H3PW12O40·4H2O as an efficient catalyst for the conversion of cellulose into partially substituted cellulose acetate

Characterization of microcrystalline cellulose prepared from long and short fibers and its application in ibuprofen tablets

As a bio-based material, microcrystalline cellulose (MCC) has been applied in many fields including pharmaceuticals, foods, and cosmetics in recent years. However, traditional preparation methods of MCC are facing many challenges due to economic and eco-environmental issues. In this study, softwood dissolved pulp was sieved to long fiber (LF) and short fiber (SF), and subsequently to prepare LF-MCC and SF-MCC by hydrochloric acid hydrolysis at different acid dosages (3-7 wt%), reaction times (30-90 min), and temperatures (75-95 °C). The as-obtained MCC products were compared in terms of morphology, size, crystallinity, and chemical structure. The results indicated that the crystallinity and yield of LF-MCC were high, with maximum values of 78.41 % and 98.68 %, respectively. The particle size distribution of SF-MCC was more uniform in the range of 20-80 μm, with a maximum of 59.44 % at 20-80 μm occupancy proportion. Moreover, SF-MCC had a typical rod-like shape and larger surface area as well as better thermal behavior than LF-MCC. When LF-MCC and SF-MCC were used as fillers in the production of ibuprofen tablets, the tablets added with LF-MCC exhibited higher hardness, friability, dissolution rate, and shorter disintegration time. Therefore, this work is very beneficial for the preparation and application of MCC.

Electron beam irradiation influencing the mechanical properties and water absorption of polycaprolactam (PA6) and polyhexamethylene adipamide (PA66)

It is known that polycaprolactam (PA6) and polyhexamethylene adipamide (PA66) are widely used industrial materials including in the irradiation industry. However, there is a lack of observation of irradiation effects on PA6 and PA66. In the current study, we firstly investigated mechanical and water absorption properties of PA6 and PA6 that were treated under irradiation doses of 200 kGy, 400 kGy, 800 kGy and 1600 kGy, respectively. The structure, mechanical properties and thermal properties of nylon after irradiation were characterized by mechanical property tests, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results indicated that the tensile strength of PA6 increased gradually while that of PA66 firstly increased and then decreased with the increase of irradiation dose. Additionally, the elongation at break of the two samples decreased obviously with the increase of irradiation dose. The water absorption of PA6 increased with the increase of irradiation dose; however, that of PA66 was almost constant regardless of irradiation. FTIR tests revealed that the carbonyl index of PA6 and PA66 increased with the increase of irradiation dose. SEM results illustrated that surface degradation of PA6 and PA66 occurred during the irradiation process.

All cellulose composites based on cellulose diacetate and nanofibrillated cellulose prepared by alkali treatment

Cellulose diacetate (CDA) composite films were synthesized by incorporation of nanofibrillated celluloses (NFCs), using a casting/evaporation technique. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) characterization indicated the presence of interaction and certain compatibility between CDA and NFCs. The CDA and NFCs were converted to cellulose II by an alkaline treatment which resulted in the formation of all cellulose composite (ACC) films, as indicated by the FTIR and XRD characterization. Significant changes were observed in their structural, thermal, mechanical, and optical transparency properties. The SEM images revealed the excellent compatibility among the constituents of the ACC films. The tensile strength, Young's modulus, and strain at break of the ACC films with 15wt% NFCs content were increased to 102.3MPa, 5.8GPa, 14.7% respectively. This work provides a promising pathway for manufacturing high performance ACC materials.

Modifying a waterborne polyacrylate coating with a silica sol for enhancing anti-fogging performance

(A) Schematic chemical reaction of polyacrylate latexes and silica sol precursor; (B) evolution of water contact angle on various samples as a function of time; (C) anti-fogging properties of the polyacrylate/silica composite coating.