Effect Of Crosslinking Agent Research Articles

Biodegradable plastic from cross-linked rice flour: Effect of cross-linking agent and plasticizer

Biodegradable plastic from cross-linked rice flour: Effect of cross-linking agent and plasticizer

Synthesis and characterization of ammonium polymer for anion removal in aqueous solutions

In a one-step thermal process using 2-[(methacryloyloxy)ethyl]trimethylammonium chloride (META), an ammonium polymer was successfully obtained for the removal of anions (nitrates, nitrites, and phosphates) from aqueous solutions. Ethylene dimethacrylate (EDMA) was used as a cross-linking agent. The effect of cross-linking agent, porogen, and polymerization time on the structure and physical properties of the obtained polymer was examined (FTIR, SEM, BET, elemental analysis). The optimal conditions for META synthesis were a monomer to porogen ratio of 20:80, 75% functional monomer content and a 12-hour polymerization time.

Effect of Crosslinking Agent on Mesoporous Spherical POSS Hybrid Particles: Synthesis, Characterization and Thermal Stability

Effect of Crosslinking Agent on Mesoporous Spherical POSS Hybrid Particles: Synthesis, Characterization and Thermal Stability

Effect of Crosslinking Agent (Zinc Chloride) on the Swelling Ratio and Water Retention Capacity of Polyacrylate and Polyvinyl Alcohol

In this study, using potassium polyacrylate (KPA), polyvinylalcohol (PVA), and zinc chloride as cross-linking agents, successfully synthesized novel superabsorbent polymers. Different weight ratios of KPA and PVA were used to prepare the polymers using polymerization solution. So, polymers with different weight ratios made from PVA and KPA. Superabsorbent polymers (SAPs) were produced using a simple approach at ambient temperature. By comparing absorption peaks, Fourier transform infrared spectroscopy (FTIR) and UV analysis were utilized to investigate the molecular interactions. The morphology of superabsorbent polymers was investigated by scanning electron microscopy (SEM). According to FT-IR, UV, and SEM results, the superabsorbent polymers (Zn-KPA and Zn-PVA) were prepared successfully. A comparison of Zn-KPA and Zn-PVA SAPs was conducted. The effects of cross-linking on water absorption were investigated. The Zn-PVA superabsorbent polymer has a maximum swelling capacity of 407%, while the swelling ratio of the Zn-KPA was 304%. Thus, these prepared superabsorbent polymers could be used for agricultural applications such as water storage. With increasing zinc chloride content and time, superabsorbent polymers’ swelling capacity has considerably improved.

Hydrogel and Effects of Crosslinking Agent on Cellulose-Based Hydrogels: A Review.

Hydrogels are hydrophilic polymer materials that can swell but are insoluble in water. Hydrogels can be synthesized with synthetic or natural polymers, but natural polymers are preferred because they are similar to natural tissues, which can absorb a high water content, are biocompatible, and are biodegradable. The three-dimensional structure of the hydrogel affects its water insolubility and ability to maintain its shape. Cellulose hydrogels are preferred over other polymers because they are highly biocompatible, easily accessible, and affordable. Carboxymethyl cellulose sodium (CMCNa) is an example of a water-soluble cellulose derivative that can be synthesized using natural materials. A crosslinking agent is used to strengthen the properties of the hydrogel. Chemical crosslinking agent is used more often than physical crosslinking agent. In this review, article, different types of crosslinking agents are discussed based on synthetic and natural crosslinking agents. Hydrogels that utilize synthetic crosslinking agent have advantages, such as adjustable mechanical properties and easy control of the chemical composition. However, hydrogels that use natural crosslinking agent have better biocompatibility and less latent toxic effect.

Effects of Crosslinking and Silicone Coupling Agent on Properties of EVA Composite Hot Melt Adhesive.

In order to improve the bonding performance, EVA composite hot melt adhesives were prepared by introducing crosslinking agent and silane coupling agent in this paper. A binary EVA resin blend as the base resin with appropriate viscosity and tensile shear strength was selected as hot melt adhesive. The effects of crosslinking agent and silane coupling agent on the properties of ethylene/vinyl acetate (EVA) composite hot melt adhesive were studied. By investigating the preparation and curing conditions of hot melt adhesive and the properties of hot melt adhesive after the introduction of dicumyl peroxide (DCP), the optimum temperature and dosage of DCP and its influence on the properties were determined. It was found that the tensile shear strength of hot melt adhesive increased from 0.247 MPa to 0.726 MPa when 2 phr DCP and 5 phr KH570 were added at the same time. The tensile strength and tensile shear strength of hot melt adhesive are only slightly improved when silicone coupling agents with different functional groups are added to EVA composite hot melt adhesive. However, it was found that excessive silane coupling agent would significantly reduce the tensile strength and shear peel strength of the material.

