Use of electron beam irradiation for improving reactivity of dissolving pulp in viscose process

Gondhalekar, Sachin C.; Pawar, Pravin; Dhumal, Sunil S.

doi:10.1007/s10967-019-06563-0

Cited by 6 publications

(7 citation statements)

References 19 publications

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“…These radicals can also lead to additional fragmentation of the polymer chain. Many studies have been conducted on the irradiation of natural polysaccharides and their derivatives in the sold state including cellulose and its derivatives [360,[364][365][366][367][368][369][370][371][372][373][374][375][376][377][378][379][380][381], chitin and chitosan [382][383][384][385][386][387][388], starch [389,390], alginate [391,392], pectin [393,394], and dextran [395,396] to name a few. It should be noted that polysaccharides are hydroscopic and absorbed moisture can affect the radiation chemistry [397].…”

Section: Sold State Irradiationmentioning

confidence: 99%

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Polymerization Reactions and Modifications of Polymers by Ionizing Radiation

et al. 2020

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Ionizing radiation has become the most effective way to modify natural and synthetic polymers through crosslinking, degradation, and graft polymerization. This review will include an in-depth analysis of radiation chemistry mechanisms and the kinetics of the radiation-induced C-centered free radical, anion, and cation polymerization, and grafting. It also presents sections on radiation modifications of synthetic and natural polymers. For decades, low linear energy transfer (LLET) ionizing radiation, such as gamma rays, X-rays, and up to 10 MeV electron beams, has been the primary tool to produce many products through polymerization reactions. Photons and electrons interaction with polymers display various mechanisms. While the interactions of gamma ray and X-ray photons are mainly through the photoelectric effect, Compton scattering, and pair-production, the interactions of the high-energy electrons take place through coulombic interactions. Despite the type of radiation used on materials, photons or high energy electrons, in both cases ions and electrons are produced. The interactions between electrons and monomers takes place within less than a nanosecond. Depending on the dose rate (dose is defined as the absorbed radiation energy per unit mass), the kinetic chain length of the propagation can be controlled, hence allowing for some control over the degree of polymerization. When polymers are submitted to high-energy radiation in the bulk, contrasting behaviors are observed with a dominant effect of cross-linking or chain scission, depending on the chemical nature and physical characteristics of the material. Polymers in solution are subject to indirect effects resulting from the radiolysis of the medium. Likewise, for radiation-induced polymerization, depending on the dose rate, the free radicals generated on polymer chains can undergo various reactions, such as inter/intramolecular combination or inter/intramolecular disproportionation, b-scission. These reactions lead to structural or functional polymer modifications. In the presence of oxygen, playing on irradiation dose-rates, one can favor crosslinking reactions or promotes degradations through oxidations. The competition between the crosslinking reactions of C-centered free radicals and their reactions with oxygen is described through fundamental mechanism formalisms. The fundamentals of polymerization reactions are herein presented to meet industrial needs for various polymer materials produced or degraded by irradiation. Notably, the medical and industrial applications of polymers are endless and thus it is vital to investigate the effects of sterilization dose and dose rate on various polymers and copolymers with different molecular structures and morphologies. The presence or absence of various functional groups, degree of crystallinity, irradiation temperature, etc. all greatly affect the radiation chemistry of the irradiated polymers. Over the past decade, grafting new chemical functionalities on solid polymers by radiation-induced polymerization (also called RIG for Radiation-Induced Grafting) has been widely exploited to develop innovative materials in coherence with actual societal expectations. These novel materials respond not only to health emergencies but also to carbon-free energy needs (e.g., hydrogen fuel cells, piezoelectricity, etc.) and environmental concerns with the development of numerous specific adsorbents of chemical hazards and pollutants. The modification of polymers through RIG is durable as it covalently bonds the functional monomers. As radiation penetration depths can be varied, this technique can be used to modify polymer surface or bulk. The many parameters influencing RIG that control the yield of the grafting process are discussed in this review. These include monomer reactivity, irradiation dose, solvent, presence of inhibitor of homopolymerization, grafting temperature, etc. Today, the general knowledge of RIG can be applied to any solid polymer and may predict, to some extent, the grafting location. A special focus is on how ionizing radiation sources (ion and electron beams, UVs) may be chosen or mixed to combine both solid polymer nanostructuration and RIG. LLET ionizing radiation has also been extensively used to synthesize hydrogel and nanogel for drug delivery systems and other advanced applications. In particular, nanogels can either be produced by radiation-induced polymerization and simultaneous crosslinking of hydrophilic monomers in “nanocompartments”, i.e., within the aqueous phase of inverse micelles, or by intramolecular crosslinking of suitable water-soluble polymers. The radiolytically produced oxidizing species from water, •OH radicals, can easily abstract H-atoms from the backbone of the dissolved polymers (or can add to the unsaturated bonds) leading to the formation of C-centered radicals. These C-centered free radicals can undergo two main competitive reactions; intramolecular and intermolecular crosslinking. When produced by electron beam irradiation, higher temperatures, dose rates within the pulse, and pulse repetition rates favour intramolecular crosslinking over intermolecular crosslinking, thus enabling a better control of particle size and size distribution. For other water-soluble biopolymers such as polysaccharides, proteins, DNA and RNA, the abstraction of H atoms or the addition to the unsaturation by •OH can lead to the direct scission of the backbone, double, or single strand breaks of these polymers.

