Ultrasonic degradation of water-soluble polymers

Koda, Shinobu; Mori, Hidefumi; Matsumoto, Katsuyuki; Nomura, Hiroyasu

doi:10.1016/0032-3861(94)90045-0

Cited by 101 publications

(51 citation statements)

References 5 publications

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“…The data in Figure 3 show that molecular weight of 0.2, 0.8, 1.4, and 2.0% chitosan decreased over time during the mechanical shearing for those either with or without concurrent UF treatment to remove the degraded small fragments at 0, 30, and 50 C. Similar degradation patterns have been reported in the literature regarding chitosan, 13,16,18 pullulan, 37 agarose, j-carrageenan, and i-carrageenan.…”

Section: Effect Of Reaction Timesupporting

confidence: 81%

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Facile method to manipulate the molecular weight and practical mass production of chitosan by mechanical shearing and concurrent ultrafiltration treatment

Tsai

Tseng

Chang

et al. 2010

J of Applied Polymer Sci

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The objective of this study was to propose a facile method to manipulate the molecular weight and practical mass production of chitosan by mechanical shearing and concurrent ultrafiltration (UF) treatment. The proposed method was based on the degradation rate and rate constant of various process variables, such as: solution temperature, reaction time, concentration of chitosan solution, with or without concurrent removal of degraded fragments during mechanical shearing. The result obtained was that the degradation rate constant was 1.8-6.0 times higher for those using UF to remove smaller degraded molecules concurrently during treatment, than that without UF treatment. The degradation rate constant increased with increasing solution temperature; however, the solution temperature should not exceed than 50 C to prevent the undesired color changes of the resulting product. A method combining mechanical shearing/UF treatment at 50 C and ultrasonic radiation or microfluidization/UF treatment at 30 C is proposed here for a facile method to manipulate the molecular weight of the resultant chitosan with an energy saving, efficient and practical mass production.

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Section: Effect Of Reaction Timesupporting

confidence: 81%

“…Decreases in degradation rate and rate constant along with degradation time have been reported in many polysaccharides, such as chitosan, 12,16 pullulan, 37 agarose, j-carrageenan and i-carrageenan.…”

mentioning

confidence: 95%

Facile method to manipulate the molecular weight and practical mass production of chitosan by mechanical shearing and concurrent ultrafiltration treatment

Tsai

Tseng

Chang

et al. 2010

J of Applied Polymer Sci

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show abstract

“…Besides, the same group reported another type of copolymer with high mechanophore content, polyester-acrylate ABA block copolymers with gDCCs in the middle block [90]. The ABA triblock architecture ensures a mechanophore-rich region near the center of the chain facilitating the selective activation near the midpoint by sonication [91][92][93]. Concurrently, Moore and co-workers designed a new mechanophore based on a gem-dichlorocyclopropanated indene which is able to release hydrochloride under mechanical stress [94].…”

Section: Mechanical Activation Of Microcyclesmentioning

confidence: 94%

Molecular Mechanochemistry: Engineering and Implications of Inherently Strained Architectures

Sheiko

2015

Topics in Current Chemistry

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Mechanical activation of chemical bonds is usually achieved by applying external forces. However, nearly all molecules exhibit inherent strain of their chemical bonds and angles as a result of constraints imposed by covalent bonding and interactions with the surrounding environment. Particularly strong deformation of bonds and angles is observed in hyperbranched macromolecules caused by steric repulsion of densely grafted polymer branches. In addition to the tension amplification, macromolecular architecture allows for accurate control of strain distribution, which enables focusing of the internal mechanical tension to specific chemical bonds and angles. As such, chemically identical bonds in self-strained macromolecules become physically distinct because the difference in bond tension leads to the corresponding difference in the electronic structure and chemical reactivity of individual bonds within the same macromolecule. In this review, we outline different approaches to the design of strained macromolecules along with physical principles of tension management, including generation, amplification, and focusing of mechanical tension at specific chemical bonds.

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“…Ultrasonic treatment for depolymerization has been considered on a variety of homo-and hetero-polysaccharides such as dextran [95], pullulan [96], chitosan [97], hyaluronic acid [98], xyloglucan [99] and starch [100]. Ultrasound irradiation can cause rupturing and mechanical damage in the starch granules by collapse of bubbles, which in turn generates the shear forces capable in breaking the polymers chains.…”

Section: Depolymerizationmentioning

confidence: 99%

Ultrasound irradiation in the production of ethanol from biomass

Karimi

Jenkins

Stroeve

2014

Renewable and Sustainable Energy Reviews

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a b s t r a c tEthanol produced from renewable biomass, such as lignocellulosic feedstock, is one of the alternative energy resources that can be environmentally friendly. However, physical and chemical barriers caused by the close association of the main components of lignocellulosic biomass, as well as starch, hinder the hydrolysis of cellulose and hemicellulose in lignocellulose as well as amylase and amylopectin in starch to fermentable sugars. One of the main goals of pretreatment for enzymatic hydrolysis is to increase the enzyme accessibility for improving digestibility of cellulose and starch. Ultrasound irradiation applied to cellulosic materials and starch-based feedstock was found to enhance the efficiency of hydrolysis and subsequently increase the sugar yield. Prior research conducted on applying ultrasonic technology for cellulose and starch pretreatment has considered a variety of effects on physical and chemical characteristics, hydrolysis efficiency and ethanol yield. This paper reviews the application of ultrasound irradiation to cellulose and starch prior to and during hydrolysis in terms of sugar and ethanol yields. It also addresses characteristics such as accessibility, crystallinity, degree of polymerization, morphological structure, swelling power, particle size and viscosity as influenced by ultrasonic treatment.

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Ultrasonic degradation of water-soluble polymers

Cited by 101 publications

References 5 publications

Facile method to manipulate the molecular weight and practical mass production of chitosan by mechanical shearing and concurrent ultrafiltration treatment

Facile method to manipulate the molecular weight and practical mass production of chitosan by mechanical shearing and concurrent ultrafiltration treatment

Molecular Mechanochemistry: Engineering and Implications of Inherently Strained Architectures

Ultrasound irradiation in the production of ethanol from biomass

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