Intrinsic Viscosity Research Articles

Evolution and comprehensive evaluation of viscoelastic characteristics of road asphalt in medium temperature region

PurposeIn order to determine the range of medium temperature zone of road asphalt, it is hoped that the evolution of viscoelastic characteristics of road asphalt under medium temperature state can be deeply explored.Design/methodology/approachIn this paper, the needle penetration test and temperature scanning test were designed for 90# and 70# bitumen as test materials, and the boundary of medium temperature zone of 90# and 70# bitumen was accurately determined by data analysis method. A mathematical model was established based on principal component analysis, and a comprehensive evaluation index was proposed to evaluate the evolution of temperature viscoelastic characteristics of road asphalt by means of standardization and rotational dimensionality reduction.FindingsThe test results show that the medium temperature zone of 90# asphalt is [−5 ± 1°C, 38 ± 1°C], and the medium temperature zone of 70# asphalt is [0 ± 1°C, 51 ± 1°C]. According to the viscoelastic response of road asphalt in the medium temperature zone, the medium temperature zone can be divided into three evolution stages: weak viscoelastic stage, viscoelastic equilibrium stage, strong viscoelastic weak stage. Analysis based on the intrinsic viscosity fillip target describing the various intrinsic viscoelastic index represents the viscoelastic properties of bitumen from different angles, and limitations inherent stick fillip for target put forward the integrated the inherent stick fillip mark information, as well as targeted and accurate evaluation of road asphalt temperature comprehensive evaluation indexes in the evolution of the viscoelastic properties of IM-T. Finally, the temperature data of asphalt pavement in several representative regions of China are compared with the determined medium temperature region, and it is proved that the research on the evolution of viscoelastic characteristics of asphalt pavement under the medium temperature condition has important practical significance.Originality/valueThe boundary of medium temperature zone of 90# and 70# base asphalt was determined, and the viscoelastic characteristic evolution of road asphalt under medium temperature state was studied deeply. Aiming at the limitation of intrinsic viscoelastic index, a comprehensive evaluation index IM-T which not only integrates the information of intrinsic viscoelastic index but also can accurately evaluate the evolution of temperature viscoelastic characteristics in road asphalt is proposed.

Impact of specimen preparation method on photovoltaic backsheet degradation during accelerated aging test

AbstractIn this study, we highlight some important factors in the specimen preparation methods for evaluating photovoltaic backsheet properties after accelerated aging. Two different sequences are considered: Method (I) cut‐then‐age: cut into 1‐cm wide strips and then expose to stress, and Method (II) age‐then‐cut: expose a larger sheet to stress and then cut into 1‐cm widths for mechanical property measurements. We also compare the effect of three cutting methods, (a) tensile specimen punch, (b) paper cutter, and (c) fresh razor blade. Several commercial backsheets were evaluated, with stress exposures including (a) pressure cooker test (PCT), (b) dry ultraviolet (UV) radiation exposure, and (c) UV combined damp heat tests. Fourier transform infrared spectrometer (FTIR) and intrinsic viscosity (IV) were used to analyze the materials on unstressed materials and samples exposed to PCT. The results show that both the cutting method and the time of cutting have an impact on the backsheet mechanical properties. Under UV exposure, Method II, age‐then‐cut, generally resulted in a higher average value, with more variation than Method I; however, if the side strips from Method II were excluded, the variation dropped to the same level. This is because the specimens at the sides of the sheet get additional damage from UV light from the exposed sides of the sample. In contrast to UV exposure, PCT specimens prepared by Method II result in lower average values and higher variability. This is attributed to embrittlement through the bulk of the sample where the cutting of embrittled specimens appears to result in more edge defects which can then initiate a break at smaller strains. The data suggest that for UV exposures, the specimens should be cut after aging and the exposed side specimens discarded, and that for PCT exposures, the specimens should be cut before the exposure.

Ultrasonic treatment of Dendrobium officinale polysaccharide enhances antioxidant and anti-inflammatory activity in a mouse D-galactose-induced aging model.

