scholarly journals The Impact of Lignin Structural Diversity on Performance of Cellulose Nanofiber (CNF)-Starch Composite Films

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 538 ◽  
Author(s):  
Yadong Zhao ◽  
Ayumu Tagami ◽  
Galina Dobele ◽  
Mikael E. Lindström ◽  
Olena Sevastyanova
Keyword(s):  
Molecular Weight ◽  
Cellulose Nanofibers ◽  
Composite Films ◽  
Structural Diversity ◽  
Decomposition Temperature ◽  
Solvent Fractionation ◽  
Film Performance ◽  
Oh Groups ◽  
Chemical Structures ◽  
The Impact

Lignin fractions having different molecular weights and varied chemical structures isolated from kraft lignins of both softwood and hardwood via a sequential solvent fractionation technique were incorporated into a tunicate cellulose nanofibers (CNF)—starch mixture to prepare 100% bio-based composite films. The aim was to investigate the impact of lignin structural diversity on film performance. It was confirmed that lignin’s distribution in the films was dependent on the polarity of solvents used for fractionation (acetone > methanol > ethanol > ethyl acetate) and influenced the optical properties of the films. The –OH group content and molecular weight of lignin were positively related to film density. In general, the addition of lignin fractions led to decrease in thermal stability and increase in Young’s modulus of the composite films. The modulus of the films was found to decrease as the molecular weight of lignin increased, and a higher amount of carboxyl and phenolic –OH groups in the lignin fraction resulted in films with higher stiffness. The thermal analysis showed higher char content formation for lignin-containing films in a nitrogen atmosphere with increased molecular weight. In an oxygen atmosphere, the phenol content, saturated side chains and short chain structures of lignin had impacts on the maximum decomposition temperature of the films, confirming the relationship between the chemical structure of lignin and thermo-oxidative stability of the corresponding film. This study addresses the importance of lignin diversities on composite film performance, which could be helpful for tailoring lignin’s applications in bio-based materials based on their specific characteristics.

The Mechanical Properties of a Thermoplastic Elastomer Produced by the Bacterium Pseudomonas oleovorans

1992 ◽  
Vol 65 (4) ◽  
pp. 761-777 ◽  
Author(s):  
K. D. Gagnon ◽  
R. W. Lenz ◽  
R. J. Farris ◽  
R. C. Fuller
Keyword(s):  
Molecular Weight ◽  
Thermoplastic Elastomer ◽  
Stationary Growth Phase ◽  
Thermoplastic Elastomers ◽  
Decomposition Temperature ◽  
Polymer Composition ◽  
Growth Time ◽  
Pseudomonas Oleovorans ◽  
Permanent Strain ◽  
Chemical Structures

Abstract PHO, a poly(β-hydroxyalkanoate) copolymer containing mostly β-hydroxyoctanoate repeating units, was produced in a fed batch fermentation process by Pseudomonas oleovorans when grown on sodium octanoate as the sole carbon source. The polymer from different batches—evaluated with regards to composition, molecular weight distribution, thermal transition temperatures, and decomposition temperature—was found to be highly consistent batch-to-batch. Polymer composition as a function of growth time did not change significantly once the culture reached the stationary growth phase. PHO when crystallized at room temperature from the melt, forms a physically crosslinked network with the crystalline regions acting as the physical crosslinks. The molecular weight between physical crosslinks was determined to be approximately 4000. The stress-strain properties, hardness, and tensile set of PHO were found to be within the range of values defined by a variety of commercially available thermoplastic elastomers with differing chemical structures. The tensile set of PHO was high, 35% after 100% elongation. Experimental evidence supports three possible sources of the high tensile set: permanent strain-induced orientation or displacement of the physical crosslinks, irreversible strain-induced crystallization, and deformation-induced changes of the size and purity/perfection of crystalline regions.

scholarly journals Isolation, Preparation and Characterization of Polylactic Acid Film Reinforced with Nano silica

2021 ◽  
Vol 2063 (1) ◽  
pp. 012028
Author(s):  
Zainab A Ali ◽  
Alaa Karem Niamah ◽  
Hannosh Widad Salih
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Water Absorption ◽  
Composite Films ◽  
Local Strain ◽  
Poly Lactic Acid ◽  
Nano Silica ◽  
Chemical Structures ◽  
Biodegradable Composite ◽  
Lactobacillus Paraplantarum

