Intrinsic Viscosity Research Articles

Commercial pectin production from dried florida orange peel: Effect of process conditions on pectin structure and function

AbstractTo determine the feasibility of using Florida, USA, oranges for pectin production, we evaluated the effects of time, temperature, and pH on pectin properties extracted from dried Valencia orange peel using a hot acid process. Juice extracted peel was collected weekly, and following pretreatment, the dried peel was pooled and used to extract pectin with time (4, 5, and 6 h), temperature (65 and 75°C), and pH (1.6 and 1.8) as process variables. Pectin properties, including yield, sugar composition, molecular weight, intrinsic viscosity, degree of methylesterification, degree of branching, degree of blockiness, absolute degree of blockiness, and Standard Acid in Glass (SAG), were determined. In addition, we evaluated the response of each variable to the process conditions using response surface methodology. The analysis of variance (anova) models for molecular weight, intrinsic viscosity, and yield were highly significant, with actual values decreasing with increasing temperature. Increasing reaction time also decreased values for molecular weight and intrinsic viscosity.Novelty impact statementThis study indicates that process time and temperature affected pectin quality, functionality, and yield. Increasing temperature had the most detrimental effect on desirability in an optimization analysis.

Stretchability above glass transition of mechanically recycled poly(ethylene terephtalate), PET

Poly(ethylene terephthalate) (PET) is nowadays an interesting polymer, largely used for food packaging applications. It has the ability to develop a pseudo-crystalline structure under stretching above its glass transition temperature. Environmental concerns have granted an increasing interest for recycled materials and thus recycled PET (rPET). Mechanical recycling of PET can affect the chains length as well as the contaminant concentration that will change is formability. Two rPET and two virgin PET (vPET) having dissimilar intrinsic viscosity were then studied by first analyzing the initial properties of the extruded sheets. The four grades were then stretched in uniaxial conditions, based on the time/temperature equivalence principle identified in the low deformations domain. A relevant parameter, the natural draw ratio (NDR) appears to be very efficient so as to discriminate the relative mechanical responses of the four grades. This parameter whose use has been comforted in industrial conditions allows to optimize the forming range of rPET, compared to vPET. • Mechanically recycled and virgin PET stretch ability above glass transition is explored, and their mechanical behavior do obey to time/temperature equivalence principle. • For all the stretching settings applied, the natural draw ratio (NDR) measured is a relevant parameter able to discriminate mechanical behavior of virgin or recycled polymers. • An optimization of the forming range is proposed where enhanced induced microstructures are obtained.

Analysis of the microscopic interactions between processed Polygonatum cyrtonema polysaccharides and water

The dissolution and microscopic interactions of processed Polygonatum cyrtonema polysaccharides in water are extremely important because they strongly influence the process to extract these polysaccharides from water. In this paper, molecular dynamics simulation methods were used to analyse the influence of extraction temperature, concentration and molecular weight on the radial distribution function (RDF), mean square displacement (MSD), diffusion coefficient (D), radius of gyration (Rg), and microstructure of processed Polygonatum cyrtonema polysaccharides in water as well as the intrinsic viscosity (η), hydrogen bond characteristics and microscopic interactions in the solutions. The research results showed that the extraction temperature, concentration and molecular weight of the polysaccharides had important effects on the RDF, MSD, D, Rg, η, hydrogen bond characteristics and the microstructure of the polysaccharide molecules, but there were some major differences. The order of the influence of the factors affecting the dissolution of polysaccharides in water was temperature > concentration > molecular weight. Extraction temperature, material fluid ratio and molecular weight had greater influence on the fluidity and dissolution state of the polysaccharides in water. As the solute concentration and molecular weight increased, hydrogen bonds between polysaccharides and water inhibited their dissolution and diffusion. Properly increasing the temperature, reducing the concentration and selecting low molecular weight polysaccharides enhanced the dissolution and diffusion of the polysaccharides in the solution system. Molecular weight was the main factor affecting the η of the polysaccharide solutions. These results can provide theoretical guidance for the extraction or tea brewing process of Polygonatum cyrtonema polysaccharides in future work.

