Polymers 2020 , 12 , 173
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2. Materials and Methods
2.1. Materials All the reagents used in this research (U.S.P grade) were obtained from Sigma-Aldrich (Palo Alto, CA, USA) and used without further purification unless otherwise stated. 2.2. Synthesis of the Polyamine Resin Polycoat 38 ® Polycoat 38 ® , which is a polyamine obtained by the A. Allen modified method [15], uses a difunctional polyamine or diamine with epichlorohydrin for the polymer synthesis with the addition of polyvinyl alcohol between 25–60 ◦ C, and it is advantageous providing strong adhesion of the cellulosic fiber web to the dryer surface during the creping process to attain a soft, bulky tissue paper web [15,16]. The diamine was placed in a 100 kg industrial pilot reactor with double jacket coupled to a steam and a water recirculatory ice bank (Disproquin S.A.S., Candelaria, Colombia). Aqueduct water was added to the pilot in order to reach 38 wt % solids. It was then heated to 50 ◦ C and stirred. A sample of 8.50 kg of epichlorohydrin were slowly added at room temperature with agitation. The exothermic reaction reached a temperature of 150 ◦ C and it was stirred for 4 h. Finally, when a kinematic viscosity between 400 and 500 cP was reached, a solution of 0.1% sulfuric acid was added to stop the reaction. The resultant polyamine cationic product was stored in plastic drums [4,15–18].
2.3. Characterization
2.3.1. Characterization of the Polycoat 38 ® FTIR measurements were performed on an infrared equipment, Thermo brand model NIcolet 6700 (ThermoFisher Scientific, Waltham, MA, USA), using KBr tablets. 1 H-NMR measurements were performed on a 400 MHz NMR Bruker Ultra Shield (Bruker Corporation, Billerica, MA, USA) using D 2 O as a solvent. GPC measurements for the molecular weight determination of the polymer were performed using a gel permeation chromatograph Agilent 1200 (Agilent Technologies, Santa Clara, CA, USA) with 2 intercrossed polymer columns Shodex ohpak (Showa Denko, Tokyo, Japan) as the stationary phase and NaNO 3 0.15M / HCOOH 0.5 M as the mobile phase, using pullulan standards for the calibration curve and a refractive index detector. Thermogravimetric analysis was performed on a TGA-2050 thermogravimetric analyzer (TA instrument, New Castle, DE, USA) adjusted in a working temperature range between 25–400 ◦ C. DSC measurements were made in a DSCQ 100 (TA instrument, New Castle, DE, USA). The ion demand of the resin was measured with an automatic particle charge analyzer (AFG Analytic GMBH, Leipzig, Germany). The non-volatile percentage was calculated using Equation (1). %Solids = W f / W i (1) where W i was the initial weight of the sample and W f was the final weight after heating at 105 ◦ C during one hour in an oven (Memmert Gmbh + Co. KG, Buchenbach, Germany). The kinematic viscosity was measured to 500 g of the sample, using the needle 1 at 50 RPM and the respective Brookfield RVT viscometer (Brookfield Engineering Laboratories Inc., Middleborough, MA, USA). The density was calculated by weighing 1.000 mL of the sample, added with a micropipette (Eppendorf, Hamburg, Germany). The pH was measured with a Hanna pH meter (Hanna Instruments Inc., Woonsocket, RI, USA). Peel adhesion test of the coating was carried out with a horizontal tensile tester ZB-WL30 (Hangzhou Zhibang Automation Technology Co., Ltd., Zhejiang, China) to tissue hand-sheets with 30 g / m 2 grammage, 5.5 cm long and 1.5 cm with, attached to a standardized aluminum panel 9.5 cm long and 1.5 cm width. In the procedure, 0.04 mL of the coating is added to the panel and spread with a bronze applicator. The paper is adhered to the panel at 105 ◦ C in an oven (Memmert Gmbh + Co. KG, Buchenbach, Germany) and its exposed edge is tightened with the tensile clamp, which removes the strip at a speed of 10 mm / min and records the force required to detach it [2]. Finally,
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