Abstract Lactic acid was isolated by using microbial fermentation in whey media which was carried out by local strain Lactobacillus paraplantarum then polymerized using the acidic medium’s polycondensation method. FTIR and H-NMR were used to characterize the isolated lactic acid monomer and polyalctic acid (PLA), and the results confirmed the chemical structures of the isolated lactic acid and PLA. GPC techniques were used to determine the molecular weight and molecular weight distribution of the prepared PLA; the result showed that the Polydispersity index (PDI) was 2.51. The Biodegradable composite films of poly lactic acid (PLA)/Nano silica powder were prepared by the composite film casting method using dichloromethane as solvent. In contrast, Nano silica was synthesis from hydrolysis of tetra ethoxysilane and was loaded in PLA in 1 to5 wt. %. The films were subjected to a tensile strength study. Thermogravimetric analysis (TGA) and differential thermal analysis (DSC) were used to evaluate PLA. Also, water absorption of the prepared composites was studied, and the result showed that the thermal stability and water absorption of these prepared films were increased with an increasing percentage of Nano silica, while the percentage of crystallinity of the PLA evaluated from DSC was 28 %.

The Chemistry of High Molecular Weight Fulvic Acid Fractions

1974 ◽  
Vol 52 (24) ◽  
pp. 4123-4132 ◽  
Author(s):  
Jean A. Neyroud ◽  
Morris Schnitzer
Keyword(s):  
Fatty Acids ◽  
Molecular Weight ◽  
Ethyl Acetate ◽  
Fulvic Acid ◽  
Phenolic Acids ◽  
Degradation Products ◽  
Building Blocks ◽  
Oh Groups ◽  
Molecular Weights ◽  
Chemical Structures

Fulvic acid (FA) was methylated, dissolved in benzene, and fractionated over Al2O3 with the aid of organic solvents of increasing polarities. This paper is concerned with fractions eluted with ethyl acetate (III), ethyl acetate — methanol (1:1) (IV), and methanol (V), which were quantitatively the most abundant ones and which we consider as being most representative of the original FA. Each fraction was characterized by chemical and spectroscopic methods and by degradation with alkaline permanganate. Fractions IV and V were also degraded by NaOH hydrolysis and by alkaline CuO-oxidation. The degradation products were identified with the aid of a gas chromatograph — mass spectrometer — computer system.The number-average molecular weights of the three fractions were: III, 821; IV, 945; and V, 1,397. Infrared, proton n.m.r., and carbon-13 n.m.r. spectra provided, except for functional groups, little detailed information on the chemical structures of the fractions. The major degradation products were benzenecarboxylic and phenolic acids in addition to smaller amounts of aliphatic (mainly n-fatty) acids. Evidence is presented that may be interpreted to indicate: (a) esterification of some of the fatty acids to OH groups of phenolic acids; (b) the existence in the fractions of ether (C—O) linkages; and (c) rupture of C—C bonds during degradation. While in both the lower and the higher molecular weight FA fractions benzenecarboxylic and phenolic acids were the basic "building blocks", the latter appeared to be more complex and more stable in the higher-molecular weight fractions, possibly because chemical bonding as well as hydrogen bonding, van der Waal's forces, and π-bonding were involved simultaneously.

scholarly journals Sequential solvent fractionation of lignin for selective production of monoaromatics by Ru catalyzed ethanolysis

RSC Advances ◽  
2017 ◽  
Vol 7 (84) ◽  
pp. 53117-53125 ◽  
Author(s):  
Jae-Young Kim ◽  
Shin Young Park ◽  
Jae Hoon Lee ◽  
In-Gyu Choi ◽  
Joon Weon Choi
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Solvent Fractionation ◽  
The Impact ◽  
Lignin Structure

The purpose of this study was to investigate the impact of lignin structure, especially its average molecular weight (Mw) on the distribution of catalytically depolymerized products.

Synthesis of CdS Nanoparticle/Amphiphilic Block Copolymer Composite Films and its Characteristics of Microstructures and Optoelectronic Properties

2009 ◽  
Vol 79-82 ◽  
pp. 887-890
Author(s):  
Yang Yen Yu ◽  
Wen Chen Chien ◽  
Yu Heng Chou
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Block Copolymers ◽  
Composite Films ◽  
Amphiphilic Block Copolymers ◽  
Hybrid Films ◽  
Chemical Structures ◽  
Cds Nanoparticle ◽  
Spherical Micelles ◽  
Prepared Composite

In this study, block copolymers of PS-b-PMSMA with various molecular weight were synthesized by atom transfer radical polymerization (ATRP). GPC analysis showed that the molecular weight distribution of the prepared PS-b-PMSMA could be controlled to be lower than 1.3 for the case of molecular weight less than 30,000. The chemical structures of the amphiphilic block copolymers of PS-b-PMSMA were well identified by FTIR. SEM showed that the spherical micelles and compound micelles were produced in hybrid films. The EDX analysis indicated that the nano-sized CdS particles have been successfully prepared in the PS-b-PMSMA composite films. The diameter of CdS particles calculated from Brus formula was about 4-5 nm. PL analysis revealed that the λmax of emission of the prepared composite materials had a red-shift as the CdS particle size increased.

