scholarly journals A Short Review on Polymeric Biomaterials as Additives for Lubricants

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1333
Author(s):  
Gobinda Karmakar ◽  
Koushik Dey ◽  
Pranab Ghosh ◽  
Brajendra K. Sharma ◽  
Sevim Z. Erhan
Keyword(s):  
Rice Bran Oil ◽  
Viscosity Index ◽  
Polymeric Materials ◽  
Gel Permeation Chromatography ◽  
Short Review ◽  
Viscosity Index Improver ◽  
Spectral Techniques ◽  
Molecular Weights ◽  
Petroleum Resources ◽  
Multifunctional Additives

With increasing environmental concerns and the depletion of petroleum resources, the development of lubricant additives from bioresources has attracted much attention recently. In this review, we reported a few polymers and polymer composites that are synthesized from vegetable oils (soybean oil, sunflower oil, rice bran oil, and castor oil) and used as multifunctional additives in the formulation of eco-friendly lubricant compositions. We mentioned the preparation of vegetable oil-based homo- and copolymers and their characterization by different spectral techniques (FTIR/NMR). The average molecular weights of the polymers are determined by gel permeation chromatography (GPC). Performance evaluations of the polymeric materials mainly as a viscosity index improver (VII), pour point depressant (PPD), and most importantly antifriction additives when blended with lubricating base oils are indicated. Standard ASTM methods have been applied to evaluate their performances. The findings have shown that all the additives discussed are non-toxic, biodegradable, and showed excellent performances compared to commercial petroleum-based additives.

scholarly journals Synthesis and In Vitro Antimicrobial Evaluation of Photoactive Multi—Block Chalcone Conjugate Phthalimide and 1,8-Naphthalimide Novolacs

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1859
Author(s):  
Periyan Durairaju ◽  
Chinnasamy Umarani ◽  
Govindasami Periyasami ◽  
Perumberkandigai Adikesavan Vivekanand ◽  
Mostafizur Rahaman
Keyword(s):  
Spectroscopic Analysis ◽  
Photophysical Properties ◽  
Gel Permeation Chromatography ◽  
13C Nmr Spectroscopy ◽  
Antimicrobial Activities ◽  
Microbial Activities ◽  
E Coli ◽  
Molecular Weights ◽  
Antimicrobial Evaluation

Herein we report new multiblock chalcone conjugate phthalimide and naphthalimide functionalized copolymers with a topologically novel architecture synthesis using nucleophilic substitution and polycondensation methodology. The structures of the synthesized novolacs were elucidated on the basis of their spectroscopic analysis including FTIR, 1H NMR, and 13C NMR spectroscopy. Further, the number-average and weight-average molecular weights of the novolac polymers were determined by gel permeation chromatography (GPC). We examined the solubility of the synthesized polymers in various organic solvents including CHCl3, CH3CN, THF, H2O, CH3OH, DMSO, and DMF and found they are insoluble in both methanol and water. The novolac polymers were evaluated for their photophysical properties and microbial activities. The investigation of the antimicrobial activities of these polymers reveals significant antimicrobial activity against the pathogens E. coli, S. aureus, C. albicans, and A. niger.

Carbon Dioxide as a Carbon Resource – Recent Trends and Perspectives

2012 ◽  
Vol 67 (10) ◽  
pp. 961-975 ◽  
Author(s):  
Markus Hölscher ◽  
Christoph Gürtler ◽  
Wilhelm Keim ◽  
Thomas E. Müller ◽  
Martina Peters ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Raw Materials ◽  
Low Cost ◽  
Polymeric Materials ◽  
Short Review ◽  
Chemical Research ◽  
Bond Forming ◽  
Bulk Chemicals ◽  
High Thermodynamic Stability ◽  
Recent Trends

