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For this study, functional precoalescence (internally crosslinked) and postcoalescence (crosslinkable) conventional latexes were made using seeded semi-continuous emulsion polymerization. Nanosize polymer latexes with or without crosslinkable functional groups were made using a modified microemulsion copolymerization process. Films cast from conventional and nanosize latex were characterized using specific end use tests and fundamental properties using dynamic mechanical analysis, modulated differential scanning calorimetry, and atomic force microscopy. This study compares conventional and nanosize latex with respect to the effect of the type and level of crosslinking, particle size and distribution on latex film formation and morphology, and end use and fundamental properties. Nanosize latex films in general have superior gloss, solvent resistance, and adhesion but inferior water resistance. Stress–strain Young’s modulus showed an increase as a function of increasing crosslinker level in the nanosize latex films.

Results of our research on crosslinked latexes and polymer nanoparticles will be reported. Goals of this long-term program have been: comparing precoalescence and post-coalescence crosslinking; synthesizing polymer nanoparticle latexes (~ 20 to 25 nm) from a variety of acrylic monomers, including crosslinking and crosslinkable monomers; and blending nanoparticle latexes with compatible conventional (~ 120 to 130 nm) latexes and understanding their effects on film formation and on fundamental and empirical film properties. As we previously reported, blending conventional and nanolatexes in an 85/15 ratio (w/w of polymer solids) effects substantial changes of fundamental film properties. Best results included reducing minimum filming temperatures (MFT) while increasing Young’s moduli by factors of two to 17. Substantial improvements in empirical film properties such as gloss (up to 97 at 60°), hardness (increased by 2–5 pencils), block resistance, and adhesion to aluminum were also found. The previous report covered only a single blend ratio. Here we report studies of blends with ratios of conventional to nanoparticle latexes ranging from 92.5/7.5 to 30/70 (w/w). As before, the latexes and nanolatexes are BMA/BA copolymers with 0–4 wt.% of 1,3-butylene glycol dimethacrylate (precoalescence crosslinker) and 0–5 wt.% of diacetone acrylamide (for post-coalescence crosslinking with adipic dihydrazide). Films cast from these blends are subjected to everyday empirical coatings tests and are characterized using instrumental tests including dynamic mechanical analysis (DMA) and modulated differential scanning calorimetry (MDSC). Film formation and film morphology are studied using atomic force microscopy (AFM). The results confirm that blending nanoparticles at ratios up to 50/50 (w/w of polymer solids) can substantially improve certain properties of conventional latex films. For many properties, the optimum ratio is around 85/15 conventional/nano; a 92.5/7.5 ratio also affords substantial improvements. As coatings, the blends have near-zero VOC.

The goal of the current work was to determine if electrochemical impedance spectroscopy (EIS) testing of a series of coated but unexposed metal panels could predict the corrosion results of other sections of the same coated panels that were subjected to both continuous and cyclic corrosion testing. Variables included metal, pretreatment, primer, and topcoat. EIS results were shown to be strongly dependent upon the time-of-residence in the electrochemical cell prior to commencement of testing, and to the choice of electrolyte used in the cell. Good correlations between EIS and corrosion testing were seen for topcoat effects, but not for pretreatment effects. EIS results appear to relate mostly to barrier properties rather than electrochemical properties of coatings. It is suggested that the variation seen in EIS solution resistance values (Rs) can be utilized to quantify total system error. Total error was estimated by three techniques: total Rs variation, panel replicate variation, and EIS reading replication. The three approaches yielded similar results: total error for equivalent circuit components expressed in log10 form was on the order of 50%, expressed as percent standard deviation.

Latexes have many product applications including functioning as a binder in coatings. For many years, coatings researchers in industry as well as in academe have been exploring various modes of crosslinking latexes. Quite often, the goal of preparing crosslinked latexes is to upgrade film properties relative to the film properties of uncrosslinked latexes. In the present report, the synthesis and properties of crosslinkable acrylic latexes prepared with either an internal crosslinker (1,3-butylene glycol dimethacrylate)—“precoalescence crosslinking”—or an external crosslinker (adipic dihydrazide)—“postcoalescence crosslinking”—at various levels of crosslinking were studied. For postcoalescence crosslinking, diacetone acrylamide was copolymerized into the latex to provide sites for subsequent reaction with adipic dihydrazide. Fundamental properties of films cast from the two types of latexes were systematically compared. These properties included gel content, dynamic mechanical properties, nano-indenter hardness and modulus, stress–strain properties as well as the characterization of latex morphology by atomic force microscopy (AFM). In addition, some specific end-use properties were determined. This study assesses the effect of type (precoalescence or postcoalescence) and level of crosslinking on the film formation process and the resulting fundamental and end-use properties as well as resulting latex film morphology.