Isolation and Structural Characterization of Alginates from the Kelp Species Laminaria ochroleuca and Saccorhiza polyschides from the Atlantic Coast of Morocco

Alginates are linear unbranched polysaccharides produced by brown seaweeds. The gel properties of this phycocolloid are mainly linked to the monomer composition, sequential structure and molecular weight of the polymeric chain. Nevertheless, these structural parameters are also dependent on the age and tissue of the thalli used. In this work, the kelp species Laminaria ochroleuca and Saccorhiza polyschides harvested from the Moroccan coast were analyzed for their alginates content and composition in different thalli parts (blade and stipe). Spectroscopic characterization (1H NMR and FT-IR), viscosity, and molecular weight of the extracted alginates were investigated. The obtained results showed that the alginate contents ranged from 20.19 ± 2 to 49.8 ± 2.4% dw. FT-IR spectroscopy exhibited similar spectra between the alginates extracted from both species and the commercial alginate. The 1H-NMR results revealed interesting variations in block composition between species, and less disparity with regard to the tissue type (M/G values ranging from 0.89 to 2.14). High mannuronate content was found in all alginates except for those extracted from the blade of L. ochroleuca. The homopolymeric fractions FMM are remarkably high compared to the FGG and heteropolymeric fractions (FGM/FMG) in S. polyschides. However, for L. ochroleuca, the heteropolymeric fractions are quite abundant, accounting for more than 34% of the polymer diads. The alginates extracted from both species indicated low values for the intrinsic viscosity. Based on the yield and the structural properties of their alginates, this study suggests that both L. ochroleuca and S.polyschides could be considered potential alginophytes to be incorporated into the industry of alginates. It also proposes an optimization of the yield, using the different thalli parts in the extraction (blade and stipe). The chemical structure and viscosity of their alginates may contribute to expanding their applications, especially in biotechnology and medical fields.

Extraction and Physico-Chemical Characterization of Chitosan from Mantis Shrimp (Oratosquilla nepa) Shell and the Development of Bio-Composite Film with Agarose.

Mantis shrimp (Oratosquilla nepa) exoskeleton, a leftover generated after processing, was used as a starting material for chitosan (CS) production. CS was extracted with different deacetylation times (2, 3 and 4 h), termed CS−2, CS−3 and CS−4, respectively, and their characteristics and antimicrobial and film properties with agarose (AG) were investigated. Prolonged deacetylation time increased the degree of deacetylation (DDA: 73.56 ± 0.09–75.56 ± 0.09%), while extraction yield (15.79 ± 0.19–14.13 ± 0.09%), intrinsic viscosity (η: 3.58 ± 0.09–2.97 ± 0.16 dL/g) and average molecular weight (Mν: 1.4 ± 0.05–1.12 ± 0.08 (×106 Da)) decreased (p < 0.05). FTIR spectra of extracted CS were similar to that of commercial CS. Among all the CS samples prepared, CS−3 had the best yield, DDA, Mν and antimicrobial activity. Therefore, it was chosen for the development of composite films with AG at different ratios (CS−3/AG; 100/0, 75/25, 50/50, 25/75 and 0/100). As the proportion of AG increased, the tensile strength (29.96 ± 1.80–89.70 ± 5.08 MPa) of the composite films increased, while thickness (0.056 ± 0.012–0.024 ± 0.001 mm), elongation at break (36.52 ± 1.12–25.32 ± 1.23%) and water vapor permeability (3.56 ± 0.10–1.55 ± 0.02 (×10−7 g m m−2 s−1 Pa−1)) decreased (p < 0.05). Moreover, lightness of the films increased and yellowness decreased. CS−3/AG (50/50) composite film exhibited high mechanical and barrier properties and excellent compatibility according to FTIR and SEM analyses. According to these finding, mantis shrimp exoskeleton could be used to produce CS. The developed bio-composite film based on an appropriate ratio (50/50) of CS−3 and AG has potential for being used as food packaging material.