Chromophore-containing methacrylate-based branched copolymers: The effect of cross-linking agent on the stability of quadratic nonlinear optical characteristics

Reactive chromophore-containing methacrylic copolymers of a linear (MMA-MAZ-GMA) and branched structure (BF-E(10), BF-E(20)) with epoxy groups for further cross-linking were synthesized. Cross-linked structures were formed either during heating, or with the addition of a cross-linking agent, for which succinic and terephthalic acids were applied. It was found that the use of special agents to obtain cross-linked polymers is more effective than just thermal cross-linking: in the first case the gel fraction content is more than 90 %, and about 80 % in the second. It was shown that when using succinic acid, the content of the gel fraction was 99 % (MMA-MAZ-GMA), 90 % (BF-E(10)) and 92 % (BP-E(20)), when using terephthalic acid – it comprised 97 %, 82 % and 85 %, respectively.

FORMULATION AND EVALUATION OF RACECADOTRIL MUCOADHESIVE MICROSPHERES

Objective: To develop and evaluate the mucoadhesive microsphere using combinations of natural polymers chitosan and xanthan gum for sustained release.
 Methods: In the present work mucoadhesive microspheres were prepared by using natural polymers like chitosan and xanthan gum by using the emulsion chemical cross-linking method. Chemical cross-linking was done by using glutaraldehyde. The 22 factorial design was employed to show the effect of cross-linking agent and processing factor-like stirring and speed. Prepared microspheres were evaluated for their particle size, surface morphology, drug entrapment efficiency, in vitro drug release, swelling index, and mucoadhesive strength.
 Results: The size of microspheres of factorial batches were in the range of 26-46 µm. The swelling index was showed in the range of 1.51-1.66 percentage. The equation of multiple regression revealed that there was significant interaction among factors. The glutaraldehyde concentration had a positive effect on % entrapment efficiency, % cumulative drug release and % mucoadhesion. Stirring speed showed a negative impact on % entrapment efficiency, % cumulative drug release and % mucoadhesion. The interactive effect of glutaraldehyde concentration and the stirring speed was found to be positive for % entrapment efficiency and % cumulative drug release. In vitro drug release study of optimized formulation F2 show 96 % of drug release with 6 h indicating sustained release behavior with diffusion mechanism. The SEM image of the optimized batch was spherical with a porous surface.
 Conclusion: The results obtained in this research work indicated that a promising potential of chitosan and xanthan gum combination for the preparation of the mucoadhesive microsphere of Racecadotril.

The effects of cross-linking agent and surfactant on the tear strength of novel vinyl polysiloxane impression materials

ObjectivesTo formulate experimental hydrophobic and hydrophilic vinyl polysiloxane (VPS) impression materials ab initio, comprising a novel cross-linking agent, tetra-functional (dimethylsilyl) orthosilicate (TFDMSOS), and a non-ionic surfactant, Rhodasurf CET-2 (ethoxylatedcetyl-oleyl alcohol), and to investigate their effects on tear strength (TS). MethodsFive experimental formulations (Exp I-V) were prepared and compared with three medium bodied commercial VPS impression materials (Aq M, Elt M, Extr M). Tear test was performed on trouser test specimens (n=12 per material), at four time points (immediately, 24, 72 and 168 hours after setting). FTIR spectroscopy was used for identifying functional bonds and cross-linking. The results were analysed with one-way ANOVA, two-way ANOVA and post hoc Tukey’s test using the SPSS PASW statistical 22 software. ResultsThe material with novel cross-linking agent (Exp II) had significantly higher TSs at all-time points compared to Exp I (control; p˂0.05). Materials incorporating both TFDMSOS and surfactant (Exp III, IV and V), had further significantly increased TS at all-time points, which were concentration dependent. Extr M had a significantly lower TS (immediately after setting and at 24 hours) compared to all Exp and other commercial materials, with the exception of Elt M (difference not significant). The TSs of Exp II-V, after 72 and 168 hours, were significantly higher for than all commercial products and Exp I. FTIR spectra showed the consumption of Si-H groups indicating crosslinking had taken place with the addition of TFDMSOS and surfactant which contributed to an increase in the TS. SignificanceTFDMSOS cross-linking agent increased the TS of Exp II significantly at all-time points compared to the control. Novel surfactant further significantly increased TS, and it was also concentration dependent. Exp VPS with improved TS have been developed, addressing one of the drawbacks of commercial VPS materials.

