Influence of Processing Conditions on Properties of Poly (Vinyl acetate)/Cellulose Nanocrystal Nanocomposites

Abstract

We investigated how different processing methods affect the morphology and mechanical properties of nanocomposites made from poly(vinyl acetate) (PVAc) and cellulose nanocrystals (CNCs). Homogeneously mixed reference PVAc/CNC nanocomposites of various compositions were first prepared by solution casting. These materials were post‐processed by mixing in a roller blade mixer (RBM) or a twin‐screw extruder (TSE) and subsequent compression molding. Transmission electron microscopy was used to elucidate the dispersion and size distribution of the CNCs and these data were correlated with the materials' mechanical properties. While RBM processed composites are virtually indistinguishable from the solution‐cast reference materials, TSE processing led to mechanical degradation of the CNCs and resulted materials with inferior mechanical properties. Direct RBM mixing of PVAc and CNCs was also explored. This process afforded materials that are much stiffer than the neat matrix, but did not reach the levels of the reference series.

Preparation and characterization of thermally stable cellulose nanocrystals via a sustainable approach of FeCl3-catalyzed formic acid hydrolysis

“…For the past few years, the preparation of cellulose nanocrystals (CNCs) and their application in composite materials have gained increasing attention because of their inherent properties like outstanding mechanical properties (elastic modulus of 130-150 GPa) (Iwamoto et al 2009), high specific surface area (up to several hundreds of m 2 /g) (Ng et al 2015), high length-to-width ratio (up to several hundreds) (Jonoobi et al 2015) combined with low density (1.6 g/cm 3 ) (Moon et al 2011), low thermal expansion (0.1 ppm K -1 ) (Song et al 2013), biodegradability and renewability. Due to their special intrinsic nanostructure and excellent properties, CNCs have wide application potential in nanomaterials, such as aerogels (Mueller et al 2015;yang et al 2015), biomedical materials (Domingues et al 2014;Dugan et al 2013;Jorfi and Foster 2015;Plackett et al 2014), packaging materials (Fortunati et al 2012;Li et al 2013b;Mihindukulasuriya and Lim 2014), optical (Biyani et al 2013;Schlesinger et al 2015) or electroconductive (Lyubimova et al 2015;Ning et al 2015;Shi et al 2013;Tang et al 2014) materials, and several mechanically reinforced nanocomposites (de Castro et al 2015;Habibi 2014;Jonoobi et al 2015;Ng et al 2015;Sapkota et al 2015;Therien-Aubin et al 2015;Yang et al 2014).…”

Thermally activated shape memory behavior of melt‐mixed polyurethane/cellulose nanocrystal composites

“…On account of their intriguing mechanical properties and potentially low toxicity, rod‐like cellulose nanocrystals (CNCs) are increasingly used to reinforce polymers, and these particles have also been considered in the context of shape memory polymers . CNCs can be isolated from (de‐lignified and bleached) cellulosic raw materials, including cotton, softwood, hardwood, tunicates, and bacteria, by controlled hydrolysis with mineral acids, such as sulfuric, hydrochloric, and phosphoric acid . This process removes the amorphous portions of the native material and yields highly crystalline, rod‐like particles with a typical diameter of 5–20 nm, a length of 100–3000 nm, and elastic moduli of 100–140 GPa, depending on the process conditions and sources.…”

Morphological investigation of cellulose acetate/cellulose nanocrystal composites obtained by melt extrusion

“…However, in the thermoplastic processing industry, melt‐extrusion associated with injection molding is the most important processing technique as it allows high production rate and the absence of a solvent. In addition, melt extrusion is suitable to high molecular weight polymers which is the case of cellulose derivatives …”