Lower Average Molecular Weight Research Articles

The comparative influence of novel extraction technologies on in vitro prebiotic-inducing chemical properties of fucoidan extracts from Ascophyllum nodosum

The influence of conventional and novel extraction technologies on the structure-prebiotic activity relationship of fucoidan extracts was investigated. Fucoidan extracted from conventional chemical (Fuc-CCE), microwave-assisted (Fuc-MAE), ultrasound-assisted (Fuc-UAE) and enzyme-assisted (Fuc-EAE) extractions were characterized and investigated for in vitro prebiotic activity. Fuc-CCE had significantly higher extract yield when compared to Fuc-MAE, Fuc-UAE, and Fuc-EAE. However, there were no significant differences in fucose and galactose contents of the extracts. Sulphate levels of Fuc-MAE and Fuc-CCE were significantly higher than those of Fuc-UAE and Fuc-EAE. Also, Fuc-MAE had significantly lower average molecular weight and higher dispersity index compared to the other extracts. Fucoidan-supplemented MRS broth from all four methods significantly (p < 0.05) increased growth rates of Lactobacillus delbruecki ssp bulgaricus compared to the un-supplemented medium. However, there was no significant difference in the growth rates of the extracts. For the L. casei strain, there was no significant difference between the supplemented and un-supplemented media. However, Fuc-MAE-supplemented media resulted in a 24.5% increase in growth rate, at 0.5% w/v concentration, compared to the un-supplemented medium. The growth rates of fucoidan extracts were comparable to that of the commercial prebiotic, inulin, thus strengthening the in vitro prebiotic claim for the fucoidan extracts. Overall, the results indicated that Fuc-MAE had better physicochemical characteristics (fucose and galactose, sulphate, molecular weight and dispersity index), but had no significant advantage over the other extracts based on in vitro prebiotic activity.

Microwave-assisted recovery of monomeric sugars from an acidic steam treated wood hydrolysate

Fractionation of components from bio-refinery wastes streams is complicated by the presence of both oligomer and lignin fractions. Microwave-assisted acid hydrolysis was used in this study to convert oligomer sugars in an industrial prehydrolysis liquor (PHL) to monomeric sugars. A total of 19.6 g/L monomeric sugars was obtained at a combined severity factor (CSF) of 3.2. Furthermore, it was found that xylan linked to lignin in a lignin-carbohydrate complex (LCC) could be liberated, resulting in lignin with a relatively low dispersity (3.12) and average molecular weight (1718 g/mol) that has high commercial value in the phenol–formaldehyde resin industry. This study presents for the first time a relatively inexpensive method for recovery of 100% of available sugars in the PHL without apparent loss in monomeric sugar as well as 50% removal of lignin as a valuable by-product. Application of this method can significantly improve the economic sustainability of forest-based biorefineries.

Antioxidative peptides of hydrolysate prepared from fish skin gelatin using ginger protease activate antioxidant response element-mediated gene transcription in IPEC-J2 cells

Excess production of reactive oxygen species (ROS) causes oxidative stress, which is associated with oxidative damage and a number of human chronic diseases. Here, novel antioxidant hydrolysates were obtained from fish skin, pig skin, pig bone and bovine skin gelatins using ginger protease, and were compared with those produced using pepsin-pancreatin. Ginger protease could hydrolyze the gelatin from fish skin to peptides with low average molecular weights (<690 Da) more efficiently than that from pig skin, pig bone and bovine skin. All gelatin hydrolysates showed higher antioxidative activities than non-hydrolysed gelatins. Especially, fish skin gelatin hydrolysate (FSGH) obtained using ginger protease exhibited the highest degree of hydrolysis (13.08%) and antioxidant activity towards DPPH radical (97.21%) and lipid peroxidation (48.46%). The FSGH was then separated into three fractions by ultrafiltration. The fraction with a molecular weight below 1000 Da demonstrated the strongest scavenging capacity for DPPH and hydroxyl radicals and inhibitory effect on lipid peroxidation. Further HPLC-ESI-QqQ-MS results revealed that this fraction mainly included two types of peptides: Gly-Pro-Y-type and X-Hyp-Gly-type tripeptides. The ARE-luciferase activity of a selection of the identified oligopeptides was examined using the IPEC-J2 cell model. The most active peptide was Gly-Pro-Ala, which showed an approximately 2.5-fold increase in ARE-luciferase activity. Additionally, Gly-Pro-Ala (0–2.5 mg/mL) activated the expression of ARE-driven antioxidant enzyme genes in a dose dependent manner, and subsequently suppressed the H2O2-induced intracellular ROS production. Overall, our results demonstrate that FSGH prepared using ginger protease could serve as a source of peptides with high antioxidative activities.

