Pré-tratamento com hidróxido de cálcio e carbonatação acelerada para fibrilação da polpa celulósica e aplicação das nanofibrilas no revestimento de papéis

Abstract

The objective of this work was to evaluate the effect of accelerated carbonation performed after application of different concentrations of calcium hydroxide (Ca(OH)2) as a prétreatment for fibrillation of cellulosic pulps in intention to obtain cellulose nanofibrils (CNF), besides to evaluate the properties of papers coated with the carbonated nanofibrils produced. Commercial pulps of pine (PIN) and eucalyptus (EUC) were pré-treated with Ca(OH)2, and subjected to accelerated carbonation, before being mechanically fibrillated for production of CNF. The work was divided into 2 manuscripts. In the first manuscript, energy consumption, degree of fibrillation, and formation of calcium carbonate were evaluated in the end of the process for the pulps in conditions treated and untreated. In the second manuscript, the CNF produced were applied as coating for sack Kraft papers, and the proprierties: water absorption, water vapor permeability (WVP), grease resistance, surface hardnes, contact angle and wettabillity were analyzed. Pre-treatment and accelerated carbonation were effective for production CNF with 35% of reduction in energy consumption during mechanical fibrilation. FTIR and light microscopy confirmed the formation of CaCO3 after the accelerated carbonation. The presence of CaCO3 in the suspensions increased the thermal stability, turbidity, and sedimentation of the CNF. Improvements were observed on grease resistance, water absorption and surface hardness of the papers coated with CNF subjected to accelerated carbonation. On the hand, proprierties as contact angle and wettability, as well as mechanical strength and WVP did not present significant improvements with the and accelerated carbonation. In this way, accelerated carbonation can be considered na alternative for the production of NFC by mechanical fibrilation, and also used to improve certain of multilayer papers.