Biotransformation of Coumarins by Filamentous Fungi: An Alternative Way for Achievement of Bioactive Analogs

2019 ◽  
Vol 16 (6) ◽  
pp. 568-577 ◽  
Author(s):  
Jainara Santos do Nascimento ◽  
João Carlos Silva Conceição ◽  
Eliane de Oliveira Silva
Keyword(s):  
Filamentous Fungi ◽  
Chemical Reactions ◽  
Biological Activities ◽  
Chemical Transformations ◽  
Chemical Structures ◽  
Pattern Structures ◽  
Pharmacological Interest ◽  
Aspergillus Sp ◽  
The Impact ◽  
Related Compounds

Coumarins are natural 1,2-benzopyrones, present in remarkable amounts as secondary metabolites in edible and medicinal plants. The low yield in the coumarins isolation from natural sources, along with the difficulties faced by the total synthesis, make them attractive for biotechnological studies. The current literature contains several reports on the biotransformation of coumarins by fungi, which can generate chemical analogs with high selectivity, using mild and eco-friendly conditions. Prompted by the enormous pharmacological interest in the coumarin-related compounds, their alimentary and chemical applications, this review covers the biotransformation of coumarins by filamentous fungi. The chemical structures of the analogs were presented and compared with those from the pattern structures. The main chemical reactions catalyzed the insertion of functional groups, and the impact on the biological activities caused by the chemical transformations were discussed. Several chemical reactions can be catalyzed by filamentous fungi in the coumarin scores, mainly lactone ring opening, C3-C4 reduction and hydroxylation. Chunninghamella sp. and Aspergillus sp. are the most common fungi used in these transformations. Concerning the substrates, the biotransformation of pyranocoumarins is a rarer process. Sometimes, the bioactivities were improved by the chemical modifications and coincidences with the mammalian metabolism were pointed out.

scholarly journals Mechanical Behavior of Hydroxyapatite-Chitosan Composite: Effect of Processing Parameters

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 213
Author(s):  
Hamid Ait Said ◽  
Hassan Noukrati ◽  
Hicham Ben Youcef ◽  
Ayoub Bayoussef ◽  
Hassane Oudadesse ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Compressive Strength ◽  
Mechanical Strength ◽  
Bone Repair ◽  
Mechanical Stability ◽  
Three Dimensional ◽  
Processing Parameters ◽  
Composite Effect ◽  
Solid Liquid ◽  
The Impact

Three-dimensional hydroxyapatite-chitosan (HA-CS) composites were formulated via solid-liquid technic and freeze-drying. The prepared composites had an apatitic nature, which was demonstrated by X-ray diffraction and Infrared spectroscopy analyses. The impact of the solid/liquid (S/L) ratio and the content and the molecular weight of the polymer on the composite mechanical strength was investigated. An increase in the S/L ratio from 0.5 to 1 resulted in an increase in the compressive strength for HA-CSL (CS low molecular weight: CSL) from 0.08 ± 0.02 to 1.95 ± 0.39 MPa and from 0.3 ± 0.06 to 2.40 ± 0.51 MPa for the HA-CSM (CS medium molecular weight: CSM). Moreover, the increase in the amount (1 to 5 wt%) and the molecular weight of the polymer increased the mechanical strength of the composite. The highest compressive strength value (up to 2.40 ± 0.51 MPa) was obtained for HA-CSM (5 wt% of CS) formulated at an S/L of 1. The dissolution tests of the HA-CS composites confirmed their cohesion and mechanical stability in an aqueous solution. Both polymer and apatite are assumed to work together, giving the synergism needed to make effective cylindrical composites, and could serve as a promising candidate for bone repair in the orthopedic field.

scholarly journals Differences in the Effects of Anthocyanin Supplementation on Glucose and Lipid Metabolism According to the Structure of the Main Anthocyanin: A Meta-Analysis of Randomized Controlled Trials

Nutrients ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 2003
Author(s):  
Risa Araki ◽  
Akira Yada ◽  
Hirotsugu Ueda ◽  
Kenichi Tominaga ◽  
Hiroko Isoda
Keyword(s):  
Lipid Metabolism ◽  
Meta Analysis ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Resistance Index ◽  
Lipoprotein Cholesterol ◽  
Controlled Trials ◽  
Oh Groups ◽  
Chemical Structures ◽  
Glucose And Lipid Metabolism

