Variation of technological properties of field natural rubber lattices from Hevea brasiliensis clones and natural rubber-based compounds

Abstract

Natural rubber (NR) is a widely used biopolymer, but the variability of its properties is a great disadvantage. In this work, variation during a 6-month period of total solids (TSC), dry rubber (DRC), ash, volatile-matter, and nitrogen content of field natural rubber (NR) lattices and mechanical properties of NR solid sheets-based compounds was studied. NR samples were collected from IAN 710, IAN 873 and FX 3864 clones of Hevea brasiliensis at a plantation within the state of Antioquia, Colombia. Rainfall, environmental temperature, relative humidity, and sunlight hours were daily registered. NR sheets-based compounds were manufactured and their rheometric and mechanical properties were measured. Significant variations (p<0.05) among clones and tappings for most of the measured properties were found. Leaf senescence was the phenological stage that presented the greatest influence on NR properties. Some recommendations to control the variation of properties of raw NR during manufacturing of rubber goods were stated.Keywords: Natural rubber; process control; variability in raw materials; rubber testing.Variación de las propiedades tecnológicas de látex de campo de caucho natural de variedades clonales de Hevea brasiliensis y de compuestos de caucho natural ResumenEl caucho natural (NR) es un biopolímero ampliamente usado, pero la variabilidad de sus propiedades es una gran desventaja. En este trabajo se estudió la variación del contenido de caucho seco (DRC), total de sólidos (TSC), cenizas, material volátil y nitrógeno de látex de campo de NR, así como de las propiedades mecánicas de compuestos basados en láminas sólidas de NR, evaluando muestras recolectadas durante 6 meses. Las muestras se obtuvieron de tres variedades clonales de Hevea brasiliensis -IAN 710, IAN 873 and FX 3864-cultivadas en una plantación en Antioquia, Colombia. En el cultivo donde se recolectó el látex se monitorearon diariamente pluviosidad, temperatura ambiente, humedad relativa y horas de sol. Se moldearon compuestos emplenado láminas de NR, determinando sus parámetros reométricos y sus propiedades mecánicas. Se encontraron diferencias estadísticamente significativas (p<0.01) para la mayoría de las propiedades evaluadas como efecto de la variedad clonal y la época de recolección. La defoliación fue la etapa fenológica que presentó la mayor influencia sobre las propiedades del NR. Se presentan algunas recomendaciones para controlar la variación de las propiedades del NR durante la fabricación de artículos con este material.Palabras clave: caucho natural; control de procesos; variabilidad en materias primas; ensayos a cauchos.

Study of Aquilaria crassna Wood as an Antifungal Additive to Improve the Properties of Natural Rubber as Air-Dried Sheets

“…In contrast, the rubber sheets with ACW at 20, 40, and 60 phr did not have growth of fungi on their sheets’ surfaces, as shown in Figure 9 b–d, respectively. This confirms that the phenolic compounds in ACW inhibited fungal growth on the dry rubber products [ 14 ]. Using ACW as a filler in rubber sheets could improve their antifungal performance.…”

“…In addition, determination of the ash contents of the ADS samples was performed according to ISO 247-2, as described elsewhere [ 14 ]. First, the rubber sample was weighed and placed inside a crucible, and this was placed in a heat-treatment oven, an Optic Ivymen System (SNOL 3/1100 LHM01, Utena, Lithuania), at 550 °C, in order to achieve total oxidation of the sample.…”