SYNTHESIS AND STUDY OF COPOLYMERS OF METHYL METHACRYLATE WİTH OLIGOPROPYLENE MACROMONOMERS

The reaction of radical copolymerization of oligopropylene macromonomer (M1) with methyl methacrylate (M2) has been carried out, the regularities of the reaction and the properties of the obtained products have been studied. It has been found that the values of the relative activity of these monomers are r1=0.02 and r2=12.2, respectively. The fact that the value of the copolymerization constant of the oligopropylene macromonomer is close to zero indicates that it is not prone to homopolymerization reactions and only undergoes copolymerization reactions. The dependence of some properties of the synthesized copolymer on their composition has been studied and it has been shown that with an increase in the amount of the fragment formed from the oligopropylene macromonomer, the softening temperature and intrinsic viscosity values of the copolymers decrease, and, accordingly, a sharp decrease in the average molecular weight is observed. This is due to the passivity of the oligopropylene macromonomer in copolymerization reactions and the high probability of a chain transfer reaction through the oligopropylene macromonomer.

Molecular Weight and Functional Group Analysis of Low Molecular Weight of Liquid Cyclic Natural Rubber

The research about molecular weight and functional group analysis of low molecular weight liquid cyclic natural rubber has been done. The aim of this research is to achievement the quality of low molecular weight of liquid cyclic natural rubber. This research has been made in several steps such as preparation of the sample of rubber, the process of molecular degradation of cyclic rubber, and characterization of LCNR by using FTIR, GPC and viscosity test. Degradation is done with the help of the phenylhydrazine reagent with oxygen gas atmosphere with a flow rate of 2 LMin-1 for 24 hours. Molecular weight analysis by GPC had result the LCNR sample had a Mw is 60,556, a Mn is 6,661, and a PDI is 11,08613. The intrinsic viscosity can be used by relating it to the molecular weight by the Mark Houwink – Sakurada (MHS) equation and get the result 63.533 for LCNR molecular weight. The C-H stretching and bending region are two of the most difficult regions to interpret in infrared spectra. The ranges between 3300 to 2750 cm-1 is the C-H stretching region, is the more practical of the two regions. The frequency with which C-H bonds are obstructed is largely determined by the type of hybridization attributed to the bond. The stronger the vibrational force constant, the higher the vibration frequency.

Efficient Synthesis of Itaconate Polyesters with Amine-Triggered Rapid Degradation and Outstanding Mechanical Properties: An Experimental and Theoretical Study on Degradation Mechanisms

A range of degradable polyesters have been developed as sustainable alternatives for commercial plastics; however, limitations of composting facilities and uncontrolled degradation in the environment hindered their viability. In this study, biobased itaconic acid was selected as an active site to control the degradation of polyesters. A series of PBXI copolyesters with Mw’s ranging from 4.86 to 8.31 × 104 g/mol and high intrinsic viscosities of more than 1.15 dL/g were successfully synthesized without any cross-linking by selecting appropriate reaction conditions, including condensation temperature and vacuum, effective inhibitor, and catalyst. The obtained copolyesters were semicrystalline, and their Tm’s could be regulated from 42.5 to 179.5 °C. They exhibited outstanding elastic modulus (120–598 MPa) and tensile strength (17.9–51.4 MPa) among degradable polymers. Degradation experiments demonstrated that the incorporation of itaconate segments could facilitate both the hydrolysis and enzymatic degradation of polyesters. The state-of-the-art computation and analysis via molecular dynamics (MD) simulations of PBXI–CALB complexes elucidated the enzymatic degradation mechanism. Experimental results proved that, at room temperature, the degradation could be stimulated and regulated by amines without a catalyst and the Mn’s of lactamization products rapidly decreased to less than 5000 g/mol within 24 h. Moreover, the copolymerized structure of copolyesters and solvent factors could influence the aza-Michael addition between amines and itaconate units. This work provides a strategy to synthesize biodegradable copolymers with the potential to undergo controlled and rapid in vivo degradation with outstanding mechanical properties.

Relationships between Size Distribution, Morphological Characteristics, and Viscosity of Cellulose Nanofibril Dispersions.

