Effect of potassium laurate on the stability of concentrated natural rubber latex preserved with an alternative to ammonia

ผลของสารละลายโพแทสเซียมลอเรตต่อการรักษาสภาพน้ำยางข้นในระบบน้ำยางที่ใช้สารแทนแอมโมเนีย

Name: Sudarat Sonsalab

keyword: Natural rubber latex

; Potassium laurate

; Preservative

; Stabilization

; Storage time

Abstract: 2-hydroxymethyl amino ethanol as a preservative was added into the concentrated natural rubber latex instead of ammonia. The whole system is called HMAE-NRL hereafter. The stability of this colloidal system was improved by addition of potassium laurate together with adjusting pH. The pH of HMAE-NRL was adjusted by adding potassium hydroxide to values of 8 and 10 before loading with various potassium laurate ranging from 0-1 wt% and 0-0.125 wt% for pH 8 and pH 10, respectively. Changes in colloidal stability of the latex were investigated by measuring mechanical stability time (MST), chemical stability time (CST), heat stability time (HST), chemical and heat stability time (CHST) along with the changes of some latex properties which are conductivity, VFA no., viscosity and surface tension at various storage times. Furthermore, critical coagulation concentration (CCC) of colloid system was also assessed. It was found that MST, CST, HST, CHST of all latices increased when storage time increased up to 80 days and then decreased afterward 120 days. The HMAE-NRL with pH 10 had longer stability time than that with pH 8 when adding the same potassium laurate loadings. The maximum increase in the stability time was observed for HMAE-NRL at pH 10 with adding 0.125 wt% of potassium laurate. The VFA number, conductivity and viscosity of all lattices increased when storage time increased. Relationship between log(MST) and conductivity of HMAE-NRL was observed consistent with linear equation. Comparing the stability of HMAE-NRL to that of HA-NRL, it was found that HA-NRL has higher degree of stability than HMAE-NR. However, it was observed that the stability of HMAE-NRL at pH 10 with 0.125 wt% potassium laurate was close to that of HA-NRL with 0.05 wt% ammonium laurate. This result indicates that natural rubber latex could be preserved with HMAE instead of ammonia to yieid acceptable MST. Regarding many disadvantages of ammonia, HMAE-NRL is a promising option but it needs to be used with potassium laurate as a surfactant and pH adjustment to 10

Thammasat University. Thammasat University Library

Address: BANGKOK

Email: preserv@tu.ac.th

Name: Panu Danwanichakul

Role: advisor

Name: Surapich Loykulnant

Role: co-advisor

Created: 2014

Modified: 2021-12-20

Issued: 2021-12-20

วิทยานิพนธ์/Thesis

application/pdf

DOI: 10.14457/TU.the.2014.558

eng

DegreeName: Master of Engineering

Level: Master's Degree

Descipline: Chemical Engineering

Grantor: Thammasat University

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