Preparation and Application of Microfibrillated Cellulose-modified Ground Calcium Carbonate

Microfibrillated cellulose(MFC) was first prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO) oxidation pretreatment and mechanical grinding in the presence of a certain amount of ground calcium carbonate(GCC).The effects of GCC dosage and grinding concentration on the fibrillation were investigated.The obtained MFC was then added to the bulk GCC to form MFC-modified GCC fillers.The properties of MFCmodified GCC fillers were compared to those of the traditional GCC fillers.Results showed that the resulting fibrils became more uniform when the dosage of GCC was 10%~15% and the concentration of the suspension was 6.97%.Compared to traditional GCC,the average particle size of the MFCmodified GCC fillers was larger.Scanning electron microscopy images showed that GCC and MFC formed a bridge structure in the MFC-modified GCC fillers.In the process of papermaking,the MFC-modified GCC fillers decreased the drainage rate but increased the retention of fillers.The prepared papers filled with MFC-modified GCC fillers had higher tensile strength than those filled with traditional GCC fillers.     

造纸非金属矿粉体材料消费现状与发展趋势

阐述了碳酸钙、高岭土、滑石等主要非金属矿粉体近几年的消费量和消费特点,比较了不同矿物粉体消费结构的变化,预测了造纸矿物粉体材料的主要研发方向及市场发展前景。     

Preparation of Ultrafine Starch Particle and its Application in Paper Coating

Despite its biodegradability, adequate cohesive strength and comparatively low cost, the use of cooked starch as a paper coating binder is limited due to its high viscosity and serious negative impact on the gloss. Starch-based bio-latex with size in the nanometer or sub-micrometer range has been developed recently to overcome these shortcomings. In this study, ultrafine starch particle (UFSP) was prepared by mechanical milling using a DYNO mill in combination with light chemical pretreatment. Model coating colors containing different dosages of UFSP were applied to base paper and the properties of the coated papers were evaluated. The results showed that the UFSP was disc-shaped with a median particle diameter of 167 nm. Water retention capacity of the coating colors was improved considerably with the addition of UFSP, i.e., the water retention value decreased by nearly 40% when styrene-butadiene latex was replaced by UFSP at a dosage of 3 pph (per hundred parts of pigment). The high shear rate viscosities of the coating colors containing no more than 2 pph of USFP were similar to that of the control coating color at shear strain rate higher than 2000 s1. The properties and performances of the coated papers were comparable to the control coated paper with single synthesized latex binder. The gloss and the print gloss of paper samples with or without USFP were 59.7% and 58.2%, 79.0% and 78.8%, respectively. Surface strength of paper samples with or without USFP were 0.96 and 0.90 m/s, respectively, while the ink absorptivity values were 34% and 33%. This study demonstrates a promising approach to obtain sub-micrometer sized starch for paper coating.     

Effects of MFC-modified GCC as Filler on the Opacity of Pulp Handsheets

Microfibrillated cellulose (MFC) was obtained by mechanical grinding of different pulps. MFC-modified ground calcium carbonate (GCC) was prepared in two different ways, designated MFC-GCC composite filler and MFC-GCC flocs filler. The opacity of pulp handsheets loaded with MFC-modified GCC was measured. The effects of MFC originated from different pulps, pretreatment method, and filler modification on the opacity of handsheets loaded with MFC-modified GCC were discussed. The results show that MFC originated from alkaline peroxide mechanical pulp (APMP) was optimal for improving the opacity of the handsheets and PFI grinding pretreatment for MFC provided a denser structure in the corresponding MFC_APMP-GCC floc filler while enzyme pretreatment was more effective in increasing the opacity of the filled paper. Under the experimental conditions, the opacity of handsheets increased from 81.0% to 82.7% when the unmodified GCC was replaced by an equivalent amount of MFC_APMP-GCC composite filler, while other properties were unchanged.     