With the growing perception of industrialized societies that fossil raw materials are limited resources, academic chemical research and chemical industry have started to introduce novel catalytic technologies which aim at the development of economically competitive processes relying much more strongly on the use of alternative carbon feedstocks. Great interest is given world-wide to carbon dioxide (CO2) as it is part of the global carbon cycle, nontoxic, easily available in sufficient quantities anywhere in the industrialized world, and can be managed technically with ease, and at low cost. In principle carbon dioxide can be used to generate a large variety of synthetic products ranging from bulk chemicals like methanol and formic acid, through polymeric materials, to fine chemicals like aromatic acids useful in the pharmaceutical industry. Owing to the high thermodynamic stability of CO2, the energy constraints of chemical reactions have to be carefully analyzed to select promising processes. Furthermore, the high kinetic barriers for incorporation of CO2 into C-H or C-C bond forming reactions require that any novel transformation of CO2 must inevitably be associated with a novel catalytic technology. This short review comprises a selection of the most recent academic and industrial research developments mainly with regard to innovations in CO2 chemistry in the field of homogeneous catalysis and processes.

Probing the molecular weights of sweetgum and pine kraft lignin fractions

TAPPI Journal ◽  
2021 ◽  
Vol 20 (6) ◽  
pp. 381-391
Author(s):  
JULIANA M. JARDIM ◽  
PETER W. HART ◽  
LUCIAN LUCIA ◽  
HASAN JAMEEL
Keyword(s):  
Molecular Weight ◽  
Black Liquor ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Systematic Investigation ◽  
Kraft Pulping ◽  
Molecular Weights ◽  
Lignin Recovery ◽  
Lignin Reactivity ◽  
Kinetics Of

The present investigation undertook a systematic investigation of the molecular weight (MW) of kraft lignins throughout the pulping process to establish a correlation between MW and lignin recovery at different extents of the kraft pulping process. The evaluation of MW is crucial for lignin characterization and utilization, since it is known to influence the kinetics of lignin reactivity and its resultant physicochemical properties. Sweetgum and pine lignins precipitated from black liquor at different pHs (9.5 and 2.5) and different extents of kraft pulping (30–150 min) were the subject of this effort. Gel permeation chromatography (GPC) was used to deter- mine the number average molecular weight (Mn), mass average molecular weight (Mw), and polydispersity of the lignin samples. It was shown that the MW of lignins from both feedstocks follow gel degradation theory; that is, at the onset of the kraft pulping process low molecular weightlignins were obtained, and as pulping progressed, the molecular weight peaked and subsequently decreased. An important finding was that acetobromination was shown to be a more effective derivatization technique for carbohydrates containing lignins than acetylation, the technique typically used for derivatization of lignin.

scholarly journals Internal donors on supported Ziegler Natta catalysts for isotactic polypropylene: a brief tutorial review

2021 ◽  
Vol 28 (10) ◽  
Author(s):  
Bharat R. Paghadar ◽  
J. B. Sainani ◽  
Samith K. M. ◽  
Poornima Bhagavath
Keyword(s):  
Polymeric Materials ◽  
Detailed Comparison ◽  
Short Review ◽  
Point Of View ◽  
Polymer Science ◽  
Cross Combination ◽  
Polymer Properties ◽  
Technical Advances ◽  
Catalyst Systems ◽  
New Applications

AbstractThe scientific and technical advances in the field of polymer science has been abundant in recent years. Amongst the various polymeric materials available in market, synthesis of polyolefins has been in the forefront since decades. A major challenge in this domain remains in attaining stereoregular polyolefins especially polypropylene (PP) and significant efforts were carried out by synthesizing various internal donors (ID) aiding the catalysts involved in producing them. This short review gives an overview of i) various generations of Ziegler–Natta (ZN) catalyst systems ii) general classes of ID that has been demonstrated by the researchers over the past decades iii) their influence on PP isotacticity and polymer properties. The coordination modes of different donor classes on supported ZN system and comparative study especially between phthalate and diether ID classes were also addressed here. This review also presents the studies carried out on phthalate catalyst structure analysis, detailed comparison study on phthalate and diether IDs in terms of PP isotacticity, regioselectivity, hydrogen response, and also their cross combination study and competitive behavior. Further a brief description on other structurally varied IDs like malonates, maleates, silyl diol esters, bifunctional donors, multi ether donors demonstrated for isotactic PP were also presented. Studies conducted on compatibility of incorporation of two different classes of IDs on a single supported ZN system for the fundamental understanding of the catalyst behavior; and also on how mixed donor approach enables in tuning the catalyst for polymer properties were also presented. This review also provides an opportunity to the young minds and the basic researchers from academic point of view by and large to create new polymeric materials with useful properties or modify the existing materials for new applications by incorporating new IDs for further improvisation of the stereo regularity in obtaining the polymers. Graphic Abstract

