MFFT is the lowest temperature which allows polymer particles in emulsion have enough activity for intercoagulation and continuous film forming. During films forming, the polymer particles have a closer arrangement. To form a continuous film, besides good dispersion emulsion, there is also the requirement of polymer particles deforming (which shows the pressure between particles forced by hydraulic pressure). Closer the particles be, stronger the pressure would become. And when particles touched each other, the pressure would force particles to deform and adhere with each other to form films. Obviously, the hard type Redispersible Polymer Powder is just like its polymer particles thermoplastic resin. The lower the temperature, the higher the hardness and more difficult to deform. That’s which leads to the MFFT. If emulsion under such temperature, even after evaporation, the polymer particles would still remain discrete and can’t form a continuous film; But when emulsion upon the temperature, while evaporating, particles would permeate, spread, deform and aggregate to form a continuous film.
MFFT is an important indicator in Redispersible Polymer Powder, especially in winter season. There are some proper measures could modify the RDP’s emulsion to meet the MFFT. For example, adding plasticizer could soften the polymer and lower the MFFT obviously.