壳聚糖/蜂蜡改善纸基材料水蒸气和氧气阻隔性能研究

围绕壳聚糖(CS)和蜂蜡(Wax)在改善纸基材料气体(水蒸气和氧气)阻隔性能方面开展研究,探讨了蜂蜡添加量及其与壳聚糖的复合方式(共混和分层)对纸基材料阻隔性能和涂层热稳定性能的影响。结果表明,涂布纸的水蒸气透过量随蜂蜡添加量的增加而降低,当蜂蜡添加量为15%时,在50%RH (相对湿度)条件下,分层涂布纸和共混涂布纸的水蒸气透过量分别降至21.87和24.13 g/(m²·d),与纯壳聚糖涂布纸相比,分别降低了80.3%和78.2%,分层涂布纸与共混涂布纸的水蒸气透过量差异不大;在75%RH条件下,分层涂布纸(163.69 g/(m²·d))和共混涂布纸(242.24 g/(m²·d))的水蒸气透过量与纯壳聚糖涂布纸相比,分别降低了79.4%和69.5%,而与共混涂布纸相比,分层涂布纸的水蒸气透过量降低了32%。共混涂布纸和分层涂布纸的氧气透过量随着蜂蜡添加量的增加而增大,当蜂蜡添加量为15%时,分层涂布纸和共混涂布纸的氧气透过量仍低至70.19和101.75 cm³/(m²...     

乙二醛接枝网状聚丙烯酰胺的合成及其在纸张增强中的作用

首先采用水溶液聚合法合成中间体网状阳离子聚丙烯酰胺(CPAM),然后与乙二醛单体进行接枝共聚制备纸张增强剂乙二醛-聚丙烯酰胺树脂(GPAM),并讨论接枝共聚反应的pH值以及m(乙二醛)/m(CPAM)等因素对GPAM树脂的特性黏度及增强效果的影响。接枝共聚的最佳条件为:pH=7.0～8.0、m(乙二醛)/m(CPAM)=0.3。合成的GPAM用于抄纸实验,讨论其应用条件对增强效果的影响。结果表明,当聚合物用量0.3%、浆料pH值7.0～8.5、助剂作用时间5min时,纸张的干抗张指数提高了24.6%,湿抗张强度达到15.7%。并用红外光谱(FT-IR)对产物的结构进行了表征。     

Acidified glycerol pretreatment for enhanced ethanol production from rice straw

Rice straw was pretreated using an industrial grade glycerol for ethanol production. The pretreatment was conducted at 130–210 °C for 1–24 h with 5% solid loading. The glucan content in the regenerated rice straw increased with increasing pretreatment temperature and time. The production of fermentable sugars initially increased as the pretreatment temperature and reaction time increased, but then decreased somewhat at the higher temperatures and with longer reaction duration. The highest amount of reducing sugar produced by the enzymatic hydrolysis was achieved at 190 °C for 10 h with 5% solid loading, optimal condition for the glycerol pretreatment of rice straw. Furthermore, it was observed that glycerol pretreatment with the addition of HCl improved the digestibility of fermentable sugars by 4–5 times that of untreated samples. Fermentation of hydrolysates resulted in an ethanol yield of 0.44 g/g sugar, corresponding to a theoretical yield of 84.3%. It was concluded that acidified glycerol is one of the good candidates of the organic solvent for the pretreatment of lignocellulosic biomass.     

我国制浆造纸装备科学技术的发展（续）

简要地讨论了制浆造纸装备及其制造业和学科建设的现状和在我国造纸工业发展中的地位和作用,探讨了近年来我国制浆造纸装备科学技术取得的进展,同时也讨论了国际先进制浆造纸装备科学技术在我国的应用现状;从科技研发、制造业状况和学科建设等方面对国内外制浆造纸装备科学技术现状进行了比较分析;提出了今后我国制浆造纸装备科学技术发展展望与对策建议.     

Ultrathin MoS2 nanosheets in situ grown on rich defective Ni0.96S as heterojunction bifunctional electrocatalysts for alkaline water electrolysis

Developing earth-abundant and highly active bifunctional electrocatalysts are critical to advance sustainable hydrogen production via alkaline water electrolysis but still challenging. Herein, heterojunction hybrid of ultrathin molybdenum disulfide (MoS₂) nanosheets and non-stoichiometric nickel sulfide (Ni_0.96S) is in situ prepared via a facile one-step hydrothermal strategy, followed by annealing at 400 °C for 1 h. Microstructural analysis shows that the hybrid is composed of intimate heterojunction interfaces between Ni_0.96S and MoS₂ with exposed active edges provided by ultrathin MoS₂ nanosheets and rich defects provided by non-stoichiometric Ni_0.96S nanocrystals. As expected, it is evaluated as bifunctional electrocatalysts to produce both hydrogen and oxygen via water electrolysis with a hydrogen evolution reaction (HER) overpotential of 104 mV at 10 mA cm⁻² and an oxygen evolution reaction (OER) overpotential of 266 mV at 20 mA cm⁻² under alkaline conditions, outperforming most current noble-metal-free electrocatalysts. This work provides a simple strategy toward the rational design of novel heterojunction electrocatalysts which would be a promising candidate for electrochemical overall water splitting.