轻质碳酸钙加填量对PCCP/LCP-1复合材料气体吸附性能的影响

利用原位生长法制备了轻质碳酸钙(PCC)加填的植物纤维纸基(PCCP)/金属有机骨架化合物(MOFs,即Zn2(BTC)4,标记为LCP-1)复合材料(PCCP/LCP-1),探讨了PCC加填量对复合材料气体吸附性能的影响;采用傅里叶变换红外光谱仪(FT-IR)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、热重分析仪(TGA)和氮气吸附法(BET)研究了LCP-1与植物纤维的键合方式以及复合材料的表面形貌、比表面积、热稳定性和吸附行为。结果表明,LCP-1与植物纤维之间以酯键结合,PCC加填量的增加可使纸张纤维网络体系暴露出更多的游离羟基,有利于提高LCP-1在PCCP表面的沉积率。此外,PCC的位阻效应降低了LCP-1在PCCP表面的生长空间,导致LCP-1尺寸变小。BET实验表明,与未添加PCC的复合材料相比,添加PCC可显著提高复合材料的吸附性能,且随着PCC加填量的增加,复合材料的氮气吸附量也逐渐提高。     

Comparative study on pyrolysis and catalytic pyrolysis upgrading of biomass model compounds: Thermochemical behaviors,kinetics, and aromatic hydrocarbon formation

In order to understand the pyrolysis mechanism, reaction kinetic and product properties of biomass and select suitable agricultural and forestry residues for the generation desired products, the pyrolysis and catalytic pyrolysis characteristics of three main components (hemicellulose, cellulose, and lignin) of biomass were investigated using a thermogravimetric analyzer (TGA) with a fixed-bed reactor. Fourier transform infrared spectroscopy (FTIR) and elemental analysis were used for further characterization. The results showed that: the thermal stability of hemicellulose was the worst, while that of cellulose was higher with a narrow range of pyrolysis temperatures. Lignin decomposed over a wider range of temperatures and generated a higher char yield. After catalytic pyrolysis over HZSM-5 catalyst, the conversion ratio increased. The ratio for the three components was in the following order: lignincellulose < biomass < xylan. The Starink method was introduced to analyze the thermal reaction kinetics, activation energy (Ea), and the pre-exponential factor (A). The addition of HZSM-5 improved the reactivity and decreased the activation energy in the following order: xylan (30.54%) > biomass(15.41%) > lignin (14.75%) > cellulose (6.73%). The pyrolysis of cellulose gave the highest yield of bio-oil rich in levoglucosan and other anhydrosugars with minimal coke formation. Xylan gave a high gas yield and moderate yield of bio-oil rich in furfural, while lignin gave the highest solid residue and produced the lowest yield of bio-oil that was rich in phenolic compounds. After catalytic pyrolysis, xylan gave the highest yield of monocyclic aromatic hydrocarbons, 76.40%, and showed selectivity for benzene and toluene. Cellulose showed higher selectivity for xylene and naphthalene; however, lignin showed enhanced for selectivity of C10 + polycyclic aromatic hydrocarbons. Thus, catalytic pyrolysis method can effectively improve the properties of bio-oil and bio-char.     

CPAM／膨润土体系下细小纤维-碳酸钙共絮聚机理及强度的研究

以杨木P-RC APMP为原料,对其进行筛分,并对P-RC APMP细小纤维与轻质碳酸钙进行共絮聚,研究了CPAM／膨润土微粒助留体系下,不同的CPAM添加量、膨润土用量及剪切力对细小纤维-碳酸钙共絮聚的影响;结果表明：随着CPAM用量的增加,细小纤维-轻质碳酸钙絮聚团的表面负电荷与浆料的Zeta电位绝对值都不断减小,细小组分的留着率不断增大;随着膨润土用量的增加,共絮聚团的平均弦长不断增大,细小组分的留着不断增大;随着剪切力的增大,细小纤维-轻质碳酸钙絮聚团的尺寸不断减小。     

