scholarly journals High molecular weight of polylactic acid (PLA): A Review on the effect of initiator

2021 ◽  
Vol 4 (1) ◽  
pp. 15
Author(s):  
Norliza Ibrahim ◽  
Anis Nuranisya Shamsuddin
Keyword(s):  
Molecular Weight ◽  
Carboxylic Acid ◽  
High Molecular Weight ◽  
Polylactic Acid ◽  
Ring Opening ◽  
Functional Group ◽  
Nitrogen Atmosphere ◽  
The Other ◽  
Hydroxyl Group ◽  
Aliphatic Polyester

This article reviews various initiator used to synthesize high molecular weight (MW >10,000 g/mol) of polylactic acid (PLA) through ring-opening polymerisation (ROP) of lactide. ROP has been chosen as the best method in producing PLA. On the other hand, stannous octoate (Sn(Oct)2) has been reported as the best catalyst used for ROP method. Many researchers have studied that polymerisation rate with the presence of only Sn(Oct)2 as catalyst is slow compared to polymerisation of lactide with the presence of initiator. An initiator is also favourable in producing high molecular weight of PLA as it can initiate the synthesis of PLA. Therefore, this review focus on ROP method catalysed by Sn(Oct)2 using different solvent as initiator. Among groups of initiators being reviewed are hydroxyl, carboxylic acid, aldehyde, aliphatic polyester and organophosphorus compound. Most of the studies applied in nitrogen atmosphere with a temperature range of 125 to 200 °C, while only one study in vacuum condition. Duration of the polymerisation time is between 1 to 24 hours. Based on the review, alcohol (hydroxyl group initiator) has been reported as the best initiator to produce high molecular weight of PLA. This functional group act as co-initiator molecule that reacts with Sn(Oct)2, forming the initiating stannous alkoxide linkage. The linkage is necessary to propagate monomer addition and hence increase the MW. 

Rapid Isolation of High Molecular Weight Urokinase from Native Human Urine

1982 ◽  
Vol 47 (03) ◽  
pp. 197-202 ◽  
Author(s):  
Kurt Huber ◽  
Johannes Kirchheimer ◽  
Bernd R Binder
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Human Urine ◽  
Gel Filtration ◽  
Chain Structure ◽  
The Other ◽  
Single Chain ◽  
Apparent Homogeneity ◽  
Sequential Adsorption

SummaryUrokinase (UK) could be purified to apparent homogeneity starting from crude urine by sequential adsorption and elution of the enzyme to gelatine-Sepharose and agmatine-Sepharose followed by gel filtration on Sephadex G-150. The purified product exhibited characteristics of the high molecular weight urokinase (HMW-UK) but did contain two distinct entities, one of which exhibited a two chain structure as reported for the HMW-UK while the other one exhibited an apparent single chain structure. The purification described is rapid and simple and results in an enzyme with probably no major alterations. Yields are high enough to obtain purified enzymes for characterization of UK from individual donors.

Barricyclin D1—a dimeric ellagitannin with a macrocyclic structure—and accompanying tannins from Barringtonia racemosa

2021 ◽  
Author(s):  
Shinji Yoshikawa ◽  
Lih-Geeng Chen ◽  
Morio Yoshimura ◽  
Yoshiaki Amakura ◽  
Tsutomu Hatano ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Natural Resource ◽  
The Other ◽  
Hydrolysable Tannin ◽  
The Family ◽  
Macrocyclic Structure

Abstract Our examination of high molecular weight polyphenolic constituents in the leaves of Barringtonia racemosa of the family Lecythidaceae uncovered five previously undescribed ellagitannins. One, barringtin M1 (1), among them was a hydrolysable tannin monomer, while remaining four, barringtins D1 (2), D2 (3), D3 (4) and barricyclin D1 (5), were all dimers. Barricyclin D1 had a first macrocyclic structure formed from casuarictin (6) and tellimagrandin I (7), and the other ellagitannins had structures related to 5. Two additional known phenolics, valoneic acid dilactone (8) and schimawalin A (9), were also isolated from the leaves. These results suggested that the leaves of B. racemosa is a natural resource rich in hydrolysable tannin oligomers.