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Section: Sold State Irradiationmentioning

confidence: 99%

“…This crosslinking is dependent on degree and type of substitution and at higher dose hydrogels can be formed [375][376][377]408,409]. Other polysaccharides have also been studied including substituted chitin and chitosan, and gum arabic [382,410,411].…”

Section: Radiation Crosslinking Of Polysaccharidesmentioning

confidence: 99%

Polymerization Reactions and Modifications of Polymers by Ionizing Radiation

et al. 2020

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“…CS2 consumption was calculated using Fock reactivity, α-cellulose content and the stoichiometric value required for the xanthation phase which is 23.5 % (expressed in g CS2 per 100 g of cellulose) (Arce et al, 2020;Gondhalekar et al, 2019a). Considering Fock's reactivity as a reaction yield of xanthation, and the α-cellulose content of the pulp, the theoretical quantity of fibres (TF) is obtained using equation 2.…”

Section: Cs2 Consumption Calculationmentioning

confidence: 99%

“…This decrease was produced by the diminution of the amorphous and crystalline regions, as proposed by Kumar et al (2016), who found a decrease in the CrI of rice straw when treated by ChCl:LA system. Gondhalekar et al (2019a), proposed that the reduction of crystallinity is caused by the weakening of the hydrogen bonding (Gondhalekar et al 2019a). Procentese et al (2015) found a slight decrease, as well, in the crystallinity index of corncob when treated with ChCl:Urea system (Procentese et al 2015).…”

Section: Xrd Spectra and Effect On Crystallinity Indexmentioning

confidence: 99%

Use of green solvents as pre-treatment of dissolving pulp to decrease CS2 consumption from viscose production

et al. 2020

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Choline chloride-based deep eutectic solvents are widely used in biomass processing. In this work, four different green solvent mixtures were used as pre-treatment of acid sulphite dissolving pulp with the hypothesis of increasing the possibilities to produce viscose fibres and decreasing the use of the harmful and toxic carbon disulphide in the process. The experiments were performed at two different pulp to solvent mass ratios. Pulp quality parameters were also measured to determine the suitability of the pre-treatment: α-cellulose, viscosity, lignin and pentosan content. In addition, X-ray diffraction analysis of pulps at the best solid to liquid ratio was performed to obtain the influence of the crystallinity index. Best results were obtained with the use of lactic acid, with reactivity values close to 94 %, giving a reduction of CS2 usage of 15.83 %. Furthermore, a linear relationship between the crystallinity index calculated by the XRD and reactivity with a regression factor of 0.87 was found.

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“…4,5,16 In addition to cleaving chains, EBI breaks up rigid crystalline cellulose regions via internal attacks, thus increasing the pulp's reactivity to derivatization. 17 Cellulose dissolution and the filterability of the rayon spinning dope are better than conventional preparation. 14 When studying the irradiation of pulp, the underlying radical mechanism must be taken into account.…”

Section: ■ Introductionmentioning

confidence: 99%

Tailoring Pulp Cellulose with Electron Beam Irradiation: Effects of Lignin and Hemicellulose

Sarosi

Bischof

Potthast

2020

ACS Sustainable Chem. Eng.

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Electron beam irradiation (EBI), which is applied industrially for sterilization of goods and cross-linking of synthetic polymers, can also be used for dissolving cellulose pulp production or whenever a reduction or an alignment of molecular mass of cellulose is needed. There is limited information about the differential performance of cellulose pulps produced by either kraft or sulfite pulping after EBI. In this study, special focus was placed on the ability of hemicellulose and lignin in kraft and sulfite pulps to protect cellulose from glycosidic chain scission and oxidation. In total, four hardwood paper and dissolving pulps with different hemicellulose and lignin contents were treated with EBI at an energy of 10 MeV and increasing doses of 0–100 kGy. Changes in the samples’ molecular weight distribution and oxidation levels were analyzed by gel permeation chromatography and fluorescence labeling of carbonyl groups. Degradation efficiency was highest at low doses, and EBI showed homogeneous cellulose degradation. Analysis of carbohydrates leached from the pulp revealed preferential dissolution of polymeric hemicellulose fragments, correlating their presence to cellulose protection from chain scissions. Lignosulfonates were found to protect cellulose from both chain scission and oxidation but, controversially, kraft lignin was found to accelerate cellulose chain scission.

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Use of electron beam irradiation for improving reactivity of dissolving pulp in viscose process

Cited by 6 publications

References 19 publications

Polymerization Reactions and Modifications of Polymers by Ionizing Radiation

Polymerization Reactions and Modifications of Polymers by Ionizing Radiation

Use of green solvents as pre-treatment of dissolving pulp to decrease CS2 consumption from viscose production

Tailoring Pulp Cellulose with Electron Beam Irradiation: Effects of Lignin and Hemicellulose

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