Coatings are commonly believed to protect metal surfaces from corrosion based on some combination of their barrier properties and electrochemical properties. Various physical and electrochemical tests were performed on seven different coatings (latex, alkyd, 2-PK epoxy, and electrocoat) to determine which properties were the main determinants of corrosion resistance in continuous and cyclic corrosion tests. Physical property tests and AC electrochemical tests were all related to barrier behavior, while DC electrochemical tests were related to electrochemical behavior. DC electrochemical properties are commonly associated with inhibitor chemistry, but can be broadly related to all components of the paint. These test results were compared with corrosion test results from both continuous (B-117) and cyclic (GM9540) accelerated tests. The best correlation was seen with a model emphasizing barrier behavior with a secondary component relating to electrochemical protection.

It has been common to assess corrosion inhibitors by ranking their relative corrosion currents at some arbitrary potential above the open circuit potential via DC potentiodynamic anodic scans. Groseclose et al.1 demonstrated that when bare steel panels are subjected to such scans, the difference in mV between the open circuit potential and breakdown potential is a sensitive measure of the panels’ tendency to corrode once coated and exposed to a corrosive environment. The present authors show that a combination of the two DC electrochemical techniques can be used to assess the relative corrosion (or inhibition) contribution of various ingredients in water-based coatings, and that those results translate into the same order of behavior when coatings utilizing those ingredients were applied to steel and tested in a corrosive environment. This technique is also shown to be capable of ranking finished liquid paints for their subsequent corrosion resistance as dried coatings on steel, and verifying the batch consistency of liquid paints in production.

The field of particle size distribution (PSD) characterization and measurement has experienced a renaissance over the past ten years. This revitalization has been driven by advances in electronics, computer technology and sensor technology in conjunction with the market pull for PSD methods embodied in cost effective user friendly instrumentation. The renaissance can be characterized by at least four activities. (1) End user innovation exemplified by techniques such as hydrodynamic chromatography (HDC), capillary hydrodynamic fractionation (CHDF) and field flow fractionation methods (SdFFF, FlFFF, and ThFFF). (2) Revitalization of older instrumental methods such as gravitational and centrifugal sedimentation; (3) Evolution of research grade instrumentation into low cost, routine, user friendly instrumentation exemplified by dynamic light scattering (DLS). (4) The attempt to meet extremely difficult technical challenges such as: (a) providing a single hybrid instrument with high resolution over a very broad dynamic range (4+ decades in size; e.g., Fraunhofer/Mie; photozone sensing/DLS); (b) PSD measurement of concentrated dispersions (acoustophoretic, dielectric measurements, fiber optic DLS (FOQELS)); (c) in-situ process particle size sensors (in-line or at line, e.g., FOQELS); (d) routine measurement of particle shape and structure (e.g., image analysis). Instrumental methods resulting from these activities are discussed in terms of measurement principles and the strengths and weaknesses of these methods for characterizing PSDs. Business and societal driving forces will impact customer perceived instrumentation and knowledge needs for the 21st century and the ability to meet the specific difficult technical challenges in particle size distribution characterization mentioned above. Anticipated progress toward meeting these technical challenges is discussed in conjunction with the associated anticipated advances in required technologies.

One of the long-sought `holy grails' of polymer characterization has been the simultaneous determination of polymer composition as a function of molecular weight distribution. The recent commercialization of a solvent evaporative interface between a Gel Permeation Chromatograph (GPC) and a Fourier Transform Infrared (FTIR) Spectrometer has provided one useful solution to the problem of determining polymer composition as a function of molecular weight for a range of polymers. This study will focus on the use of a solvent evaporative interface in conjunction with a GPC-viscometer chromatograph and a FTIR spectrometer in order to provide functional group information as a function of molecular weight. The solvent evaporative interface will be described and its use with a GPC-viscometer/FTIR system will be discussed in terms of operational variable and data analysis considerations. Application of the GPC-viscometer/solvent evaporative interface/FTIR system to a variety of polymer and coatings systems as a tool for product problem solving and elucidation will be presented. In addition, examples of the use of the solvent evaporative interface to elucidate compositional heterogeneity of copolymers will be illustrated. The potential use of the solvent evaporative interface in GPC/LC cross fractionation studies for very fine elucidation of polymer compositional heterogeneity will be discussed.