Utilization of the biological macromolecule Dendrobium officinale polysaccharide (DOP) as a functional ingredient is limited by its high intrinsic viscosity and molecular weight. The goal of the present study was to improve rheological properties of DOP by ultrasonic treatment. Such a treatment resulted in the degradation of DOP and consequent reduction of rheological properties. Among DOP samples treated with ultrasonication at low (L), medium (M), and high (H) power intensities (25, 50, 75 w/cm2), M‐DOP displayed the highest reactive oxygen species (ROS) and reactive nitrogen species (RNS) radical scavenging activity in vitro. In a mouse D‐galactose (D‐Gal)‐induced aging model, M‐DOP significantly increased activities of antioxidant enzymes and reduced levels of pro‐inflammatory cytokines in liver. Real‐time polymerase chain reaction (RT‐PCR) analysis indicated that M‐DOP upregulated messenger RNA (mRNA) expression of anti‐inflammatory/antioxidant proteins such as Nrf2 (nuclear factor erythroid 2‐related factor), hemeoxygenase‐1 (HO‐1), and NAD(P)H:quinone oxidoreductase (NQO1) in liver. In summary, M‐DOP displayed a strong radical scavenging activity in vitro, and ameliorated liver injury in the mouse aging model through the promotion of Nrf2/HO‐1/NQO1 signaling pathway.

Comparison of the change in viscosity of a polyvinyl alcohol solution by adding Polyethylene glycol and Polyvinylpyrrolidone to solutions of Polyvinylalcohol

The aim of this research is to improve the flow properties of polymers, in particular viscosity, by mixing polymers to be use in various fields. Samples prepared by stirring polyvinyl alcohol on fire for half a second in a fixed weight ratio with divergent weight ratios of polyethylene glycol and polyvinylpyrrolidone, both separately. Other samples were prepared in the same way by mixing the three polymers followed by measuring the molecular weight of all the samples. This method of preparation made the polymers insoluble in water, therefore nitric acid was used to dissolve them. Flow time of the solvent and all solutions were measured, which was used to calculate the viscosities, It has been shown that these viscosities increase with increasing concentrations of polymers in solutions by establishing a positive relationship between them, It was found that the intrinsic viscosity decreases with increasing concentrations after being graphed using intrinsic viscosity calculations from the relationship between specific viscosity and relative viscosity logogram with concentration. These results may be used in industrial medical applications as well as scientific studies.

Comparative Hydrodynamic Study on Non-Aqueous Soluble Archaeological Wood Consolidants: Butvar B-98 and PDMS-OH Siloxanes.

Butvar B-98 and PDMS-OH both have a demonstrable ability as consolidants for archaeological wood. This makes them both potential treatment options for the Oseberg collection, which is one of the most important archaeological finds from the Viking era. Both Butvar B-98 and PDMS-OH are soluble in organic solvents, offering a useful alternative to aqueous-based consolidants. Extensive characterisation studies were carried out on both of these polymers, with the use of analytical ultracentrifugation and viscometry, for the benefit of conservators wanting to know more about the physical properties of these materials. Short column sedimentation equilibrium analysis using SEDFIT-MSTAR revealed a weight-average molar mass (weight-average molecular weight) Mw of (54.0 ± 1.5) kDa (kg · mol−1) for Butvar B-98, while four samples of PDMS-OH siloxanes (each with a different molar mass) had an Mw of (52.5 ± 3.0) kDa, (38.8 ± 1.5) kDa, (6.2 ± 0.7) kDa and (1.6 ± 0.1) kDa. Sedimentation velocity confirmed that all polymers were heterogeneous, with a wide range of molar masses. All molecular species showed considerable conformational asymmetry from measurements of intrinsic viscosity, which would facilitate networking interactions as consolidants. It is anticipated that the accumulated data on these two consolidants will enable conservators to make a more informed decision when it comes to choosing which treatment to administer to archaeological artefacts.

