The Influence of Macromolecular Structure and Composition on Mechanical Properties of Films Cast from Solvent‐Free Polyurethane/Acrylic Hybrid Dispersions

Abstract

Polyurethane DispersionPolyurethane (PU) /acrylic dispersions are of great commercial interest due to the synergetic combination of the PU and acrylic polymers. In this work, a series of PU/acrylic dispersions is synthesized by a solvent-free technique and the influence of colloidal structure, grafting between the two polymers, and the nature of the two polymer phases themselves on the mechanical properties of films cast from the dispersions is explored. TEM analysis shows that the particles have a PU shell/acrylic core structure which is translated into the morphology of films cast from the dispersions. This particle/film morphology leads to the acrylic copolymer acting as a filler material and allows high T g copolymers to be employed, leading to films with very high mechanical strength. Grafting of the PU and acrylic phases leads to increased compatibility but has little effect on the mechanical properties which are largely determined by the hardness of both the diol used in the PU synthesis and more importantly the acrylic (co)polymer composition. This work allows us to propose a series of design principles in order to synthesize PU/acrylic hybrids with controlled mechanical properties.

Polyurethane/Acrylic Hybrid Waterborne Dispersions: Synthesis, Properties and Applications

“…By increasing the GMA/AN ratio, polymer films with higher modulus and higher hardness were obtained, but the elongation at break and water uptake decreased. Mehravar et al synthesized a series of hybrids with varying MMA/BA ratios . Again, it was observed that higher quantities of MMA results in higher Young’s modulus and tensile strength but with decreased elongation at break (see Figure ).…”

“…Samples grafted are shown with bold lines while nongrafted are shown with dashed lines. Reproduced from ref with permission from John Wiley and Sons.…”

“…This is in stark contrast to conventional acrylic latexes where the MFFT is limited by the T g of the polymer. The cause of this is related to the typical particle morphologies observed in PU/acrylic dispersions for which an acrylic core-PU shell is usually observed (see section ) . As a result, films cast from PU/acrylic dispersions do not have the typical requirements of acrylic dispersions and polyacrylates with significantly higher T g values can be used, which act as fillers in the final film and reinforce the mechanical properties.…”

“…Effect of macrodiol PPG, PTHF, polyester diol (Polyester) and polycarbonate diol (PCD, ETERNACOLL UH200)) on tensile stress–strain properties. Reproduced from ref with permission from John Wiley and Sons.…”

Implementation of Multivariate Artificial Neural Networks Coupled With Genetic Algorithms for the Multi-Objective Property Prediction and Optimization of Emulsion Polymers

“…Here again, the recipes that the models were trained on all had higher hardness values due to their glass transition temperatures being higher, resulting in another bias. In general, hardness has been shown to increase as the glass transition temperature of the polymer increases [72][73] . Varying the glass transition temperature in these batches was needful, as the correlation between the glass transition temperature and the hardness was not established in the network, this correlation can now be learned when the models are retrained with this data.…”