Inverse Gas Chromatography Technique Research Articles

Gas chromatographic studies on polymer-plasticizer compatibility: Interactions between food-grade PVC and epoxidized soybean oil

The technique of inverse gas chromatography was applied to study the miscibility (compatibility) of the system of PVC with epoxidized soybean oil (ESO). The PVC-ESO thermodynamic interaction parameters, χ + 23, were determined from the measured retention data for various vapour-phase “probes” in stationary phase mixtures of the components covering the entire composition range. Experiments were run in the range 90–110°C. In accordance with previous studies on polymer-polymer and polymer-plasticizer blends, the interaction parameters were found to be dependent on the temperature, the chemical nature of the probe and the blend composition. χ + 23 values were mostly negative or slightly positive up to 0.40 weight fraction of ESO, indicating relatively high compatibility of PVC and ESO for this range of compositions. They then increased with increasing plasticizer content and, at ca 0.70 weight fraction of ESO, exceeded 0.5 which is considered as the “compatibility limit value”.

Thermodynamics of polymer-paper adhesion: a review

A review of studies of polymer-paper adhesion illustrates the thermodynamic nature of the bondability of polymers to plain, uncoated paper surfaces. The bond strength depends strongly on the chemical nature of the polymer surface and on that of the fibrous paper surface. Adhesion to paper may be characterized indirectly through thermodynamic analysis of the paper substrate, or directly through paper laminate or adhesion tape peel testing. The need for adequate paper adhesion is emphasized, particularly for some of the newer printing processes (electrophotographic and thermal imaging). It is concluded that some of the indirect methods of adhesion characterization (surface energetics analysis via contact angle measurements or the inverse gas chromatography technique) may serve to characterize paper adhesion in these processes.

New approaches to the processing of rutile‐filled polyolefins

AbstractThe performance of a fluorocarbon elastomer processing additive in rutile‐filled linear low density polyethylene (LLDPE) compounds was evaluated by capillary rheometry, and blown film extrusion. Different compounding sequences were considered and their effects on the performance of the processing additive in the presence of various rutiles examined. Lower apparent melt viscosities and higher shear rates for the onset of melt fracture were observed when using certain surface treated rutiles. The nature of the surface coating applied to rutiles was found to have a great influence on the Theological properties of the filled compounds and on the dispersibility of the solids. The acid‐base characteristics of rutiles were determined by inverse gas chromatography techniques, and inherent agglomeration indexes for the pigments were measured by an application of powder rheology principles. It was found that those rutiles with high agglomeration indexes or those with highly basic surfaces interfered the most with the processing additive. Mechanisms by which rutile dispersibility and acid‐base character influence the effectiveness of the fluorocarbon elastomer processing additive are discussed.

A solution thermodynamic study of soybean oil/solvent systems by inverse gas chromatography

Inverse gas chromatography (IGC) has seen wide application in the characterization of molten polymers, fibrous materials, and natural products, such as proteins and carbohydrates, over the past fifteen years. This study describes a relatively simple IGC technique for evaluating solute‐solvent interactions using a refined soybean oil as a solvent. Utilizing soybean columns that are 5–20% by weight of the inert support has allowed the determination of a number of thermodynamic solution parameters for 22 solute‐solvent pairs in the temperature range of 55–125°C. Weight and mole fraction activity coefficients, along with Henry's Law constants at infinite dilution, are presented for six solute classes. In general, activity coefficients increase with carbon number for n‐alkanes, alkyl‐substituted benzenes, and n‐alkanoic acids at all temperatures investigated, while the reverse is found for the n‐alkanols. The activity coefficient data indicate that aromatic solutes, chlorinated hydrocarbons, ketones, and cyclohexane can readily dissolve soybean oil. Calculated heats of mixing for n‐alkanols were found to be positive (to 2.84 kcal/mole) while recorded enthalpic interactions were weak for aromatic solutes, lower alkanes, and chlorinated hydrocarbons. The relevance of the above data to such problems as oil dissolution and solvent devolatilization are discussed.

Study of compatibility of PVC and polyester-type plasticizer blends by inverse gas chromatography

The technique of inverse gas chromatography has been applied to a thermodynamic study of the miscibility (compatibility) of PVC and a polymeric (polyadipate ester) plasticizer. A number of organic solvents (probes) were used to evaluate the Flory-Huggins parameters for the PVC-plasticizer interaction in stationary phase mixtures of the two components covering the entire composition range for each component (0–100%). Experiments were carried out in the range 90–120°. The interaction parameter values were found to be dependent on the chemical nature of the probes, the temperature and the composition of the mixed (binary) phase. The results predict good polymer-plasticizer compatibility for a wide range of the above mixture (up to ca 0.55 weight fraction of plasticizer).

Starch/Solute Interaction in Water Sorption as Affected by Pretreatment

ABSTRACTThe effect of the freeze‐drying process on the structure of starch and starch‐sucrose mixtures was studied. The technique of inverse gas chromatography was used to study the interaction between organic compounds (probes) and starch (hylon 7) as well as starch‐sucrose mixtures. The structural and morphological characteristics of the starch‐solute mixtures from the thermodynamic parameters of these interactions was also examined. The porous freeze‐dried samples interacted more with certain organic probes compared with untreated starch as indicated by higher values of specific retention volumes (Vgo). Untreated starch apparently interacted only on the surface with organic probes. Freeze‐dried starch reacted only with polar organic probes, particularly those with hydrogen bonding propensity. Cluster analysis of the water sorption isotherms correlated with data obtained from the injected probes.

The Role of the Interface in Carbon Fibre-Epoxy Composites

Abstract The final performance of a composite material depends strongly on the quality of the fibre-matrix interface. The interactions developed at the interface were studied using the acid-base or acceptor-donor concept. The surface characteristics of the carbon fibres and the epoxy matrix were studied using a tensiometric method and the inverse gas chromatography technique. Acid-base surface characters could be determined allowing the interactions at the interface to be described by a specific interaction parameter. It was shown that the shear strength of the interface, as measured by a fragmentation test, is strongly correlated to this specific interaction parameter, demonstrating the importance of acid-base interactions in the fibre-matrix adhesion.