Nanolatex technology 1 : synthesis and characterization of nanosize acrylic latexes and comparison to their conventional size counterparts / Ravi G. Joshi in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 18, N° 6 (11/2021)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 18, N° 6 (11/2021) . - p. 1481-1500 Titre : Nanolatex technology 1 : synthesis and characterization of nanosize acrylic latexes and comparison to their conventional size counterparts Type de document : texte imprimé Auteurs : Ravi G. Joshi, Auteur ; Frank N. Jones, Auteur ; Theodore Provder, Auteur ; Weidian Shen, Auteur Année de publication : 2021 Article en page(s) : p. 1481-1500 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation Coalescence (Sciences physiques) Formation de film Latex Microémulsions Morphologie (matériaux) Nanoparticules Polyacryliques Polymères -- Synthèse Polymérisation en émulsion Réticulation (polymérisation) Revêtements organiques Index. décimale : 667.9 Revêtements et enduits Résumé : 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. Note de contenu : - EXPERIMENTAL : Preparation of nanoparticle latexes using improved modified microemulsion copolymerization - Materials - Preparation of conventional size precoalescence or postcoalescence crosslinked conventional latexes - CHARACTERIZATION OF LATEXES : Latex properties - Film properties of conventional latexes and nanoparticle latexes - Thermal and mechanical properties of conventional latexes and nanoparticle latexes - Measurements with AFM of conventional latexes and nanoparticle latexes - RESULTS AND DISCUSSIONS : Nanosize latex synthesis and characterization - Film formation by “precoalescence” and “postcoalescence” crosslinked latexes - Gel content results - End-use film properties - Fundamental mechanical properties - Stress–strain analysis of constituent nanosize latexes with precoalescence and postcoalescence crosslinking and comparisons with their conventional size counterparts - Dynamic mechanical properties - Table 1 : Composition table for nanosize latexes (with or without functional group) - Table 2 : Characteristics of conventional (with or without crosslinker) latexes - Table 3 : Characteristics of nanosize (with or without crosslinker) latexes - Table 4 : End-use properties of films cast from conventional latexes - Table 5 : End-use properties of films cast from nanosize latexes AFM results - Table 6 : Comparison of surface smoothness and gloss values of nanoparticle latexes and their conventional counter parts - Table 7 : Results of stress–strain analysis of nanosize latexes - Table 8 : Results of stress–strain analysis of conventional size latexes - Table 9 : Comparison of DMA values with MDSC Tg values of conventionally size precoalescence or postcoalescence crosslinked latexes - Table 10 : Comparison of DMA values with MDSC Tg values of nanosize precoalescence or postcoalescence crosslinked latexes DOI : https://doi.org/10.1007/s11998-021-00475-z En ligne : https://link.springer.com/content/pdf/10.1007/s11998-021-00475-z.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36803 [article]

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Nanolatex technology 2 : blending polymer nanoparticles with conventional latexes for synergistic property improvement / Frank N. Jones in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 18, N° 4 (07/2021)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 18, N° 4 (07/2021) . - p. 1165-1176 Titre : Nanolatex technology 2 : blending polymer nanoparticles with conventional latexes for synergistic property improvement Type de document : texte imprimé Auteurs : Frank N. Jones, Auteur ; Ravi G. Joshi, Auteur ; Theodore Provder, Auteur ; Weidian Shen, Auteur Année de publication : 2021 Article en page(s) : p. 1165-1176 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Adhésion Brillance (optique) Dureté (matériaux) Elasticité Latex Mélanges (chimie) Nanoparticules Polyacryliques Revêtements organiques Synergie Index. décimale : 667.9 Revêtements et enduits Résumé : 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. Note de contenu : - INTRODUCTION : Plan of the present study - EXPERIMENTAL : Materials - Conventional latex and nanoparticle latex characterization - FILM PROPERTY STUDIES : RESULTS AND DISCUSSION : Studies of a range of blend ratios - Bulk film properties - Conjectures - Surface film properties - Table 1 : Conventional latexes - Table 2 : Nanoparticle latexes - Table 3 : Selected properties of films cast from an 85/15 blend of thermoplastic conventional latex with a crosslinkable nanoparticle latex - Table 4 : Blends of conventional and nanoparticle latexes - Table 5 : Bulk film properties of films cast from blends of high Tg thermoplastic conventional latex and low Tg thermoplastic nanolatex - Table 6 : Bulk film properties of films cast from blends of high Tg thermoplastic conventional latex and low Tg nanolatex with 5% external crosslinker - Table 7 : Property comparison of blended latex with post-coalescence crosslinkable high and low Tg latexes - Table 8 : Surface properties for films cast from all-thermoplastic latexes and blends - Table 9 : Surface properties for films cast from all-thermoplastic latexes and crosslinkable nanolatex DOI : https://doi.org/10.1007/s11998-021-00474-0 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-021-00474-0.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36222 [article]

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