Gel Fibers Research Articles

(N-Alkyloxalamido)-Amino Acid Amides as the Superior Thixotropic Phase Selective Gelators of Petrol and Diesel Fuels.

(N-Alkyloxalamido)-amino acid amides 9-12 exhibit excellent gelation capacities toward some lipophilic solvents as well as toward the commercial fuels, petrol and diesel. Gelator 10 exhibits an excellent phase-selective gelation (PSG) ability and also possesses the highest gelation capacity toward petrol and diesel known to date, with minimum gelation concentration (MGC) values (%, w/v) as low as 0.012 and 0.015, respectively. The self-assembly motif of 10 in petrol and toluene gel fibres is determined from xerogel X-ray powder diffraction (XRPD) data via the simulated annealing procedure (SA) implemented in the EXPO2014 program and refined using the Rietveld method. The elucidated motif is strongly supported by the NMR (NOE and variable temperature) study of 10 toluene-d8 gel. It is shown that the triple unidirectional hydrogen bonding between gelator molecules involving oxalamide and carboxamide groups, together with their very low solubility, results in the formation of gel fibres of a very high aspect ratio (d = 10-30 nm, l = 0.6-1.3 μm), resulting in the as-yet unprecedented capacity of gelling commercial fuels. Rheological measurements performed at low concentrations of 10 confirmed the strength of the self-assembled network with the desired thixotropic properties that are advantageous for multiple applications. Instantaneous phase-selective gelation was obtained at room temperature through the addition of the 10 solution to the biphasic mixture of diesel and water in which the carrier solvent was congealed along with the diesel phase. The superior gelling properties and PSG ability of 10 may be used for the development of more efficient marine and surface oil spill recovery and waste water treatment technologies as well as the development of safer fuel storage and transport technologies.

Preparation of co-electrospinning membrane loaded with simvastatin and substance P to accelerate bone regeneration by promoting cell homing, angiogenesis and osteogenesis.

Bone regeneration is a complex process that requires the coordination of various biological events. Developing a tissue regeneration membrane that can regulate this cascade of events is challenging. In this study, we aimed to fabricate a membrane that can enrich the damaged area with mesenchymal stem cells, improve angiogenesis, and continuously induce osteogenesis. Our approach involved creating a hierarchical polycaprolactone/gelatin (PCL/GEL) co-electrospinning membrane that incorporated substance P (SP)-loaded GEL fibers and simvastatin (SIM)-loaded PCL fibers. The membrane could initiate a burst release of SP and a slow/sustained release of SIM for over a month. In vitro experiments, including those related to angiogenesis and osteogenesis (e.g., migration, endothelial network formation, alkaline phosphatase activity, mineralization, and gene expression), clearly demonstrated the membrane's superior ability to improve cell homing, revascularization, and osteogenic differentiation. Furthermore, a series of in vivo studies, including immunofluorescence of CD29+/CD90+ double-positive cells and immunohistochemical staining for CD34 and vWF, confirmed the co-electrospinning membrane's ability to enhance MSC migration and revascularization response after five days of implantation. After one month, the Micro-CT and histological (Masson and H&E) results showed accelerated bone regeneration. Our findings suggest that a co-electrospinning membrane with time-tunable drug delivery could advance the development of tissue engineering therapeutic strategies and potentially improve patient outcomes.

Preparation of xerogel based on syndiotactic polystyrene (sPS)/MWCNTs hybrid polymer gel for application as a dielectric material with high dielectric permittivity

