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1.
Am J Emerg Med ; 84: 81-86, 2024 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-39096713

RESUMEN

OBJECTIVE: To evaluate the characteristics and trends of pediatric water bead-related visits to US emergency departments (EDs) using a large national database. METHODS: Data from the National Electronic Injury Surveillance System regarding ED visits by individuals <20 years old associated with water beads from January 1, 2007, through December 31, 2022, were retrospectively analyzed. RESULTS: Based on 307 reported cases, there were an estimated 8159 visits (95% CI: 4447-11,870) to US EDs from 2007 through 2022 involving water beads among <20-year-olds, and more than half (55.0%) of the 307 ED cases involved <5-year-olds. Most cases were treated and released (92.2%), which was consistent across all age groups. The proportion of cases admitted was highest among children <5 years old (10.1%), and this age group accounted for 17 of the 19 admissions (89.5%) in this study. All admissions among children <5 years old involved ingestions. Ingestion was the most common mechanism of injury (45.9%), followed by ear canal insertion (32.6%), nasal insertion (11.7%), and eye injury (8.8%). Although ingestions occurred most frequently among children one (28.4%) and two (23.4%) years of age, children 3 and 4 years old accounted for one-fifth of ingestions. The number of ED cases increased rapidly by 130.9% from 55 cases in 2021 to 127 in 2022. CONCLUSIONS: The number of pediatric water bead-related ED visits is increasing rapidly. Children <5 years old are most commonly involved, usually via water bead ingestion. Increased prevention efforts are needed.


Asunto(s)
Servicio de Urgencia en Hospital , Humanos , Servicio de Urgencia en Hospital/estadística & datos numéricos , Preescolar , Estados Unidos/epidemiología , Niño , Lactante , Masculino , Femenino , Estudios Retrospectivos , Adolescente , Adulto Joven , Cuerpos Extraños/epidemiología , Recién Nacido
2.
Polymers (Basel) ; 16(14)2024 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-39065287

RESUMEN

This study aimed to experimentally investigate the compressive strength and air voids of cement pastes with varying dosages of Superabsorbent Polymer (SAP) and water-to-cement (w/c) ratios. Cement pastes were prepared using three different w/c ratios of 0.4, 0.5, and 0.6, along with different dosages of SAP ranging from 0.2% to 0.5% by weight of cement. Additionally, SAP was introduced in two forms: dry and wet. After casting the cubes, two distinct curing conditions were employed: curing at a temperature of 20 °C with a Relative Humidity (RH) of 60% (Curing 1), and water curing (Curing 2). The results revealed that the addition of SAP increased early strength when subjected to Curing 1, followed by a decrease in later strength. On the other hand, samples with SAP and water curing exhibited higher strength compared to those without SAP, especially with w/c ratios of 0.4 and 0.5. However, at a w/c ratio of 0.6, nearly all samples showed a reduction in strength compared to those without SAP. Furthermore, air void analysis was performed on all samples cured for 28 days using an image analysis technique. The samples containing wet SAP resulted in a higher total air content compared to the samples with dry SAP. Additionally, the incorporation of wet SAP in cement paste led to lower specific surface areas and a higher spacing factor than the samples with dry SAP. These findings suggest that the clumping of wet SAP particles during presoaking resulted in coarser air voids compared to the samples containing dry SAP.

3.
Materials (Basel) ; 17(13)2024 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-38998197

RESUMEN

This study aims to understand the water retention capabilities of Superabsorbent Polymers (SAPs) in different alkaline environments for internal curing and to assess their impact on the rheological properties of cement paste. Therefore, the focus of this paper is on the absorption capacities of two different sizes of polyacrylic-based Superabsorbent Polymers : SAP A, with an average size of 28 µm, and SAP B, with an average size of 80 µm, in various solutions, such as pH 7, pH 11, pH 13, and cement filtrate solution (pH 13.73). Additionally, the study investigates the rheological properties of SAP-modified cement pastes, considering three different water-to-cement (w/c) ratios (0.4, 0.5, and 0.6) and four different dosages of SAPs (0.2%, 0.3%, 0.4%, and 0.5% by weight of cement). The results showed that the absorption capacity of SAP A was higher in all solutions compared to SAP B. However, both SAPs exhibited lower absorption capacity and early desorption in the cement filtrate solution. In contrast to the absorption results in pH 13 and cement filtrate solutions, the rheological properties, including plastic viscosity and yield stress, of the cement paste with a w/c ratio of 0.4 and 0.5, as well as both dry and wet (presoaked) SAPs, were higher than those of the cement paste without SAP, indicating continuous absorption by SAP. The viscosity and yield stress increased over time with increasing SAP dosage. However, in the mixes with a w/c ratio of 0.6, the values of plastic viscosity and yield stress were initially lower for the mixes with dry SAPs compared to the reference mix. Additionally, cement pastes containing wet SAP showed higher viscosity and yield stress compared to the pastes containing dry SAP.