Rheological parameters of cellulose nanofibril dispersions (CNF) are relevant and commonly used as quality control for producing of this type of material. These parameters are affected by morphological features and size distribution of the nanofibrils. Understanding the effect of size distribution is essential for analyzing the rheological properties, viscosity control, performance of CNFs, and potential dispersion applications. This study aims at comprehending how the morphological characteristics of the CNFs and their size distribution affect the rheological behavior of dispersions. The CNF dispersions were fractionated by size, obtaining six fractions of each, which were analyzed for their morphology and rheology (viscosity, intrinsic viscosity). In the dilute region, the viscosity and intrinsic viscosity behavior of CNF dispersions are linear concerning the size distribution present in the dispersion. In the semi-dilute region, the size of the fibrils and the fiber aggregates have a relevant effect on the viscosity behavior of CNF dispersions, which are satisfactorily related (R2 = 0.997) using the rule of logarithmic additivity of the dispersion viscosities of size fractions.

Asymptotics and Summation of the Effective Properties of Suspensions, Simple Liquids and Composites

We review the problem of summation for a very short truncation of a power series by means of special resummation techniques inspired by the field-theoretical renormalization group. Effective viscosity (EV) of active and passive suspensions is studied by means of a special algebraic renormalization approach applied to the first and second-order expansions in volume fractions of particles. EV of the 2D and 3D passive suspensions is analysed by means of various self-similar approximants such as iterated roots, exponential approximants, super-exponential approximants and root approximants. General formulae for all concentrations are derived. A brief introduction to the rheology of micro-swimmers is given. Microscopic expressions for the intrinsic viscosity of the active system of puller-like microswimmers are obtained. Special attention is given to the problem of the calculation of the critical indices and amplitudes of the EV and to the sedimentation rate in the vicinity of known critical points. Critical indices are calculated from the short truncation by means of minimal difference and minimal derivative conditions on the fixed points imposed directly on the critical properties. Accurate expressions are presented for the non-local diffusion coefficient of a simple liquid in the vicinity of a critical point. Extensions and corrections to the celebrated Kawasaki formula are discussed. We also discuss the effective conductivity for the classical analog of graphene and calculate the effective critical index for superconductivity dependent on the concentration of vacancies. Finally, we discuss the effective conductivity of a random 3D composite and calculate the superconductivity critical index of a random 3D composite.

Pullulan Oxidation in the Presence of Hydrogen Peroxide and N-Hydroxyphthalimide.

The C-6 in the maltotriose unit of pullulan was oxidized in an alkaline medium (pH = 10), utilizing a green method that included hydrogen peroxide (H2O2) as an oxidant and N-hydroxyphthalimide (NHPI) as a catalyst for various reaction times. The structure of the resulting oxidized pullulans (PO) was carefully characterized by titration, intrinsic viscosity, FTIR, 13C-NMR, and zeta potential. The content of carboxyl groups in PO was dependent on reaction time and varied accordingly. Furthermore, a fast reaction rate was found in the first 2–3 h of the reaction, followed by a decreased rate in the subsequent hours. FTIR and 13C-NMR proved that the selective oxidation of the primary alcohol groups of pullulan was achieved. The oxidation also caused the glycoside linkages in the pullulan chain to break, and the viscosity of the pullulan itself went down.

Development of viscosity models of concentrated suspensions: Contribution of particle-size and shape indices

Blending cementitious powders marks multiple morphological features which dictate the rheology of cement-based suspensions. Models, whether theoretical or empirical, unveiled the convolution in describing the consequence of particles’ morphology on the rheology of cement-based suspensions. The viscosity of various cement suspensions designed with different liquid-to-binder ratios was examined. Models, for instance, Krieger–Dougherty and Mooney, were implemented to foresee the relative viscosity of the employed suspensions in terms of the coupled physical properties and dry relative solid fraction. The coefficient kE and intrinsic viscosity (η) are in good agreement with particle-size indices, including fineness index (SSA × Gs) and particle-size ratio (d502/SSA). In addition, the current models were adjusted with a focus on new coupled-physical properties, including static (αR × αS), dynamic (αF × cohesion), and total flowability (ftotal) indices. This resulted in significant improvement in the precision of determining the viscosity of concentrated cement-based suspensions.

Exploring relationships between seaweeds carrageenan contents and extracted hybrid carrageenan properties in wild and cultivated Mastocarpus stellatus, Chondrus crispus and Ahnfeltiopsis devoniensis.

