July 2018 Pub Date : 2018-08-01 DOI: 10.32964/TJ17.07.395

M. Rice, Lokendra Pal, Ronalds Gonzalez, M. Hubbe

{"title":"Wet-end addition of nanofibrillated cellulose pretreated with cationic starch to achieve paper strength with less refining and higher bulk","authors":"M. Rice, Lokendra Pal, Ronalds Gonzalez, M. Hubbe","doi":"10.32964/TJ17.07.395","DOIUrl":"https://doi.org/10.32964/TJ17.07.395","url":null,"abstract":"Nanofibrillated cellulose (NFC) treated with cationic starch was evaluated as a bonding system to permit lower degrees of refining and lower apparent density of high-mass handsheets made from bleached kraft pulp. Mixed pulp (70% hardwood, 30% softwood) was formed into sheets with the optional addition of 5% by dry mass of NFC. The default addition of NFC was compared with a system in which the NFC had been pretreated either with cationic starch (at various levels) or optionally followed by colloidal silica. Comparative tests also were carried out with separate addition of cationic starch to the main furnish. Unrefined fibers (514 mL CSF) were compared with low-refined (473 mL CSF) and high-refined (283 mL CSF) pulp mixtures. The NFC that had been pretreated with cationic starch at a high level was especially effective at boosting the tensile strength and stiffness of sheets prepared from pulp that had been refined at a low level, thus achieving improved strength at relatively low apparent density (high bulk) of the handsheets. The results support a strategy, for applicable grades of paper, of using cationic starchpretreated NFC in place of refining energy applied to the main fiber furnish. It was further established that colloidal silica can be employed as a further pretreatment of the cationic starch–treated NFC as a means of promoting dewatering in the combined system.","PeriodicalId":319984,"journal":{"name":"July 2018","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134279474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 16

Effect of pH and enzymes on strength of recycled fibers during refining pH和酶对再生纤维精制强度的影响

July 2018 Pub Date : 2018-08-01 DOI: 10.32964/TJ17.07.407

Ashoka Ghosh, Breland T. E. Thornton, P. Hart

引用次数: 2

Effects of lignin chemistry on oxygen delignification performance 木质素化学对氧脱木质素性能的影响

July 2018 Pub Date : 2018-08-01 DOI: 10.32964/TJ17.07.373

Valéria J. Gomes, H. Jameel, Hou‐min Chang, R. Narron, J. Colodette, P. Hart

{"title":"Effects of lignin chemistry on oxygen delignification performance","authors":"Valéria J. Gomes, H. Jameel, Hou‐min Chang, R. Narron, J. Colodette, P. Hart","doi":"10.32964/TJ17.07.373","DOIUrl":"https://doi.org/10.32964/TJ17.07.373","url":null,"abstract":"The present work focused on characterizing the chemical and structural properties of isolated lignin from six hardwoods and their kraft pulps in an attempt to better understand the relationship between lignin’s chemical properties and resultant oxygen delignification performance. Several hardwood samples were cooked under the same conditions with varying alkali charges to obtain unbleached pulps with kappa numbers between 19 and 20. These pulps were then subjected to an oxygen delignification stage. Both processes were evaluated for pulp quality, residual lignin, and O-stage delignification efficiency. The oxygen delignification stage was carried out under fixed conditions and evaluated with regards to kappa number, which was corrected for hexenuronic acid (HexA) contributions.Results revealed that different hardwood species exhibited differing oxygen delignification efficiencies. A high correlation was found between the O-stage delignification efficiency and the content of phenolic groups in the unbleached lignin, which confirmed that free phenolic groups are the reactive site for molecular oxygen attack. When different hardwood species were compared, the HexA contents were not found to affect O-stage delignification efficiencies.","PeriodicalId":319984,"journal":{"name":"July 2018","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134551081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Influence of tensile straining and fibril angle on the stiffness and strength of previously dried kraft pulp fibers 拉伸应变和纤维角对预干燥硫酸盐浆纤维刚度和强度的影响

July 2018 Pub Date : 2018-07-01 DOI: 10.32964/TJ17.07.383

John Long, W. Batchelor

{"title":"Influence of tensile straining and fibril angle on the stiffness and strength of previously dried kraft pulp fibers","authors":"John Long, W. Batchelor","doi":"10.32964/TJ17.07.383","DOIUrl":"https://doi.org/10.32964/TJ17.07.383","url":null,"abstract":"It has long been known that in individual wood fibers, the tensile mechanical properties are heavily determined by the nature of the cellulose chains in the fibers. Both elastic tensile modulus and strength are directly related to the fibril angle, which is the steepness with which the cellulose chains wind their way around the fiber in the secondary wall of the middle layer, named the S2 layer. Classic work from the 1970s measured modulus and strength in wood fibers as a function of the fibril angle and compared the results with theoretical models. The measurements were hampered by the presence of defects in the fibers, some which occurred naturally and others which resulted from pulp processing. In this study, we performed more accurate measurements of strength and modulus in single fibers of radiata pine by loading the fibers in cycles, gradually pulling some of the defects out of the fibers in an attempt to obtain defect-free values of modulus and strength. We then plotted these properties against measured fibril angle and compared our results with theoretical models. The results show that even when the fiber had reached maximum load before fracture, at a given value of fibril angle, it still had a measured modulus that is around half the theoretically expected value. The results suggest that the load required to fully remove defects from the fibers may be larger than the fibers can bear before fracturing.","PeriodicalId":319984,"journal":{"name":"July 2018","volume":"121 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121771256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

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