The effectiveness of anthocyanins may differ according to their chemical structures; however, randomized clinical controlled trials (RCTs) or meta-analyses that examine the consequences of these structural differences have not been reported yet. In this meta-analysis, anthocyanins in test foods of 18 selected RCTs were categorized into three types: cyanidin-, delphinidin-, and malvidin-based. Delphinidin-based anthocyanins demonstrated significant effects on triglycerides (mean difference (MD): −0.24, p < 0.01), low-density lipoprotein cholesterol (LDL-C) (MD: −0.28, p < 0.001), and high-density lipoprotein cholesterol (HDL-C) (MD: 0.11, p < 0.01), whereas no significant effects were observed for cyanidin- and malvidin-based anthocyanins. Although non-significant, favorable effects on total cholesterol (TC) and HDL-C were observed for cyanidin- and malvidin-based anthocyanins, respectively (both p < 0.1). The ascending order of effectiveness on TC and LDL-C was delphinidin-, cyanidin-, and malvidin-based anthocyanins, and the differences among the three groups were significant (both p < 0.05). We could not confirm the significant effects of each main anthocyanin on glucose metabolism; however, insulin resistance index changed positively and negatively with cyanidin- and delphinidin-based anthocyanins, respectively. Therefore, foods containing mainly unmethylated anthocyanins, especially with large numbers of OH groups, may improve glucose and lipid metabolism more effectively than those containing methylated anthocyanins.

scholarly journals Improving Rheological and Mechanical Properties of Various Virgin and Recycled Polypropylenes by Blending with Long-Chain Branched Polypropylene

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1137
Author(s):  
Sascha Stanic ◽  
Thomas Koch ◽  
Klaus Schmid ◽  
Simone Knaus ◽  
Vasiliki-Maria Archodoulaki
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Test ◽  
Reactive Extrusion ◽  
Original Material ◽  
Melt Flow Rate ◽  
Single Screw Extruder ◽  
Pp Blends ◽  
The Impact ◽  
Long Chain

Blends of two long-chain branched polypropylenes (LCB-PP) and five linear polypropylenes (L-PP) were prepared in a single screw extruder at 240 °C. The two LCB-PPs were self-created via reactive extrusion at 180 °C by using dimyristyl peroxydicarbonate (PODIC C126) and dilauroyl peroxide (LP) as peroxides. For blending two virgin and three recycled PPs like coffee caps, yoghurt cups and buckets with different melt flow rate (MFR) values were used. The influence of using blends was assessed by investigating the rheological (dynamic and extensional rheology) and mechanical properties (tensile test and impact tensile test). The dynamic rheology indicated that the molecular weight as well as the molecular weight distribution could be increased or broadened. Also the melt strength behavior could be improved by using the two peroxide modified LCB-PP blends on the basis of PODIC C126 or PEROXAN LP (dilauroyl peroxide). In addition, the mechanical properties were consistently enhanced or at least kept constant compared to the original material. In particular, the impact tensile strength but also the elongation at break could be increased considerably. This study showed that the blending of LCB-PP can increase the investigated properties and represents a promising option, especially when using recycled PP, which demonstrates a real “up-cycling” process.

scholarly journals An Effective Method for Preparation of Liquid Phosphoric Anhydride and Its Application in Flame Retardant Epoxy Resin

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2205
Author(s):  
Qian Li ◽  
Yujie Li ◽  
Yifan Chen ◽  
Qiang Wu ◽  
Siqun Wang
Keyword(s):  
Flame Retardant ◽  
Epoxy Resin ◽  
Epoxy Resins ◽  
Oxygen Index ◽  
Decomposition Temperature ◽  
Ease Of Use ◽  
Limiting Oxygen Index ◽  
Good Thermal Stability ◽  
Low Viscosity ◽  
The Impact

A novel liquid phosphorous-containing flame retardant anhydride (LPFA) with low viscosity was synthesized from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and methyl tetrahydrophthalic anhydride (MeTHPA) and further cured with bisphenol-A epoxy resin E-51 for the preparation of the flame retardant epoxy resins. Both Fourier transform infrared spectroscopy (FT-IR), mass spectrometry (MS) and nuclear magnetic resonance (NMR) measurements revealed the successful incorporation of DOPO on the molecular chains of MeTHPA through chemical reaction. The oxygen index analysis showed that the LPFA-cured epoxy resin exhibited excellent flame retardant performance, and the corresponding limiting oxygen index (LOI) value could reach 31.2%. The UL-94V-0 rating was achieved for the flame retardant epoxy resin with the phosphorus content of 2.7%. With the addition of LPFA, the impact strength of the cured epoxy resins remained almost unchanged, but the flexural strength gradually increased. Meanwhile, all the epoxy resins showed good thermal stability. The glass transition temperature (Tg) and thermal decomposition temperature (Td) of epoxy resin cured by LPFA decreased slightly compared with that of MeTHPA-cured epoxy resin. Based on such excellent flame retardancy, low viscosity at room temperature and ease of use, LPFA showed potential as an appropriate curing agent in the field of electrical insulation materials.

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