The deformation-strength characteristics of films made from a mixture of HDPE and LLDPE modified with chalk were studied. It is shown that the introduction of a chalk concentrate of more than 16 wt.% (the content of chalk concentrate is 20 wt.%) has a negative effect on the strength and relative elongation at break of the composition of HDPE with LLDPE, as well as on the strength of the welded joint of polymer films. The strength of the films in the longitudinal and transverse directions significantly depends on the composition of the composition. The strength of the weld, obtained by ultrasonic welding, decreases sharply when the chalk content in the system is more than 16 wt.%. The introduction of more than 10 wt.% LLDPE into a HDPE-based chalk-filled composition is inadvisable..

The rheological properties of compositions based on HDPE with the addition of chalk concentrate and linear low-density polyethylene (LLDPE), as well as the thermal stability of the investigated compositions, were studied by capillary viscometry and DSC. It is shown that the introduction of chalk concentrate with chalk content of 80 wt.% into HDPE sharply reduced the compositions thermal stability and changed the compositions flow character. The addition of LLDPE to chalk-filled HDPE resulted in a decrease in the effective viscosity and an increase in the thermal stability of the compositions.