scholarly journals Selective Depolymerization and Effects of Homolysis of Poly(L-lactic acid) in a Blend with Polypropylene

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
Haruo Nishida ◽  
Yoshiro Arazoe ◽  
Takayuki Tsukegi ◽  
Wang Yan ◽  
Yoshihito Shirai
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Magnesium Oxide ◽  
Volatile Product ◽  
Selective Degradation ◽  
Activation Energy Of Degradation

Blends of poly(L-lactic acid) (PLLA) and polypropylene (PP), which are candidates for the practical use of PLLA, were investigated for selective degradation of PLLA, resulting in quantitative conversion of PLLA components into cyclic monomers, lactides, using magnesium oxide (MgO) as a depolymerization catalyst. Obviously, the catalyst MgO selectively accelerated only the PLLA depolymerization in the blends, dominantly generating L,L-lactide as a volatile product and separating the PP component. Expected effects of homolysis in the blend system were also determined as slight changes in activation energy of degradation for both the components and through the suppression of degradation by an antioxidant.

scholarly journals Magnesium Oxide‐Catalyzed Conversion of Chitin to Lactic Acid

ChemistryOpen ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 307-307
Author(s):  
Kodchakon Kun‐asa ◽  
Prasert Reubroycharoen ◽  
Kiyoyuki Yamazaki ◽  
Naoki Mimura ◽  
Osamu Sato ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Magnesium Oxide

Kinetic Model of the 1,2-Propanediol Oxidation Reaction in the Presence of 3wt%Pd/α-Al2O3 Catalyst

2021 ◽  
Vol 903 ◽  
pp. 143-148
Author(s):  
Svetlana Cornaja ◽  
Svetlana Zhizhkuna ◽  
Jevgenija Vladiko
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Kinetic Model ◽  
Catalytic Oxidation ◽  
Molecular Oxygen ◽  
Oxidation Reaction ◽  
Main Product ◽  
Oxidation Process ◽  
Water Solution ◽  
Reaction Conditions

Supported 3wt%Pd/α-Al₂O₃ catalyst was tested in selective oxidation of 1,2-propanediol by molecular oxygen. It was found that the catalyst is active in an alkaline water solution. Lactic acid was obtained as the main product of the reaction. Influence of different reaction conditions on 1,2-PDO conversion and oxidation process selectivity was studied. Partial kinetic orders of the reaction with respect to 1,2-propanediol, c0(NaOH), p(O2), n(1,2-PDO)/n(Pd)) were determined and an experimental kinetic model of the catalytic oxidation reaction was obtained. Activation energy of the process was calculated and was found to be about 53 ± 5 kJ/mol.

Electrical Conductivity of Magnesium Oxide/Molten Carbonate Eutectic Coexisting System

2019 ◽  
Vol 74 (9) ◽  
pp. 739-742
Author(s):  
Elena V. Nikolaeva ◽  
Andrey L. Bovet ◽  
Irina D. Zakiryanova
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Magnesium Oxide ◽  
Solid Phase ◽  
Specific Conductivity ◽  
Maxwell Model ◽  
Impedance Method ◽  
Molten Carbonate ◽  
Carbonate Ions ◽  
Alkali Carbonate

AbstractThe electrical conductivity of molten ternary alkali carbonate eutectic, coexisting with MgO particles, has been investigated. The conductivity was measured by the AC impedance method. The apparent activation energy ΔEa increased with the MgO content. This fact can be attributed to the effect of the solid phase. The specific conductivity of those systems could not be described using the Maxwell model over the solvation process of the carbonate ions on the particles of the magnesium oxide.

Study on the Crystallization Activation Energy of Poly (L-lactic acid) Nucleated with P-tert-butylcalix[8]arene

2018 ◽  
Vol 26 (2) ◽  
pp. 169-175
Author(s):  
Yaoqi Shi ◽  
Liang Wen ◽  
Zhong Xin
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crystallization Temperature ◽  
Nucleating Agent ◽  
Crystallization Activation Energy ◽  
Temperature Range ◽  
Chain Mobility

The crystallization activation energy (Δ E) of a polymer comprises the nucleation activation energy Δ F and the transport activation energy Δ E*. In this paper, the Δ E of poly (L-lactic acid) (PLLA) nucleated with nucleating agent p- tert-butylcalix[8]arene (tBC8) was calculated. The results showed that the Δ E of nucleated PLLA was 165.97 kJ/mol, which is higher than that of pure PLLA. The reason why Δ E of PLLA increased when incorporating nucleating agent was studied. The increment of glass transition temperature ( Tg) for nucleated PLLA revealed that the polymer chain mobility was restricted by tBC8, which was considered as the reason for the increase of Δ E*. Further, polyethylene glycol (PEG) was added to improve the chain mobility, thus eliminated the variation of the transport activation energy Δ E* caused by tBC8. Then the effect of the increment of crystallization temperature range on the increase of Δ F was also taken into consideration. It was concluded that both decreasing the mobility of chain segments and increasing the crystallization temperature range caused an increase of Δ E for PLLA/tBC8.