Investigation of the Effects of Non-Conjugated Co-Grafts on the Spectroelectrochemical and Photovoltaic Properties of Novel Conjugated Graft Copolymers Based on Poly(3-hexylthiophene).

A new type of polysiloxane copolymers, with conjugated–regioregular poly(3-hexylthiophene) (P3HT) and non-conjugated-poly(ethylene glycol) (PEG)-grafts have been synthesised, and their properties have been studied alongside those of the parent conjugated polymer (P3HT). Spectroelectrochemical and conductometric analyses revealed an early rise of the conductance of the polymers. Once spectral changes begin taking place, the conductance is stable, implying a loss of mobility of charge carriers, even though standard doping/dedoping patterns are observed. Prototype bulk heterojunction solar cells have been fabricated, based on P3HT/[6,6]-Phenyl-C61-butyric acid methyl ester (PCBM), as well as by substituting P3HT for each of the copolymers. The prototype solar cells achieved PCEs of up to 2.11%. This is one of the highest reported power conversion efficiency (PCE) for devices based on P3HT with low average molecular weight Mn = 12 kDa. Strong correlation between the structure of the copolymer and its photovoltaic performance was found. Elongation of PEG copolymer chain and the use of methyl group instead of terminal hydroxyl groups significantly improved photovoltaic performance.

Co-pyrolysis of biomass and plastic wastes: investigation of apparent kinetic parameters and stability of pyrolysis oils

This work is dedicated to the co-pyrolysis of real waste high density polyethylene (HDPE) and biomass (rice straw) obtained from agriculture. Mixtures of raw materials were pyrolyzed in their 0%/100%, 30%/70%, 50%/50%, 70%/30%, 100%/0% ratios using a thermograph. The atmosphere was nitrogen, and a constant heating rate was used. Based on weight loss and DTG curves, the apparent reaction kinetic parameters (e.g., activation energy) were calculated using first-order kinetic approach and Arrhenius equation. It was found that decomposition of pure plastic has approximately 280 kJ/mol activation energy, while that of was considerably less in case of biomass. Furthermore, HDPE decomposition takes by one stage, while that of biomass was three stages. The larger amount of raw materials (100 g) were also pyrolyzed in the batch rig at 550°C to obtain products for analysis focussing to their long-term application. Pyrolysis oils were investigated by Fourier transformed infrared spectroscopy and standardized methods, such as density, viscosity, boiling range determination. It was concluded, that higher plastic ratio in raw material had the advantageous effect to the pyrolysis oil long-term application. E.g., the concentration of oxygenated compounds, such as aldehydes, ketones, carboxylic acids or even phenol and its derivate could be significantly decreased, which had an advantageous effect to their corrosion property. Lower average molecular weight, viscosity, and density were measured as a function of plastic content.

The Supramolecular and Coordination Chemistry of Cobalt(II) Extraction by Phosphinic Acids

A combination of mass spectrometry, DFT calculations and 31P{1H} NMR spectroscopy has been used to define the mode of action of the commercial cobalt extractant, bis(2,4,4‐trimethylpentyl)phosphinic acid (CYANEX®272, L1H) in Co recovery. The nature of the CoII complexes formed in the water‐immiscible phase is determined largely by the propensity of phosphinates to form strong interligand H‐bonds in the outer coordination sphere and also to form stable µ2‐Co–O–P–O–Co bridges. At low Co loading levels, the predominant species is the 4:1 complex, [Co(L1·L1H)2], in which coordinated neutral phosphinic acid ligands form strong H‐bonds to adjacent anionic phosphinates. At higher Co loading, oligomers such as [(L1·L1H)Co(L12Co)n(L1·L1H)] are formed with µ2‐phosphinate bridging, resulting in a substantial increase in the viscosity of the water‐immiscible phase. The presence of tris(2,4,4‐trimethylpentyl)phosphine oxide (L2) in the commercial formulation reduces the viscosity because its incorporation into oligomeric complexes such as [(L2)Co{L13CoL1CoL13Co}mL1] can terminate chains, resulting in a lower average molecular weight. The uptake of Zn by L1H shows a very similar dependence of viscosity on loading, and DOSY spectra and mass spectrometry demonstrate that higher molecular weight species are present at high Zn loading.

