The scaling up of highly filled polymer clay nanocomposites with regard to clay loading

Moodley, Kerissa (2016-12)

Thesis (MSc)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: Water-based polymer clay nanocomposites (PCN) based on styrene-co-butyl acrylate copolymers (PSBA/MMT) were prepared with clay loadings of up to 50 wt.%. The resultant materials showed instability with regard to particle size and morphology due to increased viscosity of the dispersion which was further evidenced by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Additionally the dry films were found to show exfoliated to intercalated clay platelet morphologies in the polymer matrix as the amount of clay increased. These latexes showed increasing glass transition temperatures (Tg) with clay loadings up to 40 wt.%, which was attributed to the clay platelets absorbing the heat. Increasing the loading to 50 wt.% showed a decrease in Tg which was due to restricted molecular motions of the polymer in the nanocomposite. Thermal stability, determined using TGA, showed a decreasing trend as the amount of clay present in the PCNs increased. The next part of the study was dedicated to scaling up the current procedure to suit industrial needs and thus the PCNs were prepared without the use of typical emulsification devices. The hybrid latexes obtained showed unstable particles as well as large amounts of coagulum as the amount of clay present in the latexes increased. Dynamic mechanical analysis (DMA) results were contradictory to those of the latexes produced on a smaller scale. This was due to melt pressing of the films which caused crosslinking of the polymer and exhibited an increasing storage modulus as the clay loading increased. The Tgs showed similar results to those of the PSBA/MMT latexes. The thermal stability of the films showed a similar onset peak with the exception of the 50 wt.% sample which showed a higher onset temperature. This is confirmed with the use of TEM which shows heterogeneous dispersion of clay platelets which could lead to the early onset temperature. The overall stability of the latexes decreased as the amount of clay present in the PCN’s increased and using a clay content of 50 wt.% is unsuitable. The comparison of these scaled up nanocomposites to the ones prepared on the lab scale shows that the material properties are compromised.

AFRIKAANSE OPSOMMING: Water-gebaseerde polimeer klei nanosamestellings (PKN) gebaseer op stireen-mede-butylacrylaat kopolimere (PSBA / MMT) bereid was om met 'n hoë klei beladings van tot 50 wt.%. Die gevolglike materiaal gewys onstabiliteit met betrekking tot deeltjiegrootte en morfologie as gevolg van verhoogde viskositeit van die verstrooiing wat verder bewys deur transmissie elektronmikroskopie (TEM) en dinamiese lig verstrooiing (DLS). Verder die droë films gevind om te wys exfoliated om interkalêre klei plaatjie morfologieen in die polimeermatriks as die bedrag van klei toegeneem. Hierdie latexes getoon toenemende glasoorgangstemperature (Tg) met klei beladings tot 40 wt.%, Wat toegeskryf word aan die klei plaatjies absorbeer die hitte. Die verhoging van die laai tot 50 wt.% toon 'n afname in Tg wat as gevolg van beperkte molekulêre bewegings van die polimeer in die nanosaamgestelde was. Termiese stabiliteit, bepaal met behulp van TGA, het 'n dalende neiging as die bedrag van klei teenwoordig in die PKNs toegeneem. Die volgende deel van die studie is gewy aan verhoogde gebruik die huidige prosedure wat gevolg moet industriële behoeftes en dus is die PKNs voorberei sonder die gebruik van tipiese emulsifisering toestelle te pas. Die baster latexes verkry het onstabiele deeltjies asook groot hoeveelhede coagulum as die bedrag van klei teenwoordig is in die latexes toegeneem. Dinamiese meganiese analise (DMA) resultate was teenstrydig met dié van die latexes geproduseer op 'n kleiner skaal. Dit was as gevolg van smelt druk van die films wat kruisbinding van die polimeer veroorsaak en uitgestal 'n toenemende stoor modulus soos klei laai toegeneem. Die Tg se gewys soortgelyke resultate met dié van die PSBA / MMT latexes. Die termiese stabiliteit van die films het 'n soortgelyke aanvang hoogtepunt met die uitsondering van die 50 wt.% monster wat 'n hoër aanvang temperatuur gewys. Dit word bevestig met die gebruik van TEM wat skeef verspreiding van klei plaatjies wat kan lei tot die vroeë aanvang temperatuur toon. Die algehele stabiliteit van die latexes afgeneem as die bedrag van klei teenwoordig is in die PKN se verhoogde en met behulp van 'n klei-inhoud van 50 wt.% ongeskik is. Die vergelyking van hierdie afgeskaal tot nanosamestellings die kinders voorberei op die laboratorium skaal dui daarop dat die materiaal eienskappe gekompromitteer.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/100208
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