TEMPO-氧化纤维素纳米纤维对染料的吸附性能及其在有色纸中的应用研究

为改善有色纸制备过程中染料流失及相关污染问题,本研究基于纳米纤维素的高比表面积和丰富官能团特点,提出将TEMPO-氧化纤维素纳米纤维（TOCNF）用于有色纸的制备,以提高染料留着率,降低废水中的染料含量,重点分析了TOCNF对染料（活性红195）的吸附性能及其对有色纸染色性能和物理性能的影响。结果表明,TOCNF对染料的吸附性能良好,上染率可达30.4%,且随着温度的提高、反应时间延长、染料浓度的提高以及TOCNF用量、NaCl用量和Na2CO3用量的增加,TOCNF对染料的吸附性能逐渐提高;TOCNF的加入不仅可显著提高有色纸染色性能（色差最高可达3.81）,而且可提高其力学性能。     

Highly Conductive Fractal-structured Silver Particles for Preparing Flexible Printed Circuits via Screen Printing

Fractal-structured silver particles(FSSPs) are conductive materials with a micron-scale trunk and nanoscale branches, and are characterized with high electrical conductivity and high connectivity. In this study, FSSPs were added to an aqueous additive solution for synthesizing a conductive ink,which was used to prepare two types of printing electrodes via screen printing. The first type included two flexible printed electrodes(FPEs): an FPE on a polyethylene terephthalate(PET) film and an FPE on paper. The second one was a polydimethylsiloxane(PDMS)-embedded FPE. The PETbased FPE exhibited high electrochemical stability when its sheet resistance was 0.38 Ω/sq for a 50%(w/w) content of FSSPs in the prepared conductive ink. Moreover, the embedded FPE demonstrated excellent mechanical properties and high chemical stability. In addition, the embedded structure was endowed with stretchability, which is important for different devices,such as flexible biomedical sensors and flexible electronics.     

基于有限元法的纸机压榨部机架机械性能分析

利用有限元分析的方法,对压榨部机架及加压臂的机械性能进行分析.通过对机架和加压臂的静力分析,得出在静力载荷作用下机架及加压臂的变形及应力分布,校核了机架和加压臂的静力刚强度.通过对机架的模态分析,得到机架的模态频率和模态振型,提出了模型机架的最适宜运行车速为880 m/min,并通过对模态频率分布的分析,提出在一阶模态频率后还有600 m/min的提速空间.     

羟甲基乙醇木素的改性及对纸张强度性能的影响

以H2O2-Fe(Ⅱ)为引发剂,对羟甲基乙醇木素与丙烯酰胺进行接枝共聚反应,探讨了丙烯酰胺和引发剂用量、反应温度和时间对接枝率的影响,对制得的共聚物进行了红外光谱分析并将改性产物进行浆内添加实验.结果表明,当丙烯酰胺与羟甲基乙醇木素质量比为1.5、引发剂与羟甲基乙醇木素质量比为0.06、反应温度为60℃、反应时间3h,可得到最高的接枝率,改性羟甲基乙醇木素能明显提高纸张各项强度.     

CPAM/膨润土体系中剪切力对细小纤维-碳酸钙共絮聚影响的研究

以杨木P-RC APMP为原料,对其进行筛分,并对P-RC APMP细小纤维与轻质碳酸钙（PCC）进行共絮聚,研究了CPAM/膨润土微粒助留体系下,剪切力对细小纤维-PCC共絮聚团大小、颗粒结构的影响;结果表明：随着剪切力的增大,细小纤维-PCC絮聚团的尺寸不断减小;在高转速下,絮聚团虽然被打碎,但悬浮液中单独的白色颗粒很少（PCC）,体系中还是有许多小的絮聚体.     

内切纤维素酶预处理对漂白马尾松纤维形态和结构的影响

针对制备纤维素微纤丝(CMF)所需要高能耗的问题,采用内切纤维素酶对漂白马尾松纤维进行预处理,研究内切纤维素酶预处理过程中,纤维形态、纤维素聚集态和纤维性能所发生的变化。结果表明,内切纤维素酶优先作用于纤维表面,不会对纤维产生明显的起皮、剥皮现象,但是对纤维的切断作用较强,导致内切纤维素酶用量增大时,纤维的平均长度逐渐减小,宽度增加,保水值和Zeta电位逐渐下降,打浆度在酶预处理初期略有下降,之后不断增大;内切纤维素酶主要作用于纤维素的无定形区,使纤维素的结晶度增大,最后在80%~82%之间波动;若要纤维素完全发生水解,还需外切纤维素酶和纤维二糖酶的协同作用。