Pulp and paper
Mostafa Khaje-mahmouid; Mehrnaz Azadi boyaghchi; Mohsen Mohammadi achachlui; majid ghahramanafshar
Abstract
Background and objectives: Paper bleaching is a concern of many conservationists. Research has been conducted with the aim of evaluating some traditional bleaching materials used in the preservation of documents and books, such as hydrogen peroxide and sodium borohydride, which shows that these materials ...
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Background and objectives: Paper bleaching is a concern of many conservationists. Research has been conducted with the aim of evaluating some traditional bleaching materials used in the preservation of documents and books, such as hydrogen peroxide and sodium borohydride, which shows that these materials do not significantly improve the mechanical properties of historical papers. Also, investigating the effect of reducing agents on oxidized papers has shown the effectiveness of tert-butylamine borane complex. In another study, five dyeing processes with oxidizers (calcium hypochlorite, hydrogen peroxide in two concentrations, light bleaching and potassium permanganate) and two dyeing processes with reducing agents (sodium borohydride and tert-butylamine borane) were compared. And their effect on pure cellulose (Whatman filter paper) and two different historical papers have been investigated. The results indicate that all the tested dye removal methods have led to a clear increase. Due to the differences of opinion, in this research, the effectiveness of two reducing agents sodium borohydride and sodium dithionite on the appearance and structural characteristics of paper is investigated.Methodology: In this research, Whatman Filter Paper No. 1 (Whatman Filter Paper No. 1) made in England with a thickness of 180 microns, a diameter of 11 cm, a base weight of 87 grams per square meter and an ash percentage of 0.06% was used. Chemical reagents including potassium persulfate, sodium borohydride and sodium dithionite in the highest purity were prepared in a laboratory from Merck, Germany.Three solutions including potassium persulfate (2% by weight/volume), sodium borohydride (1% by weight/volume), sodium dithionite (1% by weight/volume) in distilled water (distilled water, pH; 7), to perform tests on zinc. Paper samples have been used by immersion.Whatman filter paper samples were subjected to oxidation in 2% peta persulfate in distilled water for 2 days (48 hours) and then the samples were immersed. Next, the identified samples were modified by two solutions of sodium borohydride and sodium dithionite 1% in distilled water for 1 to 5 hours and then purified in holy water. Also, the samples were subjected to accelerated aging according to ASTM standard number D4714-96 at a temperature of 90±2 centigrade and a relative humidity of 50±2% for 384 hours. Test methods include potentiostat, colorimetry, tensile strength, pH measurement, scanning electron microscope and infrared examination.Results: The results show that potassium persulfate is the most neutralizing solution among the three solutions used on the first day, and it also indicates the reducing power of two solutions of sodium dithionite and sodium borohydride, which according to the test results, sodium borohydride is the reducing power. Compared to sodium dithionite. The sample prepared with pH 92.3, after accelerated aging, was accompanied by an increase of several units of pH after modification with two reducing substances. Examining the data obtained from the tensile strength test shows that in comparison with the tested samples with a tensile index of 1.06, the samples modified with sodium borohydride and sodium dithionite increased the index in all five modified periods. Tensile of paper samples. The infrared spectrometry investigation of the samples modified with sodium borohydride and sodium dithione shows that this old material improves the structure of cellulose after aging by reviving the C=O bonds to C-O and reducing the area of 1640 cm-1. Accelerated. The reduction of the absorption band in the region of 1640 cm-1 has been opened in almost all time cases with this material compared to the modified sample. Based on the data, samples modified with sodium borohydride and sodium dithionite had a significant increase (approximately 25 units) in the L-factor (light-darkness) after aging, indicating that two substances have increased the brightness of the sample by reviving the color compounds. In the microscopic examination of the surface of the fibers, in the samples identified with potassium persulfate, local separation of the fibers is observed. In the samples modified with sodium borohydride and sodium dithionite, fibers with higher consistency and entanglement are observed.Conclusion: Double bonds and carbon groups in paper samples formed with potassium persulfate have been the main responsible for the yellowness and darkness of the paper, the reducing agents sodium borohydride and sodium dithionite reduce this aldehyde and ketone to hydrocarbon and as a result. With the loss of multiple conjugates, the light absorption of the paper is reduced and this causes the paper to lighten. The double bonds and their regeneration also cause rearrangement of the chain cells, which has resulted in increasing the mechanical resistance and strength of the paper samples.
Kobra Dadmohamadi; Mohsen Mohammadi Achachluei; Mohammad taghi Jafari
Abstract
The aim of this study was to evaluate the effect of cellulose nanofiber treatment on discoloration of historical papers. In this study, two types of cellulose nanofiber suspensions with a concentration of 1% by weight with water and ethanol were prepared. After treatment, the prepared samples were subjected ...