MWCNTs were dispersed in sPS gel in both pristine as well as functionalized form to observe its effect on structure, morphology, thermal as well as dielectric properties of the resulting hybrid polymer gel. Since, the ortho-xylene induces clathration in pure sPS polymer in α-phase leading to thermoreversible gelation resulting in the δ-crystalline phase (sPS gel). Therefore, the removal of solvent from solvated δ-crystalline phase gives non-solvated δe-crystalline phase (sPS xerogel). The three dimensional fibrillar networks, as observed with scanning electron microscopy (SEM) and atomic force microscopy (AFM), have the polymer chains with s(2/1)2 helical conformation which makes the gel elastic. Fourier transform infra red spectroscopy (FTIR) shows the conformation change from trans planar to s(2/1)2 helical as indicated by the disappearance of peak at 541 cm−1 and appearance of peak at 537 cm−1 and 571 cm−1. The peak at 7.9° confirms the δ-crystalline phase presence whereas the absence of solvent is indicated by peak absence at 10°. Differential scanning calorimetry (DSC) thermogram confirms the δ to γ phase transition in the 100–150 °C temperature range. As we get an intermingled structure of gel fibers and MWCNTs, therefore, the dielectric behavior showed the percolative nature of the hybrid sPS xerogel. The pure sPS xerogel displayed no response to the frequency change whereas due to interfacial polarization, hybrid sPS xerogel responded to frequency change.

“Bungee” ionic gel fiber:strength, strain, and multifunctional properties

To adapt to rapid economic and technical development, multifunctional fibers are an active area of research. However, most multifunctional fiber materials exhibit low strength, stretching ability, and elastic recovery. To improve the mechanical properties of multifunctional fibers, an ionic gel fiber was synthesized in this work with high strength, and stretching ability- by random ultraviolet (UV) copolymerization between methacrylic acid and N-isopropylacrylamide in 1-ethyl-3-methylimidazolium ethyl sulfate. The copolymerized ionic gel fibers exhibit high fracture strength and high elastic recovery, they also exhibit anti-freezing capacity, high-temperature resistance, and self-healing. This UV copolymerization method can be applied to other monomers, offering a means of preparing multifunctional fibers.

Enhancing the ROS Sensitivity of a Responsive Supramolecular Hydrogel Using Peroxizyme Catalysis.

Hydrogels that can disintegrate upon exposure to reactive oxygen species (ROS) have the potential for targeted drug delivery to tumor cells. In this study, we developed a diphenylalanine (FF) derivative with a thioether phenyl moiety attached to the N-terminus that can form supramolecular hydrogels at neutral and mildly acidic pH. The thioether can be oxidized by ROS to the corresponding sulfoxide, which makes the gelator hydrolytically labile. The resulting oxidation and hydrolysis products alter the polarity of the gelator, leading to disassembly of the gel fibers. To enhance ROS sensitivity, we incorporated peroxizymes in the gels, namely, chloroperoxidase CiVCPO and the unspecific peroxygenase rAaeUPO. Both enzymes accelerated the oxidation process, enabling the hydrogels to collapse with 10 times lower H2O2 concentrations than those required for enzyme-free hydrogel collapse. These ROS-responsive hydrogels could pave the way toward optimized platforms for targeted drug delivery in the tumor microenvironment.

Effect of Flow Velocity on Laminar Flow in Microfluidic Chips.

Gel fibers prepared based on microfluidic laminar flow technology have important research value in constructing biomimetic scaffolds and tissue engineering. The key point of microfluidic laminar flow technology is to find the appropriate fluid flow rate in the micropipe. In order to explore the influence of flow rate on the laminar flow phenomenon of a microfluidic chip, a microfluidic chip composed of an intermediate main pipe and three surrounding outer pipes are designed, and the chip is prepared by photolithography and the composite molding method. Then, a syringe pump is used to inject different fluids into the microtubing, and the data of fluid motion are obtained through fluid dynamics simulation and finite element analysis. Finally, a series of optimal adjustments are made for different fluid composition and flow rate combinations to achieve the fluid's stable laminar flow state. It was determined that when the concentration of sodium alginate in the outer phase was 1 wt% and the concentration of CaCl2 in the inner phase was 0.1 wt%, the gel fiber prepared was in good shape, the flow rate was the most stable, and laminar flow was the most obvious when the flow rate of both was 1 mL/h. This study represents a preliminary achievement in exploring the laminar flow rate and fabricating gel fibers, thus offering significant reference value for investigating microfluidic laminar flow technology.