Prediction of thickening efficiency of olefin copolymers and kinematic viscosities of the blended base oils by determining intrinsic viscosities of the copolymers in cyclohexane

The engine oil contains various performance additives along with polymer-based viscosity index improver, which are made from special types of flexible long chain polymers whose functionality is derived from their thickening efficiency, viscosity-temperature relationship, and shear stability. Olefin copolymers of the type ethylene/propylene copolymer are extensively used as viscosity index improver for engine oil formulations whose performance is a function of their composition, co-monomer sequence distribution and molar mass. Polymer coils interact with base oil and make it increasingly resistant to flow which accounts for substantial changes in viscosity parameters i.e. kinematic viscosities and viscosity index of blended base oils. Intrinsic viscosity of a polymeric solution is an important “dilute solution viscosity” parameter, which is easily measurable using Ubbelohde viscometer.In the present work, intrinsic viscosity of twenty samples of laboratory synthesized olefin copolymer in cyclohexane at 30 °C were correlated with their thickening efficiencies, kinematic viscosities of the olefin copolymer blended base oils at 40 °C and 100 °C. These correlation studies enable prediction of performance of olefin copolymer in blended base oil based on an easily and quickly measurable intrinsic viscosity parameter, leading to faster screening of large number of olefin copolymers for their utility as viscosity index improver in lubricants, in a short span of time with limited resources.

Confronting the Challenge of Cellulose Molecular Weight Measurement: An Accurate, Rapid, and Universal Method with Ionic Liquid as an Additive.

Molecular weight parameters are the key fundamental information of polymer materials, but the accurate characterization of the molecular weight of cellulose is extremely difficult due to its strong hydrogen bonding network. Herein, we demonstrated two new methods to accurately and rapidly measure the molecular weight parameters of cellulose by using 1-butyl-3-methylimidazolium acetate (BmimAc) ionic liquid (IL) as an additive. Cellulose is rapidly dissolved in BmimAc/DMSO (1:1, w/w) at room temperature at first. Then, DMAc is added to dilute the solution, and finally, the molecular weight and molecular weight distribution of cellulose samples are measured by the gel permeation chromatography (GPC) method with BmimAc/DMSO/DMAc (1:1:18, w/w) as the mobile phase. Such a simple method is suitable to all kinds of cellulose samples and exhibits an extremely high analytical efficiency which is 50 times higher than the previous GPC methods. In addition, a viscosity method that is available for industrial application was proposed by using the BmimAc/DMSO/DMAc (1:1:8, w/w) system with low viscosity. The relationship between the intrinsic viscosity of the cellulose/BmimAc/DMSO/DMAc solution and the molecular weight of cellulose is well established and is applicable to cellulose samples of Mw = 4.5 × 104 to 1.8 × 106, which is the widest applicable range among the reported viscosity methods. Overall, two new methods based on the use of BmimAc as an additive have many advantages, such as wide applicable range, simple preparation process, mild dissolution condition, no degradation or aggregation of cellulose, high accuracy, fast detection, and low IL consumption, overcoming the existing problems in the traditional methods. It is expected to be used as a standard procedure to characterize the molecular weight of cellulose in academia and industries.

Increasing hardwood kraft pulp yield using sodium methyl mercaptide

Abstract The objective of this work was to determine the effect of sodium methyl mercaptide (SMM) as an additive on the minimization of carbohydrate peeling reactions in Rock/Hard Maple (Acer saccharum) chips during kraft pulping. Two methods were evaluated for SMM addition to the pulping process: 1) pre-treatment before pulping and 2) co-addition with white liquor. The experimental results showed about 2.5% (on wood basis) increase in the kraft pulp yield after pre-treatment with 4.38% SMM (on wood basis) or the co-addition of the same amount of SMM with white liquor. The use of 4.38% SMM allowed a decrease in the white liquor effective alkali charge of 3% (on wood basis) to produce the target 14–15 kappa pulp. The 4.38% SMM charge was determined to be the optimum for both pre-treatment and co-addition. The increase in kraft pulp yield was mostly due to increased retention of cellulose (about 0.8% on wood) and xylan (about 1.8% on wood). The retention of glucomannan was insignificant in all cases. Based on the increase in intrinsic viscosity, it is concluded that the increased cellulose yield with SMM addition is caused by both reduced primary peeling and faster delignification rate (less alkaline hydrolysis followed by secondary peeling). The increased xylan retention is due to the lower effective alkali concentration during kraft pulping with SMM addition.