Comparison of Branched and Linear Perfluoropolyether Chains Functionalization on Hydrophobic, Morphological and Conductive Properties of Multi-Walled Carbon Nanotubes.

The functionalization of multi-walled carbon nanotubes (MW-CNTs) was obtained by generating reactive perfluoropolyether (PFPE) radicals that can covalently bond to MW-CNTs’ surface. Branched and linear PFPE peroxides with equivalent molecular weights of 1275 and 1200 amu, respectively, have been thermally decomposed for the production of PFPE radicals. The functionalization with PFPE chains has changed the wettability of MW-CNTs, which switched their behavior from hydrophilic to super-hydrophobic. The low surface energy properties of PFPEs have been transferred to MW-CNTs surface and branched units with trifluoromethyl groups, CF3, have conferred higher hydrophobicity than linear units. Porosimetry discriminated the effects of PFPE functionalization on meso-porosity and macro-porosity. It has been observed that reactive sites located in MW-CNTs mesopores have been intensively functionalized by branched PFPE peroxide due to its low average molecular weight. Conductivity measurements at different applied pressures have showed that the covalent linkage of PFPE chains, branched as well as linear, weakly modified the electrical conductivity of MW-CNTs. The decomposed portions of PFPE residues, the PFPE chains bonded on carbon nanotubes, and the PFPE fluids obtained by homo-coupling side-reactions were evaluated by mass balances. PFPE-modified MW-CNTs have been characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), static contact angle (SCA), surface area, and porosity measurements.

Antioxidant activity of purified ulvan in hyperlipidemic mice

Several studies have reported that ulvan from the alga Ulva pertusa (Chlorophyta) exhibits substantial antioxidant and antihyperlipidemic activities; however, which group of heteropolysaccharides play roles in these activities remains unknown. In this study, three purified ulvan (PU1, PU2 and PU3) have been obtained by DEAE-Sepharose fast-flow column. The antioxidant activity was detected via the model of hyperlipidemic Kunming mice, including malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in liver. PU3, which possessed the highest uronic acid content (24.09%) and sulfate content (23.99%) as well as the lowest average molecular weight (83,094 Da), exhibited the stronger antioxidant activity than other examples. It significantly decreased MDA (29.2%; P < 0.05), increased SOD (36.4%; P < 0.05) and CAT (43.6%; P < 0.05) compared with hyperlipidemia group. In conclusion, PU3 may be potential sources of natural antioxidant to protecting against the liver damage of oxidative stress induced by cholesterol-rich diet.

Multi-scale structural changes in lintnerized starches from three coloured potatoes

Three kinds of potato starch were treated with 2.2 N HCl at 35 °C for 40 days, and their susceptibility to acid hydrolysis and the resulting structural changes were evaluated. Red potato starch was more susceptible to acid hydrolysis and presented highest rate of hydrolysis. Lintnerized starches had relatively low average molecular weights and z-average radius of gyration. HPAEC analyses showed three lintners presented different molecular size distributions. Lintnerized yellow potato starch had few chains of DP ≤ 12 (2.58 mol%) and more chains of DP ≥ 37 (8.16 mol%). Furthermore, the similarities of the branch-chain length distributions before and after debranching indicated the lintners consisted primarily of linear molecules. After lintnerization, most starch granules were degraded, and the birefringence disappeared from some granules. X-ray diffraction patterns revealed that the relative crystallinity significantly increased after lintnerization. DSC analyses showed that lintners displayed broader thermal-transitions.

Fabricating soy protein hydrolysate/xanthan gum as fat replacer in ice cream by combined enzymatic and heat-shearing treatment

Soy protein hydrolysates (SPH) and their blends with xanthan gum (SPH/XG), produced via a combination of enzymatic hydrolysis and heat-shearing treatment, were used as fat replacers in the production of reduced fat ice cream. The physicochemical properties of soy protein isolate (SPI) and its hydrolysates with 1% (SPH1) and 5% degree of hydrolysis (SPH5) were characterized. The results suggested that enzymatic hydrolysis produced a lower average molecular weight (Mw), particle size, viscosity, and water holding capacity compared with SPI, but increased the solubility, oil holding capacity, and foaming capacity. The particle size of the SPH5/XG fat replacer was significantly reduced by enzymatic hydrolysis and heat-shearing treatment. In addition, the incorporation of XG could stabilize the composite system, as indicated by rheology measurement. The sensory properties of ice creams were correlated with the physicochemical measurements. The results illustrated that 50% fat-substituted ice cream with SPH5/XG (96:4) had an appearance, taste, and texture similar to that of 10% full fat ice cream, and the overall performance was acceptable among the low-fat ice cream samples. Therefore, SPH/XG treated by enzymatic hydrolysis and microparticulation is an alternative choice as a fat replacer in typical ice cream production.

