The influence of crosslinker concentration on PVA insulation characteristics

Summary This paper is the second in a two-part series on in situ polymerization of bioactive monomers as an alternative to conventional preservative treatments. In this part of the study, bioactive monomers were evaluated for their ability to provide resistance to decay and protection against fire. Five bioactive monomers were synthesized: (1) pentachlorophenolyl acrylate (PCPA), (2) tributyltin acrylate (TBTA), (3) 8-hydroxyquinolyl acrylate (HQA), (4) 5,7-dibromo-8-hydroxyquinolyl acrylate (DBHQA), and (5) diethyl-N1N-bis (acryloxyethyl) aminomethyl phosphonate (Fyrol 6 acrylate, F6A). Southern pine sapwood samples were treated with acrylate solutions at different retention levels and with various amounts of crosslinker (trimethylolpropane trimethacrylate, TMPTM), then polymerized in situ. Methyl methacrylate (MMA) was used as the control. Biological resistance to the brown-rot fungus Gloeophyllum trabeum was determined on acetone-leached and unleached samples. PCPA showed some biological efficacy in the absence of crosslinker, but otherwise provided no more protection than did MMA alone. TBTA was biologically effective at all retention levels except with crosslinker concentration ≥10 %. HQA was biologically effective at ≥ 2% retention. F6A was not biologically effective, although unleached wood treated with 10% F6A and 5% or no crosslinker showed some resistance to decay. The 5% DBHQA plus 5% crosslinker treatment was biologically effective in both leached and unleached wood. The effects of the highest treatment level of each monomer, after polymerization, were also evaluated by thermogravimetric analysis. All treatments provided some resistance to fire. The best treatment was 10 % F6A, which resulted in the lowest mass loss (67.0 %) and the lowest maximum temperature of pyrolysis (308.5 °C).

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Tuning the Mechanical and Geometric Properties of Electrochemically Aligned Collagen Threads Towards Applications in Biohybrid Robotics

Journal of Biomechanical Engineering ◽

10.1115/1.4049956 ◽

2021 ◽

Author(s):

Wenhuan Sun ◽

Jason Paulovich ◽

Victoria Webster-Wood

Keyword(s):

Tensile Modulus ◽

Solution Concentration ◽

Cross Sectional ◽

Geometric Properties ◽

Wide Range ◽

Crosslinker Concentration ◽

High Degree ◽

The Impact ◽

Fabrication Parameters ◽

Manufacturing Parameters

Abstract Electrochemically Aligned Collagen (ELAC) threads fabricated by the isoelectric focusing (IF) of collagen have previously shown potential in tissue engineering and more recently in the fabrication of biohybrid robot structures. For applications in biohybrid robotics, ELAC structures are needed that are both robust and compliant enough to facilitate muscle actuation. However, studies on the effects of IF parameters, and the interactions of such fabrication parameters, on the mechanical and geometric properties of resulting ELAC threads have not been previously found in literature. Understanding the impact of these manufacturing parameters on the material properties is critical to facilitate biohybrid robot design. In this study, the effects of IF duration, IF voltage, and collagen solution concentration were investigated and showed statistically significant effects on adjusting ELAC properties via single-factor experiments. The interactions between parameters exhibited significant joint effects on ELAC property tuning through two-factor experiments. Scanning electron microscopy and 2,4,6-trinitrobenzenesulfonic assays revealed the correlation between high mechanical properties and a combination of low porosity and high degree of crosslinking. By simply tuning IF parameters without changing other fabrication steps, such as crosslinker concentration, ELAC threads with a wide range of mechanical and geometric properties were fabricated. The average tensile modulus of the resulting ELAC threads ranged from 198±90 to 758±138 MPa. The average cross-sectional area ranged from 7756±1000 to 1775±457 µm2. The resultant mapping between IF parameters and ELAC thread properties enabled the production of strong and flexible threads with customizable properties.

