Title screen

[References: p. 479 (16 tit.)]

The investigations have been pursued with the purpose of studying thermo-mechanical effects on structural polymercharacteristics in the process of LDPE production. Industrial specimens of low molecular polyethylene (LMPE) of orthorhombicstructure and LDPE from the low pressure product separator (LPPS) with reasonable monoclinic phase content and without beingunder any strain effect have been used as objects. With similar short-chain branching (SCB) the polymers had significant differencein crystallinity degree, enthalpies and melting and crystallization temperatures and density. Experiments on the specimens have beencarried out during compression molding lower and above melting resin points with annealing or without it. Macro-structuralparameters have been controlled with WAXS, flotation densitometry and differential scanning spectroscopy (DSC) methods. It wasfound that the thermo-mechanical effects on LMPE deposits did not lead to the appearance of monoclinic crystal structure either tochanges of the polymer properties being controlled. In LDPE case the similar experiments did not lead to the change of monoclinicand orthorhombic phase content ratio in polymer, and consequently of the physical characteristics. It is presumed that in LDPE casethe predominant cause of monoclinic phase formation in both experimental and industrial conditions is a macromolecule structure,specifically SCB presence but not physical effects. Lack of monoclinic structure is probably explained by the different crystalstructure formation mechanism.