Evaluation of different local drug delivery systems in the management of chronic periodontitis: A comparative study

Periodontal disease is an immune-inflammatory disease affecting the soft tissues and alveolar bone and surrounding periodontal tissues. The standard treatment involves scaling and root planing (SRP) which removes the sub gingival microbial deposits effectively and the gingival health is maintained. Sometimes the treated areas may show regrowth of the microorganisms and the non-surgical periodontal treatment alone cannot eliminate the micro-organisms in mild periodontitis cases due to the difficulty in reaching the subgingival areas which are deeper and in complex root morphologies. So now a days the non-surgical periodontal treatment combined with the use of systemic antimicrobial agents and host modulating agents has shown to use effectively in the treatment of periodontal diseases.All the patients who were diagnosed with chronic periodontitis underwent initial therapy i.e., full-mouth scaling and root planing. Then the oral hygiene instructions were given to the patients and were recalled after 1 week (baseline visit). A total of 20 patients who met the inclusion criteria and showed satisfactory condition after the initial therapy with persistent periodontal pockets were included in this study. They were randomly assigned into two groups i.e., Group-A: metronidazole gel (metrogyl) and Group B: tetracycline fibre groups with 10 patients in each group. The periodontal clinical parameters like plaque index (PI), gingival index (GI) and periodontal pocket depth (PPD) were evaluated at the baseline visit before the application of local drug delivery and 15 and 30 days after the local drug delivery application.The mean plaque scores were reduced from 1.41±0.04 at baseline to 1.04±0.14 at 30 days. Likewise in Group-B the mean PI scores reduced from 1.50±0.10 at baseline to 1.25±0.18 at 30 days. The mean gingival index scores reduced from 1.41±0.04 at baseline to 1.01±0.04 at 30 days. Likewise in Group-B mean GI Scores reduced from 1.36±0.03 at baseline to 0.99±0.06 at 30 days. The mean PPD scores were reduced from 5.65±0.12 at baseline to 3.15±0.10 at 30 days in Group-A. Likewise in Group-B mean PPD scores reduced from 5.68±0.06 at baseline to 3.26±0.10 at 30 days. This study demonstrated that although thorough SRP is an effective treatment method for elimination of chronic periodontal pockets, improved results can be obtained by adjunctive use of locally administered metronidazole gel and tetracycline fibers.

Preparation of para-aramid aerogel fiber structurally colored by light scattering through wet spinning and supercritical drying

This research is an investigation of the preparation conditions for para-aramid aerogel fibers that are structurally colored by Rayleigh scattering, an angle-independent structural color. It is well known that structural color has the angle dependence of colors. However, there is currently a desire for materials with angle-independent structural color. During the fibers’ spinning process, the microstructures of the fibers are generated. The effect of spinning conditions is investigated by measuring the optical properties of the wet gel fibers. The neutralization speed of negatively charged PPTA fibrils has a significant impact on the formation of the dense microstructure. Spinning under the fast neutralization speed condition makes it possible to achieve the blue-colored fiber derived from Rayleigh scattering. The influence of neutralization speed on the microstructure of the fibers is confirmed by FE-SEM characterization. Furthermore, spinning using a narrow inner diameter needle decreases the whiteness component derived from Mie scattering of the fibers, resulting in a more vivid blue color. The angle-independent structurally colored fibers hold great promise for application in clothing, interiors, and industrial materials.

