Producing nanofibres from carrots with a chemical-free process.

The production of nanofibres (NF) from fresh carrots residue was investigated with a mechanical process without using any pulping or bleaching chemicals. Refining with a PFI mill followed by mechanical fibrillation with a homogenizer was used to produce fine NF. Blanching with hot water was carried out to leach the extractives from carrot fibres prior to refining. The energy required to prepare carrot pulp is one order of magnitude lower than for wood pulp and the fibrillation of nanofibres from carrot residue is four times lower in energy than using wood pulp as feedstock. The average diameter and length of carrot NF are 18 nm and 5.1 µm, respectively. The chemical composition of the manufactured nanofibers, as measured by HPLC, was 53% glucose and 47% xylose. Translucent and strong flexible films were prepared from the carrot NF using a filtration based papermaking process. The strength and water vapor permeability of these carrot NF paper like composites are similar to those derived from wood-fibre of comparable dimensions.

Effect of cationic polyelectrolytes on the performance of paper diagnostics for blood typing.

We investigated the effect that two common types of cationic polyelectrolytes used in papermaking might have on the performance of paper diagnostics using blood typing as an example. The results were analyzed in terms of red blood cells (RBC) retention and antibody-antigen specificity. Two questions were addressed: (1) can poly(amido-amine) epichlorohydrin (PAE) typically used for paper wet strength affect the diagnostic performance? (2) can high molecular weight cationic polyacrylamide (CPAM) employed as retention aid enhance or affect the selectivity and sensitivity of paper diagnostics? A series of paper varying in type of fibers and drying process were constructed with PAE and tested for blood typing performance. Residual PAE has no significant effect on blood typing paper diagnostics under normal conditions. Positives are unaffected with PAE, while negatives lose slight sharpness as some RBCs are unselectively retained. CPAM, the most common retention aid, can also be used to retain cells and biomolecules on paper. Paper towel was treated with CPAM solutions varying in polymer concentration and charge density and tested for blood typing. We found that CPAM dried on paper can retain RBC. CPAM affects the negative tests by retaining non-specifically individual RBC on fibers. RBC retention increases non-linearly with the CPAM charge density and concentration. As expected, wet CPAM retain RBCs at concentrations higher than 0.1wt%. As paper diagnostics are becoming a reality, more realistic papers than the Whatman filter paper will be engineered. This study provides guidance on how best use the required polymeric wet-strength and retention agents.