بررسي امكان ساخت كاغذ بادوام با استفاده از خمير وارداتي اكاليپتوس

Investigation on possibility of making durable paper with imported Eucalyptus pulp

Permanent or durable paper is a kind of paper that has a high degree of permanenee and is likely to retain the properties which influence readability and document handling when storing in a protected environment for a long period. Permanence depends mainly on the chemical stability of the paper itself. Stability may be impaired by chemieal reactions involving the paperʹs own components and by reactive agents from the environment and human being i.e., from air or filing enclosures. Poor chemical stability produces a chain reaction whieh in long term storage has a pronounced adverse effect on the mechanical or optical properties of the document. The main reactions causing mechanical deterioration are acid hydrolysis and oxidation . Yellowing is due to photochemical and thermal processes. Whatever the fibers used to make paper are longer, alkaline paper making is used, cationic elements such as Fe+2 , Fe+), Cu+2 , Mn+2 and kappa number of pulp are minor, it is expected that the paper made is more permanent .In this research imported bleached Eucalyptus kraft pulp was used. The used pulp was refined according to tappi test method 1ʹ248 cm-85 with PFI mill to reach freeness (30005) CSF at number of beating revolutions 12000 .Hand sheets were made aecording to SCAN C25-65 standard with grammage 70gr I .AKD 1m2 sizing were used2% oven dry weight of pulp and EDTAas chelating agent was used in concentrations 0, 0.25 , 0.5 , 0.75 pereent. For more assurance deionized water was used. furthermore, 20% ealeium carbonate was used as residual alkaline and filler. Then hand sheets were laid under U.V radiation with wavelengths between 330 to 440 nm in 0,10, 20, 30, 40 and 50 hours interval and were eonditioned in controlled temperature and relative humidity. pH of Extractivesolutions were adjusted between 7 to 7.5 . At last, each strength indices were measured with three measurement frequencies and to eompare the amount of mean strengths of produced handsheets, variation analysis (ANOVA) and Duncan test were used with SPSS software and the charts were drawn with Excel software. Variables (times of conditioning and EDTA concentrations) has significant effect on breaking length, and time of conditioning is strictly obvious. Conditioning lime has significant effect on breaking length, lear resistance, folding endurance and burst strength. Inerease of chelating agent (EDTA) concentration has signifieant effect on tear resistance, folding endurance, burst and tensile strength. Increase of radiation time on hand sheets eauses decrease of tensile strength that is significant.