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Synthesis, Applications and Swelling Properties of Poly (Sodium Acrylate-Coacrylamide) Based Superabsorbent Hydrogels

Journal of the chemical society of pakistan ◽

10.52568/000784/jcsp/41.04.2019 ◽

2019 ◽

Vol 41 (4) ◽

pp. 668-668

Author(s):

Saud Hashmi Saud Hashmi ◽

Saad Nadeem Saad Nadeem ◽

Zahoor Awan Zahoor Awan ◽

Adeel ur Rehman Adeel ur Rehman ◽

Ahsan Abdul Ghani Ahsan Abdul Ghani

Keyword(s):

Rate Constant ◽

Polymeric Materials ◽

Water Soluble ◽

Ion Concentration ◽

Copolymer Composition ◽

Swelling Properties ◽

Swelling Capacity ◽

Swelling Rate ◽

Crosslinker Concentration ◽

Superabsorbent Hydrogels

Superabsorbent hydrogels constitute a group of polymeric materials with three-dimensional network structure, which can swell to absorb an enormous amount of water or aqueous solutions. This property enables various commercial applications of hydrogels such as water holding capability in agriculture and superabsorbent material for baby diapers. Several novel superabsorbent hydrogels based on acrylic acid-co-acrylamide copolymers were synthesized under variation of copolymer compositions through free radical polymerization. N,N’methylenebisacrylamide (MBA) was used as a water soluble crosslinker and potassium persulphate (KPS) as an initiator. Effect of varying the copolymer composition, change in crosslinker concentration, and effect of environmental parameters (pH, temperature, and ion concentration) on both swelling capacity and swelling rate were examined. These gel shows maximum swelling at neutral pH-7, whereas increasing salt concentration in water decrease the swelling capacity. It was found interesting that an increase in crosslinker concentration from 0.020% to 0.16%, the swelling capacity decreases up to 70% while the swelling rate increases from 0.007g water/g dry hydrogel sec to 0.024g water/g dry hydrogel sec, respectively because there is a compromise exists between entropic spring forces between network connection points and the hydrostatic pressure of the water diffusing into the gels. Dynamic swelling curve obtained were fitted to the three different kinetic models namely Peleg’s kinetic model, pseudo 1st order as proposed by Lagergen and pseudo 2nd order kinetics. All these models provided a good agreement with the experimental data; However on the bases of statistical parameters (RMSE, R2 and X2) the Peleg’s model was selected as the most appropriate model for this study. Analyzing rate constant for Peleg’s models at different swelling temperatures disclosed that increasing temperature could only increase the swelling rate without affecting the swelling capacity of the hydrogels. Experimental values for rate constant k1 of Peleg’s model at different temperature shows a sharp decrease from 0.57545 at 30 oC to 0.1535 at 75 oC that contemplated the rate of swelling at 75 oC was 65% faster than that of 30 oC. The diffusion mechanisms in hydrogels were proven to be tailorable by increasing cross-linker concentration and temperature, leading towards the Fickian type diffusion behavior. The synthesized superabsorbent hydrogels were also tested for water retention applications in agriculture.

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Development of New Formula Microcapsules from Nutmeg Essential Oil Using Sucrose Esters and Magnesium Aluminometasilicate

Pharmaceutics ◽

10.3390/pharmaceutics12070628 ◽

2020 ◽

Vol 12 (7) ◽

pp. 628

Author(s):

Inga Matulyte ◽

Giedre Kasparaviciene ◽

Jurga Bernatoniene

Keyword(s):