Synthesis and characterization of novel methacrylate copolymers having pendant piperonyl group: monomer reactivity ratio, thermal degradation kinetics, and biological activity

2021 ◽  
Vol 29 (9_suppl) ◽  
pp. S1432-S1445
Author(s):  
Ibrahim Erol ◽  
Bayram Gencer ◽  
Zeki Gurler
Keyword(s):  
Biological Activity ◽  
Degradation Kinetics ◽  
Gel Permeation Chromatography ◽  
Reactivity Ratio ◽  
Thermal Degradation Kinetics ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Monomer Reactivity Ratio ◽  
Bacteria And Fungi ◽  
Photo Stability

In this study, 2-{[(2H-1,3-benzodioxol-5-yl)methyl]amino}-2-oxoethyl 2-methylprop-2-enoate (BMAOME) monomer was synthesized, and copolymers were prepared with glycidyl methacrylate (GMA). Structural characterizations of the compounds were performed using FTIR, 1H-, and 13C-NMR techniques. Monomer reactivity ratio values were calculated by Finemann–Ross (FR) and Kelen–Tudos (KT) methods. The Tg value of the polymers was determined by differential scanning calorimetry (DSC) and their thermal stability was determined by thermogravimetric analysis (TGA). The molecular weights (w and n) and polydispersity index of the polymers were determined by gel permeation chromatography. The Ea value of thermal decomposition was determined by using the Ozawa and Kissinger methods. The photo-stability of the copolymers was investigated. Furthermore, the photo-stability of the copolymers and the biological activity of polymers against different types of bacteria and fungi were investigated.

scholarly journals Lifetime Prediction Methods for Degradable Polymeric Materials—A Short Review

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4507 ◽  
Author(s):  
Angelika Plota ◽  
Anna Masek
Keyword(s):  
Polymeric Materials ◽  
Short Review ◽  
Isoconversional Method ◽  
Lifetime Prediction ◽  
Accelerated Ageing ◽  
Radiation Chemical ◽  
Degradation Reactions ◽  
Wlf Model ◽  
Advanced Isoconversional Method ◽  
The Impact

The determination of the secure working life of polymeric materials is essential for their successful application in the packaging, medicine, engineering and consumer goods industries. An understanding of the chemical and physical changes in the structure of different polymers when exposed to long-term external factors (e.g., heat, ozone, oxygen, UV radiation, light radiation, chemical substances, water vapour) has provided a model for examining their ultimate lifetime by not only stabilization of the polymer, but also accelerating the degradation reactions. This paper presents an overview of the latest accounts on the impact of the most common environmental factors on the degradation processes of polymeric materials, and some examples of shelf life of rubber products are given. Additionally, the methods of lifetime prediction of degradable polymers using accelerated ageing tests and methods for extrapolation of data from induced thermal degradation are described: the Arrhenius model, time–temperature superposition (TTSP), the Williams–Landel–Ferry (WLF) model and 5 isoconversional approaches: Friedman’s, Ozawa–Flynn–Wall (OFW), the OFW method corrected by N. Sbirrazzuoli et al., the Kissinger–Akahira–Sunose (KAS) algorithm, and the advanced isoconversional method by S. Vyazovkin. Examples of applications in recent years are given.

scholarly journals Cellulase-Assisted Extraction, Characterization, and Bioactivity against Rheumatoid Arthritis of Astragalus Polysaccharides

