Volume 34, Issue 3

Pulp-polylactic acid composites (PPCs) with monoethanolamine, alkaline sulfite-anthraquinone, unbleached and bleached soda bagasse pulps and polylactic acid (PLA) were successfully fabricated using twin-screw extrusion. The results were compared with bagasse flour-PLA composites (WPCs) as reference. The results indicated that the mechanical strengths of produced composites with pulp fibers were increased compared to the neat PLA and bagasse flour-PLA composites. Monoethanolamine and alkaline sulfite-anthraquinone fibers due to their surface chemical structure had a superior compatibility with PLA compared with other used bio-fibers which has been confirmed by SEM micrographs too. FTIR was used to investigate the effect of different chemical treatments on the bio-fibers. The results of XRD analysis showed that the crystallinity of PPCs was substantially improved by incorporation with pulp fibers compared to WPCs composites. The water absorption of the PPCs is different due to using the diverse bio-fibers. According to DMA analysis, the tan delta was substantially decreased when PLA was reinforced by different bio-fibers. The biodegradation of green composites were characterized and the results showed that the biodegradability of the PLA was increased due to addition of bagasse pulp biofibers.

Effective utilization of fibrous materials plays a major role in techno-economic viability of the resources. Sunflower stalk (SS) as one of highest bio-fibrous waste was assessed respect to fiber features in biorefinery approach. The lumen diameter, wall thickness and fiber length were measured as (∼12 µm), (5.25 µm) and (1.58 mm), respectively. The wider lumen diameter makes its suitable for chemical treatments and purification. The applied Pulping conditions decreased the fiber length and wall thickness, with the least reduction by soda-anthraquinone. Derived indices involved rigidity and flexibility coefficients, aspect and Runkel ratios, solid and Luce’s shape factors were also calculated based on the measured values. The aspect ratio (77.5) put SS fibers as very good resources for lignocellulosic products and composites. The flexibility coefficient (57) belongs to the elastic category and was not altered by pulping. The Runkel ratio was lesser than 1 (>0.9) but decreased by the pulping, to some extent. The Luceʼs shape factor was nearly calculated 0.5, near to the bagasse and eucalyptus species. Solid factor (0.17) and rigidity coefficient (0.51) were considered to be good fiber resource. Totally due to the SS fiber characteristics, the agricultural waste suitability for value adding bio-based production could be reported.

Lime mud (LM) is a by-product originated from the causticization process of papermaking industry. Microscopic structural changes of LM in carbonization process lead to defects on its performance. Regulating the growth of calcium carbonate obtained from the carbonization process and preventing its influence on the surface microstructure of LM has become the key to achieve the self-digestion of this solid waste. In this study, microscopic structural changes of LM co-carbonized with sodium polyacrylate (PAAS) were investigated. The results showed that, compared with traditional carbonation, the microstructure of LM co-carbonized with PAAS was changed remarkably. The newly calcium carbonate formed in the carbonization process would be solidified and coated on the LM surface. Then LM co-carbonized with PAAS would have a smaller specific surface area, pore volume and pore size, which significantly improved its application performance when it was used as paper filler. In addition, a potential technique for improving the surface microstructure of calcium carbonate particle was proposed.

Effect of using diethylenetriamine pentaaceticacid (DTPA) as carbohydrate protector in ozone stage on delignification efficiency, bleaching efficiency, selectivity, metal ions, strength, morphological properties and effluent properties of wheat straw pulp was studied. Using DTPA during ozone treatment viscosity of pulp was improved by 1.1 units, delignification efficiency improved by 13.8 % and pulp brightness improved by 2.5 units compared to that of control. Most importantly the selectivity of ozone treatment was improved by 124 %. Ozone treatment along with DTPA reduced the Fe, Cu and Mn content in the pulp by 52 %, 27 % and 70 %, respectively. Use of DTPA in ozone stage improved the bleached pulp viscosity by 9 %, post colour number by 27 % and reduced the pulp shrinkage by 5 % compared to control pulp. DTPA treated and control pulps have comparable physical strength and morphological properties.

The fiber morphology, the content of hydrogen bonds (HBs) of different models, cellulose crystalline structure, water retention value (WRV), and strength properties of eucalyptus pulp bleached by different bleaching methods (hydrogen peroxide bleaching and sodium dithionite bleaching) were investigated. The results of fourier transform infrared spectrometer (FTIR) showed that the content of intramolecular hydrogen bonds (HB intra ) increased by 11.6 % and 4.8 % after hydrogen peroxide bleaching and sodium dithionite bleaching, respectively. The energy of the hydrogen bonds was changed after bleaching treatment. The hydrogen bonding distances showed a small change after different bleaching treatment. The results of X-ray diffraction (XRD) demonstrated a decrease in the average width of crystallite size in the (002) lattice plane after different bleaching treatment, which was the same trend with the variability of cellulose crystallinity. Compared with the unbleached pulp, the WRV and strength properties of the bleached pulp increased after each bleaching process. Tear index of handsheets made from the hydrogen peroxide and sodium dithionite bleaching pulps were 46.0 % and 54.8 %, respectively. The sodium dithionite bleaching treatment had more significant effects on fiber swelling capability.

