The article presents the results of a dilatometric study of the crystallization of modified with structure-forming agent composites based on aluminum hydroxide and a mixture of high and low density polyethylenes. The influence of aluminum hydroxide concentration on the regularity of the change in the dependence of the specific volume, as well as the free specific volume on temperature, has been established. The crystallization onset temperature and the approximate values of the glass transition temperature of composite materials are determined. The studies were carried out in the process of stepwise cooling of the samples at a load of 5.3 kg on an IIRT-1 device converted into a dilatometer. The concentration of aluminum hydroxide varied within 1–30 wt.%. A mixture of high and low density polyethylene was taken in a 50/50 ratio. Titanium dioxide was used as a structure-forming agent in an amount of 1.0 wt.%. It has been established that with an increase in the concentration of aluminum hydroxide, the crystallization onset temperature of modified composites based on a mixture of polyethylenes remains unchanged and is equal to 105⁰C. It is shown that with an increase in the content of aluminum hydroxide in the polymer mixture, a regular increase in the density of the composites is observed

doi.org/10.32737/0005-2531-2023-2-69-77