Selective adsorption of fatty acid methyl esters onto a commercial molecular sieve or activated charcoal prepared from the &lt;i&gt;Acrocomia aculeata&lt;/i&gt; cake remaining from press-extracting the fruit kernel oil

Mixing light biodiesel at low concentrations (not exceeding 5% by volume) with mineral kerosene is thought to be an interesting alternative to aviation fossil fuels without the need for engine adjustments. From the environmental point of view, this addition would mean significantly minimizing the impacts of conventional fuel emissions. The adsorption of relatively short molecular chain (C8, C10 and C12) fatty acid methyl esters (FAME), constituents of the biodiesel produced from the macauba oil, was investigated using two types of adsorbents: A commercial molecular sieve 13X and the activated charcoal prepared from the macauba cake remaining after press-defatting the macauba fruit kernel. The adsorption experiments were performed on a glass column filled with the adsorbent. The activated charcoal is more efficient than the molecular sieve for selectively adsorbing FAME with C8, C10 and C12 carbon chains. The process of separating shorter chains from biodiesel by adsorption was proven to be adequate and does not compromise the energy balance. This study indicates that the charcoal obtained from the macauba cake remaining after extracting the oil might be suitable for the selective separation of fatty acid esters, which could potentially lead to the preparation of lighter biodiesel (of lower average molecular weight) than that produced from the crude oil.

In-situ preparation and characterization of ultra-high molecular weight polyethylene/diamond nanocomposites using Bi-supported Ziegler-Natta catalyst: Effect of nanodiamond silanization

In this study, reinforcement of ultra-high molecular weight polyethylene (UHMWPE) was investigated using the sol-gel surface modified diamond nanoparticles (NDs). Nanocomposite samples were synthesized via in-situ polymerization using bi-supported Ziegler-Natta catalyst. Fourier transform infrared spectroscopy, thermogravimetric analysis and contact angle measurements proved the proper silanization (∼1.9%) of NDs. Characterization of the catalysts revealed decrease in the activity of catalysts in presence of NDs which were responsible for the lower average molecular weight of the samples. Field emission scanning electron microscopy revealed an improved dispersion of the modified NDs in UHMWPE matrix by silanization. The incorporation of 2 wt.% unmodified and modified NDs enhanced the storage modulus (≤106% and ≤124%) and tensile strength (≤33% and ≤86%), respectively. Also, improvement in shore D and scratch hardness strength can be achieved in presence of NDs. Furthermore, tribological properties of the samples were investigated and discussed accordingly.

Predicting apparent singlet oxygen quantum yields of dissolved black carbon and humic substances using spectroscopic indices

Dissolved black carbon (DBC) is ubiquitous in aquatic systems, being an important subgroup of the dissolved organic matter (DOM) pool. Nevertheless, its aquatic photoactivity remains largely unknown. In this study, a range of spectroscopic indices of DBC and humic substance (HS) samples were determined using UV–Vis spectroscopy, fluorescence spectroscopy, and proton nuclear magnetic resonance. DBC can be readily differentiated from HS using spectroscopic indices. It has lower average molecular weight, but higher aromaticity and lignin content. The apparent singlet oxygen quantum yield (Φsinglet oxygen) of DBC under simulated sunlight varies from 3.46% to 6.13%, significantly higher than HS, 1.26%–3.57%, suggesting that DBC is the more photoactive component in the DOM pool. Despite drastically different formation processes and structural properties, the Φsinglet oxygen of DBC and HS can be well predicted by the same simple linear regression models using optical indices including spectral slope coefficient (S275-295) and absorbance ratio (E2/E3) which are proxies for the abundance of singlet oxygen sensitizers and for the significance of intramolecular charge transfer interactions. The regression models can be potentially used to assess the photoactivity of DOM at large scales with in situ water spectrophotometry or satellite remote sensing.

