Derivati celuloze i škroba, natrijeva karboksimetil celuloza (CMC) i natrijev karboksimetil škrob (CMS) istraženi su kao modifikatori površine i inhibitori posivljenja u procesu pranja standardne pamučne tkanine u tvrdoj i mekoj vodi pri različitim temperaturama. Odabrani polimeri su karakterizirani određivanjem stupnja supstitucije (DS), viskoznosti i morfološkim značajkama. Istraživanje je koncipirano kroz analizu utjecaja mehanike, kemije i temperature kao čimbenika Sinner-ovog kruga procesa pranja pri temperaturama 40 °C, 60 °C i 90 °C na svojstva pamučne tkanine. Utjecaj mehanike je praćen u dva procesna sustava različitih hidrodinamičkih performansi, a kemijski utjecaj varijacijom sastava kupelji u tvrdoj i mekoj vodi, pri čemu su deterdžentu dodani CMC, CMS, njihova mješavina (CMC+CMS), CMC niske viskoznosti (CMC LV) i CMC visoke viskoznosti (CMC HV). Pamučne tkanine prije i nakon 10 ciklusa pranja su karakterizirane preko sadržaja rezidualnih tvari, primjenom skenirajuće elektronske mikroskopije (SEM), skenirajuće elektronske mikroskopije s elementarnom analizom (SEM-EDS) i infracrvene spektroskopije s Fourierovom transformacijom (FTIR). Primijenjeni polimeri u sastavu deterdženta analizirani su kroz potencijal modifikacije površine pamučne celuloze i inhibiranje prijelaza prljavštine sa standardnih donora zaprljanja na modificirane i nemodificirane pamučne tkanine. Stupanj modifikacije pamučne tkanine u procesu pranja deterdžentom uz dodatak odabranih polimera dodanih deterdžentu u tvrdoj i mekoj vodi pri navedenim temperaturama praćen je mjerenjem potencijala strujanja u ovisnosti o pH kalijevog klorida iz kojeg je određen zeta potencijal. Dobiveni rezultati zeta potencijala i sadržaja rezidualnih tvari standardnih pamučnih tkanina prije i nakon pranja ukazali su na razlike između pojedinih polimera, te na svrhovitost provedbe hijerarhijske klasterske analize u ocjeni potencijala primijenjenih polimera u modifikaciji površine obzirom na složenost procesa pranja i potrebu povezivanja pojedinih parametara Sinner-ovoga kruga. Odnos naboja površine pamučnih tkanina opranih u laboratorijskom uređaju u tvrdoj i mekoj vodi pokazuje da CMC HV u svim analiziranim uvjetima tvrdoće vode i temperature ima najveći potencijal modifikacije, odnosno najviše povećava negativnu vrijednost zeta potencijala pamučne tkanine.
|Abstract (english)|| |
Cellulose and starch derivatives, sodium carboxymethyl cellulose (CMC) and sodium carboxymethyl starch (CMS) were investigated in the washing process as surface modifiers of standard cotton fabric and antiredeposition agents in hard and soft water at 40 °C, 60 °C and 90 °C. Selected polymers were characterized by determining the degree of substitution (DS), viscosity and morphological characteristics. The research was conceived through the analysis of the influence of mechanics, chemistry and temperature as factors of the Sinner cycle of the washing process at temperatures of 40 °C, 60 °C and 90 °C on the properties of cotton fabric. The influence of mechanics is monitored through two process systems of different hydrodynamic performances. The chemical effect was monitored through the largest number of variations in the composition of the bath in hard and soft water, CMC, CMS, their mixture (CMC + CMS), CMC low viscosity (CMC LV) and CMC high viscosity (CMC HV) added to the detergent. The applied polymers were analyzed through the potential of modifying the surface of cotton cellulose and inhibiting the depostion of stain from standard donors to modified and unmodified cotton fabrics. The degree of modification of cotton fabric in the washing process with detergent and selected polymers added to detergent in hard and soft water at selected temperatures was monitored by measuring the streaming potential from which the zeta potential was determined. The surface charge of cotton fabrics before and after modification in washing was measured in electrolyte solution, 0.001 mol / L KCl through a titration procedure from alkaline to acidic media. The obtained results of zeta potential and residual matter content of standard cotton fabrics before and after washing indicated differences between individual polymers, and the expediency of hierarchical cluster analysis in assessing the potential of applied polymers in surface modification. Cotton fabrics before and after 10 wash cycles were characterized by residual substance content, using scanning electron microscopy (SEM), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), Fourier Transform Infrared (FTIR) spectroscopy. The