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Non-isothermal melt- and cold-crystallization, melting process, and optical and mechanical properties of PLLA: the effect of TAPH

Huang Hao, Lv Yang, Zhao Lisha, Tan Ninghui, Cai Yanhua

Materials Science Poland

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2024

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Vol. 42, No. 2

100--112

EN

We synthesized a new phenylacetic hydrazide derivative (TAPH) by acylation and amination to prepare modified poly(L-lactide) (PLLA) materials. The non-isothermal melt- and cold-crystallization, melting process, optical and mechanical properties of modified PLLA were studied with the objective of correlating TAPH to PLLA crystallization and other performances. Non-isothermal melt crystallization showed that TAPH as a heterogeneous additive was able to promote crystallization and accelerate the crystallization rate of PLLA. Unfortunately, an increase in the cooling rate during cooling led to a decrease in crystallization ability. Non-isothermal cold-crystallization results disclosed that PLLA/TAPH’s coldcrystallization behavior depended on the heating rate; and upon a given heating rate, with an increase in TAPH loading, a shift toward the low-temperature side of the cold-crystallization peak further confirmed the nucleation effect of TAPH. The melting processes of PLLA/TAPH effectively depended on TAPH, the heating rate, and previous crystallization behaviors including non-isothermal crystallization and isothermal crystallization. Additionally, the double-melting peaks that appeared during the melt were thought to be due to melting-recrystallization. In terms of the optical property, the influence of TAPH on PLLA’s transparency was extremely negative as 2 wt% TAPH caused PLLA’s transparency to be zero. A comparative study on mechanical properties showed that TAPH could enhance PLLA’s tensile modulus and tensile strength, but elongation at break of any PLLA/TAPH was lower than that of pure PLLA.

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Synthesis, structure and properties of V(V) monooxido complex with ONO tridentate Schiff base

Jurowska Anna, Szklarzewicz Janusz, Hodorowicz Maciej, Gryboś Ryszard

Science, Technology and Innovation

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2019

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Vol. 4, no. 1

21--29

EN

The oxidovanadium(V) Schiff base complex of formula [VO(L)(EtO)(EtOH)] (where H2L = Schiff base ligand derived from 5-methoxysalicylaldehyde and phenylacetic hydrazide) was synthesized and described. Complex crystalizes in triclinic P-1 space group. Octahedral geometry of the vanadium(V) centre is filed with oxido, ONO L2- ligand and two solvent molecules both in ethoxo and as neutral ethanol form. The complex is neutral, with 5- and 6-memebered ring formed by ONO ligand coordinated in octahedral plane with oxido and EtOH ligands in vertical positions. Two isomers are present in the unit cell, with different position of 5-membered ring versus vertical plane. The elemental analysis, magnetic susceptibility, thermogravimetry and spectroscopy (IR, UV-Vis) measurements were measured and are discussed. The cyclic voltammetry measurements show irreversible processes for vanadium(IV/V) redox system. Thermal stability both in a solid state (TG and SDTA measurements) as well as in solutions (at pH 7.0 and 2.0, studied by UV-Vis spectroscopy) is discussed.

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Synthesis, structure and properties of V(IV) complex with N’-[(E)-(2,3-dihydroxyphenyl)metylidene]-2- phenylacetohydrazide

Szklarzewicz Janusz, Jurowska Anna, Hodorowicz Maciej, Gryboś Ryszard

Science, Technology and Innovation

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2019

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Vol. 4, no. 1

1--8

EN

The synthesis and physicochemical properties of new vanadium(IV) complex of formula [VO(L)(phen)] is described. The L denotes ONO tridentate Schiff base derived from 2,3-dihydroxybenzaldehyde and phenylacetic hydrazide, while phen = 1,10-phenanthroline used as a co-ligand to stabilize the V(IV) oxidation state. The single crystal X-Ray crystal structure indicates on octahedral geometry of vanadium centre, with 1,10-phenanthroline nitrogen trans to the V=O bond. The complex crystalizes in a monoclinic P21/c space group, very unusual is that only one isomer is present in the crystal structure. The structure is stabilized by very weak hydrogen bonds and H··π and π···π interactions. The phenyl ring of hydrazide is strongly curved from ONO ligand plane by 70.95˚. The spectroscopic characterization (IR, UV-Vis) as well as the cyclic voltammetry measurements are presented and discussed