The types and amounts of carrageenans present in a set of Mastocarpus stellatus, Chondrus crispus and Ahnfeltiopsis devoniensis, are assessed by solid-state NMR performed directly on dried and powdered seaweeds. The resulting chemical analysis is compared with the chemical structure and gel elasticity of the hybrid carrageenans extracted from these three carrageenophytes. ν-carrageenan is only found in a single sample of M. stellatus, whereas C. crispus and A. devoniensis essentially contain ι- and μ-carrageenans. A significant amount of κ-carrageenan is found in all samples of M. stellatus, whereas this type of carrageenan was found in a single sample of A. devoniensis. Hybrid carrageenans (HK) made of κ-, ι-, μ- and ν-carrageenan units were found in all hot extracts from the seaweeds, and their respective contents are in line with earlier reports on the HK extracted from these seaweeds. No correlations between the carrageenan contents in eight seaweeds and the chemical structures of their corresponding extracted HK can be found. However, a positive nonlinear correlation between the intrinsic viscosity of extracted HK and their gel elastic modulus is found in a set of 8 carrageenophytes.

Polysaccharides from tropical green seaweed Chaetomorpha antennina induces non-specific immune responses and improves antioxidative activities in common carp (Cyprinus carpio) leukocyte culture cell line

Polysaccharides from seaweeds are promising biomolecules that could sustainably improve the health status of cultured fish species. In this study, water-soluble polysaccharides extracted from Chaetomorpha antennina were investigated to determine their physicochemical characteristics and biological activities. C. antennina water-soluble polysaccharides (CAWP) comprised mainly of carbohydrate (69.0 ± 2.3 %), sulphate (12.6 ± 0.5 %), uronic acid (8.8 ± 0.1 %) and protein (3.5 ± 0.2 %). High Performance Anion Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD) analysis revealed that CAWP contained mostly arabinose (17.1 ± 2.3 mg/L), galactose (9.3 ± 1.0 mg/L), glucose (5.1 ± 0.6 mg/L), xylose/mannose (1.4 ± 0.6 mg/L) and a small proportion of fucose (0.3 ± 0.1 mg/L). CAWP, with intrinsic viscosity of 0.66 dL/g and estimated molecular weight of 318 kDa, were non-toxic to Carp leukocyte culture (CLC) cell line at concentrations ≤25 μg/mL. CAWP at concentrations of 12.5 and 25 μg/mL stimulated CLC to release significant amount of nitric oxide (NO), reactive oxygen species (ROS) and augmented phagocytic activity. Intracellular antioxidant activities indicated that CAWP did not induce oxidative damage in CLC but could improve superoxide dismutase activity (SOD), total glutathione (tGSH) and decrease malondialdehyde (MDA) level. The findings from our study provide a foundation for the applicability of water-soluble polysaccharides from C. antennina in the aquaculture industry as a potent immunomodulatory agent. • Chaetomorpha antennina is a rich source of sulphated polysaccharides. • Induction of oxidative burst response in Carp leucocytes • Phagocytosis of Red Zymosan® bioparticles by Carp leucocytes • Improved intracellular antioxidant activities

Investigation of rheological behaviors of aqueous gum Arabic in the presence of crystalline nanocellulose

An investigation on the effects of addition of crystalline nanocellulose (CNC) on both the intrinsic viscosity and rheological behavior of gum Arabic (GA) is undertaken. An adapted, facile method of CNC synthesis from microcrystalline cellulose (MCC) is used. At low concentrations of both CNC and GA, intrinsic viscosity of GA appears unaffected. However, the rheological behavior of 20 wt% and 40 wt% GA solutions is markedly affected by the introduction of CNC, even at very low concentrations. Enhanced viscosity and shear thinning properties are demonstrated with increased addition of CNC within the range studied, as are similar increases in storage modulus. Mechanisms are proposed for interactions between GA and CNC that may cause the observed effects, based on previous studies found in the literature. The use of CNC as a food grade viscosity modifier of GA and likely other polymer solutions is confirmed, and suggestions for further investigation are provided.