The crystallization behaviors and mechanical properties of poly(l-lactic acid)/magnesium oxide nanoparticle composites

RSC Advances ◽  
2016 ◽  
Vol 6 (50) ◽  
pp. 43855-43863 ◽  
Author(s):  
Junping Jia ◽  
Jinjun Yang ◽  
Yun Zhao ◽  
Hui Liang ◽  
Minfang Chen
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Magnesium Oxide ◽  
Solution Casting ◽  
Casting Method ◽  
Oxide Composite ◽  
Solution Casting Method ◽  
Oxide Nanoparticle ◽  
Surface Modified ◽  
Nanoparticle Composites

Nanocomposites of biodegradable PLLA and magnesium oxide composite (PLLA/MgO-NPs) and surface modified magnesium oxide composite (PLLA/m-MgO-NPs) were prepared using a solution casting method.

Apparent activation energy of degradation of poly[acrylonitrile-co-(N-vinylpyrrolidone)]

2004 ◽  
Vol 53 (6) ◽  
pp. 740-743 ◽  
Author(s):  
Hou Chen ◽  
Cheng-guo Wang ◽  
Hua-su Cai ◽  
Chuan-sheng Cui
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Activation Energy Of Degradation ◽  
Poly Acrylonitrile

Effect of polyconjugation in poly-p-phenyleneterephthalamide on the activation energy of degradation

1984 ◽  
Vol 15 (3) ◽  
pp. 189-192
Author(s):  
L. P. Zosin ◽  
V. A. Zakrevskii ◽  
T. A. Stark ◽  
N. D. Min'kova
Keyword(s):  
Activation Energy ◽  
Activation Energy Of Degradation

scholarly journals Adsorption and Decomposition of Peroxides on the Surfaces of Dispersed Oxides Fe2O3, Cr2O3 and V2O5

2019 ◽  
Vol 3 (1) ◽  
pp. 13
Author(s):  
Volodymyr Dutka ◽  
Olena Aksimentyeva ◽  
Nataliya Oschapovska ◽  
Yaroslav Kovalskyi ◽  
Halyna Halechko
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Effective Activation Energy ◽  
Equilibrium Constants ◽  
Langmuir Equation ◽  
Effective Activation ◽  
Activation Energy Of Degradation ◽  
Degradation Reaction ◽  
Desorption Equilibrium ◽  
Adsorption Desorption

The adsorption of peroxides on dispersed oxides Fe2O3, Cr2O3 and V2O5 was studied. It is shown that the adsorption of peroxides is described by the Langmuir equation. The adsorption of benzoyl peroxide grows within Fe2O3<Cr2O3<V2O5. Adsorption-desorption equilibrium constants (K) for Cr2O3 and V2O5 are the same, but for Fe2O3 this value is 6 times higher. The decomposition of peroxides is observed in the solution and on the surface of adsorbents. The effective activation energy (E) of the thermal decomposition of peroxides in the studied systems is in the range of 80–140 kJ/mol. The activation energy of degradation of peroxides on the surface (Es) of the dispersed oxides studied is lower. The degradation reaction of peroxides on the surface of Fe2O3 and V2O5 has an oxidation-reducing nature, during which free radicals are produced. On the surface of Cr2O3, there is a heterolytic decay of peroxides. The parameters of the reaction of peroxides decomposition are found. The decomposition of peroxides in the presence of Fe2O3, Cr2O3 and V2O5 in styrene is accompanied by the formation of polystyrene both in the solution and on the surface of the adsorbent.

Lactic acid–magnesium oxide nanocrystal interactions: how nanoparticle size and shape affect chemistry and template oligomerization

2009 ◽  
Vol 33 (9) ◽  
pp. 1951 ◽  
Author(s):  
Erin M. Beavers ◽  
Kenneth J. Klabunde ◽  
Biobing Wang ◽  
Susan Sun
Keyword(s):  
Lactic Acid ◽  
Magnesium Oxide ◽  
Nanoparticle Size ◽  
Size And Shape
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