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The morphological properties and particle size characteristics of micro- and nanofibrillated cellulose (NFC) and lignin-containing NFC (LNFC) produced by a microfluidizer processor were investigated. The effects mechanism of lignin-containing on the adsorption of NFC and the stable properties of organic dyes suspension were also studied. The results showed that the preparation process and final performance of NFC were affected by the key factors including lignin, homogenization pressure, and number of homogenization cycles. The increase in the homogeneity of the fibrillated cellulose was minor for the NFC samples, while LNFC samples showed a larger increase in the homogeneity of the particle size distribution. The influence of lignin was reflected both in improved fibrillation efficiency and in the final organic dye dispersion properties achieved by LNFC addition, primarily observed as deceased particle sizes and fibril dimensions. This study indicated that pollution-free dispersion of organic dyes can be realized through the application of lignin-containing NFC.

It is desirable to develop biodegradable ultraviolet (UV)-shielding materials from renewable resources, as the demand for sustainability is ever increasing. In this work, a novel lignin-TiO2 UV-shielding composite was synthesized successfully via a hydrothermal method induced by nanofibrillated cellulose (NFC). Comprehensive characterization showed that the lignin-TiO2@NFC composite induced by NFC had good nanoparticle size, shape, and thermal stability. The sunscreen performance of lignin-TiO2@NFC was investigated via mixture with unmodified hand cream. The UV-visible (vis) transmission spectra results revealed that the unmodified cream with 10 wt% lignin-TiO2@NFC absorbed approximately 90% of UV light in the full UV band (200 nm to 400 nm), which indicated that lignin-TiO2@NFC had a good UV-shielding ability.

Clogging is a critical problem that restricts the delamination of fibers in a high-pressure homogenizer (HPH). In this work, bleached bamboo pulp fibers were pretreated in TEMPO/NaBr/NaClO system prior to high-pressure homogenization to study the clogging condition in a high-pressure homogenizer. Effects of the additional amount of NaClO on the functional groups and morphologies of the bamboo pulp fiber were evaluated by conductometric titration, Fourier transform infrared spectroscopy (FTIR), fiber morphology analysis, and scanning electron microscopy (SEM). The fiber morphology analyzer revealed that the addition of NaClO facilitated to reduce the length of the fiber. The SEM images showed that TEMPO-mediated oxidation had a destructive effect on the fiber surface. The carboxylate contents of bamboo pulp fibers increased with the addition of NaClO, which were beneficial for increasing the critical concentrations of suspensions in the HPH. Nanocelluloses were successfully isolated from the TEMPO-oxidized bamboo pulp with different clogging critical concentrations, as were revealed by atomic force microscopy (AFM).

A three-component flame-retardant system was prepared based on in situ polymerization of ammonium polyphosphate (APP), diatomite (DE), and aluminium trihydroxide (ATH) to improve the flame retardance and smoke suppression properties of fibrous materials. Compared to the two-component system of APP-DE, the addition of APP-10% DE-4% ATH dosed at a filler load of 20% of the fibrous material reached a limited oxygen index of 27.5%, which was approximately 9.1% higher than the two-component system. The lower mass loss rate and higher residual mass at high temperatures resulted in excellent flame retardance. The synergistic effect on alleviating combustion and reducing heat release was shown by the 16.6%, 22.1%, and 12.5% decreases in the peak heat release rate, total heat release, and average effective heat combustion, respectively. Superior fire resistance was demonstrated by a higher fire performance index and a lower mass loss. A smoke suppression effect was shown by the peak smoke release rate and the total smoke release results that were 28.7% and 15.8% lower than the two-component system, respectively. Based on the porous structure of DE and generated aluminum oxide (Al2O3), the outstanding adsorption effect and flame-retardant effect was also demonstrated by the production rate of carbon monoxide (CO) and carbon dioxide (CO2).

Four flame retardants and styrene-acrylic latex were used to make flame-retardant air filter paper via emulsion impregnation. The compositions and flame retardant mechanism of the flame retardants were investigated by using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The flame retardance of air filter paper was evaluated using TGA and limiting oxygen index (LOI) meter, and the physical properties and pore structure of the flame-retardant air filter paper were measured using stiffness tester, burst tester, and aperture analyzer. The results showed that the optimal ratio of flame retardant to styrene-acrylic latex was 1:1.4. The synergistic effect of boron, phosphorus and nitrogen made FR3 have good flame-retardant effect on air filter paper. Air filter paper with FR3 also had good physical strength and suitable pore size distribution.

Ammonium polyphosphate–diatomite composite filler (APP-diatomite composite filler) was modified with silane coupling agent KH550 to improve the flame retardancy of filled paper. Cone calorimeter was used to analyze the heat and smoke releasing rates, as well as smoke toxicity of the filled paper. The distribution of the composite filler particles in paper and the morphology of the charred residues after combustion were investigated by scanning electron microscope (SEM), and the chemical structure of the charred residues was studied with fourier transform infrared spectroscopy (FTIR). Results show that the peak heat releasing rate (PHRR), total heat release (THR) and peak mass loss rate (PMLR) of the filled paper with the modified APP-diatomite decreased markedly, compared with those for the control paper, while the charred residue after combustion increased. In addition, the filled paper had an increased peak rate of smoke release (RSR) and increased total smoke release (TSR) and peak CO production rates, but a decreased peak CO 2 production rate. It was also found that part of the carbon element in the charred residue of the paper loaded with the modified APP-diatomite was in the forms of C=C=C, C≡C and C≡N, and the charred residue had a relatively more intact structure without apparent fiber breakage and longitudinal cracks.

Fiber classification of aramid fibrids was carried out using a Bauer-McNett fiber classifier, and the molecular weight and thermal properties of different sizes of aramid fibrids were determined with viscometry and differential scanning calorimetry (DSC), respectively. Aramid handsheets were made from different sizes of aramid fibrids and aramid short fibers, and the relationship between mechanical strength of aramid handsheets and thermal properties of aramid fibrids was examined. In addition, aramid papers from four different sources were also investigated to elucidate the relationship between their thermal properties and mechanical strength. It was found that aramid fibrids passing through 30-mesh screens and remaining on 50-mesh screens and aramid fibrids with narrower molecular weight distribution are suitable for the production of high-strength aramid papers. Lower crystallinity and wider molecular weight distribution are important contributors to the lower mechanical strength of domestic aramid paper when compared to that of Nomex paper.