Glass transition temperature acrylic dispersion

Copolymers with acrylates (vinyl acrylics) or other vinyl esters are also commonly produced, mostly as aqueous dispersions. They are, independent of the nature of the comonomer, often referred to as copolymers or terpolymers . The presence of comonomers of course heavily influences a number of physical properties like the glass transition temperature and melting point, water solubility or flexibility, to name just a few. 

Series I Acrylic Latex Emulsions. A series of four acrylic latex emulsions varying in glass transition temperature (Tg) (3) were applied first. Tg is the temperature at which the resin changes from a relatively flexible to a relatively stiff material. The acrylic latexes are made from water-insoluble monomers such as acrylates and alkyl acrylates polymerized in emulsion form to produce an aqueous dispersion or latex of the polymer. Upon drying, the emulsion is irreversibly broken so that the applied material becomes wash-fast. The application requires no catalyst or high temperature heating. 

Supriyatno H., Yamashita M., Nakagawa K., and Sadaoka Y., Optochemical sensor for HCl gas based on tetraphenylporphyrin dispersed in styrene-acrylate copolymers Effects of glass transition temperature of matrix on HCl detection. Sens. Actuators B, 85, 197-204, 2002. 

At the phenomenological level it may be known that Solvent A works well with acrylic dispersions while Solvent B is better for vinyl dispersions. Experimentally the important question of how much to add can be determined by systematic experimentation. However, for fine tuning some theoretical knowledge about the influence of transient solvent on the glass transition temperature (Tg), and tihe influence this will have on the minimum film forming temperature (MFT) is usefiil. This would undoubtedly lead to some consideration of the distribution (partitioning) of the solvent between the aqueous and polymer phases, which can be... 

BM-400B is a dispersion system of SBR fine particles in water. These particles are random copolymer molecnles, i.e., styrene and butadiene, containing some other minor elements such as acrylic ester and organic acids. The copolymer is an elastomer with a glass transition temperature of -5°C. Its chemical formula is. 

A white ink composition for inkjet textile printing has been developed that protects the discoloring of the dye on the textile piece (48). An anionic water-soluble resin which is obtained by neutralizing the resin is used as the polymer dispersant. The resin includes copolymers such as an acryUc acid/n-butyl acrylate/benzyl meth-acrylate/styrene copolymer with a glass transition temperature of 40°C. 

It is well-known that viscosity, self-diffusion coefficient and glass transition temperature are a strong function of molecular weight (MW). The film formation characteristics of an acrylic (BM A/MM A/M AA) latex as a function of its average MW is reported. The latex with the high MW is compared to an identical formulation with a low MW. The latex dispersions are prepared by standard techniques of emulsion polymerisation using an anionic surfactant, ammonium dodecyl benzene sulphonic add, and ammonium persulphate... 

The monomers used for preparation of acrylic polymers vary in nature and can generally be classified as hard (such as methylmethacrylate, styrene and vinyl acetate) or soft (such as ethyl acrylate, butyl acrylate, 2-ethyl hexyl acrylate). Reactive monomers may also have hydroxyl groups (such as hydroxy ethyl acrylate). Acidic monomers such as methacrylic acid are also reactive and may be included in small amounts in order that the acid groups may enhance pigment dispersion. The practical coating systems are usually copolymers of hard and soft monomers. The polymer hardness is characterized by its glass transition temperature, Tg. The Tg (K) of the copolymer can be estimated from the Tg of the individual Tg (K) of the homopolymers with weight fractions and Wj,... 

Acrylic dispersions (pure acrylics and styrene acryHcs) are extremely versatile. The big variety of available acrylic and methacrylic esters together with styrene offer almost unlimited opportunities to choose for the glass transition temperature and the hydrophilic/hydrophobic properties. Acrylic esters tend to form cross-Hnked polymers by abstraction of the a-hydrogen atom, methacryHc esters in contrast form polymer chains which are not cross-Hnked. Acrylics are resistant against oxidation by air and degradation by Hght. The main appHcation areas are coatings and adhesives. 

The principal monomers butadiene, styrene, vinyl acetate, (meth)acrylates and acrylonitrile essenhally determine the material properties of films made from the corresponding dispersions the glass transition temperature, the water absorption capacity, the elasticity, etc. Auxiliary monomers, which are only used in a small proportion, usually <5 %, control important properties such as colloid-chemical stabilization (acrylic acid, methacrylic acid, acrylamide, methacrylamide), crosslinking within the particles (difunctional acrylates, divinylbenzene, etc.) or hydrophilic properties (OH-containing monomers, such as hydroxyacrylates). Reactive monomers which still contain a latently reactive group even after incorporation into the polymer, for example glycidylmethacrylate or N-methylol(meth)acrylamide, can form a network between various particles and polymer molecules after film formation. 

Adhesion and cohesion of polyacrylate dispersions can be varied over a broad range and matched to many appHcations through the type and combination of low Tg ( soft ) and high Tg ( hard ) monomers, the choice of auxiharies, and the control of the molecular weight and process parameters [26-29]. Some examples are given below. The influence of glass transition temperature (Tg) of acrylic homopolymers on tack (according to A. Zosel [30, 31]) at various temperatures is shown in Fig. 8-2. 

Impact Modifiers. Notched impact strength and ductility can be improved with the incorporation of impact modifiers, which can also lower the brittle-ductile transition temperature and give much improved low temperature toughness. Impact modifiers are rubbers (often olefin copolymers) that are either modified or contain functional groups to make them more compatible with the nylon matrix. Dispersion of the rubber into small (micrometer size) particles is important in order to obtain effective toughening (19). Impact modifiers can be combined with other additives, such as glass fiber and minerals, in order to obtain a particular balance of stiffness and toughness. Modified acrylics, silicones, and polyurethanes have also been proposed as impact modifiers. 

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