Synthesis and characterization of PnVCL grafted agar with potential temperature-sensitive delivery of Doxorubicin

Thermo-responsive copolymer, Agar agar-graft-poly(N-vinylcaproactam) (AA-g-PnVCL) was prepared by grafting N-vinylcaprolactam units onto the Agar backbone. Graft copolymer was synthesized by free-radical polymerization, using 2,2′-Azobis(2,4-dimethylvaleronitrile) (AMVN) as an initiator in the nitrogen atmosphere. In order to evaluate the composition effect different ratios between Agar agar, nVCL and AMVN were used. The formation of AA-g-PnVCL was confirmed by FT-IR, TGA, 1H NMR, and XRD techniques. Viscosity average molecular weight (Mη‾) was determined after the measurement of intrinsic viscosity. Turbidity measurements of dilute aqueous solutions were used to determine the lower critical solution temperature (LCST) of the new polymer. The grafting was evaluated by estimation of the percentage of grafting, grafting efficiency and percentage of conversion. One of the prepared polymer models (dried powder Model 4 with AA/VCL ratio 1:20 and VCL/AMVN ratio 20:1) showed the desired temperature-sensitive behavior (LCST 40 °C) and was further characterized. Its swelling was investigated with the determination of swelling indices in different media and at different temperatures. SEM images of dried and lyophilized gels were taken in order to investigate the morphology of the systems. Viscous and elastic moduli were determined at different temperatures for gel characterization. Doxorubicin (Dox) was chosen as a model drug and it was formulated into an injectable gel drug delivery system. Its loading and in vitro drug release was studied. The cytotoxicity of the proposed Dox loaded Model 4 was further characterized by the MTT test on H9c2 cardio blasts. The results showed successful preparation of a new temperature-sensitive polymer AA-g-PnVCL. Model 4 showed sufficient grafting efficiency and desired LCST for potential application as a modified drug delivery carrier. The proposed dosage form showed delayed release at 25° and 37 °C and rapid release at 40 °C. These results suggest that AA-g-PnVCL could be a potential stimuli-responsive material for controlled drug delivery in tumor chemotherapy with reduced cardiotoxicity of Doxorubicin.

Effect of Oxalic Acid Concentration and Different Mechanical Pre-Treatments on the Production of Cellulose Micro/Nanofibers

The present work analyzes the effect of process variables and the method of characterization of cellulose micro/nanofibers (CMNFs) obtained by different treatments. A chemical pre-treatment was performed using oxalic acid at 25 wt.% and 50 wt.%. Moreover, for mechanical pre-treatments, a rotary homogenizer or a PFI mill refiner were considered. For the mechanical fibrillation to obtain CMNFs, 5 and 15 passes through a pressurized homogenization were considered. The best results of nanofibrillation yield (76.5%), transmittance (72.1%) and surface charges (71.0 µeq/g CMNF) were obtained using the PFI mill refiner, 50 wt.% oxalic acid and 15 passes. Nevertheless, the highest aspect ratio (length/diameter) determined by Transmission Electron Microscopy (TEM) was found using the PFI mill refiner and 25 wt.% oxalic acid treatment. The aspect ratio was related to the gel point and intrinsic viscosity of CMNF suspensions. The values estimated for gel point agree with those determined by TEM. Moreover, a strong relationship between the intrinsic viscosity [η] of the CMNF dispersions and the corresponding aspect ratio (p) was found (ρ[η] = 0.014 p2.3, R2 = 0.99). Finally, the tensile strength of films obtained from CMNF suspensions was more influenced by the nanofibrillation yield than their aspect ratio.

Lepidium perfoliatum seed gum: investigation of monosaccharide composition, antioxidant activity and rheological behavior in presence of salts

