The structure of γ-aminopropyltriethoxysilane (APS) has been studied in aqueous solution and as a solid using Fourier transform infrared spectroscopy. The monomeric aminosilane forms an internal cyclic chelate structure when hydrolyzed. Two vibrational bands have been found near 1575 and 1600 cm −1 in condensed aminopropylsiloxane polymer. The band at 1575 cm −1 is assigned to the NH 2 deformation mode of the acceptor amine groups involved in strong hydrogen bonding and the band at 1600 cm −1 is assigned to the NH 2 groups. Heat treatment causes the formation of nonring chain-structured aminosilanes. In the study of the structure of APS coupling agent on high-surface-area silica gel (Cab-O-Sil) and E-glass fibers, it was found that the aminosilane adsorbed on silica as essentially a monolayer and the amino group chemically interacted with the glass surface. The adsorbed APS on E-glass fiber exists as a multilayer, and formed a predominately cyclic ring structure in the coupling agent interphase.

The structure of γ-aminopropyltriethoxysilane on glass surfaces

This paper reviews the most widely used models for explaining how plasticizers render PVC flexible. These models include the gel, lubricity, and free volume theories; kinetic theories; and mathematical models which predict on the basis of plasticizer structure how much a plasticizer will lower the polymer glass transition in a flexible PVC compound. Since plasticization results from interactions between plasticizer and polymer, methods which have been used to study either the strength or the permanence (or both) of those interactions are also briefly discussed. Tools which have often been used to study plasticizer-PVC interactions include infrared and nuclear magnetic resonance spectroscopy, compression and humid-aging tests, dynamic mechanical analysis, torque rheometer tests, plasticizer-resin clear point temperature measurements, plastisol gelation/fusion by hot stage measurements, and others. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers

A brief overview of theories of PVC plasticization and methods used to evaluate PVC‐plasticizer interaction

In recent years, many studies on the analysis of microplastics (MP) in environmental samples have been published. These studies are hardly comparable due to different sampling, sample preparation, as well as identification and quantification techniques. Here, MP identification is one of the crucial pitfalls. Visual identification approaches using morphological criteria alone often lead to significant errors, being especially true for MP fibers. Reliable, chemical structure-based identification methods are indispensable. In this context, the frequently used vibrational spectroscopic techniques but also thermoanalytical methods are established. However, no critical comparison of these fundamentally different approaches has ever been carried out with regard to analyzing MP in environmental samples. In this blind study, we investigated 27 single MP particles and fibers of unknown material isolated from river sediments. Successively micro-attenuated total reflection Fourier transform infrared spectroscopy (μ-ATR-FTIR) and pyrolysis gas chromatography-mass spectrometry (py-GCMS) in combination with thermochemolysis were applied. Both methods differentiated between plastic vs. non-plastic in the same way in 26 cases, with 19 particles and fibers (22 after re-evaluation) identified as the same polymer type. To illustrate the different approaches and emphasize the complementarity of their information content, we exemplarily provide a detailed comparison of four particles and three fibers and a critical discussion of advantages and disadvantages of both methods.

Comparison of μ-ATR-FTIR spectroscopy and py-GCMS as identification tools for microplastic particles and fibers isolated from river sediments

Plastics are found to be major debris composing marine litter; microplastics (MP, < 5 mm) are found in all marine compartments The amount of MPs tends to increase with decreasing size leading to a potential misidentification when only visual identification is performed These last years, pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) has been used to get information on the composition of polymers with some applications on MP identification The purpose of this work was to optimize and then validate a Py-GC/MS method, determine limit of detection (LOD) for eight common polymers, and apply this method on environmental MP Optimization on multiple GC parameters was carried out using polyethylene (PE) and polystyrene (PS) microspheres The optimized Py-GC/MS method require a pyrolysis temperature of 700 °C, a split ratio of 5 and 300 °C as injector temperature Performance assessment was accomplished by performing repeatability and intermediate precision tests and calculating limit of detection (LOD) for common polymers LODs were all below 1 μg For performance assessment, identification remains accurate despite a decrease in signal over time A comparison between identifications performed with Raman micro spectroscopy and with Py-GC/MS was assessed Finally, the optimized method was applied to environmental samples, including plastics isolated from sea water surface, beach sediments, and organisms collected in the marine environment The present method is complementary to μ-Raman spectroscopy as Py-GC/MS identified pigment containing particles as plastic Moreover, some fibers and all particles from sediment and sea surface were identified as plastic

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Optimization, performance, and application of a pyrolysis-GC/MS method for the identification of microplastics

Different commercial materials, such as polyurethane (PU), plasticized PVC (PVC), glass, Gore-tex, and Dacron, were coated with a well-characterized biomaterial (PUPA) based on polyurethane and poly(amido-amine) components. Two different classes of coating were obtained due to the different characteristics of the substrates. In the case of PVC and polyurethane which are soluble in the solvent of the PUPA-coating solution, there was penetration and blending of the coating and underlying materials. In the case of glass, Gore-tex, and Dacron, which are insoluble in the solvent of the coating solution, only a superficial layer of PUPA could be obtained. The coating stability was investigated and the interaction between coating and underlying material studied by FT-IR. All the stable coatings showed the ability to bind as much heparin as PUPA material by itself.

Coating of commercially available materials with a new heparinizable material.

The molecular structure of plasticized and unplasticized poly(vinyl chloride) (PVC) has been examined. The crystalline vibrational spectrum, obtained for normal commercial PVC, is in agreement with that of extended syndiotactic PVC, prepared from urea complex. The plasticized PVC spectra indicate that the crystalline regions are not solvated by the plasticizer. The plasticizer does solvate amorphous chain segments, and this possible results in complex formation of the type C=O...Cl-C between the carbonyl of the plasticizer and the chloride atom of PVC.

J. L. Koenig

Papers

Fourier Transform Infrared Study of Plasticized and Unplasticized Poly(vinyl chloride)