4.
Pest Manag Sci ; 2024 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-39072976

RESUMEN

BACKGROUND: Acrylamide-based bait has super water absorption making it highly attractive to subterranean termites that are lured by wood with high water content. This study investigated the control efficiency of these baits on subterranean termites. In particular, we evaluated the water-absorption capacity, attractiveness to subterranean termites, and control efficiency of these baits on subterranean termites through wooden blocks (Populus deltoides and three types of particleboards). RESULTS: The results indicated a substantial water absorption capacity of acrylamide (70.6%; control: 14.8%) and a strong attraction for feeding subterranean termites (P. deltoides: 198 highest; 81 lowest subterranean termites individuals; combination of neem leaves and walnut shells: 168 highest; 36 lowest subterranean termites individuals). When acrylamide was combined with boric acid at the highest concentration, it resulted in the lowest wood consumption rates (P. deltoides: 24.1%; control: 63.8%, combination of neem leaves and walnut shells: 32.5%; control: 62.1%). CONCLUSIONS: In conclusion, this research supports the commercial viability of employing innovative acrylamide-based toxic baits and particleboards for subterranean termite management. © 2024 Society of Chemical Industry.

5.
Polymers (Basel) ; 16(12)2024 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-38932105

RESUMEN

The adsorption mechanism of superabsorbent polymer (SAP) can provide theoretical guidance for their practical applications in different environments. However, there has been limited research on the mechanism of attapulgite-sodium polyacrylate. This research aimed to compare the Cd(II) adsorption characteristics and water retention properties of organic-inorganic composite SAP (attapulgite-sodium polyacrylate, OSAP) and organic SAP (polyacrylamide, JSAP). Batch experiments were used to investigate the kinetics of Cd(II) adsorption, as well as the thermodynamic properties and factors influencing these properties. The results show that the Cd(II) adsorption capacity was directly proportional to the pH value. The maximum adsorption capacities of OSAP and JSAP were of 770 and 345 mg·g-1. The Cd(II) adsorption for OSAP and JSAP conformed to the Langmuir and the quasi-second-order kinetic model. This indicates that chemical adsorption is the primary mechanism. The adsorption process was endothermic (ΔH0 > 0) and spontaneous (ΔG0 < 0). The water adsorption ratios of OSAP and SAP were 474.8 and 152.6 in pure water. The ratio decreases with the increase in Cd(II) concentration. OSAP and JSAP retained 67.23% and 38.37% of the initial water adsorption after six iterations of water adsorption. Hence, OSAP is more suitable than JSAP for agricultural and environmental ecological restoration in arid and semi-arid regions.

6.
Int J Biol Macromol ; 270(Pt 1): 132303, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38744366

RESUMEN

In order to solve ecological remediation issues for abandoned mines with steep slopes, a kind of hydrogels with high cohesion and water-retaining were designed by inorganic mineral skeleton combining with polymeric organic network cavities. This eco-friendly hydrogel (MFA/HA-g-p(AA-co-AM)) was prepared with acrylic acid (AA)-acrylamide (AM) as network, which was grafted with humic acids (HA) as network binding point reinforcement skeleton and polar functional group donors, KOH-modified fly ash (MFA) as internal supporter. The maximum water absorption capacities were 1960 g/g for distilled water, which followed the pseudo-second-order model. This super water absorption was attributed to the first stage of 62 % fast absorption due to the high specific surface area, pore volume and low osmotic pressure, moreover, the multiple hydrophilic functional groups and network structure swell contributed to 36 % of the second stage slow adsorption. In addition, the pore filling of water in mesoporous channels contributed the additional 2 % water retention on the third stage. The high saline-alkali resistance correlated with the electrostatic attraction with MFA and multiple interactions with oxygen-containing functional groups in organic components. MFA and HA also enhanced the shear strength and fertility retention properties. After 5 cycles of natural dehydration and reabsorption process, these excellent characteristics of reusability and water absorption capacity kept above 97 %. The application of 0.6 wt% MFA/HA-g-p(AA-co-AM) at 15° slope could improve the growth of ryegrass by approximately 45 %. This study provides an efficient and economic superabsorbent material for ecological restoration of abandoned mines with steep slopes.