Effect of cross-linking agent on ethylene vinyl acetate/polyoctenamer modified bitumen

The objective of the present work is to investigate the combined effect of polyoctenamer polymer and a cross-linking agent (i.e. sulphur) in order to overcome the traditional deficiencies such as low elastic recovery and high-temperature storage stability in ethylene-vinyl acetate (EVA) modified bitumen. Ten test samples were prepared through the modification of asphalt with EVA in the presence of trans-polyoctenamer (TPOR) polymer and sulphur at various percentages. The physical and rheological properties, including penetration, softening point, elastic recovery, viscosity, storage stability and superpave performance of the EVA-modified asphalt were then compared to that of conventional EVA-polyoctenamer modified asphalt. It was seen from results that the storage stability of the EVA-modified asphalt was significantly improved in the presence of polyoctenamer and sulphur. The elastic recovery, dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR) and bending beam rheometer (BBR) tests reported that such modification has a substantial effect in enhancing the elastic properties and the overall rheological properties of the modified asphalt.

Effect of Crosslinking Agent and Branching Agent on Morphological and Physical Properties of Poly(Butylene succinate) Foams

To enhance a viscosity of poly(butylene succinate) (PBS), a crosslinking agent (i.e. dicumyl peroxide, DCP) or branching agent (i.e. Desmodur®N3300, N3300) was incorporated with various amount ranging from 0 to 4 phr via an internal mixer. The thermal transition, rheological properties (e.g. storage modulus, loss modulus, and complex viscosity) and gel content of the compound were determined via differential scanning calorimeter, rheometer, and gel content measurement, respectively. The results revealed that less degree of crystallinity, higher viscosity and more crosslinked structure were detected as increasing amount of DCP and N3300. Subsequently, a compression moulding technique was used to prepare PBS foam with a chemical blowing agent, i.e. azodicarbonamide (ADC). Scanning Electron Microscopy was acquired to examine cell size, cell size distribution, cell structure, and cell density. Besides, physical properties, e.g. foam density and physical appearance, were investigated. The results indicate that the degree of crystallinity, viscosity, and crosslinked structure affect the morphological and physical properties of PBS foams, i.e. greater viscosity and crosslinked structure causing obstacle for cell growth, and less degree of crystallinity allowing easier cell nucleation and cell growth.

Effect of cross-linking agent on the properties of asphalt rubber

Effect of cross-linking agent on the properties of asphalt rubber

Preparation and Anti-Fouling Property of Acryloylmorpholine-Grafted PVDF Membrane: The Effect of Cross-Linking Agent

Abstract Inspired by the hydration capability of hydrogel materials, cross-linked poly(N-acryloylmorpholine) (PACMO) chains were designed into poly(vinylidene fluoride) (PVDF) backbones to synthesize the copolymers (PVDF-g-PACMO) using the radical polymerization method. These copolymers were then cast into the porous membranes via immersion phase inversion. The effects of N,N′-methylenebisacrylamide (MBAA) in the reaction solution on the structure and performance of as-prepared copolymer membranes were evaluated by elemental analysis, X-ray photoelectronic spectroscopy, field emission scanning electron microscopy, water contact angle measurement, protein adsorption and filtration experiment. The grafting degree of PACMO increases with the increase of MBAA amount in the reaction solution, which endows the copolymer membrane with a good hydrophilicity. The protein adsorption and irreversible membrane fouling decrease and then further increase with the elevated grafting degree of PACMO. This result indicates that the anti-fouling property of membrane not only depends on the surface hydrophilicity and but also associates with the grafting structures of PACMO. This work provides a fundamental understanding of various grafting structures governing the performance of anti-fouling properties.