Quantitation of the analysis of coatings surface roughness by a contact profilometer was undertaken to obtain improved repeatability and meaningfulness of data. This effort involved interfacing the profilometer to a personal computer for data acquisition and analysis, optimizing operational variables involved in the measurement process and improving methods for quantitative data analysis of the roughness profiles. The quantitative methods of data analysis explored included the use of various surface profile roughness averages, power spectrum analysis through zone integrals, auto-correlation function analysis and fractal analysis of the surface roughness profile. Quantitative parameters obtained from the above methods were correlated with visual and optical methods for evaluating appearance for a variety of coatings. The superiority of correlation with evaluations of appearance and repeatability of multiple runs will be demonstrated for fractal numbers obtained from a fractal analysis of surface roughness profiles.

This study describes the methodology used in the conceptualization, design, and implementation of a minicomputer system to automate data acquisition, reduction, and analysis from a multi-instrument facility at Glidden-Durkee's Dwight P. Joyce Research Center. The instruments to be automated consist of gas chromatographs, gel permeation chromatographs, a disk centrifuge photosedimentometer, a light-scattering photometer, an autoviscometer, a torsional pendulum, an ultraviolet visible spectrophotometer, and a liquid chromatograph. Both the existing and the desired methods for servicing these instruments are described and then used in showing how management science was used to specify the minicomputer system objectives in terms of system hardware/software characteristics. The steps taken in matching the system characteristics with vendors' stated capabilities are discussed and include designing and using a benchmark to simulate the system and evaluate vendor service and software/hardware functioning, detailing of the functional software requirements, and programming/testing of the system. Recommendations are provided, based on these experiences, for the attainment of system objectives within the constraints of in-house and vendor resources. Finally, an up-to-date evaluation is included of system performance with regard to the original specifications.

The objective of this paper is to critically evaluate the performance of the newly introduced Millipore Waters GPC-viscometer system. In particular, the capabilities of the data analysis methodology are evaluated and limitations are identified. Potential modifications to improve the data analysis methodology and to make it more user friendly are suggested. The characterization of molecular weight, molecular weight distribution and polymer branching for polymer standards and polymers of commercial interest are reported.

LIGHT SCATTERING METHODS AND APPLICATION FRACTIONATION METHODS AND APPLICATIONS (ULTRA CENTRIFUGATION, CAPILLARY HYDRODYNAMIC FRACTIONATION, FIELD FLOW FRACTIONATION) ELECTROPHORETIC, ELECTROKINETIC AND ACOUSTIC ATTENUATION METHODS

Fourteen papers cover three areas of film formation: Aspects of film formation mechanism, film property development in thermoplastic and crosslinkable systems, and the morphology and film structure of the resulting films. Advanced instrumental measurements are used to define morphology and determine unique film structures as well as to provide input into models of the film formation process.

The field of particle size distribution (PSD) characterization and measurement has experienced a renaissance over the past ten years. This revitalization has been driven by advances in electronics, computer technology and sensor technology in conjunction with the market pull for PSD methods embodied in cost effective user friendly instrumentation. The renaissance can be characterized by at least four activities. (1) End user innovation exemplified by techniques such as hydrodynamic chromatography (HDC), capillary hydrodynamic fractionation (CHDF) and field flow fractionation methods (SdFFF, FlFFF, and ThFFF). (2) Revitalization of older instrumental methods such as gravitational and centrifugal sedimentation; (3) Evolution of research grade instrumentation into low cost, routine, user friendly instrumentation exemplified by dynamic light scattering (DLS). (4) The attempt to meet extremely difficult technical challenges such as: (a) providing a single hybrid instrument with high resolution over a very broad dynamic range (4+ decades in size; e.g., Fraunhofer/Mie; photozone sensing/DLS); (b) PSD measurement of concentrated dispersions (acoustophoretic, dielectric measurements, fiber optic DLS (FOQELS)); (c) in-situ process particle size sensors (in-line or at line, e.g., FOQELS); (d) routine measurement of particle shape and structure (e.g., image analysis). Instrumental methods resulting from these activities are discussed in terms of measurement principles and the strengths and weaknesses of these methods for characterizing PSDs. Business and societal driving forces will impact customer perceived instrumentation and knowledge needs for the 21st century and the ability to meet the specific difficult technical challenges in particle size distribution characterization mentioned above. Anticipated progress toward meeting these technical challenges is discussed in conjunction with the associated anticipated advances in required technologies.

This book covers recent advances in hyphenated and multidimensional chromatographic techniques for elucidating the structure, composition, molecular weight, and branching distributions in complex polymers. It describes a variety of detectors along with associated data analysis methods and combines these with site-exclusion chromatography, field flow fractionation methods, and liquid chromatographic methods. It applies these methods to a wide range of polymeric materials.