Research Articles

Biomass represents an abundant and relatively low cost carbon resource that can be utilized to produce platform chemicals such as levulinic acid. Novel oligomeric flame retardants, the poly(MDP-PDCP-MA)s (PMPMs), were designed and synthesized using diphenolic acid as one of the raw materials, which is derived from levulinic acid. To change the molar ratio of reactants, a series of PMPM samples with different nitrogen contents were obtained and characterized by FTIR and solid-state 13C NMR spectroscopy. The solubility test and thermogravimetric analysis (TGA) indicated a good solvent-resistant property and thermal stability. The flame retardancy and thermal behavior of ABS with 30% loading of different PMPM samples were investigated by limiting oxygen index test (LOI), TGA, and microscale combustion colorimeter (MCC). The results showed that PMPMs are effective charring agents that can increase the thermal stability and flame retardancy of ABS. Scanning electron microscopy (SEM) observations of the residue of ABS/PMPM blends indicated the compact charred layer formed was responsible for improving the thermal stability and char yield of ABS with low nitrogen content in PMPM-1 flame retardant.

“Water-in-water” emulsions of cross-linked and hydrophobically associating cationic polyacrylamide (CHCPAM) with cationic groups (methacrylatoethyl trimethyl ammonium chloride, DMC), hydrophobic groups (octadecyl methacrylate, OA), and cross-linked groups (N, N’-methylene bisacrylamide, MBA) were prepared by dispersion polymerization. The structure of the copolymer was confirmed by FTIR and 1HNMR analyses. The prepared “water-in-water” emulsions possessed high solids content, low viscosity, good stability, and water solubility. Optical microscope images showed that the diameters of most emulsion particles were several microns. Appropriate concentrations of OA and MBA for a stable dispersion system were in the range of 0 to 0.1 wt% and 0 to 50 ppm. “Water-in-water” emulsions of CHCPAM can be directly used as a retention aid without further processing. They have a comparative retention rate, better anti-shearing ability, and better salt resistance, compared to commercial CPAM. The cross-linked structure of CHCPAM contributed to the anti-shearing ability. Intermolecular and intramolecular hydrophobic association of CHCPAM was the most important factor in improving resistance to salt.

Dry wastes (dw) generated in processing mangoes, composed (in dry weight) mainly of soluble carbohydrates (71 ± 2%) and fiber (16 ± 1%), were evaluated as substrates in a “home-made” solid-state fermentation (using polyurethane foam as inert support matrix, various C:N ratios, moisture contents, and incubation periods) of Trichoderma asperellum T8a, a promising biological control agent against the mango pathogen Colletotrichum gloeosporioides (causal agent of anthracnose). Highest spore production (2.5 x 106 up to 76 ± 3 x 108 spores g-1 dw) occurred after 8 days of incubation [at 28 ± 1 °C, relative humidity of 85 ± 5%, photoperiod of 12h (540 Lux) – 12h (20 Lux)] at a C:N ratio of 26, and a moisture content of 78%. Scanning electron microscopy showed that T. asperellum T8a was able to grow on mango industrial wastes and into polyurethane foam. The extensive growth can be related to cellulases secreted by this fungus, liberating glucose from these wastes to its growth. Most (94 ± 1%) of the spores grown on mango industrial wastes survived storage at 4 °C for 7 days and were equally effective as those grown on potato dextrose agar medium (86 ± 4% viable) in biological control tests against C. gloeosporioides ATCC MYA 456. Results indicate the potential use of mango industrial wastes as substrates to produce T. asperellum T8a spores in situ (mango orchards) under a cheap “home-made” solid-state fermentation, reducing problems associated with wastes disposal and permitting the production of a biological control agent against C. gloeosporioides.

Effects of the mixing method of K2CO3 with the source biomass and thermal history on the properties of the mangosteen peel activated carbons (MSACs) were investigated. The one-step impregnation activation process was found to be remarkably effective in increasing the mesoporosity of the activated carbon (L-MSAC) as well as BET surface area (SBET) and total pore volume, compared to the solid-solid dry mixing method in a two-stage process. The better fit of Langmuir isotherm indicates a maximum adsorption capacity of Cu(II) to be 21.74 mg·g^-1 for L-MSAC, which makes it a promising adsorbent for the removal of copper ion from aqueous solutions.

Fully bleached kraft bamboo pulp (BPFs), fully bleached kraft softwood pulp (SPFs), and bleached cotton linter pulp (CPFs), which have different crystallinities, were oxidized in the TEMPO-NaBr-NaClO system with ultrasonic treatment for producing nanocrystals. The carboxylate content of nanocrystals made from BPFs, SPFs, and CPFs were 2.10, 2.02, and 1.66 mmol/g, respectively. Nanocrystals of BPFs and SPFs had widths of 5 to 15 nm and lengths of 400 to 800 nm. The length and width of CPFs nanocrystals were 200 to 400 nm and 15 to 25 nm. The oxidizing rates of BPFs, SPFs, and CPFs were different. These differences could be attributed to crystallinity. Crystallinity affected microstructures, chemical process, and the efficiency of ultrasonication. Crystallinity also shaped the nanocrystals, since nanocrystals consist of the residual crystalline regions after chemical oxidation and ultrasonication. Fibers of lower crystallinity (such as bamboo) showed a higher reactivity, and the nanocrystals made from low crystallinity materials were longer, thinner, more rapidly formed, and required less energy in their preparation.

