Publikace detail

Study of molecular weight development in emulsion polymerization of styren-acrylate and methylmethacrylate-acrylate copolymers

Autoři: Válka Roman | Podzimek Štěpán | Machotová Jana

Rok: 2018

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
eng	Study of molecular weight development in emulsion polymerization of styren-acrylate and methylmethacrylate-acrylate copolymers	The work deals with the preparation of acrylic copolymers via emulsion radical polymerization and study of molecular weight development of styrene n-buthylacrylate; styrene-ethylacrylate; methylmethacrylate- n-buthylacrylate and methylmethacrylate-ethylacrylate copolymyers (with different weight ratio of monomers) determined by asymmetric flow field-flow fractionation (A4F) with multi-angle light scattering detector (MALS). The polymerizations were carried out in water at 85° C using ammonium persulfate as initiator. The samples for determination of molecular weight were taken during polymerization at given time. The solid content of samples and conversion of the monomers was also investigated. The solid content of prepared latexes was about 30% and overall conversion of monomers was about 97%. It was found that the molecular weigh decreased with increasing content of methylmethacrylate (MMA) and styrene (ST) comonomers in the recipe. The influence of ST content on the molecular weight was greater then the influence of MMA content. The addition of 5 wt% ST led to an important reduction of molecular weight. In the case of MMA, a similar decrease of molecular weight was achieved by the addition of 25 – 50 wt % MMA. This finding can be explained by steric bulk of styrene units attached to the polymer chain that block the backbone tertiary C-H bonds which are the centers of transfer reactions, thereby preventing transfer reactions to the polymer.	emulsion polymerization; molecular weight; chain reaction to polymer; A4F - MALS

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