Blends of amphiphilic, hyperbranched polyesters and different polyolefins

A hyperbranched polyester based on 3,5-dihydroxybenzoic acid was completely modified with dodecanoyl chloride to result in an amphiphilic, globular po lymer, which has a polar core and a nonpolar outer sphere with the ability both to incorporate an organic dye and to interact with a nonpolar matrix. A series of blends were prepared using either polypropylene or polyethylene (HDPE) as the matrix. The content of the polyester as disperse phase was v aried between 0.05 and 20 wt %. The blends with polyester contents up to 5% were prepared for colorization of polyolefins using the polyester as a dye carrier. The blends with higher polyester contents were prepared in order to investigate the influence of the hyperbranched material on the material properties. The blends exhibited a heterogeneous morphology with very small particle sizes even at high polyester concentrations. The melt rheology me asurements resulted in a reduced complex viscosity for both polyolefins whe n the hyperbranched polyester was added. The observed melt viscosity of the i-PP blends deviated from the linear mixing rule, whereas the HDPE blends followed it. The use of amphiphilic hyperbranched polyesters as dye carrier s allowed a homogeneous distribution of an organic dye in a polyolefin matr ix with similar dynamic-mechanical behavior of the blends compared to the c ase of pure polyolefins. The dyed samples exhibited good stability in extra ction experiments.