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The morphology of polymer/nanofibrillated cellulose (NFC) composite sheets produced using different techniques and its influence on low strain stiffness were assessed by optical and transmission electron microscopy. Solvent processing led to relatively homogeneous NFC dispersions and significant reinforcement of the in-plane Young's modulus. The continuous cellular networks obtained by wet comingling of polylactide powder or latex with NFC also provided efficient and essentially scale independent reinforcement, in spite of the extensive agglomeration of the NFC. However, the irreversible nature of these networks is incompatible with low pressure thermoplastic processing routes such as physical foaming, and while they may be broken up by e.g. extrusion, this led to substantial loss in reinforcement, particularly at temperatures above the glass transition temperature of the matrix, consistent with the observation of isolated low aspect ratio NFC aggregates in the extruded specimens., QC 20150612

The morphology of polymer/nanofibrillated cellulose (NFC) composite sheets produced using different techniques and its influence on low strain stiffness were assessed by optical and transmission electron microscopy. Solvent processing led to relatively homogeneous NFC dispersions and significant reinforcement of the in-plane Young's modulus. The continuous cellular networks obtained by wet-comingling of PLA powder or latex with NFC also provided efficient and essentially scale-independent reinforcement, in spite of the extensive agglomeration of the NFC. However, the irreversible nature of these networks is incompatible with low pressure thermoplastic processing routes such as physical foaming, and while they may be broken up by e.g. extrusion, this led to substantial loss in reinforcement, particularly above Tg, consistent with the observation of isolated low aspect ratio NFC aggregates in the extruded specimens., QC 20150528

There is increasing research interest in nanocellulose aerogels because they have low density, hierarchical structure and they are biodegradable and biocompatible. Typically, aerogels are made by supercritical drying, freeze drying and vacuum drying. This work will report the effects that different drying methods have on textural properties of aerogels., QC 20140929

To assemble complex structures with short cycle times, the feasibility of welding thermoplastic (TP) to thermoset (TS) composites is demonstrated using a phenomenological approach. The effect of the thermal degradation of the TS composite (AS4/3501-6) on its shear strength is assessed in order to minimize the TS degradation during the welding process. The degradation is reported to decrease the shear strength in an exponential way. A layer of TP (polysulphone [PSU]) is cocured at the surface of the AS4/3501-6 laminate during its cure cycle in an autoclave. Two laminates are then welded together using a resistance welder. The highest shear strengths, which are close to the shear strength of bulk AS4/3501-6 autoclave-processed baseline, occur for a welding time and temperature of 10 s and 300 deg C, respectively. Higher and lower temperatures induce degradation and low consolidation of the weld, respectively. The welding interface between the TP layers is the strongest, while failure is mixed and occurs at interfaces between TS and TP and at interfaces between TP and heating element at the fiber/matrix interfaces. Further investigations are required to optimize the welding processing parameters and to identify the bonding, degradation, and failure mechanisms using a more fundamental and molecular approach., Prepared in collaboration with Composite and Polymer Technology Laboratory, Swiss Federal Institute of Technology, Switzerland and University of Delaware, Newark, DE.