Asunto(s)
Hidrogeles , Resistencia al Corte , Hidrogeles/química , Restauración y Remediación Ambiental/métodos , Sustancias Húmicas , Adsorción , Ceniza del Carbón/química , Agua/química , Nutrientes/química , Acrilatos/química
7.
Int J Biol Macromol ; 266(Pt 2): 131360, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38580017

RESUMEN

A humic acid-gelatin (HA-Gel) hydrogel, a gallic acid-xanthan gum (GA-XG) hydrogel, a HA-Gel/GA-XG hydrogel, and superabsorbent polymer (SAP) of HA-Gel/GA-XG/polyacrylamide (PAM) hydrogel were synthesized using electron beam irradiation method. The capability of synthesized hydrogels in loading and controlled release of fulvic acid (FA) was studied. The chemical and physical structure of sorbents was confirmed by various analyses. The effect of irradiation dose on mechanical properties, gel percentage, swelling, and absorbency under load (AUL) of the sorbents was investigated. By changing the hydrogel structures into the SAP form, its swelling capacity was increased from 37 to 320 g/g. Both hybrid hydrogel and SAP were reusable for up to 7 cycles. The maximum fertilizer loading capacities for SAP and hybrid hydrogel were 402.1 and, 175.5 mg g-1, respectively. In comparison to hydrogels, the SAP showed a slower FA-release performance. Thus, in soil media, 86 % of FA was released in 15-20 days from the hybrid hydrogel while with the SAP, 81 % of FA was released in 30-35 days. The significant improvement in the growth of fodder corn treated with FA-loaded SAP in the greenhouse media in comparison to the control groups showed the effective performance of the designed SAP, favoring its practical applications.


Asunto(s)
Benzopiranos , Gelatina , Hidrogeles , Polisacáridos Bacterianos , Zea mays , Hidrogeles/química , Benzopiranos/química , Polisacáridos Bacterianos/química , Gelatina/química , Zea mays/química , Preparaciones de Acción Retardada/química , Electrones , Polímeros/química , Fertilizantes , Ácido Gálico/química , Sustancias Húmicas
8.
Microbiol Resour Announc ; 13(4): e0003124, 2024 Apr 11.
Artículo en Inglés | MEDLINE | ID: mdl-38488369

RESUMEN

Chryseobacterium sp. MHB01, Rhodococcus qingshengii MHB02, and Agrobacterium tumefaciens MHB03 were isolated from superabsorbent polymer granules cultured with an arbuscular mycorrhizal fungus. Whole-genome sequencing of these three strains revealed genome sizes of 4.57 Mb, 7.13 Mb, and 5.49 Mb with G + C contents of 36.9%, 62.5%, and 58.2%, respectively.

9.
Materials (Basel) ; 17(4)2024 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-38399157

RESUMEN

The paper concerns destructive and non-destructive (NDT) evaluation of the effect of the addition of superabsorbent polymer (SAP) used as a carrier of mixing water and a means of internal curing on the durability of concrete. The research concerns testing of five concretes-an ordinary reference concrete and four concretes differing in the content of mixing water introduced into the concrete mix in the form of pre-saturated SAP particles (25%, two variants of 50% and 75% of the total mixing water in the form of SAP hydrogel). The research consisted of 4 stages of tests. The subsequent stages involved the analysis of the effect of using SAP as a carrier of mixing water on the particular characteristics of concrete mix and hardened concrete, i.e., consistency and density of concrete mix (1st stage), carbonation tested using two indicators-phenolphthalein and thymol phenolphthalein (2nd stage), and finally: the homogeneity of the concretes' structure by means of ultrasonic method (determination of ultrasonic pulse velocity) 28 days after production (3rd stage) and 3 years after production (4th stage). The ultrasonic pulse (or wave) velocity was then correlated with the content of water applied in the form of SAP hydrogel. The statistical analysis of results showed that the method of introducing the mixing water into the concrete mix in the form of pre-absorbed superabsorbent polymer, although it changed the concrete mix consistency, did not significantly affect the concrete ability to resist carbonation. Meanwhile, after 3 years, the densification of the microstructure of concrete with SAP has been observed.