Theoretical design and selectivity researches on the enrofloxacin imprinted polymer

In this paper, enrofloxacin (ENRO) was chosen as the template molecule, 4-vinylpyridine (4-Vpy), acrylamide (AM), trifluoromethacrylic acid (TFMAA), and 2-hydroxyethyl methacrylate (HEMA) were selected as the functional monomers, with the following cross-linking agents, ethylene glycol dimethacrylate (EDMA), pentaerythritol triacrylate (PETA), and trimethylolpropane trimethacrylate (TRIM). The stable complex configurations formed by ENRO and four monomers at the molar ratio of 1:1 were calculated using the density functional theory at the B3LYP/6-31G(d,p) level. Their natural bond orbital charges and the action sites were discussed to screen the appropriate functional monomer. The optimal molar ratio of template–monomer complex and the effects of cross-linking agent were investigated. The nature of the imprinting interaction was also researched via the infrared spectrum. The results reveal that the complex formed from ENRO and TFMAA has the strongest hydrogen bond interaction. When the molar ratio is 1:7, the complex has the most stable configuration. Owning to the weakest interaction between EDMA and ENRO, and the strongest interaction between EDMA and TFMAA, EDMA is considered as the suitable cross-linking agent, in comparison with PETA and TRIM for ENRO-MIPs. After the removal of ENRO molecule, the most stable ENRO-TFMAA complex owing to the better binding capacity to ENRO is compared with its structural analogues (ciprofloxacin, sparfloxacin, pefloxacin, ofloxacin, and sarafloxacin). This study provides a reliable theoretical guidance for the preparation of new ENRO-MIPs.

Characterizing SBS modified asphalt with sulfur using multiple stress creep recovery test

The effect of cross-linking agent and SBS content on SBS modified asphalt were investigated using multiple stress creep recovery (MSCR) test. Nonlinear viscoelastic characterization of MSCR curve was also performed to derive nonlinear viscoelastic parameters. Cross-linking agent can prominently improve high temperature properties of SBS modified asphalt, especially at lower polymer content. The effect of increasing SBS content is more prominent for binders at lower SBS content. MSCR test failed to distinguish 5.0% and 5.5% SBS modified asphalt in this limited study. All binders modified from 3.0% to 5.5% SBS with sulfur have sufficient delayed elastic response according to AASHTO TP 70. When cross-linking agent was not used, only high dosage SBS modified binders are considered to be modified with an acceptable elastomeric polymer in this study. In addition, there is strong linear relationship between percent recovery and Jnr and such relationship is not dependent on stress level, but is concerned with test temperature. The nonlinear parameter G2 derived from MSCR curve can be used to identify the existence of cross-linking agent and characterize the elastic response of SBS modified binder. The parameter PS% shows potentiality in evaluating modified binder’s ability to resist permanent deformation. However, PS% used in this study should be further investigated to confirm the applicability for highly modified asphalt.

Improved performance of a reactive polymer-based bituminous mixes – effect of cross-linking agent

Polymer-modified bitumen (PMB) is being practiced today worldwide as pavement performance boosters for ensuring its long life under extreme conditions of load, climate, traffic density, etc. Various national and international specs on the subject recommend a series of polymer chemistries for this application, but elastomeric polymers such as styrene–butadiene–styrene (SBS) are preferred due to their certain inherent advantages. However, universally a need is felt to allow the use of different classes of polymers, to enable producers of PMBs to cut cost through wider availability of polymers. Our research studies focused on preparing a PMB formulation, based on a reactive polymer, belonging to trans-polyoctenamer group. This research study showed that the PMB produced in the lab, by blending a reactive polyoctenamer polymer along with a trace amount of sulphur as a cross-linking agent, gives excellent performance almost equivalent to SBS-based PMB. There was a noticeable improvement in the elastic recovery properties.

Effect of cross-linking agent on the properties of asphalt rubber

Cross-linking agent has recently been introduced into asphalt rubber (AR) as an additive, mainly with the goal of improving workability of this material. This study was performed to investigate the high temperature properties of AR when combined with Trans-polyoctenamer (TOR) at 0%, 3% and 6% of the weight of crumb rubber. High temperature properties were evaluated using the Dynamic Shear Rheometer (DSR) and the separation properties by Tubes in conjunction with DSR method. Results showed that (1) addition of TOR in the AR can effectively increase the G*/sin(delta) of the binders in both the original state as well as RTFO residue, with up to a 20% increase in G*/sin(delta) found for a dose of 6% TOR; (2) addition of TOR into AR can also decrease the phase angle of the binders in the original state as well as RTFO residue; up to a 1.8% decrease in phase angle was found for a dose of 6% TOR; (3) addition of the TOR can significantly decrease the separation of AR binders, as evaluated by DSR testing. An absolute difference in failure temperatures of 20% less than the control was found for a dose of 3% TOR in PG 67-22 asphalt. The influence of TOR on the separation of AR made with PG 64-22 asphalt was less than that of AR made with PG 67-22 asphalt.