The effect of coumaryl alcohol incorporation on the structure and composition of lignin dehydrogenation polymers

BackgroundLignin dehydrogenation polymers (DHPs) are polymers generated from phenolic precursors for the purpose of studying lignin structure and polymerization processesMethodsHere, DHPs were synthesized using a Zutropfverfahren method with horseradish peroxidase and three lignin monomers, sinapyl (S), coumaryl (H), and coniferyl (G) alcohols, in the presence of hydrogen peroxide. The H monomer was reacted with G and a 1:1 molar mixture of S:G monomers at H molar compositions of 0, 5, 10, and 20 mol% to study how the presence of the H monomer affected the structure and composition of the recovered polymers.ResultsAt low H concentrations, solid-state NMR spectra suggest that the H and G monomers interact to form G:H polymers that have a lower average molecular weight than the solely G-based polymer or the G:H polymer produced at higher H concentrations. Solid-state NMR and pyrolysis–MBMS analyses suggest that at higher H concentrations, the H monomer primarily self-polymerizes to produce clusters of H-based polymer that are segregated from clusters of G- or S:G-based polymers. Thioacidolysis generally showed higher recoveries of thioethylated products from S:G or S:G:H polymers made with higher H content, indicating an increase in the linear ether linkages.ConclusionsOverall, the experimental results support theoretical predictions for the reactivity and structural influences of the H monomer on the formation of lignin-like polymers.

The effect of gelatin hydrolysate from pygostyle of broiler produced by enzymatic hydrolysis process of Aspergillus niger to prophylaxis

Kuntana YP, Balia R, Murad S, Hidayat YA, Partasasmita R. 2017. The effect of gelatin hydrolysate from pygostyle of broiler produced by enzymatic hydrolysis process of Aspergillus niger to prophylaxis of osteoporosis white rat. Nusantara Bioscience 9: 361- 366. The pygostyle of the broiler is a cartilage tissue containing collagen, a mucoprotein being a plasma expander. The hydrolysis process of collagen by enzyme can produce gelatin hydrolysate differently compared to that from commercial gelatin because it has an amino acid composition with low average molecular weight. It becomes an advantage because it can be directly absorbed by the digestive tract. In addition, the enzymatic process can be done in short time with the low cost and also environment-friendly approach. This process can be assisted by Aspergillus niger, i.e., safe microorganisms (GRASS). A. niger has a protease enzyme that can digest collagen into gelatin hydrolysate. The enzyme is extracellularly removed so that its utilization does not require high input value expenditure. Gelatin hydrolysate can reduce the disease of osteoporosis. The objective of this study was to know the effect of gelatin hydrolysate produced from chicken bones in the favor of A. niger for increasing the benefit products. The specific targets are to find the amount of gelatin hydrolysate, precisely eliminated osteoporosis of rat (Rattus norvegicus). The experimental research was conducted in the laboratory with using complete randomized design followed by the descriptive analysis with 5 treatment and 5 replication. CCl4 dose 0,14 mL/g BW (P1 as a negative control), Potatoes dextrose Broth (PDB) dose 0,5 mL/g BW (P2 positive control), gelatin hydrolysate dose 0.25; 0.5; 0.75 mL/g BW (P3-P5). The observed parameters were including body weight and histological observation of musculoskeletal tissue in terms of measurement of fiber muscle, cartilage and collagen diameter. The test animal used was male white rat (R. norvegicus) Wistar strain aged 2-3 months with body weight 185-200 g. Data were analyzed using ANOVA and Duncan test. The results show that gelatin hydrolyzate as an environmentally friendly product serves as a prevention of immune diseases and degenerative diseases such as osteoporosis.

Effect of Graphene Oxide on the Reaction Kinetics of Methyl Methacrylate In Situ Radical Polymerization via the Bulk or Solution Technique.

The synthesis of nanocomposite materials based on poly(methyl methacrylate) and graphene oxide (GO) is presented using the in situ polymerization technique, starting from methyl methacrylate, graphite oxide, and an initiator, and carried out either with (solution) or without (bulk) in the presence of a suitable solvent. Reaction kinetics was followed gravimetrically and the appropriate characterization of the products took place using several experimental techniques. X-ray diffraction (XRD) data showed that graphite oxide had been transformed to graphene oxide during polymerization, whereas FTIR spectra revealed no significant interactions between the polymer matrix and GO. It appears that during polymerization, the initiator efficiency was reduced by the presence of GO, resulting in a reduction of the reaction rate and a slight increase in the average molecular weight of the polymer formed, measured by gel permeation chromatography (GPC), along with an increase in the glass transition temperature obtained from differential scanning calorimetry (DSC). The presence of the solvent results in the suppression of the gel-effect in the reaction rate curves, the synthesis of polymers with lower average molecular weights and polydispersities of the Molecular Weight Distribution, and lower glass transition temperatures. Finally, from thermogravimetric analysis (TG), it was verified that the presence of GO slightly enhances the thermal stability of the nano-hybrids formed.

