Cellulose Nanocomposites

The great potential of cellulose nanoparticles (CNs) in the development of cellulose nanocomposites is to take advantage of the high mechanical properties of crystalline cellulose combined with its low density (1.6 g cm-3). The specific properties (elastic and tensile strength divided by density) of crystalline cellulose is higher than most materials, as shown in the figure. To date research has generally approached the utilization of CNs from two viewpoints: CN reinforced polymer matrix composites) and 100% cellulose materials (neat CN films). The properties of both composite types are strongly dependent on the CN network formation in which the high surface area and strong inter-particle hydrogen bonds in CN's allow the formation of high strength networks structures. As expected CN composites properties are much lower than crystalline cellulose, but there are opportunities for improvement. Additionally, the small particle size combined with the smaller void sizes within the network structures allows for optical transparency. Some variety of CN composites produced to date can be, transparent, have tensile strengths greater than cast iron, and have very low thermal expansion coefficients (CTE).

Shear-Casting of Neat CNC and NFC films

Ongoing research with nanofibrillated cellulose (NFC) and cellulose nanocrystals (CNC's) has focused on network-structured composites with NFC and/or CNC being the dominant phase (ie greater than 50 vol%). The goal of this program is to: i) to use shear based casting techniques to produce alignment of NFC and CNCs within cast films to induce mechanical property anisotropy within the resulting films, ii) identify and characterize key variables that influence CN alignment retained in dried films, iii) develop processing routs/protocols for tailoring the CN network structure. This work will be closely linked with the metrology and predictive modeling programs to offer experimental validation of model predictions.