10.
Polymers (Basel) ; 16(2)2024 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-38256996

RESUMEN

Superabsorbent polymers (SAPs) are hydrophilic, polymeric network materials renowned for their ability to enhance various properties of cementitious materials. This investigation examines the impact of SAP size on the hydration degree, porosity, and compressive strength of cement pastes and concrete under diverse curing conditions and ageing periods. The findings reveal that SAP addition stimulates the hydration of the C2S phase, particularly during the early curing stages, thereby favouring early strength development. However, the effect of SAPs on hydration promotion diminishes as their size increases. Conversely, the size of SAPs affects the hydration range of their action, and the 400 µm SAP demonstrates the most extensive range of hydration enhancement, reaching up to 105 µm. Additionally, SAPs effectively reduce porosity in small pores (4 nm-10 µm), with 200 µm and 400 µm SAPs exhibiting the highest efficacy. While analysing the effects of SAPs on larger pores (>10 µm), the results show that although larger SAPs result in larger average porosity, the total porosity is effectively reduced, particularly in samples incorporating 400 µm SAP. The compressive strength of cement paste, even after 28 days, is slightly reduced following the introduction of SAPs. However, the strength of concrete, due to the naturally occurring pores eliminating the negative effects of the pores produced by SAPs, is significantly increased following the introduction of SAPs, especially 400 µm SAP.

11.
BMC Biotechnol ; 23(1): 47, 2023 10 31.
Artículo en Inglés | MEDLINE | ID: mdl-37907900

RESUMEN

γ-polyglutamic acid (γ-PGA) is a biomarker that can be directly obtained by microbial fermentation. Poly(amino acid) superabsorbent polymers (SAPs) were prepared with purified γ-PGA as raw material and ethylene glycol diglycidyl ether (EGDGE) as a cross-linking agent. However, γ-PGA fermentation broth has a high viscosity, requires complex extraction and separation processes, and entails high energy consumption, resulting in the high cost of poly (amino acid) SAPs. Therefore, the coupling fermentation processes of glutamate polyglutamic acid, the process of using glutamate fermentation broth instead of pure glutamate powder for fermentation, and the process of treating the fermentation broth under conditions of centrifugation, UV irradiation, and high temperature, were studied. The results showed that the yield of γ-PGA after centrifugation decreased by 5%, but it did not affect the synthesis of hydrogels, and the addition of γ-PGA fermentation broth had a significant effect on the performance of γ-PGA-co-PASP SAPs. The proposed method not only helps avoid the separation of complex γ-PGA fermentation broth and reduces the cost, but it also helps improve the performance of the super-absorbent resin, which has great application potential.


Asunto(s)
Ácido Glutámico , Ácido Poliglutámico , Ácido Poliglutámico/química , Fermentación
12.
Nanomaterials (Basel) ; 13(18)2023 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-37764604