Identification of organic compounds in ocean basement fluids

We have analyzed the dissolved organic carbon, OC, in ocean basement fluids using Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry (FT-ICR-MS). The compounds identified at the two sites, near the Juan de Fuca and Mid-Atlantic Ridges (North Pond), differ substantially from each other and from seawater. Compared to Juan de Fuca, North Pond organics had a lower average molecular weight (349 vs. 372g/mol), 50% more identifiable compounds (2181 vs. 1482), and demonstrably lower average nominal oxidation state of carbon (−0.70 vs. −0.56). The North Pond fluids were also found to have many more N- and S-bearing compounds. Based on our data, the marine subsurface can alter the types of dissolved OC, DOC, compounds in seawater.

Molecular Weights of Bovine and Porcine Heparin Samples: Comparison of Chromatographic Methods and Results of a Collaborative Survey.

In a collaborative study involving six laboratories in the USA, Europe, and India the molecular weight distributions of a panel of heparin sodium samples were determined, in order to compare heparin sodium of bovine intestinal origin with that of bovine lung and porcine intestinal origin. Porcine samples met the current criteria as laid out in the USP Heparin Sodium monograph. Bovine lung heparin samples had consistently lower average molecular weights. Bovine intestinal heparin was variable in molecular weight; some samples fell below the USP limits, some fell within these limits and others fell above the upper limits. These data will inform the establishment of pharmacopeial acceptance criteria for heparin sodium derived from bovine intestinal mucosa. The method for MW determination as described in the USP monograph uses a single, broad standard calibrant to characterize the chromatographic profile of heparin sodium on high-resolution silica-based GPC columns. These columns may be short-lived in some laboratories. Using the panel of samples described above, methods based on the use of robust polymer-based columns have been developed. In addition to the use of the USP’s broad standard calibrant for heparin sodium with these columns, a set of conditions have been devised that allow light-scattering detected molecular weight characterization of heparin sodium, giving results that agree well with the monograph method. These findings may facilitate the validation of variant chromatographic methods with some practical advantages over the USP monograph method.

Characterizing the degradation of PDMS stamps in nanoimprint lithography

Within this work we investigate the lifetime of soft PDMS stamps as a critical parameter for the up-scaled fabrication of microstructures via nanoimprint lithography. We propose the characterization of the PDMS hardness as a suitable parameter for the stamp degradation. The increasing hardness for a larger number of imprints is attributed to resist diffusion into the PDMS volume and possibly subsequent cross-linking. Force-distance measurements with an atomic force microscope were applied to demonstrate for two acrylic materials that a lower average molecular weight leads to a faster degradation. Using a temperature-assisted UV-imprint process with an epoxy material (SU-8 2002) enabled more than 100 imprints without measurable degradation due to the complex molecular structure which we assume to reduce the resist diffusion. This can be a key development towards a higher stamp lifetime and finally an industrial realization of NIL.

Effect of Desulfonation of Lignosulfonate on the Properties of Poly(Lactic Acid)/Lignin Composites

To utilize the lignin generated by the paper industry and reduce the cost of poly(lactic acid) (PLA), PLA/lignin composites were prepared from PLA and different ratios of lignosulfonate (LS) or desulfonated lignosulfonate (DLS) particles using a casting method. The physicochemical properties of the lignins were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), gel permeation-high performance liquid chromatography (GPC), and elementary analysis. The results indicate that the sulfur content of the original LS was successfully reduced to half by desulfonation to produce DLS, which was found to have a higher thermal stability and a lower average molecular weight than LS. Additionally, the thermal stability, crystallization, compatibility, mechanical, hydrophobicity, and optical properties of the PLA/lignin composites were also meticulously evaluated. Comparison of the PLA/DLS and PLA/LS composites revealed that the incorporation of DLS into PLA improved compatibility, thermal stability (T5% and Tmax), and hydrophobicity, while the mechanical properties remained almost unchanged. In addition, both PLA/DLS and PLA/LS exhibited UV light absorption capacity. Finally, the low-rate addition of both LS (10%) and DLS (5%) accelerated the crystallization of PLA, but crystallization was delayed with higher lignin content.