Essential Oil ◽

Sodium Alginate ◽

Calcium Chloride ◽

Physical Parameters ◽

Polysorbate 80 ◽

Sucrose Esters ◽

Crosslinker Concentration ◽

Volatile Liquids ◽

Materials Used ◽

Nutmeg Essential Oil

Essential oils are volatile liquids which evaporate and lose their pharmacological effect when exposed to the environment. The aim of this study is to protect nutmeg essential oil from environmental factors by encapsulation (shell material, sodium alginate) and determine the influence of crosslinker concentration (2%, 5% calcium chloride), different emulsifiers (polysorbate 80, sucrose esters), and magnesium aluminometasilicate on microcapsule physical parameters, encapsulation efficiency (EE), swelling index (SI), and other parameters. Nutmeg essential oil (NEO)-loaded calcium alginate microcapsules were prepared by extrusion. The swelling test was performed with and without enzymes in simulated gastric, intestinal, and gastrointestinal media. This study shows that the crosslinker concentration has a significant influence on EE, with 2% calcium chloride solution being more effective than 5%, and capsules being softer with 2% crosslinker solution. Using sucrose esters, EE is higher when polysorbate 80 is used. The swelling index is nearly three times higher in an intestinal medium without enzymes than in the medium with pancreatin. Microcapsule physical parameters depend on the excipients: the hardest capsules were obtained with the biggest amount of sodium alginate; the largest with magnesium aluminometasilicate. Sucrose esters and magnesium aluminometasilicate are new materials used in extrusion.

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Synthesis of Water Resistance and Moisture-Permeable Nanofiber Using Sodium Alginate–Functionalized Waterborne Polyurethane

Polymers ◽

10.3390/polym12122882 ◽

2020 ◽

Vol 12 (12) ◽

pp. 2882

Author(s):

Wen-Chi Lu ◽

Fu-Sheng Chuang ◽

Manikandan Venkatesan ◽

Chia-Jung Cho ◽

Po-Yun Chen ◽

...

Keyword(s):

Mechanical Strength ◽

Sodium Alginate ◽

Calcium Chloride ◽

Strain Curve ◽

Cost Effective ◽

Waterborne Polyurethane ◽

Hydrophilic Nature ◽

Initial Modulus ◽

Humid Region ◽

Crosslinker Concentration

The development of nontoxic and biodegradable alginate-based materials has been a continual goal in biological applications. However, their hydrophilic nature and lack of spinnability impart water instability and poor mechanical strength to the nanofiber. To overcome these limitations, sodium alginate (SA) and waterborne polyurethane (WPU) were blended and crosslinked with calcium chloride; 30 wt % of SA exhibited good compatibility. Further addition of 10 wt % calcium chloride improved the water stability to an extremely humid region. Furthermore, the stress–strain curve revealed that the initial modulus and the elongation strength of the WPU/SA and WPU/CA blends increased with SA content, and the crosslinker concentration clearly indicated the dressing material hardness resulted from this simple blend strategy. The WPU/SA30 electrospun nanofibrous blend contained porous membranes; it exhibited good mechanical strength with water-stable, water-absorbable (37.5 wt %), and moisture-permeable (25.1 g/m2–24 h) characteristics, suggesting our cost-effective material could function as an effective wound dressing material.

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Bimodality and Increased Amount of Crosslinker Enhances Tensile Properties of the Silicone Networks

e-Polymers ◽

10.1515/epoly.2007.7.1.1302 ◽

2007 ◽

Vol 7 (1) ◽

Author(s):

Gul Bali Shah

Keyword(s):