Renewable Furfural-Based Polyesters Bearing Sulfur-Bridged Difuran Moieties with High Oxygen Barrier Properties

With the goal of achieving high barrier with bio-based materials, for example, for packaging applications, a series of novel furfural-based polyesters bearing sulfide-bridged difuran dicarboxylic acid units with high oxygen barrier properties were synthesized and characterized. For the novel poly(alkylene sulfanediyldifuranoate)s, a 11.2–1.9× higher barrier improvement factor compared to amorphous poly(ethylene terephthalate) was observed which places the novel polyesters in the top class among previously reported 2,5-furandicarboxylic acid (FDCA) and 2,2′-bifuran-based polyesters. Titanium-catalyzed polycondensation reactions between the novel synthesized monomer, dimethyl 5,5′-sulfanediyldi(furan-2-carboxylate), and four different diols, ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol, afforded difuran polyesters with high intrinsic viscosities (0.76–0.90 dL/g). These polyesters had good thermal stability, decomposing at 342–363 and 328–570 °C under nitrogen and air, respectively, which allowed processing them into free-standing films via melt-pressing. In tensile testing of the film specimens, tensile moduli in the range of 0.4–2.6 GPa were recorded, with higher values observed for the polyesters with shorter diol units. Interestingly, besides the low oxygen permeability, the renewable sulfide-bridged furan monomer also endowed the polyesters with slight UV shielding effect, with cutoff wavelengths of ca. 350 nm, in contrast to FDCA-based polyesters, which lack significant UV light absorption at over 300 nm.

Characterization, optimization, and evaluation of preservative efficacy of carboxymethyl cellulose/hydromagnesite stromatolite bio-nanocomposite.

Currently, researchers are focusing on the development of nano-additive preservatives during the worldwide COVID-19 pandemic. This research aimed to constitute a small sized preservative nano-formulation which emerges from the biopolymer carboxymethyl cellulose (a green stabilizing agent) and hydromagnesite stromatolite (a fossilized natural additive). In this study, we investigated the optimization of the experimental design of carboxymethyl cellulose/hydromagnesite stromatolite (CMC/HS) bio-nanocomposites using a green and one-step sonochemical method at room temperature. In addition, we constructed a mathematical model which relates the intrinsic viscosity with all operating variables, and we carried out statistical error analysis to assess the validity of the proposed model. The characterization and chemical functional groups of CMC/HS bio-nanocomposites were determined by different advanced techniques such as SEM, HRTEM, DLS, FTIR, XRD, and BET. The challenge test was used to show the preservative efficacy of CMC/HS bio-nanocomposites against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, and Aspergillus brasiliensis. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltrazolium bromide (MTT) assay was performed on L929 cells to evaluate the in vitro cytotoxicity of CMC/HS bio-nanocomposites. According to the results, we showed that the synthesized CMC/HS bio-nanocomposites have no cytototoxic effects on L929 fibroblast cells and could be considered to be an alternative green nano-additive preservative against pathogenic microorganisms.

Sulfated lactose-modified chitosan. A novel synthetic glycosaminoglycan-like polysaccharide inducing chondrocyte aggregation

Lactose-modified chitosan (CTL) is sulfated using SO3·py or SO3·DMF as sulfating agents. The two products are characterized by elemental analysis, FT-IR, 1H,13C-DEPT-HSQC and 1H,13C-HSQC-TOCSY experiments which allow the extent and selectivity of chemical sulfation to be determined. Dynamic Light Scattering shows a pH-dependent association of the sulfated polysaccharides which are described as flexible by the Smidsrød's B parameter and the intrinsic viscosity at infinite ionic strength. Shear viscosity and intrinsic viscosity show that sulfation protocols lead to chain scission which is more pronounced when SO3·DMF is used. The sulfated samples are able to induce aggregation of human bone marrow mesenchymal stem cells, resulting in the formation of smaller nodules compared to the unmodified CTL sample. Over time, the sample with the higher degree of sulfation allows further aggregation between cell clusters while the sample with the lower degree of sulfation shows dissolution of the aggregates.