RESUMEN

To improve the water absorbency and water-retention rate of superabsorbent materials, a porous calcium carbonate composite superabsorbent polymer (PCC/PAA) was prepared by copolymerization of acrylic acid and porous calcium carbonate prepared from ground calcium carbonate. The results showed that the binding energies of C-O and C=O in the O 1s profile of PCC/PAA had 0.2 eV and 0.1-0.7 eV redshifts, respectively, and the bonding of -COO- groups on the surface of the porous calcium carbonate led to an increase in the binding energy of O 1s. Furthermore, the porous calcium carbonate chelates with the -COO- group in acrylic acid through the surface Ca2+ site to form multidirectional crosslinking points, which would increase the flexibility of the crosslinking network and promote the formation of pores inside the PCC/PAA to improve the water storage space. The water absorbency of PCC/PAA with 2 wt% porous calcium carbonate in deionized water and 0.9 wt% NaCl water solution increased from 540 g/g and 60 g/g to 935 g/g and 80 g/g, respectively. In addition, since the chemical crosslinker N,N'-methylene bisacrylamide is used in the polymerization process of PCC/PAA, N,N'-methylene bisacrylamide and porous calcium carbonate enhance the stability of the PCC/PAA crosslinking network by double-crosslinking with a polyacrylic acid chain, resulting in the crosslinking network of PCC/PAA not being destroyed after water absorption saturation. Therefore, PCC/PAA with 2 wt% porous calcium carbonate improved the water-retention rate by 244% after 5 h at 60 °C, and the compressive strength was approximately five-times that of the superabsorbent without porous calcium carbonate.

13.
Materials (Basel) ; 16(14)2023 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-37512327

RESUMEN

Crystalline admixture (CA) can be incorporated into concrete to achieve self-healing of concrete cracks. In this study, both CA and superabsorbent polymer (SAP) were used as self-healing agents to investigate the effects of CA on the self-healing performance and mechanical properties of mortar with internally added SAP at different self-healing ages. The healing effect of cracks in mortar is assessed by crack observation and impermeability. The structure and composition of the filler in the cracks were analyzed by microscopic experiment. The experimental results indicate that CA enhances the healing of cracks in mortar specimens. The chemical reactions of CA primarily contribute to significantly improving the early-age crack-healing ability of the specimens, and the water absorption and expansion ability as well as the internal curing effect of SAP also facilitate the crack-healing process. Increasing the CA content leads to an increase in the Ca/Si ratio of C-S-H, causing a transition from a layered structure to a more compact needle-like structure. When 4% CA was added to the mortar, it resulted in an adequate formation of needle-like C-S-H structures, which eventually penetrate and fill the pits formed by SAP, compensating for the strength loss caused by SAP.

14.
Polymers (Basel) ; 15(14)2023 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-37514451

RESUMEN

The water absorption and release properties of superabsorbent polymers' (SAP) internal curing agent are affected by many factors, such as solution properties, the ambient temperature and humidity and the particle size of SAP, which determine the curing effect and the durability of cement concrete structures directly. In this paper, the variation rule of the water absorbing capacity of SAP in simulated cement paste under different solutions and environmental conditions was studied. Based on microscopic image technology, the dynamic swelling behavior of the SAP particles was explored. The water release performance of SAP in cement paste was analyzed by both the tracer method and the negative pressure method. The results show that the water absorption of SAP in cement paste varied from 27 to 33 times. The ionic valence had a significant effect on the water absorption capacity of SAP, which suggests that the larger the ionic radius, the lower the absorption of SAP. The higher the temperature of the solution, the greater the water absorption rate of SAP. While the SAP particle size was less than 40-80 mesh, a slight 'agglomeration effect' was prone to occur, but the absorption state of SAP was more stable. Based on the swelling kinetic equation of SAP and the time-dependent swelling morphology of SAP in cement paste, a swelling kinetic model was established. The water release performance of SAP was less affected by the capillary negative pressures, and it would not release the water prematurely during the plastic stage, which was conducive to the continuous internal curing process of hardened paste in the later stage.

15.
J Funct Biomater ; 14(5)2023 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-37233375

RESUMEN

Designing a functional and efficient blood-clotting agent is a major challenge. In this research, hemostatic scaffolds (GSp) were prepared from the superabsorbent, inter-crosslinked polymer sodium polyacrylate (Sp) bound to a natural protein gelatin (G) loaded with thrombin (Th) by a cost-effective freeze-drying method. Five compositions were grafted (GSp0.0, Gsp0.1, GSp0.2, GSp0.3, GSp0.3-Th) where the concentration of Sp varied but the ratios of G remained the same. The fundamental physical characteristics that increased the amounts of Sp with G gave synergistic effects after interacting with thrombin. Due to the presence of superabsorbent polymer (SAP) swelling capacities in GSp0.3 and GSp0.3-Th surge forward 6265% and 6948%, respectively. Pore sizes became uniform and larger (ranging ≤ 300 µm) and well-interconnected. The water-contact angle declined in GSp0.3 and GSp0.3-Th to 75.73 ± 1.097 and 75.33 ± 0.8342 degrees, respectively, thus increasing hydrophilicity. The pH difference was found to be insignificant as well. In addition, an evaluation of the scaffold in in vitro biocompatibility with the L929 cell line showed cell viability >80%, so the samples were nontoxic and produced a favorable environment for cell proliferation. The composite GSp0.3-Th revealed the lowest HR (%) (2.601%), and the in vivo blood-clotting time (s) and blood loss (gm) supported hemostasis. Overall, the results showed that a novel GSp0.3-Th scaffold can be a potential candidate as a hemostatic agent.