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The aim of this study was to evaluate the effect of cellulose nanofiber treatment on discoloration of historical papers. In this study, two types of cellulose nanofiber suspensions with a concentration of 1% by weight with water and ethanol were prepared. After treatment, the prepared samples were subjected to moist-heat aging according to TAPPI T 544 sp-03 standard and colorimetric, pH, ATR-FTIR spectroscopy and SEM microscopy were performed before and after aging. Examination of ATR-FTIR spectra obtained from the samples showed that the application of cellulose nanofiber treatment does not cause damage to the paper structure. After application of two treatments with cellulose nanofibers, the color of the samples became brighter, but after accelerated aging, the brightness of the samples decreased.The darkening of the color of the samples was caused by their exposure to accelerated aging conditions and the treatment of cellulose nanofibers did not cause discoloration. The pH of the samples increased after application of both types of cellulose nanofiber treatments, but after accelerated aging, the pH decreased slightly.
kobra dadmohamadi; Mohsen Mohammadi; Mohammad taghi Jafrai
Abstract
In this study, the effect of cellulose nanofibers on the properties of handmade papers produced from hemp and wood pulp fibers was assessed. Also, the nanofiber application as a strength enhancer for restoration of handmade papers was investigated. Firstly, handmade paper samples were prepared. Cellulose ...
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In this study, the effect of cellulose nanofibers on the properties of handmade papers produced from hemp and wood pulp fibers was assessed. Also, the nanofiber application as a strength enhancer for restoration of handmade papers was investigated. Firstly, handmade paper samples were prepared. Cellulose nanofibers with weight percentages of 0.5, 1 and 2% were prepared as a suspension in water the samples were treated by the suspensions. Blank and treated samples were tolerated accelerated aging process and then pH, colorimetric and tensile strength tests were performed. Comparison of blank and treated samples results showed that the tensile strength of the both groups of hemp (H) and wood pulp (WP) papers were increased after treatment by cellulose nanofibers. Aging process caused to reduction in tensile strength of treated samples but it was increased in comparison with blank samples before and after aging. The pH of the papers in both groups was in the alkaline range after the treatment and aging. Brightness of papers was increased after the treatment and color changes in the samples were due to their accelerated aging conditions.
kobra dadmohamadi; Mohsen Mohammadi; mohammad taghi jafari
Abstract
Surface sizing of historical papers by starch sizing was performed with the aim of investigating the effect of this material on the aesthetic and mechanical properties of historical papers. For this purpose, starch sizing with a weight concentration of 3% were used and pH, colorimetric, angle of contact ...
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Surface sizing of historical papers by starch sizing was performed with the aim of investigating the effect of this material on the aesthetic and mechanical properties of historical papers. For this purpose, starch sizing with a weight concentration of 3% were used and pH, colorimetric, angle of contact and tensile strength tests were performed before and after aging of the samples. The results showed that the pH of samples non-sizing and samples containing starch sizing decreased after aging but it is still in the alkaline range. The brightness of the samples was slightly reduced after sizing with starch before and after aging and the color of the samples tends to darken. Tensile strength of paper samples containing starch sizing before and after aging increased compared to samples non-sizing. The results of measuring the angle of contact also showed that starch sizing no effect on increasing the resistance of paper to wetting and does not prevent the surface of the paper from getting wet.
Management and Economics wood
mahboob abdolalizadeh; mehrnaz azadi boyaghchi; mohammad mohammadypour; mohsen mohammadi achachluei
Abstract
Paper works are more attacked by biological agents such as fungi, bacteria and insects due to its organic nature. In archives, most of the biological destruction of paper is related to fungi. The importance of paper works conservation has led to applying different methods to fungus removal. ...
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Paper works are more attacked by biological agents such as fungi, bacteria and insects due to its organic nature. In archives, most of the biological destruction of paper is related to fungi. The importance of paper works conservation has led to applying different methods to fungus removal. The chemical disinfection is of of the most common disinfection methods. In this research, the application of Thiophanate methyl in paper destructive fungi has been studied. Laboratory studies to evaluate the effects of Thiophanate methyl on paper and fungus include accelerated ageing, the evaluation of effectiveness of antifungal Thiophanate methyl on fungi such as Aspergillusniger, Aspergillusflavus and Penicilliurnsp and determination of antifungal stability after accelerated ageing. Examination shows that Thiophanate methyl has successfully prevented spread of fungus in all density of 10, 50, 100,200 and 500 ppm. Aspergillus flavus fungus had a slight growth at 10 ppm, but no growth were observed in other density. Aspergillusniger fungus had no growth capacity in density more than 100 ppm. According to the results, treated papers are still able to control fungus growth after being in accelerated ageing condition. In general, the results obtained by fungus growth halo and non-growth halo indicate that all fungi are controllable in density of 200 ppm.