Poly-L-Arginine Molecule Properties in Simple Electrolytes: Molecular Dynamic Modeling and Experiments.

Physicochemical properties of poly-L-arginine (P-Arg) molecules in NaCl solutions were determined by molecular dynamics (MD) modeling and various experimental techniques. Primarily, the molecule conformations, the monomer length and the chain diameter were theoretically calculated. These results were used to interpret experimental data, which comprised the molecule secondary structure, the diffusion coefficient, the hydrodynamic diameter and the electrophoretic mobility determined at various ionic strengths and pHs. Using these data, the electrokinetic charge and the effective ionization degree of P-Arg molecules were determined. In addition, the dynamic viscosity measurements for dilute P-Arg solutions enabledto determine the molecule intrinsic viscosity, which was equal to 500 and 90 for ionic strength of 10−5 and 0.15 M, respectively. This confirmed that P-Arg molecules assumed extended conformations and approached the slender body limit at the low range of ionic strength. The experimental data were also used to determine the molecule length and the chain diameter, which agreed with theoretical predictions. Exploiting these results, a robust method for determining the molar mass of P-Arg samples, the hydrodynamic diameter, the radius of gyration and the sedimentation coefficient was proposed.

Ethylene glycol-soluble Ti/Mg-citrate complex catalyst for synthesis of high intrinsic viscosity poly(ethylene terephthalate)

Antimony-free poly(ethylene terephthalate) (PET) has been synthesized through polycondensation of p-phthalic acid and ethylene glycol, and then subjected to a viscosity-increasing process by liquid-state polycondensation (LSP). For both of these processes, a novel environmentally benign ethylene glycol-soluble Ti/Mg bimetal (TM) catalyst has been used. The structure of the TM catalyst has been comprehensively characterized and its catalytic activity in the polycondensation reaction has been evaluated and compared with those of other titanium-based catalysts. The results reveal that the TM catalyst is a chelated complex with high catalytic activity for polycondensation to afford PET without significant side reactions. Indeed, the LSP process catalyzed by TM affords a PET product with high intrinsic viscosity suitable for industrial yarn production (1.08 dL/g) within 60 min, and that exhibits higher thermostability with increasing intrinsic viscosity. Finally, the kinetics of the TM-catalyzed polycondensation has been probed based on the variation of intrinsic viscosity with increasing polycondensation time.

Rheological properties of Sesbania cannabina galactomannan as a new source of thickening agent.

The present study evaluated the rheological properties of galactomannan from Sesbania cannabina. The intrinsic viscosity of galactomannan was determined to be 8.63± 0.06 dl/g. Moreover, the onset of galactomannan coil overlap occurred at 5.12± 0.13g/L. With increasing concentration, galactomannan showed a more distinct shear-thinning behavior, which was well characterized by the Cross model. Notably, the viscosity of polysaccharide showed a negative relationship with the temperature, while the activation energy decreased with increasing polysaccharide concentration. Furthermore, at high concentrations, the galactomannan solution showed stability after heating or freezing, as well as over the wide pH range of 5.0-9.0. Dynamic viscoelasticity measurements reveal a gradual transition from viscous to elastic behavior of galactomannans with an increasing frequency. It is anticipated that S. cannabina galactomannan will find interesting applications as a natural thickener due to the comprehensive description of its rheological properties presented herein. PRACTICAL APPLICATION: The investigated S. cannabina galactomannan has shown a higher viscosity and heat stability at high concentration, as well as a good stability at the pH range of 5-9. The S. cannabina galactomannan may be employed as stabilizers in the food field.