16.
Materials (Basel) ; 16(7)2023 Mar 31.
Artículo en Inglés | MEDLINE | ID: mdl-37049107

RESUMEN

The hybrid use of a superabsorbent polymer (SAP) and expansive agent (EA) is beneficial for mitigating the autogenous shrinkage of ultra-high-performance concrete (UHPC) without compromising strength. However, the unclear mechanisms behind the synergetic effect of the two materials may hinder the more effective applications of this method. This study clarifies the interactions between SAP and CaO-based EA (CEA) in a UHPC matrix by quantifying the content and distribution of water and hydration products, underlining their influence on the strength and autogenous shrinkage evolution. The high strength of 135 MPa can be achieved in systems with a reasonable combination (S1E1, 0.1 wt%SAP, and 1 wt%CEA), and after 7 days, a 24% reduction in shrinkage was found in the same system, which is more effective than the use SAP or CEA alone at the same dose. The mitigating effect on the autogenous shrinkage of a UHPC matrix with hybrid materials at different stages depends on the competition between the water retention for self-desiccation and portlandite formation. With the continuing formation of hydration products, the microporosity of UHPC matrix under internal curing conditions at 28 d is considerably reduced, resulting in a more compact microstructure. This study also finds a suppressed crystallization pressure of growing portlandite in the extra space provided by emptied SAP, which explains the lost expansion of CEA.

17.
Polymers (Basel) ; 15(6)2023 Mar 16.
Artículo en Inglés | MEDLINE | ID: mdl-36987251

RESUMEN

The purpose of this study is to assess water-polymer interaction in synthesized starch-derived superabsorbent polymer (S-SAP) for the treatment of solid waste sludge. While S-SAP for solid waste sludge treatment is still rare, it offers a lower cost for the safe disposal of sludge into the environment and recycling of treated solid as crop fertilizer. For that to be possible, the water-polymer interaction on S-SAP must first be fully comprehended. In this study, the S-SAP was prepared through graft polymerization of poly (methacrylic acid-co-sodium methacrylate) on the starch backbone. By analyzing the amylose unit, it was possible to avoid the complexity of polymer networks when considering S-SAP using molecular dynamics (MD) simulations and density functional theory (DFT). Through the simulations, formation of hydrogen bonding between starch and water on the H06 of amylose was assessed for its flexibility and less steric hindrance. Meanwhile, water penetration into S-SAP was recorded by the specific radial distribution function (RDF) of atom-molecule interaction in the amylose. The experimental evaluation of S-SAP correlated with high water capacity by measuring up to 500% of distilled water within 80 min and more than 195% of the water from solid waste sludge for 7 days. In addition, the S-SAP swelling showed a notable performance of a 77 g/g swelling ratio within 160 min, while a water retention test showed that S-SAP was capable of retaining more than 50% of the absorbed water within 5 h of heating at 60 °C. The water retention of S-SAP adheres to pseudo-second-order kinetics for chemisorption reactions. Therefore, the prepared S-SAP might have potential applications as a natural superabsorbent, especially for the development of sludge water removal technology.

