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Thesis (Ph. D.)--Institute of Paper Chemistry, 1948. / Bibliography: leaf 70.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1943. / Bibliography: leaves 130-131.

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Thesis (DSc (Chemistry and Polymer Science))--University of Stellenbosch, 2005. / Aqueous polyurethane (PU) dispersions were synthesized for use in paper coatings. These PUs contained a polyester polyol soft segment (content of between 65 to 75%) and a urethane hard segment (content of between 30 to 35%). Triethylamine (TEA) was used as the neutralizing agent. The polyester polyol segment consisted of neopentyl glycol (NPG), adipic acid, 1,4-cyclohexane dicarboxylic acid (1,4-CHDCA) and 2-phosphonobutane- 1,2,4-tricarboxylic acid (PBTCA), while the urethane hard segment consisted of toluene diisocyanate (TDI), dimethylolproponic acid (DMPA) and ethylene glycol (EG) as a chain extender for increasing the hard segment content. Waxes and fillers were incorporated into the PU coating mixtures to investigate their effect on the barrier properties of the PU. Two types of fillers were used: nano-fillers and micro-fillers. The nano-fillers used included the Cloisite nano-clays NC15A, NC93A and NC30B, and the micro-fillers used included talc, kaolin clay and barium sulfate. Two different polyester polyols were synthesized: one containing a phosphate and the other containing no phosphate. The polyols were characterized in terms of their acid value, hydroxyl value and molecular mass. The PUs synthesized from the polyol containing no phosphate showed unfavourable barrier properties compared to results achieved with the phosphate-containing PU. The PU dispersions were applied to paperboard, and then dried at a maximum temperature of 130oC for 15 to 60 seconds, depending on the coating volume. The PU-coated paperboard was characterized primarily by determining the moisture vapour transmission rate (MVTR), and by scanning electron microscopy (SEM). PU films (stand alone, not supported by paper) were prepared by heating the concurrent PU dispersion in Teflon holders over three different temperature stages (60, 90 and 120oC) for about 2 days. The dried films were then characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. The PU coatings showed self-assembly properties, which were affected primarily by the ionic content (comprising of DMPA, PBTCA and excess TEA) and emulsion viscosity. These self-assembly properties were analyzed by static contact angle (SCA) and MVTR measurements. It was found that the final coating properties were affected by the self-assembly mechanism of the PU. Generally, the phosphated PU coatings had lower MVTR values than the non-phosphated PU coatings. SEM analysis showed that the phosphated PU coatings had no pinholes, while the non-phosphated PU coatings had pinholes. DMA analysis showed that the phosphated PUs had higher Tg values than the non-phosphated PUs. Further, the inclusion of the phosphate monomer increased the emulsion stability and the compatibility between the hard and soft segments of the PU. Also, the exfoliated PU nanocomposites at 1% filler loading gave much better MVTR results compared to the PU microcomposites. It also rendered the coating to be non-blocking, with minimal change in MVTR.

Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Aqueous polyurethane (PU) dispersions were synthesized for the use in paper coatings. These PUs contained a polyester polyol soft segment (content of 60-70%) and a urethane hard segment (content of 30-40%). This was followed by grafting using four different grafting agents. Triethylamine (TEA) was used as the neutralizing agent. The polyester polyol segment consisted of neopentyl glycol (NPG), adipic acid, 1,4-cyclohexane dicarboxylic acid (1,4-CHOCA) and 2-phosphonobutane-1 ,2,4- tricarboxylic acid (PSTCA), while the urethane hard segment consisted of hydrogenated 4,4-diphenylmethane diisocyanate, dimethylolproponic acid (OMPA), 3-hydroxypivalic acid (HPA) and hydroxyethylene methacrylate (HEMA). The grafting agents used were lauryl methacrylate (LMA), n-butyl methacrylate (n-SMA), methyl methacrylate (MMA) and styrene. Two different polyester polyols were synthesized, one containing 10% phosphate and the other none. The polyols were characterized in terms of their acid value, hydroxyl value and molecular mass. The PUs synthesized from the polyol containing 0% phosphate were grafted with LMA, while the phosphate-containing PUs were grafted with each of the all four grafting agents. The resulting dispersions were applied to paperboard, and then dried at a maximum temperature of 100°C. The PU-coated paperboard was characterized using the moisture vapour transmission rate (MVTR), and scanning electron microscopy (SEM) techniques. PU films (not supported by paper, stand alone) were prepared by heating the PU dispersion in Teflon holders up to 130°C for 6 hours. The dried films were then characterized by thermogravimatric analysis (TGA), differential scanning calorimetry (OSC), dynamic mechanical analysis (OMA) and Fourier transform infrared spectroscopy (FTIR). MVTR-analysis showed that the phosphated PU coatings had a minimum MVTR-value at 0% grafting, and that its overall MVTR-values were much lower than that of the non-phosphated PU coatings. SEM-analysis showed that the phosphated PU coatings had no pinholes at a maximum of 8% grafting, while the non-phosphated PU coatings showed pinholes at all levels of grafting. OMA-analysis showed that the phosphated PU samples had higher Tg's (Tg onset between O-S°C)than that of the non-phosphated PU samples (Tgonset below -SO°C). / AFRIKAANSE OPSOMMING: POLI-URETAAN DISPERSIES VIR PAPIER BEDEKKINGS Waterige poli-uretaan (PU) dispersies is gesintetiseer vir gebruik as papierbedekkings. Hierdie poli-uretane het 'n poliester poli-ol sagte segment (60-70% inhoud) en 'n uretaan harde segment (30-40% inhoud) bevat. Die poli-uretane is met vier verskillende ent-middels geêent. Trietielamien (TEA) is as neutraliseermiddel gebruik. Die poli-ester poli-ot segment het bestaan uit: neopentielglikol (NPG), adipiensuur, 1,4-sikloheksaandikarboksielssuur (1,4- SHDKS) en 2-fosfonobutaan-1 ,2,4-trikarboksielssuur (FSTKS). Die uretaan harde segment het bestaan uit: hidrogeneerde 4,4-difenielmetaandiisosianaat, dimetielpropioonsuur (DMPS), 3-hidroksipivaalsuur (HPS) en hidroksietileenmetakrilaat (HEMA). Laurielmetakrilaat (LMA), n-butielmetakrilaat (n-SMA), metielmetakrilaat (MMA) en stireen is as entmiddels gebruik. Twee verskillende poli-ester polihidroksie verbindings is gesintetiseer: een met 10% fosfaat en een met geen fosfaat, en gekarakteriseer in terme van hulle suurwaardes, hidroksiwaardes en molekulêre massas. Die PUs wat vanaf die fosfaat-bevattende poli-ol gesintetiseer is, is met LMA geêent, terwyl die fosfaat-bevattende PUs met al vier entmiddels geêent is. Papier (Eng. paperboard) is met hierdie dispersies bedek en by 100°C gedroog. Die PU-bedekte papier is gekarakteriseer in terme van vogdeurlaatbaarheidstransmissie (Eng: MVTR - the moisture vapour transmission rate), en skandeerelektonmikroskopie (SEM). PU-films wat nie deur papier gestut is nie is ook voorberei deur die verhitting van die PU dispersies in Teflon houers (130°C, 6 ure). Die droë films is daarna gekarakteriseer deur middel van termogravimetriese analise (TGA), differensiêle skandeerkalorimetrie (DSC), dinamiese meganiese analise (OMA) en Fourier-transformasie infrarooispektroskopie (FTIR). Resultate van MVTR analises het getoon dat die fosfaat-bevattende PU bedekkings 'n mimimum MVTR-waarde by 0% enting gehad het, en dat die totale MVTR waardes baie laer was as die van die nie-fosfaatbevattende bedekkings. SEM het gewys dat die fosfaat-PU bedekkings by 8% enting geen mikrogaatjies (Eng. pinholes) gehad net nie, terwyl die PU bedekings met geen fosfaat mikrogaatjies (Eng. pinholes) by alle vlakke van enting gehad het. OMA analises het getoon dat die monsters van die fosfaatbevattende PU hoër Tg waardes gehad het (Tg begin tussen 0 en 5 "C) as die nie-fosfaatbevattende PU monsters (Tg begin onder -50°C).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1942. / Includes bibliographical references (p. 78).