Preparation and Characterization of Chitosan-Insulin-Tripolyphosphate Membrane for Controlled Drug Release: Effect of Cross Linking Agent

The term Diabetes Mellitus (DM) comprises a group of metabolic disorders characterized by chronic hyperglycemia resulting from defects in the secretion and/or action of insulin. The Insulin therapy constitutes the preferred treatment for DM, consisting of daily subcutaneous insulin injections to control blood glucose levels. The chitosan studied for Biomedicine is a biomaterial that can be used for controlled release of drugs whose release rate can be controlled by Sodium Tripolyphosphate (TPP), which is an ionic cross linker of the chitosan. Present study, therefore, was aimed to develop and evaluate membranes of chitosan and chitosan cross linked by TPP for use in controlled release of insulin system, with the purpose of obtaining an alternative to the injectable administration of this drug. The developed membranes were characterized by the techniques of Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), High Performance Liquid Chromatography (HPLC) and Evaluation of Cell Viability of Macrophages (MTT). With the FTIR technique the interaction between chitosan, tripolyphosphate and insulin was identified. Chemical elements present in chitosan, insulin and sodium tripolyphosphate membranes were detected by EDX technique. By SEM technique, the changes in the morphology of the membrane containing insulin, with the presence of granular particles of varying sizes, could be observed when compared to pure chitosan. With HPLC assay insulin was identified and it was shown that it gets separated from chitosan membrane even when the membrane was cross linked by the TPP, though at a reduced rate. The crosslinking agent was effective to control the rate of insulin release. The biocompatibility of the prepared membranes was confirmed by cell viability of macrophages using the MTT assay. The developed membranes, therefore, have potential for use as a biomaterial in controlled release systems for insulin.

Synthesis of Hexadecyl Methacrylate/Methyl Methacrylate Copolymer by High Internal Phase Emulsion Template and its High Oil-Absorbing Properties

Emulsion templating of high internal phase emulsion was used to synthesize high oil-absorption resins with hexadecyl methacrylate and methyl methacrylate as monomers. Effects of cross-linking agent, emulsifier, initiator and porogen, polymerization temperature, polymerization time, the water/oil volume ratio, and the dosage of co-monomer on the properties of high oil-absorption resins were discussed. The optimum polymerization conditions for synthesis of high oil-absorbing resin were obtained. The highest oil absorbency in trichloromethane was 34 g/g. The oil absorbency of the resin remained constant after three times recovery.

Characterization and in vitro and in vivo evaluation of cross-linked chitosan films as implant for controlled release of citalopram

The aim of the present study is to develop cross-linked chitosan (CH) films that can release drug over an extended period of time and that too in a controlled manner. A solution of different percentages of CH, is prepared in 1% lactic acid, followed by addition of citalopram (CTP) and then reacted with increasing amounts of glutaraldehyde (GL) to obtain films with different cross-linking densities. Prepared films are characterized for their physical and mechanical properties. The films are then subjected to in vitro drug release studies using pH 7·4 phosphate buffer saline (PBS) as dissolution medium and cumulative amount of drug released is calculated. Kinetic analysis of drug release is performed using Power law model and Higuchi’s model. With increase in concentration of CH, water absorption capacity and mechanical strength are increased; whereas, water vapour permeability and elasticity of the films are decreased. The effect of cross-linking agent, GL, is such that with an increase in the amount of GL, water vapour permeability, water absorption capacity and elasticity of the films are decreased; whereas, mechanical strength increased to some extent and then decreased. In vitro release studies indicate that films containing 3% CH, cross-linked with 2–3% GL and films containing 4% CH, cross-linked 1% GL are able to sustain the drug release for a prolonged time along with releasing almost complete drug in a desired period. Out of these batches, films containing 3% CH, cross-linked with 2–3% GL are having sufficient strength, water vapour permeation, water absorption capacity and elongation at break for implantation purpose. The in vitro degradation studies and histopathological studies were carried out with a sample film (batch C3 as in table 1) in rabbit model. In vitro degradation study indicates that the films maintained their integrity for desired implantation. The histopathological studies under optical microscope indicates that on implanting, there is no evidence of any inflammation, any foreign body granuloma or any necrosis or hemorrhage. Tissue configuration remains unaltered after 30 days of implantation. So, it can be suggested that cross-linked CH films of above said composition can be used as implant for long term application in depression and related disorders.