Improvement of mechanical strength of mortars by different morphological zinc oxide nanoparticles

This study presents novel nano-mixtures containing zinc oxide (ZnO) nanoparticles (NPs) to enhance the mechanical properties of cement mortars. Different morphological ZnO NPs were synthesised through the green sonochemical method, using tragacanth gum/Kappa carrageenan (TG/κ-C) and tragacanth gum/chitosan (TG/CS) as biopolymer matrices. The ZnO NPs were characterised using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, X-ray diffraction, Zetasizer and Brunauer–Emmett–Teller techniques. The intrinsic viscosities of TG/κ-C-ZnO and TG/CS-ZnO NPs were investigated to determine the miscibility of the polymeric blends in aqueous solution as affected by sonication time and composition ratios. The average diameters for the spherical and prism-like ZnO NPs were around 266 nm and 355 nm, respectively. Seven different cement mortar specimens containing TG/κ-C-ZnO and TG/CS-ZnO NPs were prepared in ratios of 0, 0.1, 0.5 and 1% by weight, and the flexural and compressive strengths of the specimens were determined at the ages of 7 and 28 days. The results indicate that there is a significant improvement in the mechanical performance of different morphological ZnO NP-based cement mortar composites. In comparison, it was observed that specimens containing TG/κ-C-ZnO NPs had much better results than TG/CS-ZnO NPs. Moreover, the workability problem encountered by using only ZnO NPs has been overcome with the presented biopolymers used in this study.

Influence of network defects on the conformational structure of nanogel particles: From "closed compact" to "open fractal" nanogel particles.

We propose an approach to generate a wide range of randomly branched polymeric structures to gain general insights into how polymer topology encodes a configurational structure in solution. Nanogel particles can take forms ranging from relatively symmetric sponge-like compact structures to relatively anisotropic open fractal structures observed in some nanogel clusters and in some self-associating polymers in solutions, such as aggrecan solutions under physiologically relevant conditions. We hypothesize that this broad "spectrum" of branched polymer structures derives from the degree of regularity of bonding in the network defining these structures. Accordingly, we systematically introduce bonding defects in an initially perfect network having a lattice structure in three and two topological dimensions corresponding to "sponge" and "sheet" structures, respectively. The introduction of bonding defects causes these "closed" and relatively compact nanogel particles to transform near a well-defined bond percolation threshold into "open" fractal objects with the inherent anisotropy of randomly branched polymers. Moreover, with increasing network decimation, the network structure of these polymers acquires other configurational properties similar to those of randomly branched polymers. In particular, the mass scaling of the radius of gyration and its eigenvalues, as well as hydrodynamic radius, intrinsic viscosity, and form factor for scattering, all undergo abrupt changes that accompany these topological transitions. Our findings support the idea that randomly branched polymers can be considered to be equivalent to perforated sheets from a "universality class" standpoint. We utilize our model to gain insight into scattering measurements made on aggrecan solutions.

Impact of atmospheric pressure cold plasma on the rheological and gelling properties of high methoxyl apple pectin

Cold plasma is an emerging sustainable method for modification of hydrocolloids. In the present study, atmospheric pressure pin-to-plate cold plasma was employed for modification of high-methoxyl apple pectin (DE∼68%). Chemical modifications are rigorous, and often require huge amounts of solvents and chemicals. Hence, the use of sustainable and “green” techniques such as cold plasma need to be investigated for their ability to impact the rheological and gelling properties of pectin. Intrinsic viscosity, apparent viscosity and viscoelastic properties of cold plasma-treated pectin dispersions and gels were studied. Kinetic studies were undertaken to evaluate the effect of cold plasma on the degradation and gelation of pectin. Improvement in rheological properties was observed for short plasma treatments at lower voltages (190 V|9 min and 210 V|6 min). Prolonged treatments at higher voltage treatments (210 and 230 V) had a negative impact on the rheological and gelling properties. The depolymerization, monitored by the intrinsic viscosity exhibited second-order degradation kinetics. The pseudoplastic pectin dispersions transitioned towards Newtonian-like behavior after plasma treatments. The thermal stability of the pectin dispersions decreased by 29% after a plasma treatment of 230 V for 15 min. A decline in gel strength and stability was confirmed by the decline in critical and cross-over strain during strain-sweep experiments. The gel formation of pectin in the presence of sucrose was a two-step process. The energy gap between the high-temperature and low-temperature region decreased as the plasma treatment progressed. To summarize, it is necessary to optimize the intensity of the plasma treatments to achieve the desired rheological properties.