Comparative analysis of the residues of granular support bath materials on printed structures in embedded extrusion printing

Embedded extrusion printing facilitates the fabrication of complex biological structures using soft hydrogels that are challenging to construct using conventional manufacturing methods. While this targeting strategy is appealing, the residues of support materials on the printed objects have been overlooked. Here, we quantitatively compare the bath residues on fibrin gel fibers printed in granular gel baths that are conjugated with fluorescent probes for visualization, including physically crosslinked gellan gum (GG) and gelatin (GEL) baths and chemically crosslinked polyvinyl alcohol baths. Notably, all support materials can be detected on a microscopic scale, even on structures without any visible residues. Quantitative results indicate that baths with smaller size or lower shear viscosity show more and deeper diffusion into the extruded inks, and the removal efficiency of support materials depends mainly on the dissolving property of the granular gel baths. The residual amount of chemically cross-linked support materials on fibrin gel fibers is 28–70 μg mm−2, which is tens of times higher than physically cross-linked GG (7.5 μg mm−2) and GEL (0.3 μg mm−2) baths. Meanwhile, cross-sectional images suggest that most gel particles are distributed around the fiber surface, but a small amount is in the fiber center. Such bath residues or the blank pores created by the removal of gel particles induce changes in product surface morphology, physicochemical and mechanical properties, impeding cell adhesion. This study will draw attention to the effects of residual support materials on printed structures and encourage the development of new strategies to diminish these residues or to take advantage of the residual support baths to improve product performances.

Gelled lyotropic nematic liquid crystals

ABSTRACT Lyotropic liquid crystal gels (LLC gels) are versatile materials which combine the anisotropy of a liquid crystal with the mechanical stability of a gel. We succeeded in gelling the rare calamitic nematic NC phase of two different micellar LLC systems with the low molecular weight gelator (LMWG) 3,5-bis-(5-hexylcarbamoyl-pentoxy)-benzoic acid hexyl ester (BHPB-6). The systems of choice are: (1) a binary LLC system with the surfactant N,N-dimethyl-N-ethyl-1-hexadecylammonium bromide (CDEAB) and water; (2) a ternary LLC system with the surfactant N,N,N-trimethyl-N-tetradecylammonium bromide (C14TAB), n-decanol, and water. The obtained gels show optical birefringence and no macroscopic flow. Freeze fracture electron microscopy (FFEM) images show ribbon-like gel fibres that form the gel network and can stack into thicker bundles, while small-angle X-ray scattering (SAXS) confirms the coexistence of the nematic NC phase and the gel network. The growth of the gel network was monitored with time-resolved SAXS measurements. Additionally, significant gel ageing effects were observed in rheology measurements, showing that the gel strengthens with time. With this study, we considerably broaden the pool of available surfactant-based LLC gels and pave a way to macroscopically aligned LLC gels with the goal to apply them as stimuli-responsive actuators and sensors.

Recent developments in artificial spider silk and functional gel fibers

AbstractIt is highly desirable to develop fiber materials with high strength and toughness while increasing fiber strength always results in a decrease in toughness. Spider silk is a natural fiber material with an excellent combination of high strength and toughness, which is produced from the spinning dope solution by gelation and drawing spinning process. This encourages people to prepare artificial fibers by mimicking the material, structure, and spinning of natural spider silk. In this review, we first summarized the preparation of artificial spider silk prepared via such a gelation process from different types of materials, including nonrecombinant proteins, recombinant proteins, polypeptides, synthetic polymers, and polymer nanocomposites. In addition, different spinning approaches for spinning artificial spider silk are also summarized. In the third section, some novel application scenarios of the artificial spider silk were summarized, such as artificial muscles, sensing, and smart fibers.

Comparative clinical evaluation of a local drug delivery of cranberry and garcinia fruit gel with tetracycline fibers for amelioration of periodontitis: A split mouth study.