The objective of this study is to analyze and foresee potential outliers in pulp and handsheet properties for larger data sets. The method is divided into two parts comprising a generalized Extreme Studentized Deviate (ESD) procedure for laboratory data followed by an analysis of the findings using a multivariable model based on internal variables (i. e. process variables like consistency and fiber residence time inside the refiner) as predictors. The process data used in this has been obtained from CD-82 refiners and from a laboratory test program perspective, the test series were extensive. In the procedure more than 290 samples were analyzed to get a stable outlier detection. Note, this set was obtained from pulp at one specific operating condition. When comparing such “secured data sets” with process data it is shown that an extended procedure must be performed to get data sets which cover different operating points. Here 100 pulp samples at different process conditions were analyzed. It is shown that only about 60 percent of all tensile index measurements were accepted in the procedure which indicates the need to oversample when performing extensive trials to get reliable pulp and handsheet properties in TMP and CTMP processes.

This work conducted an investigation on the water retention value (WRV) of pulp fibers measured by the conventional centrifugation method (with a screen filter) and the maximum content of fiber bonding water (MCFBW) measured by a headspace gas chromatography (HS-GC), a method with no fine loss, developed recently. The results showed there is an excellent correlation (R2=0.988{R^{2}}=0.988) between these two methods. However, the WRVs measured by the centrifugation method are consistent lower than the MCFBWs from the HS-GC method and the absolute differences were significantly increases for the refined pulp fibers, i. e., about 50–70 compared to 30+ for the pulps without treatment. The information from this study provides the insight of the real WRVs of the pulps from different processes.

Tea stalk was used for producing carboxymethyl cellulose (CMC), and a response surface methodology was used to model effective factors relative to the degree of substitution (DS). The optimum values of the independent variables were an alkalization time of 107 min, monochloroacetic acid at 3.11 g, and an etherification time of 171 min, at which the CMC had a DS of 0.668. The yield of CMC in optimization condition was 75.9 %. The optimized CMC was in a good agreement with the commercial CMC, as based on Fourier transform infrared spectroscopy and X-ray diffractometry analyses. The optimized CMC was used to enhance paper strength, and with economic factors and paper strength enhancement taken into account, the appropriate amount of optimized CMC was determined to be approximately 0.3 %. When the amount of optimized CMC was at 0.3 %, the tensile index, burst index, tearing index, and folding endurance were 26.7 N m/g, 1.0kPam2/g1.0\hspace{0.1667em}\text{kPa}\hspace{0.1667em}{\text{m}^{2}}/\text{g}, 12.1mNm2/g12.1\hspace{0.1667em}\text{mN}\hspace{0.1667em}{\text{m}^{2}}/\text{g}, and 2.0, respectively. Together, these results indicated that the optimized CMC exhibited comparable paper strengthening properties relative to that of commercially available CMC.

A number of studies have reported on the mechanical properties of paper coatings and the influence of various parameters on cracking at the fold. Failure at the pigment-binder interface is important to understand because it likely controls how coating layers fail or crack in different applications and processes. In this study, a model system of a calcium carbonate surface in contact with latex and starch binders was used to evaluate the interfacial bonding performance affecting failure in tensile mode. Samples of calcium carbonate marbles with binder films between them were tested in tensile tests and the results were compared with those of pure binder films. In addition, contact angles of calcium carbonate, latex and starch were measured. The failed surfaces were analyzed using Raman spectroscopy and scanning electron microscopy (SEM). All sample involving the calcium carbonate surface failed at a maximum stress of around 25 % compared to that of pure films. Samples that contained starch exhibited larger maximum stress values than pure latex system. The strain at failure for these samples did not depend on the starch content to a large extent. While Raman results did not indicate any residual latex particles on the adhesively failed surfaces, SEM microscopy confirmed that at least part of the failure was still cohesive because regions of binder were present on the surface.

A convenient and quick method has been developed for simultaneous detection of several low molecular weight chlorinated organic compounds (LMWC) in polyamideamine-epichlorohydrin (PAE) solution, using headspace-solid phase microextraction-gas chromatography (HS-SPME-GC). The method consists of extracting a sample containing 0.42 g/mL NaCl with an 85 µm polyacrylate (PA) coated fiber at an extraction temperature of 45∘C{45^{\circ }}\text{C}, for an extraction time of 30 mins, and desorbing the analytes at 240∘C{240^{\circ }}\text{C} for 6 mins. Under these optimized conditions, relatively low limits of detection (LOD) of the analytes, good linearity (r2≥0.9934{r^{2}}\ge 0.9934) and precision (relative standard deviation (RSD≤4.38%\text{RSD}\le 4.38\hspace{0.1667em}\% )) were obtained. Taking into account the matrix effect, standard addition methodology was applied to validate this method and recovery values were between 91.59 % and 109.69 %. This method is therefore well-suited for accurate determination of low levels of LMWC in PAE.