Application of a Universal Calibration Method for True Molar Mass Determination of Fluoro-Derivatized Technical Lignins by Size-Exclusion Chromatography

The determination of the true molar mass distribution (MMD) of lignin is highly important to understand the physicochemical characteristics for lignin-based value-added applications. It is imperative to develop a universal method to quantify accurate MMD of lignin using size exclusion chromatography (SEC), as the conventional method with polymer standards provides irregular MMD results. This work aims to evaluate the MMD of five lignin samples (Protobind 1000, Organosolv, Indulin, Pine Kraft and Eucalyptus Kraft) in THF. Different derivatization methods (acetylation, fluorobenzylation and fluorobenzoylation) were performed. FTIR and 19F NMR analyses were used to follow derivatization. The MMDs of derivatized and underivatized lignins were determined by the conventional method and compared with the universal calibration method developed using intrinsic viscosity. The 19F NMR spectra provided the information to quantify the degree of substitution of lignin hydroxyl groups, to calculate the true molar mass of the derivatives of lignin monomers. The obtained MMDs values for all the derivatized lignin by universal calibration were found to be three to five times higher than that of the conventional calibration. The polydispersity values obtained with the acetylation method were higher than the fluoro-derivatives. The results demonstrated that fluoro-derivatization is an appropriate method to apply to higher molar mass technical lignins and lacks solubility and aggregation issues.

Study of the Chain Condensation Process from a Dilute to a Concentrated Solution and the Transformation of the Chain Conformation from a Solution to a Film for the Conjugated Polymer PFO.

The chain behavior in a precursor solution and its condensation process are still key issues that have been paid close attention to but have not been solved yet for semirigid conjugated polymers. In this research, the chain condensation process from a dilute to a concentrated solution and the transformation of the chain conformation from a solution to a film for the conjugated polymer poly(9,9′-dioctylfluorene) (PFO) were investigated by a scaling law method obtained from rheological measurements. By establishing a scaling relationship between specific viscosity and concentration, it was found that the motion of molecular chains conformed to the Zimm model in dilute solution, and the motion of molecular chains conformed to the Rouse model in semidilute unentangled solution as well as conformed to the Edwards tube model in semidilute entangled solution. Furthermore, it was also found that toluene is a θ solvent for PFO at 25 °C. Some important physical parameters in connection with PFO intrinsic properties were also obtained here, such as intrinsic viscosity [η] = 136.84 mL g–1, root-mean-square end-to-end distance R = 41.4 nm, and Kuhn segment length b = 6.28 nm. In particular, this was the first time that the effect of the film-forming process of spin coating on the transformation proces of the PFO chain conformation from the precursor solution to a film was studied, and the spin-coating time (t) was found to be several orders of magnitude longer than the PFO chain relaxation time (τZ(τR)). This research enriches knowledge and understanding of the chain behavior in the precursor solution for semirigid conjugated polymers and reveals the correlation of chain behaviors in solution with the film’s condensed state structure in the process of chain dynamic evolution from a solution to a film.

Fabrication and Properties of Self-crimp Side-by-Side Bicomponent Filaments Composed of Polyethylene Terephthalates with Different Intrinsic Viscosity

Abstract Self-crimp side-by-side bicomponent filaments (SBSBFs) were prepared via melt spinning using two kinds of polyethylene terephthalate (PET) with great disparity of intrinsic viscosity. The influence of the volume ratio on the surface morphology, crystallinity, crimping properties, mechanical properties and shrinkage properties of the bicomponent filaments was investigated using wide-angle X-ray diffraction, a differential scanning calorimetry (DSC), scanning electron microscope, etc. As the proportion of the low-viscosity component increases, the shrinkage in boiling water or hot air, as well as the shrinkage force and the sonic orientation factor of the bicomponent filaments decrease, and the DSC heating curves change from double peaks to a single peak. These phenomena should be ascribed to the high orientation and low crystallinity of the high-viscosity PET component and low orientation and high crystallinity of the low-viscosity PET component. Moreover, the crimp property of the bicomponent filament with a volume ratio of 50:50 is superior to those with other volume ratios.