Bacillus licheniformis SVD1 exhibited highest production of three different polysaccharides when sucrose was used as the carbon source for polysaccharide production and yeast extract was used as the nitrogen source. Polysaccharides were characterized using size exclusion chromatography (SEC), thin layer chromatography (TLC), gas chromatography with mass spectrometry (GCMS), and Fourier Transform Infrared (FTIR) analysis. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were used to examine the topography of the cells and polysaccharides. The cell-associated polysaccharides were composed of galactose, while two different polysaccharides were present in the extracellular medium, one of 2,000 kDa (EPS1), consisting of fructose monomers and identified as a levan with (2→6)-linkages and (1→2)-branching linkages. The other extracellular polysaccharide (EPS2) consisted of mannose and galactose and had a range of sizes as identified through SEC. All three polysaccharides displayed an immune modulatory effect as measured using Interleukin 6 (IL6) and tumor necrosis factor alpha (TNFα).

A simple measurement method for pressure sensitive adhesives (PSA) in an agglomeration deinking system of mixed office waste paper was studied. This method was based on the different scanning performance of ink and PSA specks in hot-pressed and oven-dried handsheets with the change of contrast values that had been selected and set in the image analysis software. The numbers of ink specks per square meter (NPM) were well recognized at both low and high contrast values and exhibited a very good linear relationship within a range of contrast values. The PSA specks, on the other hand, could not be recognized at the low contrast values and could only be recognized at high contrast values. The NPM value of the ink specks was found to have the highest values at the high contrast values and could be accurately predicted by its NPM value at the low contrast values. Thus, the NPM value of the PSA specks could be easily calculated by the total NPM of the handsheet at the high contrast value minus the projected NPM of the ink specks from its low contrast conditions. Compared to the dye method, which was also used on the measurement of microstickies, this method is suggested as a simple and quick laboratory tool to measure the relative quantity of PSA in the mixed office waste paper with minimum interference from the residual toner ink.

The effect of commercial heat treatment on physical and mechanical properties of compression wood (CW) and opposite wood (OW) of black pine (Pinus nigra Arnold) was investigated. Black pine logs containing CW were cut parallel to the pith and separated into CW and OW sections. A commercial heat treatment process was applied to pine lumber at 180 and 210 ºC for 3 hours. Water absorption (WA), contact angle (CA), swelling, modulus of rupture (MOR), modulus of elasticity (MOE), and impact bending strength (IBS) were measured. The results showed that heat treatment decreased water absorption and swelling of the CW and OW of black pine. Heat treatment at 210 °C temperature decreased the longitudinal swelling of CW by 51.4%. Higher immersion time lowered the effect of heat treatment on the WA values. The CA values of the CW and OW increased due to heat treatment. Heat treatment reduced the MOR, MOE, and IBS values. The results indicated that MOR, MOE, and CA values were highly affected in the CW; on the other hand, the IBS value was highly affected in the OW by heat treatment compared to control groups. The results indicate that heat-stabilized CW can be used more widely and effectively in the forest products industry.

Most research on the upgrading of bio-oil by cracking has been done under atmospheric pressure, which results in a catalyst coke yield as high as 20 wt%. In this paper, pressurized cracking, as well as co-cracking with methanol proved to be an effective solution for relieving catalyst deactivation. HZSM-5 catalyst was found to deactivate rapidly in the cracking process of pure ketones. However, when methanol was used as the co-cracking substance for ketones under 2 MPa, ketones reached a full conversion of 100 % without obvious catalyst deactivation. The highest selectivity of bio-gasoline phase from co-cracking of ketones and methanol reached a value of 31.6%, in which liquid hydrocarbons had a relative content of 97.2%. The co-cracking of hydroxypropanone and methanol had lower bio-gasoline phase selectivity but better oil phase quality (liquid hydrocarbons selectivity up to 99%) than those of cyclopentanone and methanol. Based on the experimental results, the promotion mechanism of methanol on cracking of ketones in bio-oil was illustrated by a co-cracking mechanism model.

The main objective of this research was to study the feasibility of incorporating organosolv semi-chemical triticale fibers as the reinforcing element in recycled high density polyethylene (HDPE). In the first step, triticale fibers were characterized in terms of chemical composition and compared with other biomass species (wheat, rye, softwood, and hardwood). Then, organosolv semi-chemical triticale fibers were prepared by the ethanolamine process. These fibers were characterized in terms of its yield, kappa number, fiber length/diameter ratio, fines, and viscosity; the obtained results were compared with those of eucalypt kraft pulp. In the second step, the prepared fibers were examined as a reinforcing element for recycled HDPE composites. Coupled and non-coupled HDPE composites were prepared and tested for tensile properties. Results showed that with the addition of the coupling agent maleated polyethylene (MAPE), the tensile properties of composites were significantly improved, as compared to non-coupled samples and the plain matrix. Furthermore, the influence of MAPE on the interfacial shear strength (IFSS) was studied. The contributions of both fibers and matrix to the composite strength were also studied. This was possible by the use of a numerical iterative method based on the Bowyer-Bader and Kelly-Tyson equations.