Interfaces in Cross-Linked and Grafted Bacterial Cellulose/Poly(Lactic Acid) Resin Composites

Abstract

This article presents approaches to maximize the mechanical performance of bacterial cellulose/poly(lactic acid) composites through chemical modification of the interface. This is achieved by both cross-linking the layered bacterial cellulose structure and by grafting to the matrix material. Unmodified and glyoxalized bacterial cellulose (BC) networks have been embedded in poly(lactic acid) (PLA) resin and then in maleated resin using a compression molding method. The effect of these chemical modifications on the physical properties of these composites is reported. The tensile properties of the composites showed that Young's moduli can be increased significantly when both BC networks and PLA were chemically modified. Interface consolidation between layers in BC networks has been achieved by glyoxylation. An improved interface between BC and PLA has been achieved by grafting polar maleic anhydride monomers along the backbone structure of PLA. The effect of these modifications on stress-transfer was quantified using Raman spectroscopy. Two competitive deformation mechanisms are identified; namely the mobility between BC layers, and between BC and PLA. The coupling strength of these interfaces could play a key role for optimization of these composites' mechanical properties.

Modification of interfacial adhesion with a functionalized polymer in PLA/wood composites

“…Strength, on the other hand, was often smaller than that of the uncoupled composite indicating poor interfacial adhesion [42,44]. Quero [45] and Avella [46], however, observed the increase of composite strength upon the application of the functionalized polymer.…”

In situ processing of cellulose nanocomposites

“…BC has been used as reinforcement in different polymeric matrices such as cellulose acetate butyrate, polylactic acid, polyhydroxy butyrate, starch, hydroxyl ethyl cellulose, polyvinyl alcohol, acrylic resin, epoxidised soyabean oil etc [17,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. In the ex situ synthesis of BC nanocomposites the penetration of the second component through the BC network may not be uniform which results into a non-homogeneous structure.…”

Green Chemical Modifications of Nanocellulose for Use in Composites

“…The weight averaged molecular weights of PLA and MAPLA are measured to be 212 kDa and 122 kDa, respectively. 50 This resulted in a significantly reduced tensile strength of BC gloxyal /MAPLA.…”

“…Properties of (glyoxalized) BC nanopaper and its (maleic anhydride grafted) PLLA nanocomposites. E, σ, and ε indicate tensile modulus, tensile strength, and engineering strain-tofailure, respectively 49,50. …”