The use of clay filler materials in dispersion coatings is a well-established method to provide improved barrier properties to the coated paper substrate, in particular lowering the water vapour transmission rate (WVTR) through the coating. In this paper we demonstrate the use of small spherical silica particles (∼100–220 nm) as an additive to a clay-latex coating formulation is able to provide further improvements to the barrier properties, when compared to the equivalent silica-free coatings. A significant decrease in both the water vapour transmission rate and the direct water uptake of water (Cobb120{\text{Cobb}_{120}} wettability test) is observed for coatings containing as little as 1 % silica additive.

Surface sizing chemical (mostly oxidized or enzymatically modified starch) flows into the pores of cellulose network and also remains on the surface affecting the surface and intrinsic properties of paper. Polyvinyl alcohol (PVA) can be used for surface sizing because it is a water soluble polymer and has high film forming ability. Due to economic constraints, using PVA alone for surface sizing is not a good option. Current study explored the effects of using oxidized starch and PVA in mixed ratios (80:20, 50:50 and 20:80) on mechanical and surface properties of paper. The surface sizing with sizing weight of 3.5±0.3 g/m 2 was done. The results of the study showed that the breaking length, burst index, air permeance, gloss, Cobb 60 and optical properties like brightness, whiteness, flouroscence of paper were better for mixed ratios in comparison to only oxidized starch. After surface sizing with PVA, the value of air permeance (time of air leak) was increased to 200 Gurley second in comparison to 9 only for base paper. Surface sizing with blends of oxidized starch solution and PVA solution i. e. 80S+20P, 50S+50P and 20S+80P increased the time of air leak by 900 %, 1455 % and 1788 %, respectively in comparison to base paper.

The chemical oxygen demand (COD) of waste water from bamboo heat treatment is mainly organic macromolecule compound which degraded from hemicellulos, lignin and extractives. COD is toxic to aquatic organism and human body and very difficult to degrade. The paper studied the possibility of pre-treating the bamboo heat treated waste water (BHTWW) by combination of iron-carbon micro electrolysis and Fenton method. Orthogonal experiment was designed with 3 factors: the initial pH value, retention time and H 2 O 2 dosage, and carried out with a dynamic sampling device with 2:1 iron carbon ratio. Results showed that the iron-carbon micro electrolysis and Fenton were proved to be a potential method in pre-treating BHTWW, and the optimum parameter should be pH 3.0, 40 min residence time and 0.5 % H 2 O 2 . After pre-treating, the removal rate of COD was 60.29 %, and B/C (biochemical oxygen demand after 5 days (BOD 5 )/COD increased from 0.037 to 0.32, the biodegradability was significantly improved. During the pretreatment, the nutrients in BHTWW had been oxidized, the double bound, conjugated double bond in guaiac lignin were opened or broken and degraded into more small molecular, nutrients such as TOC (total organic carbon) content, total nitrogen and total sugar content all decreased which all contributed for the increase of B/C. The microstructure of activated carbon appeared broken and collapses after pretreatment which indicated that they were eroded or involved during the micro electrolysis reaction.

OCC have been the most important raw material for production of papers for industrial grades. The quality of OCC fibers have been deteriorated by repeated recycling process. In order to overcome the defects of OCC CAT has been developed as a new strategy for old corrugated container (OCC), which could generate mild mechanical action. The effect of CAT was proven through the previous researches which showed the increase of the fiber properties, such as WRV, freeness, and strength properties, and positive effect on paper strength. Based on the results, mill-scale application of CAT was performed at a linerboard mill located in Republic of KOREA. In this paper, mill-scale CAT was designed with higher power and dimension compared to the previous lab-scale CAT, which was equipped at the screw press outlet in a papermaking process. Fiber properties, final product quality, and energy consumption were analyzed with the installation of mill-scale CAT. Freeness and WRV were improved with an increase of passing time, and mean fiber length was constant simultaneously. In terms of process runnability, there was no problem during the test. Furthermore the outstanding achievement was found that the energy could be saved using CAT by around 30 % compared to double-disc low-consistency refining. Consequently CAT could be a new alternative for treatment of OCC without any troubles.

In this work, the fundamentals of upstream flow over cylinders and forming fabrics are investigated, and measures for characterization of fabrics are proposed. Two-dimensional flow over one cylinder, two cylinders, and one and two rows of cylinders, are analysed numerically. By studying different configurations and various Reynolds numbers, the upstream flow features are characterized. It is concluded that cylinders have a short range of upstream flow impact, shortest for rows of cylinders with small spacings. For Re∈[10,80]Re\in [10,80], the Reynolds number dependency is weak. It is shown that a downstream row positioned in tandem has negligible impact on the upstream flow, while a displaced second row influences the upstream flow if the spacing in the first row is larger than one diameter. The pressure drop required to drive the flow over the cylinders depends non-linearly on the porosity of the configuration. Flow measures of the upstream flow are proposed, which in addition to the volume flow per area are used to characterize fabric flow properties. The conclusions from the cylinder study also hold for industrial fabrics, and it can be explained how properties of the fabric influence the final paper. The wave-length of flow periodicity is studied in relation to drainage marking. This study demonstrates that simulations can greatly improve pure experimental-based fabric characterization.