Effect of ammonia preservative systems in centrifuged latex characteristics and latex film properties

Concentrated latex processing facilities are confronted with issues related to high residual phosphate levels in latex. This study was conducted to determine the effects of ammonia preservative systems on residual phosphate levels. Two grades of CL namely, 0.7% ammoniated CL (HACL) and the 0.2% ammoniated CL (LACL) were studied under this survey. Both HACL and LACL samples were characterized for initial total phosphate levels and for other basic latex properties. At the initial stage, the LACL had the higher mean total phosphate level of 434.20 ± 2.20 ppm, while the HACL had the lower level of 412.02 ± 1.42 ppm. Changes in latex properties such as total phosphate levels and soluble magnesium levels of the samples were monitored once a week for a month adhering to ISO standard procedures. A statistically significant interaction between the storage time and the ammonia concentration (p < 0.05) on phosphate content was observed. Moreover, the mechanical properties of latex films of both LACL and HACL were studied as well. A statistically significant (p<0.05) impact of ammonia concentration on latex film properties was observed. The LACL had the lowest mean for tensile strength (2.49 ± 0.03 MPa), while the HACL had the highest (2.73 ± 0.08 MPa). HACL recorded the highest elongation at break (886 ± 9.31%). In addition, the LACL had the lowest mean for tear strength (8.41 ± 0.01 MPa), while the HACL had the highest (8.78 ± 0.05 MPa). The highest phosphate concentration throughout the storage period was recorded in the LACL sample. Further, the highest mechanical properties were observed in HACL sample over LACL sample. Hence, this study concludes that high phosphate levels impair the mechanical properties of thin films of CL.