The present study formulates and evaluates a polyberry gel comprising extracts of cranberry (Vaccinium macrocarpon) and brindle berry (Garcinia cambogia) in patients suffering from chronic periodontitis. The polyberry gel was evaluated for various physicochemical parameters, in vitro permeability and stability, and the active phytoconstituents were quantified by High-performance thin layer chromatography (HPTLC). Total phenolic content, total antioxidants, and ascorbic acid were estimated in the two extracts by in vitro assays. Patients suffering from chronic periodontitis with probing pocket depth (PPD) up to 5 mm were divided into 3 groups of 21 patients each and treated with scaling and root planing (SRP) or SRP followed by subgingival placement of polyberry gel or tetracycline fibers (standard). Plaque Index (PI), Gingival Index (GI), PPD, Clinical Attachment Level (CAL), and the salivary aspartate aminotransferase (AST) and C-reactive protein (CRP) levels were recorded at baseline and after 1 month. A significant (P < 0.01) reduction in the periodontic disease parameters was observed in the standard and gel-treated groups between their baseline and 1-month time-interval readings. The polyberry gel treatment significantly (P < 0.05 for AST and P < 0.01 for the rest) attenuated the periodontitis-elevated PI, GI PPD, CAL, AST and CRP levels when compared with SRP at the end of the study and was comparable with tetracycline. The amelioration of periodontitis and gingival inflammation may be attributed to the potent antioxidant activity of the polyphenolic phytoconstituents of the gel. The polyberry gel may thus be used as a safe adjunct to SRP/tetracycline in chronic periodontitis.

Composite magnetic sheet as sorbent for oil spill Clean-up

Water is the most vital resource required for the survival. But the cleanliness of this resource has been compromised in the form of oil spills which occurs due to the tanker disaster, transportation and storage of oil. It is extremely urgent to find the effective counter measure for oil spill treatment which aims oil spill-recovery strategy. Out of all the measures, development of a good biodegradable sorbent for spillage has sustained interest. To solve this environmental problem of oil spill, magnetic Sheet was synthesised by using lumen loading procedure using alkali treated bamboo fibers and cobalt ferrite nanoparticles (CoFe 2 O 4 ). Lumen loading permits the ferrite particles to be introduced solely into the lumens of bamboo fibres. For aiming this, CoFe 2 O 4 nanoparticles were first prepared by the sol–gel method and fibers were pre-treated with 6 % NaOH. Then synthesised ferrites were merged with the fibers. The samples were characterized by employing Scanning Electron Microscopy (SEM-EDS), Fourier transform infrared (FTIR), X-ray Diffraction (XRD). SEM confirms the deposition of cobalt ferrites nano particles on the surface and into the macropores of fibers. The sorption capacity for raw bamboo fibers, alkali treated bamboo fibers and composite sheet was calculated for three different type of oil such as mustard oil, coconut oil and olive oil. The sorption capacity shown by the raw bamboo fiber, 6 % NaOH treated bamboo fiber and composite magnetic sheet was in the range 1.8–2.2 g, 16.2–18.8 g and 1.8–2.4 g of oil per gram of sample respectively. The outcomes propose that the prepared magnetic sheet can be used as absorbent for oil-spill clean-up.

Development of Synthesis Method for Gel Fibers with Shear-Induced Multi-Core Structure

Development of Synthesis Method for Gel Fibers with Shear-Induced Multi-Core Structure

Gel‐spinning of ultra‐high molecular weight polyethylene by a twin‐screw extruder with an ultra‐large length‐to‐diameter ratio

AbstractA twin‐screw extruder with an ultra‐large length‐to‐diameter (L/D) ratio of 136 was developed and applied in the gel‐spinning process of ultra‐high molecular weight polyethylene (UHMWPE). UHMWPE gel fibers with concentrations of 6–18 wt% were produced at barrel temperatures of 150–180°C and screw speeds of 10–40 rpm. The residence time of the UHMWPE gel solution in the extruder increased with the increase of solution concentration and barrel temperature and decreased with the increase of screw speed. The tensile properties and crystallinity of the UHMWPE gel fibers decreased with the increase of solution concentration. Due to the great shear effect of the ultra‐large L/D ratio, the barrel temperature and screw speed could be lower to optimize the structure and tensile properties of UHMWPE fibers. Compared to the extruder with the L/D ratio of 36, the tensile strength, modulus, and elongation at break of the gel fibers prepared by the extruder with the L/D ratio of 136 were increased by 148.8%, 117.6%, and 54.2%, respectively. The crystallinity of the gel fibers was increased by 50.6%. The fiber had a dense and smooth surface with oriented fibrils, which indicates the great ability of the ultra‐large L/D ratio for disentanglement of molecular chains.