18.
Int J Biol Macromol ; 233: 123556, 2023 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-36746303

RESUMEN

This study prepared microcrystalline cellulose (MCC) from the Para rubber leaves (RL) via mechanical and chemical treatments in order to reduce the amount of waste RL by making it a value added product. The obtained MCC had a cellulose content of 61 % with a high crystallinity index of 67.35 %. The MCC-graft-polyacrylate (MCC-g-PA) was then prepared using N,N'-methylenebisacrylamide (MBA) at 0.05 wt% of acrylic acid via radical polymerization, and was then used as an additive in PA superabsorbent polymers (SAP). The presence of 0.05 g MCC-g-PA in PA (0.1 g) was found to exhibit a 1.17-fold greater water absorbency than the neat PA SAP, which was due to the increased level of hydroxyl and carboxylate groups from the added MCC-g-PA. The MCC-g-PA/PA SAP exhibited a similar reusability to the commercial SAP and could be degraded via cellulase and laccase enzymes.


Asunto(s)
Polímeros , Goma , Celulosa/química , Polimerizacion
19.
Materials (Basel) ; 16(3)2023 Jan 26.
Artículo en Inglés | MEDLINE | ID: mdl-36770089

RESUMEN

The super absorbent polymer (SAP) has been attracting extensive concerns due to its strong capacity in water absorption and retention. The amorphous hydrogels formed by the post-absorbent SAP have the potential of clogging the micro-cracks in asphalt materials and refraining the rainwater from infiltrating. This provides the possibility of applying SAP in asphalt pavements to seal or fill the cracks and relieve the distresses caused by rainwater infiltration in the underlying layers. Before exploring the cracking sealing mechanism of SAPs in asphalt pavements, a series of experiments were performed to evaluate the feasibility and influences of SAPs in asphalt mastics and asphalt mixtures on their mechanical performances and functionalities. Firstly, the basic properties of SAPs were analyzed, and then the rheological properties of the asphalt mastics using SAP replacing mineral powder (10%, 20%, 30%, and 40% by volume) were explored. The water stability and infiltration reduction effect of the asphalt mixtures incorporated with SAP were evaluated by the Marshall stability test, immersion Marshall stability test, freeze-thaw splitting strength test, Cantabro test, and permeability test. The test results indicated that SAPs could be used in the asphalt mixtures to partially substitute mineral powder with desirable mechanical performances. When less than 10% of the mineral powder was replaced by the SAP, the high-temperature performance and fatigue life of the asphalt mastics could be improved to some extent, but both declined after the content of the SAP was larger than 10%. Due to the hydrogels formed by SAPs after water absorption, the water stability of the asphalt mixtures deteriorated with the increased content of SAPs. Moreover, the results from the permeability tests implied that the SAP hydrogels could fill the seepage channels in the material, thus improving the migration and infiltration resistances of the asphalt mixtures. With the increased contents of SAPs, the permeability coefficients of the asphalt mixtures could be reduced up to 55%. Based on the research findings in this study, when an appropriate amount of SAP was added in the asphalt materials, desirable temperature stability, water stability, and fatigue resistance could be achieved regarding actual requirements from applications. At the same time, the addition of SAPs could effectively refrain the infiltration and migration of rainwater in asphalt pavements, thus potentially mitigating the effect of water erosion on the underlying layers.

20.
Int J Biol Macromol ; 233: 123643, 2023 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-36775220

RESUMEN

An eco-friendly superabsorbent polymer (SAP) was prepared by grafting 2-acrylamido-2-methyl-1-propanesulfonic acid onto microcrystalline cellulose in lithium chloride/N, N-dimethylacetamide system. The synthesized SAP (cellulose-g-PAMPS) was characterized by FTIR, TGA, SEM, 1H NMR, 13C NMR and XRD. The water absorption equilibrium of cellulose-g-PAMPS could be achieved within 10 min in distilled water. Moreover, the maximum water absorption capacities of cellulose-g-PAMPS in distilled water, 0.9 wt% NaCl solution and 3.2 wt% Na2CO3 solution were 648.9, 298.4 and 207.3 g·g-1, respectively. The water absorption behavior of cellulose-g-PAMPS was interpreted by the pseudo-second-order model. Furthermore, cellulose-g-PAMPS could be used in some extreme conditions due to its high acid and alkali resistance. The water retention rate of cellulose-g-PAMPS could be maintained above 90 % at 25 °C for 6 h. As a consequence, the synthesized SAP can be applied to increase the plant growth and survival time under drought conditions, even under saline alkali conditions.


Asunto(s)
Moléculas de Patrón Molecular Asociado a Patógenos , Polímeros , Polímeros/química , Celulosa/química , Agua/química
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