ash values for cotton fabrics washed in hard water depend on the washing conditions, and generally are 6 to 10 times higher than the ash values of cotton fabrics washed in soft water. The generation of incrustations in hard water and deposition on the surface of cotton fabrics at 60 °C and 90 °C is higher compared to 40 °C, which confirms the insufficient potential of the builder to bind alkaline earth ions at 60 °C and 90 °C. A review of all results shows that the high degree of water hardness and washing temperature have a dominant influence on the total ash content of washed cotton fabrics. A comparison of the values of ash from fabrics washed with detergent of different composition in hard water at all temperatures with the values of ash from cotton fabrics washed only in hard water indicates that washing with detergent affected the additional incrustations on the fabric surface, generally six times at 40 °C, eight times at 60 °C and almost quadruple at 90 °C. This can be attributed to the conditions of washing standard cotton fabric without soiling for 10 cycles with detergent, whose ingredients were not act to remove stain. Some organic components (soap and anionic surfactants) in the detergent in interaction with ions of alkaline earth ions generated moderately soluble and / or insoluble deposits, which burdened the surface of cotton fabric and increased the content of residual substances (total ash). Slightly lower values in total ash of cotton fabric washed in a laboratory washing machine compared to fabric washed in a laboratory device can be explained by a stronger mechanical and hydrodynamic effect when washed in a laboratory washing machine. Based on the obtained spectrograms, FTIR spectroscopy is not a suitable method for characterization of such a modified cotton fabric in different washing procedures. Washing with detergent in soft and hard water at different temperatures affects the changes in the zeta potential of cotton fabrics. The values were less negative compared to unwashed cotton fabric. Minor negative values may indicate the impossibility of complete dissociation of the active groups of cellulose. The detergent containing builders softened the water, while its other ingredients were not focused on the primary task – stain removal, but partly overloaded the cotton surface. The surface charge of a CMS-modified fabric in hard water at 60 °C is similar to the surface charge of a standard cotton fabric in a highly alkaline media. Based on the obtained ratios, it can be concluded that CMC as a modifier in detergent has a more favorable effect on increasing the negative charge of the surface of cotton fabric in soft water at 40 ° C and 60 °C. Zeta potential curves indicate a dominant influence of CMC in the CMC + CMS mixture over the CMS. Following the differences between the curves and the values of the zeta potential, it can be seen that polymer-modified cotton fabrics in soft water have a more negative surface charge compared to polymer-modified fabrics in hard water. Based on the obtained ratios, CMC as a polymer had the effect of increasing the negative charge of the surface of cotton fabric modified in soft water at 40 °C, 60 °C and 90 °C. Cotton fabrics modified with a CMC at 90 °C in hard water had a less negative surface charge compared to almost all other polymer-modified cotton fabrics. This is related to the influence of elevated temperature (90 °C) on the weaker potential of CMC, and not to the degree of deposits, since their content on the surface of detergent-modified fabrics with CMC at 40 °C, 60 °C and 90 °C in hard water is almost equal (0.84%; 1.01%; 1.49%), and soft water is low (from 0.20% to 0.27%). The polymers, CMC HV and CMC LV added to the detergent in the wash at 40 °C had the effect of increasing the negative charge of the cotton fabric, thus showing the highest degree of modification. The degree of settling of residual substances on the surface of fabric washed at 40 °C and 90 °C did not affect the orientation of the CMC HV, which confirmed the more negative charge of the cotton fabric surface. Exceptionally, in these conditions, the CMC HV polymer has the greatest potential for reducing the zeta potential, ie lower values compared to unwashed cotton fabric. The charge ratio of the surface of cotton fabrics washed in a laboratory device in hard and soft water showed that CMC HV in all analyzed conditions of water hardness and temperature had the greatest potential for modification, ie increased the negative value of the zeta potential of cotton fabric.