by decreasing the onset of the induction period and promoting the earlier appearance of the main exothermic peak. The m - and p -nitrobenzoic acids accelerated the hydration of C 3 S, whereas o -nitrobenzoic acid acted as a retarder. Both m -and p -aminobenzoic acids retarded the hydration by delaying the appearance of the main exothermal peak. o -Aminobenzoic acid showed a similar effect to that of the reference at early times by not affecting the induction period and the maximum rate-of-heat peak. However, it increased slightly the amplitude of the main exothermic peak. The compounds that promoted the appearance of a heat peak at periods of 1 h or earlier exhibited an acceleration effect. In the presence of retarders this peak did not appear.

Characterization of ethylene-propylene-diene monomer (EPDM) roofing membranes using thermogravimetry and dynamic mechanical analysis

Abstract The effect of heat-aging at 100 °C and 130°C on three EPDM roofing materials was studied by thermogravimetry (TGA), dynamic mechanical thermal analysis (DMA) and tensile testing. It was found that both TGA and DMA can be used in a routine manner to explain the changes in mechanical properties of EPDM roofing membranes. In general, the results showed that the degradation of the material increased with heating temperature and exposure duration. It was also shown that aging at elevated temperatures can reduce the time required to evaluate the effect of heat on mechanical properties of polymer-based roofing materials.

A Handy Indicator of Resolution in Raman Spectroscopy

There are now numerous spectroscopy laboratories located throughout North America and in the rest of the world in which an Instruments S. A. U-1000 Ramanor spectrometer is employed to collect Raman data. Often, these measurements involve the use of different laser lines to excite the Raman spectra. During the course of our own work over the past six years on this type of instrument, we have needed to have knowledge of the actual resolution in wavenumbers rather than simply the slit-width settings in microns for a variety of argon- and krypton-ion laser lines. To aid us in this endeavor, we have constructed the curve shown in Fig. 1 using information provided by Instruments S. A. for the dispersion of the 1.0-m double monochromator of the U-1000 spectrometer when equipped with two 1800 grooves/mm−1 holographic gratings. The equation for this curve is: Res. = {(0.2254 − 1.436∗10−3∗λ + 3.959∗10−6∗λ2 − 5.645∗10−9∗λ3 + 4.073∗10−12∗λ4 − 1.177∗10−15∗λ5)∗μ} [1a] or μ = Res./(0.2254 − 1.436∗10−3∗λ + 3.959∗10−6∗λ2 − 5.645∗10−9∗λ3 + 4.073∗10−12∗λ4 − 1.177∗10−15∗λ5) [1b] where the resolution is given in cm−1, λ is the wavelength in nm, and μ is the slit width in μm. The equation governs the range of the U-1000 monochromator from 300.0 to 909.1 nm. The resolutions for commonly used wavelengths, in Raman spectroscopy, are given in Table I. Furthermore, since for a given wavelength the plot of slit width vs. resolution is linear, the equations of the lines for the wavelengths shown in Table I are listed in Table II. It is hoped that this handy resolution guide will prove useful to other members of the Raman spectroscopic community.

Sealants and Adhesives

Many sealants used in the construction industry are required to maintain functional performance characteristics over many years. While in service, sealants are exposed to environmental factors such as UV radiation, water, oxygen, and thermal cycling. Depending on which face of the building sealants are placed, type of substrate, and geographic region, they may be exposed to extreme environmental conditions, stress, and strain gradients. Hence, sealants are susceptible to weather-induced degradation. In general, degradation involves both chemical and physical processes with the chemical reactions usually preceding the physical process. It also discusses that testing of adhesives is necessary in order to determine the level of performance and/or predicted durability. Some of the tests provide information on the working properties of the adhesive, such as viscosity, which affects mixing, application, and spreadability as well as wetting and penetration of the substrate. Other test methods measure the amount of resin present. This not only influences the viscosity of the adhesive, but also the performance of the bonded assembly.

An FT-Raman study of solid-state ion exchange in zeolites

Abstract This work describes the first application of FT-Raman spectroscopy to the investigation of solid-state ion exchange. The contact-induced ion exchange between the following zeolites was examined: Li-exchanged zeolite A (Li-A) and zeolite Y (Na-Y), Li-A and zeolite X (Na-X), Li-A and Ca-exchanged zeolite A (Ca-A). The solid-state ion exchange between zeolite Y (Na-Y, NH4-exchanged Y) and metal salts (LiCl and CaCl2) was also studied. The results were verified by powder X-ray diffraction. They are also in good agreement with those obtained from other techniques. The study demonstrates that FT-Raman spectroscopy is a useful tool for the study of ion exchange of zeolites in the solid-state.

Retarding and Water Reducing Admixtures

This chapter explains how several techniques have been used to obtain an understanding of the action of retarders/water reducers, such as the mechanism of their action, rate of hydration, setting times, microstructure, etc. The techniques that have yielded important results, include differential thermal analysis (DTA), thermogravimetry (TG), differential scanning calorimetry (DSC), scanning electron microscopy, chemical shrinkage measurements, isotherms, and loss on ignition. These techniques are generally applied on samples that are hydrated for certain periods of time. The conduction calorimetry, however, follows the instantaneous evolution of heat as a function of time. It provides a method of quickly assessing the relative rates of hydration in the presence of different amounts/types of admixtures. The time of termination of the induction period gives information on the relative retarding action of various types of retarders.

Evaluating the effects of aging on the thermal properties of EPDM roofing materials

Abstract Two ethylene-propylene-diene monomer (EPDM) roofing membranes (111 and 112) were artificially aged in air-circulating ovens set at 130°C for 7 and 28 days. The effects of aging were studied by comparing various chemical data obtained by thermoanalytical techniques. The techniques used were dynamic mechanical analysis (DMA), thermomechanical analysis (TMA), differential scanning calorimetry (DSC) and simultaneous thermogravimetry/differential thermal analysis (TG/DTA). These techniques were found to be useful in monitoring and characterizing the influence of aging on the chemical and physical properties of EPDM roofing materials. Heat aging induced a significant change in T g , the coefficient of thermal expansion (CTE), and the chemical composition for EPDM 111. This was not the case for EPDM 112. Based on these results, it was found that EPDM 112 was less affected by heat aging than EPDM 111.

Investigation of the Effect of Heat on Specially Formulated Thermoplastic Polyolefin (TPO) Films by Thermogravimetry, Dynamic Mechanical Analysis, and Fourier Transform Infrared Spectroscopy

To explore the use of chemical methods of analysis in investigating the performance of thermoplastic polyolefins (TPO), the ASTM D08.18 Subcommittee undertook a study to evaluate TPO films of known composition. These specially formulated films with varying amounts of stabilizers were heat-aged for up to 56 days according to ASTM D 6878-03 and then analyzed using dynamic mechanical analysis (DMA), thermogravimetry (TG), and Fourier transform infrared (FTIR) spectroscopy. These techniques were found to be useful in characterizing the effect of heat on the TPO films under study and it is believed that they could be used to evaluate actual TPO membranes. Please note that these are films and not roof membranes. The formulations used for the films could be modified for use in actual membranes.