BackgroundIn the present study, the effects of NaCl and CaCl2 (0–200 mM) on the rheological properties of Lepidium perfoliatum seed gum (LPSG) as a novel potential source of hydrocolloid were investigated. Sugar composition and FTIR analysis were measured to supply more structural information.ResultsThe results illustrated that LPSG had small amounts of uronic acids (6.65%) and it is likely an arabinoxylan-type polysaccharide (it has 44.66% and 31.99% xylose and arabinose, respectively). The FTIR spectra also revealed that LPSG behaved like a typical polyelectrolyte due to the presence of carboxyl and hydroxyl groups. It was observed that the gum solutions exhibited viscoelastic properties in the presence of NaCl and CaCl2 salts. The tan δ values for all samples were less than 1 but greater than 0.1, exposing the weak gel-like behavior at different ion types and ionic strengths. With increasing salts concentrations, the limiting values of strain mostly increased due to the interchain interactions (from 1.46 to 4.61 and from 0.99 to 2.13 for NaCl and CaCl2, respectively). Therefore, the addition of salts increased the stiffness of mucilage solutions in the concentrated regime. The results of frequency sweep tests revealed that storage and loss moduli were increased with increasing ion concentration. This effect was more pronounced for LPSG solutions containing Ca2+. Among various models, the model of Higiro1 showed a higher efficiency to evaluate the intrinsic viscosity of LPSG for all co-solutes (R2 ≥ 0.98). With increasing the concentration of salts, the intrinsic viscosity of LPSG decreased. Calcium ions had a more diminution effect on intrinsic viscosity than sodium ions.ConclusionsTrying to adjust the salt concentration could modify the rheological properties of food products. Because food contains a variety of additives, further research should look into the rheological properties of LPSG at different pHs, as well as the presence of other salts and sugars often employed in the food industry. LPSG has the potential to be used in biomedical, pharmaceutical, food industries, tissue engineering, and cosmetic applications due to its biocompatibility, rheological properties, and antioxidant activities.Graphical

Biodegradable Poly(butylene succinate) Copolyesters Modified by Bioresoured 2,5-Tetrahydrofurandimethanol

The problems of fossil-based resources and pollution caused by traditional nondegradable polymers have led to the need for biobased monomers and polyesters, presenting more environmentally friendly features. 2,5-Tetrahydrofurandimethanol (THFDM), a biobased monomer containing an aliphatic ring structure and an ether group, was introduced into the molecular chain of polybutylene succinate (PBS) as a sustainable unit to optimize its performance and improve its sustainability. The poly(butylene-co-tetrahydrofurandimethylene succinate) (PBTS) copolyesters were synthesized using a melt polycondensation method. The copolyesters exhibited relatively high intrinsic viscosity (1.03–1.71 dL/g). The Tg values of PBTS copolyesters increased significantly along with the introduction of THFDM (from −32.2 to −12.9 °C). According to the investigation using WAXD (wide-angle X-ray diffraction) analysis and successive self-nucleating annealing (SSA) measurement, it was revealed that the introduction of THFDM reduced the crystallization ability of PBTS while increasing its crystal content with relatively low lamella thickness. This phenomenon was mainly attributed to the aliphatic rings, which limited the movement and regular stacking of the molecular chains. The degradation rate and toughness of the copolyesters improved due to the decrease of crystallization degree. Meanwhile, the gas barrier property of PBTS slightly decreased but remained at a relatively high level. The permeabilities of O2 and CO2 were lower than that of commercially available PBAT. In summary, the introduction of THFDM not only improved the biobased resources content and the sustainability of copolyesters but also improved the toughness and degradation performance without sacrificing gas barrier performance.

Physicochemical and rheological characterization of a novel hydrocolloid extracted from Althaea officinalis root

Althaea officinalis L. root polysaccharide (AOP) was extracted, and its physicochemical and rheological properties were investigated. Gel permeation chromatography results showed that the molecular weight was 1560 kDa. High-performance liquid chromatography indicated that it was an acidic heteropolysaccharide consisting of five types of monosaccharides including galacturonic acid (40.2%), rhamnose (31.7%), glucose (13.68%), galactose (9.07%), and arabinose (5.35%). The intrinsic viscosity value for AOP in deionized water was 9.4 dl g−1. The AOP solutions at different concentrations (0.5%, 1%, 2%, and 3% w/v), showed shear-thinning behavior, and the apparent viscosity decreased in the presence of different concentrations of NaCl and at different pHs. The frequency sweep test showed the AOP solutions at concentrations less than 0.5% and above 1% exhibited viscous and weak gel behavior, respectively. Since the hysteresis phenomenon was observed in the temperature sweep test of 2% AOP solution, it can be considered as a thermal irreversible gel during the heating and cooling process.