Elastic Modulus ◽

Tensile Properties ◽

Phase Inversion ◽

Volume Fraction ◽

Polymer Networks ◽

Short Chain ◽

Percent Elongation ◽

Bimodal Networks ◽

Crosslinker Concentration ◽

First Time

AbstractThe effect of bimodality i.e. blending short and long chain (0 to 80 % w/w) silicone prepolymers, and that of concentration of the crosslinker on the tensile properties such as percent elongation at break (%Eb), ultimate tensile strength (UTS), 100 % modulus and elastic modulus (E) has been investigated. It was found out that the greater amount of crosslinker used for crosslinking provide an additional reinforcement to the silicone network whereas bimodality further significantly accentuates this effect. Remarkably, the %Eb of the silicone networks was found to increase to an average of 2.4 times than that of the monomodal network, cured in each of the three series of bimodal networks cured with 3.9, 9.1 and 12.3% of crosslinker. The optimum property in each case was observed at about 70 mol % of P100. The over all order of sensitivity of these properties up to about 70 mol % of short chain prepolymer has been observed to be as: %Eb > UTS > 100% modulus > elastic modulus. It has been shown that in addition to the previously published reports the tensile properties are acutely dependent not only upon the degree of crosslinking and primary molecular weight; but also on bimodality and crosslinker concentration for preparation of the unfilled silicone polymer networks. The concept of phase inversion (or phase transition) associated with the optimum properties in polymer blends has for the first time been applied to the bimodal polymer networks. It has been observed that the maxima in tensile properties generally corresponds to phase inversion which takes place at 0.5 volume fraction (70 mol %) of short chain (P100) prepolymer which is in accordance with the literature for other systems.

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Preparation of a Novel Fracturing Fluid System with Excellent Elasticity and Low Friction

Polymers ◽

10.3390/polym11101539 ◽

2019 ◽

Vol 11 (10) ◽

pp. 1539 ◽

Cited By ~ 3

Author(s):

Yang Zhang ◽

Jincheng Mao ◽

Jinzhou Zhao ◽

Tao Xu ◽

Anqi Du ◽

...

Keyword(s):

Polymer Solution ◽

Network Structure ◽

Oil And Gas ◽

Sodium Dodecyl ◽

Interaction Mechanism ◽

Intermolecular Forces ◽

Fracturing Fluid ◽

Deep Wells ◽

Oil And Gas Resources ◽

Crosslinker Concentration

The quaternary polymer was synthesized by radical polymerization and characterized by 1H NMR. The tests of critical associating concentration and SEM suggest that there is a multilayered and robust network structure in the polymer solution. An excellent elasticity in the polymer solution by the first normal stress difference, viscoelasticity, and thixotropy was observed. The critical crosslinker concentration of polymer with sodium dodecyl sulfate and its interaction mechanism were investigated. According to the reaction kinetics, the supramolecular structure had the lowest activation energy, stable network structure, and greater thermal stability. Then the polymer was employed in the fracturing fluid due to its excellent elasticity using the intermolecular forces, which showed superior sand suspension capacity by dynamic sand suspension measurement. Meanwhile, a theoretical analysis was proposed as to why polymer solution has excellent suspension and drag reduction properties. Therefore, this polymer could be an alternative in many fields, especially in fracking, which is significant for the development of oil and gas resources in deep wells.

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Properties and Synthesis of Kaolin / Potassium Polyacrylate / Acrylamide Composite Superabsorbent Resin

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.287-290.1331 ◽

2011 ◽

Vol 287-290 ◽

pp. 1331-1334

Author(s):

Hao Ren ◽

Jie Li ◽

Yu Fen Zhang ◽

Tai Zhong Huang

Keyword(s):

Aqueous Solution ◽

Saline Water ◽

Monomer Concentration ◽

Water Absorbency ◽

Solution Polymerization ◽

Synthetic Resin ◽

Polymer Molecules ◽

Aqueous Solution Polymerization ◽

Crosslinker Concentration ◽

Superabsorbent Resin

The aqueous solution polymerization methods were used for the synthesis of superabsorbent resin. The effects of different experimental factors on synthetic resin water absorbency were investigated in this paper. The variables examined in this study included monomer concentration, neutralization degree, initiator and crosslinker concentration, reaction temperature and time, etc. The maximum absorbencies of distilled and 0.9% saline water are 919 times and 92 times respectively under optimum condition. Analysis from FTIR and SEM shown the polymer molecules can be firmly fixed with kaolin, the bonding of kaolin and polymer is good in CSR.

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