Nanoscale Kevlar Liquid Crystal Aerogel Fibers.

Aerogel fibers, the simultaneous embodiment of aerogel porous network and fiber slender geometry, have shown critical advantages over natural and synthetic fibers in thermal insulation. However, how to control the building block orientation degree of the resulting aerogel fibers during the dynamic sol–gel transition process to expand their functions for emerging applications is a great challenge. Herein, nanoscale Kevlar liquid crystal (NKLC) aerogel fibers with different building block orientation degrees have been fabricated from Kevlar nanofibers via liquid crystal spinning, dynamic sol–gel transition, freeze-drying, and cold plasma hydrophobilization in sequence. The resulting NKLC aerogel fibers demonstrate extremely high mechanical strength (41.0 MPa), excellent thermal insulation (0.037 W·m–1·K–1), and self-cleaning performance (with a water contact angle of 154°). The superhydrophobic NKLC aerogel fibers can cyclically transform between aerogel and gel states, while gel fibers involving different building block orientation degrees display distinguishable brightness under polarized light. Based on these performances, digital textiles woven or embroidered with high- and low-orientated NKLC aerogel fibers enable up to 6.0 Gb information encryption in one square meter and on-demand decryption. Therefore, it can be envisioned that the tuning of the building blocks’ orientation degree will be an appropriate strategy to endow performance to the liquid crystal aerogel fibers for potential applications beyond thermal insulation.

Eco-friendly additive construction: Analysis of the printability of earthen-based matrices stabilized with potato starch gel and sisal fibers

• A prototype 3D printing system for construction ecofriendly composites was developed. • A printable composite made with soil, starch gel, and fibers was designed. • The inclusion of starch gel positively affects properties in fresh and hardened state. • The incorporation of sisal fibers allow controlling shrinkage cracking in printed filaments. 3D printing for construction purposes is a disruptive technology with the potential for rapid and massive applications making it a feasible alternative for social housing, temporary shelters after disasters, and, recently, for extraterrestrial habitats. However, most of the matrices used for construction by 3D printing are based on hydraulic cement as the main constituent, which is not easily available in remote locations and is an important greenhouse gases generator. Therefore, a good understanding to formulate and evaluate alternative matrices using soil and organic materials with the required fresh and hardened-state properties compatible with this emerging technology is needed. This article studies the printable capabilities of eco-friendly earthen-based matrices which uses potato starch as a natural stabilizer for raw soil mortars aiming to obtain 3D printed filaments with adequate fresh and hardened-states properties. The aqueous starch gel was combined with sisal fibers in the printing mixture to control shrinkage cracking problems during hardening. The optimization of the dosage of the stabilizer was carried out considering different tests in fresh and hardened printed filaments namely, pumpability and extrudability, stacking, shear vane, shrinkage cracking, Vicat needle, compression strength, and capillarity absorption tests. The results indicate that printable earthen-based matrices reinforced with 1 % of sisal fibers by weight of soil and stabilized with aqueous starch gels with concentrations up to 5 % (w/w) showed improved workability and minor cracking and can be used for 3D printing. These promising results in the field of material science combined with novel 3D printing technology that is also presented in the article open new lines of research for eco-friendly alternatives for the construction industry.

