A Low-Density Polyethylene (LDPE)/Macca Carbon Advanced Composite Film with Functional Properties for Packaging Materials

Macca carbon (MC) powder, a biomass derived from macadamia nut cultivation that emits far-infrared (FIR) radiation, was incorporated into low-density polyethylene (LDPE) by melt-compounding and subsequent melt-extrusion operations. Optical microscopy, scanning electron microscopy, differential scanning calorimetry, thermal gravitational analysis, mechanical properties, FIR emission power, barrier properties, transmission properties, antimicrobial activity assays, and storage tests were used to evaluate the manufactured LDPE/MC composite viability sheets for antimicrobial packaging applications. The physical properties and antibacterial activity of composite films were significantly correlated with the amount of MC powder used. The higher the MC powder content in the LDPE/MC composite film, the better the FIR emission ability. Only the MC powder at 0.5% by weight displayed adequate fundamental film characteristics, antibacterial activity, and storage performance, allowing lettuce and strawberries to remain fresh for more than 7 and 5 days, respectively, outside the refrigerator. This study demonstrates that FIR composites made from MC powder are a distinct and potential packaging material for future application in the food industry.</jats:p

A Low-Density Polyethylene (LDPE)/Macca Carbon Advanced Composite Film with Functional Properties for Packaging Materials

Macca carbon (MC) powder, a biomass derived from macadamia nut cultivation that emits far-infrared (FIR) radiation, was incorporated into low-density polyethylene (LDPE) by melt-compounding and subsequent melt-extrusion operations. Optical microscopy, scanning electron microscopy, differential scanning calorimetry, thermal gravitational analysis, mechanical properties, FIR emission power, barrier properties, transmission properties, antimicrobial activity assays, and storage tests were used to evaluate the manufactured LDPE/MC composite viability sheets for antimicrobial packaging applications. The physical properties and antibacterial activity of composite films were significantly correlated with the amount of MC powder used. The higher the MC powder content in the LDPE/MC composite film, the better the FIR emission ability. Only the MC powder at 0.5% by weight displayed adequate fundamental film characteristics, antibacterial activity, and storage performance, allowing lettuce and strawberries to remain fresh for more than 7 and 5 days, respectively, outside the refrigerator. This study demonstrates that FIR composites made from MC powder are a distinct and potential packaging material for future application in the food industry

Deciphering the discoloration in the manufacturing of natural rubber

Abstract Many naturally occurring color components, especially non-rubber components, are present in natural rubber (NR) latex, limiting some NR applications, particularly for light-colored NR products in high demand. Non-rubber components, like lipids and proteins, can be removed from NR to reduce its yellow color. This study looked at the factors that influence the yellow index (YI) in NR and NR latex discoloration techniques. Proteins were a crucial factor directly determining the YI of NR. Thus, increasing the number of centrifugation washings, speed, and time was used to remove proteins to minimize the YI of NR. Percentage of total solid content (% TSC) of field NR latex, the blend ratio between cream rubber and skim latex, or bottom fraction from fresh-field NR latex collected from centrifugation process, were also important factors. The addition of sodium metabisulphites as a polyphenol oxidase (PPO)-reducing agent reduced the YI significantly. The oxidative breakdown of endogenous non-rubber components at high temperatures was also confirmed to serve the increase in YI value due to air-drying conditions of NR.</jats:p

The Method to Produce Light-Color Natural Rubber

It is known that natural rubber (NR) has a naturally occurring color, which restricts to some applications of NR, especially for producing light-colored NR products. Thus, this present work was an attempt to find the appropriate method for promoting the light color NR. First, the color substances in NR were extracted by a certain method and subjected to analysis by Thin layer chromatography (TLC). They were separated by hexane/diethyl ether (7:3 v/v). The separation was detected using 3% cupric acetate in 8% phosphoric acid (H3PO4) and heated at 180 degree C. It was found that the color extracts from NR comprise of various compounds such as carotenoids, free fatty acids, tocotrienols, oxidized proteins, etc. Developments of light color NR were carried out by the addition of enzymatic browning inhibitors, i.e., sodium metabisulphite (SMS) in latex and the employment of some chemicals, i.e., proteolytic enzyme, sodium hydroxide, to discolor the rubber. It was found that the color index of NaOH-treated rubber or saponified rubber (SP) was lightest, whereas the color of urea-treated rubber or deproteinized rubber (DP) was close to the centrifugation rubber. The treatment of SMS showed an insignificant effect on the decoloring of NR. DP and SP showed very low nitrogen content, so these may be effective methods to produce light-color NR.</jats:p

Improvement of Filler-Rubber Interaction by Grafting of Acrylamide onto Saponified Natural Rubber under Ultraviolet Radiation as a Continuous Process

Silica and carbon black have been widely used as the main reinforcing fillers for improving the properties of natural rubber (NR). In a silica-filled rubber compound, it is known that the low compatibility between NR and silica affects the mechanical properties of rubber products. In order to overcome this drawback, the functionalized saponified NR (FSPNR) was carried out by grafting acrylamide (AM) onto the saponified NR (SPNR) under UV radiation as a continuous process. An increasing in the bound rubber content and Mooney viscosity was found as an increasing AM content. Storage modulus at low strain amplitude of the silica-filled FSPNR was lower than that of the raw NR. In addition, SEM micrographs showed the good dispersion of silica in FSPNR. These confirmatory evidences indicate the improvement of rubber-filler interaction and the reduction of filler-filler interaction by functionalization under UV radiation.</jats:p