Rubber-lignin-ammonium polyphosphate bio-composite foams: Fabrication, thermomechanical properties and flame retardancy.

Bio-composite foams based on Epoxidized Natural Rubber (ENR) filled with lignin (LG) and ammonium polyphosphate (APP) were fabricated via batch foaming. The addition of APP accelerated the foaming process at lower temperatures. Pre-mixing induced ionic and hydrogen bonding between the LG and the APP particles, which reduced crosslinking between LG and ENR. The resulting ENR bio-composite foams with LG/APP exhibited a significant increase in compressive strength (up to 700 %) and modulus (up to 600 %) compared to the ENR foam baseline. Furthermore, the LG/APP foams demonstrated lower thermal conductivity than both the ENR foam baseline and foams containing only LG or APP, attributed to optimal thermal conduction in the solid phase and convection within the pore cells. The combination of APP and LG produced synergistic effects, with phosphorus (from APP) and high carbon content (from LG) enhancing flame-retardant efficiency. This study highlights the potential of these sustainable bio-composite foams for applications requiring enhanced thermal insulation and flame retardancy attributes for insulation and other practical applications.

Sustainable barrier paper coating based on alpha-1,3 glucan and natural rubber latex.

There is an increasing interest in utilizing more sustainable and inherently biodegradable materials alternatives ideally derived from renewable resources for modern material applications, especially in the area of packaging materials. This work employed the polysaccharide alpha-1,3-glucan derived from an enzymatic polymerization process as a functional additive for natural rubber (NR) latex-based coating films. Coating formulations containing NR and 9-50 wt% alpha-1,3 glucan were prepared and then applied to paper substrates at different thicknesses. The effect of coating formulations on the barrier properties (e.g., oxygen, oil, water vapor barrier), the viscosity, and dry and wet tensile properties were investigated. The NR/glucan coatings exhibited outstanding tensile properties and balanced oxygen and oil barrier performance. However, higher glucan loading could be detrimental to moisture barrier. Overall, this study indicated that the NR/glucan coating films are comparable in performance to commercial coating formulations while providing a renewable, potential to be recycled with paper, and biodegradable alternative.

Enzymatic polymerization designed alpha-1,3 glucan particle morphology as reinforcing fillers of dipped and casted rubber films.

In this work, enzymatic polymerization derived microcrystalline glucan (MCG) polysaccharides fillers were employed as novel sustainable fillers of natural rubber (NR) films. MCG has a designed platelet morphology, with high crystallinity and colloidal stability in aqueous media and rubber lattices. NR films composed of 0-10 phr MCG were then fabricated using dipping and casting processes. The incorporation of MCG in the NR led to a remarkable enhancement in the tear strength, tensile properties, toughness, and an increase in water vapor permeability but a decrease in ethanol permeation. This behavior is appealing in gloves, where high sweat permeation from hands to the environment and limited to no solvent penetration from the environment to the skin is desired. The study indicated that the enzymatically polymerized MCG are effective reinforcing fillers for NR latex and potentially other elastomers offering the potential for appealing physical property improvements.