Catalytic Ring-Opening Polymerization of Renewable Macrolactones to High Molecular Weight Polyethylene-like Polymers

2011 ◽  
Vol 44 (11) ◽  
pp. 4301-4305 ◽  
Author(s):  
Inge van der Meulen ◽  
Erik Gubbels ◽  
Saskia Huijser ◽  
Rafaël Sablong ◽  
Cor E. Koning ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Ring Opening ◽  
Ring Opening Polymerization

THE APPLICATION OF THE ARNDT–EISTERT REACTION TO THE SYNTHESIS OF FATTY ACIDS OF HIGH MOLECULAR WEIGHT

1950 ◽  
Vol 28b (9) ◽  
pp. 556-560 ◽  
Author(s):  
F. A. Vandenheuvel ◽  
P. Yates
Keyword(s):  
Fatty Acids ◽  
Molecular Weight ◽  
Carboxylic Acid ◽  
Stearic Acid ◽  
High Molecular Weight ◽  
Efficient Method ◽  
Convenient Method ◽  
Ultraviolet Absorption ◽  
Aliphatic Carboxylic Acid ◽  
Eicosanoic Acid

The Arndt–Eistert reaction offers a convenient method for the synthesis of the higher members of the aliphatic carboxylic acid series. Nonadecanoic acid, eicosanoic acid, and heneicosanoic acid have been prepared successively from stearic acid in good yields. An efficient method of purification of the synthetic products is described. The ultraviolet absorption maxima for some diazoketones derived from the higher members of the aliphatic carboxylic acid series are recorded.

Lipase-catalyzed ring-opening copolymerization of ω-pentadecalactone and δ-valerolactone by reactive extrusion

2020 ◽  
Vol 22 (3) ◽  
pp. 662-668
Author(s):  
Changcun Li ◽  
Shuaijun Pan ◽  
Weijian Xu ◽  
Yanbing Lu ◽  
Peipei Wang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Ring Opening ◽  
Reactive Extrusion ◽  
Novozyme 435

This work demonstrates the synthesis of poly(ω-pentadecalactone-co-δ-valeroLactone) with high molecular weight (Mn = 71.3 kDa) and low polydispersity (Đ = 1.67) within 6 hours by reactive extrusion (REX) using a lipase catalyst (Novozyme-435).

THE ROLE OF ADSORPTION IN CONTROLLING THE RATE OF REACTION OF CHLORAMBUCIL WITH PROTEIN

1963 ◽  
Vol 41 (4) ◽  
pp. 931-939 ◽  
Author(s):  
J. H. Linford
Keyword(s):  
Molecular Weight ◽  
Carboxylic Acid ◽  
Bovine Serum Albumin ◽  
Inverse Relationship ◽  
Reaction Rate ◽  
The Other ◽  
Alkylation Reaction ◽  
Rate Of Reaction

Two proteins, haemoglobin and bovine serum albumin, have been studied with respect to their rates of alkylation by chlorambucil in vitro at 37 °C and pH 8.4. The proteins are of nearly the same molecular weight and free carboxylic acid content, but the alkylation reaction is 30 times faster with haemoglobin. On the other hand, the adsorption of chlorambucil by albumin is 20 times greater than that exhibited by haemoglobin. This inverse relationship between extent of adsorption and reaction rate suggests that adsorption protects the chlorambucil from activation in the solvent.

scholarly journals ELECTROPHORETIC STUDIES ON PR8 INFLUENZA VIRUS

1944 ◽  
Vol 80 (6) ◽  
pp. 549-559 ◽  
Author(s):  
Gail Lorenz Miller ◽  
Max A. Lauffer ◽  
W. M. Stanley
Keyword(s):  
Molecular Weight ◽  
Influenza Virus ◽  
High Molecular Weight ◽  
Isoelectric Point ◽  
High Speed ◽  
The Other ◽  
Active Virus ◽  
Electrophoresis Method

Crude preparations of PR8 influenza virus, obtained by high-speed centrifugation, contain two electrophoretically distinct components. One of these, present to the extent of 10 to 20 per cent, was identified by electrophoresis, centrifuge, and activity tests, as an impurity similar to or identical with a high molecular weight acidic substance shown by Knight to be elaborated by normal uninfected embryos. The other component, present to the extent of 80 to 90 per cent, appeared to represent the active virus. The virus fraction was separated from the impurity by repeated fractional centrifugation. It then appeared homogeneous in the analytical centrifuge and in the Tiselius apparatus, and possessed an isoelectric point at pH 5.3 as measured by the micro-electrophoresis method.

scholarly journals Cutinase-Like Enzyme from the Yeast Cryptococcus sp. Strain S-2 Hydrolyzes Polylactic Acid and Other Biodegradable Plastics

2005 ◽  
Vol 71 (11) ◽  
pp. 7548-7550 ◽  
Author(s):  
Kazuo Masaki ◽  
Numbi Ramudu Kamini ◽  
Hiroko Ikeda ◽  
Haruyuki Iefuji
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Polylactic Acid ◽  
Biodegradable Plastics ◽  
Remote Homology ◽  
High Molecular Weight Compound ◽  
Polybutylene Succinate

ABSTRACT A purified lipase from the yeast Cryptococcus sp. strain S-2 exhibited remote homology to proteins belonging to the cutinase family rather than to lipases. This enzyme could effectively degrade the high-molecular-weight compound polylactic acid, as well as other biodegradable plastics, including polybutylene succinate, poly (ε-caprolactone), and poly(3-hydroxybutyrate).

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