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Ling Cao ◽  
Mi Yu ◽  
Chonghui Wang ◽  
Yunhui Bao ◽  
Minghui Zhang ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
High Performance ◽  
Biological Activities ◽  
Gel Permeation Chromatography ◽  
Type Ii Collagen ◽  
Therapeutic Effects ◽  
Molecular Weights ◽  
Assisted Extraction ◽  
Synovial Membranes ◽  
Cellulose Column

This study investigated the effect of cellulase on the isolation of crude Astragalus polysaccharide (APS), analyzed the monosaccharide component of deproteinized APS, detected the molecular weights of purified APS, and examined the biological activities and the preliminary mechanism against rheumatoid arthritis (RA). Compared with water extraction method, cellulase-assisted extraction increased the yield of crude APS to 154% and polysaccharide contents to 121%. Crude APS was then purified by ethanol precipitation, Sevag deproteinization, and high-performance liquid chromatography (HPLC) analysis; monosaccharide contents of APS were different after cellulase-assisted method, especially galacturonic acid content which significantly increased. DEAE-52 cellulose column chromatography isolated three polysaccharide fractions, including a neutral polysaccharide (APS-water) and two acidic polysaccharides (APS-NaCl1 and APS-NaCl2). Using high-performance gel permeation chromatography (HPGPC), the molecular weights of APS-water, APS-NaCl1, and APS-NaCl2 were identified as 67.7 kDa, 234.1 kDa, and 189.4 kDa, respectively. Then their therapeutic effects and possible mechanism against RA were explored using type II collagen-induced arthritis (CIA) rat model. APS could significantly reduce paw swelling, serum concentration of IL-1β and TNF-α, and the expression levels of NF-κB-p65 and IκBα in synovial membranes in CIA rats. Our study indicated that cellulase significantly increases the yield and polysaccharide contents of crude APS, improves the product quality, and preserves the biological features against RA in CIA rats.

scholarly journals Purification and characterization of two human erythrocyte arylamidases preferentially hydrolysing N-terminal arginine or lysine residues

1978 ◽  
Vol 175 (3) ◽  
pp. 1051-1067 ◽  
Author(s):  
K K Mäkinen ◽  
P L Mäkinen
Keyword(s):  
Substrate Inhibition ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Gel Permeation Chromatography ◽  
Ph Optimum ◽  
Preparative Scale ◽  
Molecular Weights ◽  
Gel Permeation ◽  
Lysine Residues ◽  
Enzyme I

Two arylamidases (I and II) were purified from human erythrocytes by a procedure that comprised removal of haemoglobin from disrupted cells with CM-Sephadex D-50, followed by treatment of the haemoglobin-free preparation subsequently with DEAE-cellulose, gel-permeation chromatography on Sephadex G-200, gradient solubilization on Celite, isoelectric focusing in a pH gradient from 4 to 6, gel-permeation chromatography on Sephadex G-100 (superfine), and finally affinity chromatography on Sepharose 4B covalently coupled to L-arginine. In preparative-scale purifications, enzymes I and II were separated at the second gel-permeation chromatography. Enzyme II was obtained as a homogeneous protein, as shown by several criteria. Enzyme I hydrolysed, with decreasing rates, the L-amino acid 2-naphtylamides of lysine, arginine, alanine, methionine, phenylalanine and leucine, and the reactions were slightly inhibited by 0.2 M-NaCl. Enzyme II hydrolysed most rapidly the corresponding derivatives of arginine, leucine, valine, methionine, proline and alanine, in that order, and the hydrolyses were strongly dependent on Cl-. The hydrolysis of these substrates proceeded rapidly at physiological Cl- concentration (0.15 M). The molecular weights (by gel filtration) of enzymes I and II were 85 000 and 52 500 respectively. The pH optimum was approx. 7.2 for both enzymes. The isoelectric point of enzyme II was approx. 4.8. Enzyme I was activated by Co2+, which did not affect enzyme II to any noticeable extent. The kinetics of reactions catalysed by enzyme I were characterized by strong substrate inhibition, but enzyme II was not inhibited by high substrate concentrations. The Cl- activated enzyme II also showed endopeptidase activity in hydrolysing bradykinin.

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