A novel desiccant compound for air humidification and dehumidification

• A novel silica gel-based desiccant material for open air systems is proposed. • Silica gel is mixed with sodium polyacrylate, vinyl glue and polypropylene fibers. • The maximum water uptake on dry silica gel mass basis is equal to 0.32 kg kg −1 . • Thermal and sorption stability of new and on-purpose aged samples are observed. • Dehumidification capacity is around 3.5 g kg −1 when the regeneration occurs at 52 °C. Currently, there is an increasing interest in the development of HVAC systems based on solid desiccant materials to achieve efficient and affordable air dehumidification and humidification processes. Many research efforts deal with the development of novel composite materials suitable to manufacture such devices. In this work we present a novel silica gel-based desiccant compound, which can be used to prepare different products, such as sheets, monolithic components, and coatings. The proposed formulation is based on a combination of silica gel, sodium polyacrylate, vinyl glue and polypropylene fibers. The preparation procedure of the sorbent material and its characterization (adsorption capacity, morphology and surface analysis, mechanical properties by pull-off test, structural and thermal stabilities of new and aged samples and volatile compounds emissions) are described in detail. A small-scale prototype has been also manufactured and experimentally tested under typical operating conditions of air dehumidification processes. Results show that the proposed material has a suitable sorption capacity (maximum water uptake equal to 0.32 kg kg −1 ), good mechanical properties (pull adhesion strength around 2.74 MPa) and stability (decomposition threshold of 400 °C). The performances achieved by the prototype are comparable with those of a reference silica gel packed bed system, highlighting that the desiccant material performs adequately also at system scale.

Spectroscopic characterization (Raman and infrared) of Aloe maculata from the north Argentina region

In this work we present the Fourier-transform infrared (FTIR) and Raman spectra of Aloe maculata (A.maculata)(“maculata” = with spots) gel after elimination of the aloin fraction. The analyzed samples were harvested from two zones of different heights in northern Argentina. From the FTIR measurements it was possible to identify the presence of pectin in the gel, where an analysis of the degree of esterification was done on the basis of characteristic marker bands for the different aloe samples. The effect of the storage time of both samples was also monitored revealing that the degree of esterification undergoes a decrease upon the storage time in all samples. By this way, it was determined that the samples of A. maculata collected from the high lands, present a higher esterification degree in pectins than those collected from the low lands. In order to better follow the distribution of the different spectral signals, we performed a Raman mapping in a selected area. The Raman measurements helped to determine the characteristics of the different fibers of the Aloe gel. Furthermore, theoretical calculations carried out on a molecular model of one important aloe gel component, the acemannan, aided in the assignment of the modes of the groups present in the gel samples. This investigation is important in order to assess the influence of the harvesting place and the storage time on the use and commercialization of the aloe products, since a higher degree of esterification gives rise to a higher viscosity and, consequently, a better bioavailability.

Structural evolution of UHMWPE gel fibers as high degree plasticized system during stretching: An in-situ wide and small angle X-ray scattering study

Ultra-high molecular weight polyethylene (UHMWPE) gel fibers filled with high content of plasticization deformed at room temperature were characterized by using in-situ wide-angle X-ray diffraction (WAXD)/small-angle X-ray scattering (SAXS), and ex-situ differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The structural evolution dependence on the plasticization content and stretching speed was stressed. The gel fibers with 96 wt% plasticization exhibited higher orientation than the fibers with 88 wt% plasticization stretched at the same stretching speed. Both gel fibers presented the stretch-induced crystallization as quantified by an increase in crystallinity index. Partial crystallites were found to be induced in the manner of fragmentation-recrystallization accompanied by fibrillization. However, when stretched beyond a threshold strain, the orientation factor, crystallinity index, and long period of both gel fibers changed slowly, which corresponded to the transition from the inability of the structure to continue evolving smoothly. A new mechanism for the structural evolution of high-plasticized UHMWPE gel fibers was proposed to summarize the above results. • The structural evolution in high content plasticized UHMWPE systems was studied. • Effect of degree of plasticization on the structural evolution was compared. • Effect of stretching speed on the structural evolution was compared. • In-situ WAXD/SAXS technique was used for the study.