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.     

碱回收白泥精制碳酸钙对AKD施胶剂的吸附特性研究

用紫外分光光度法和颗粒电荷滴定法测定了几种碱回收白泥精制碳酸钙(LMCC)和商品碳酸钙(包括PCC1、PCC3、GCC1和GCC2)填料对AKD施胶剂的吸附特性。结果显示,LMCC和GCC1对AKD的吸附量高于实验用其他商品碳酸钙,GCC1的比表面积远低于LMCC,但其AKD吸附量却高于LMCC,这可能与填料的电荷特性密切相关。LMCC加填后成纸的施胶度最差,且随干燥温度的增加LMCC对AKD施胶的负面影响增加,AKD吸附量最高的GCC1加填纸的施胶度远高于LM-CC加填纸,这与通常所认为的吸附量越高的填料对AKD施胶的影响越大相矛盾,有可能LMCC对AKD施胶的影响并非单纯的吸附原因。     

不同纤维原料对羧乙基微纤化纤维素膜性能的影响

采用6种不同的纤维原料（漂白硫酸盐阔叶木浆、漂白硫酸盐竹浆、漂白硫酸盐针叶木浆、棉短绒浆、漂白针叶木化学机械浆和玉米芯纤维素）经羧乙基化预处理和机械研磨制备了微纤化纤维素（Microfibrillarized cellulose,MFC）,并通过涂布法制备了MFC膜。探讨了原料羧基含量、研磨程度和原料种类对MFC及其膜性能的影响。结果表明,随着预处理后漂白硫酸盐阔叶木浆羧基含量的增加,MFC的保水值由98%增加到538%,MFC膜的孔隙率由37%下降至19%。当羧基含量为0.8 mmol/g时,MFC膜的抗张强度最高,达53 MPa。另外,随着研磨程度（次数）的增加,所得MFC纤丝化程度提高,MFC膜的强度先升高后降低,最高值为75 MPa。在最优的羧乙基化预处理条件和研磨程度下,由6种不同纤维原料制备的MFC膜中,漂白硫酸盐竹浆所得MFC膜的强度最高,为84 MPa,其孔隙率为25%。     

研磨碳酸钙的胶乳改性及其在加填纸中的应用

采用胶乳对填料级研磨碳酸钙(GCC)进行表面改性,对改性GCC的基本性能及其加填性能进行了研究。结果表明,采用胶乳对GCC进行表面改性时,胶乳在GCC表面的吸附率超过了99%;经过胶乳改性后,填料的白度略有降低,填料平均粒径虽然变大但粒度分布变窄;与未改性GCC相比,改性GCC加填纸的强度性能得到明显提高,在胶乳用量为2.0%(对GCC)、保持纸张强度性能不变条件下,纸张灰分含量从15.8%提高到31.1%,同时光散射系数得到明显改善;且改性GCC可明显提高纸张的施胶性能。     

Carboxyethylated Microfibrillated Cellulose Fibers Prepared from Different Raw Materials

Carboxyethylation pretreatment was used to prepare microfibrillated cellulose(MFC)in this study.In order to evaluate the adaptability of this pretreatment method,carboxyethylated MFC was prepared from six different cellulosic materials.The carboxyl content,degree of polymerization,water retention value,charge density,chemical structure,size distribution,and micromorphology of the materials before and after pretreatment and grinding were studied and compared.The viscosity,ultraviolet(UV)transmittance,and thermal stability of the MFC samples at a certain concentration were determined.The results showed that the carboxyl content,water retention value,charge density,degree of polymerization,size distribution,and micromorphology of the pretreated and ground samples varied with those of the raw materials.The initial viscosity varied based on the type of raw material used.The MFC suspension prepared from cotton linter pulp had the highest UV transmittance,while the MFC prepared from bleached softwood kraft pulp had the highest viscosity at a low shear rate.After thermal degradation,the amount of residual char from the MFC prepared with the thermo-mechanical pulp was slightly higher than that of the other MFCs.This study demonstrates that carboxyethylation is an effective pretreatment method for different cellulosic materials.     

阳离子球形聚电解质刷的助留助滤性能

制备了以碳球(CS)为核、甲基丙烯酰氧乙基三甲基氯化铵(DMC)为壳的阳离子球形聚电解质刷(CS-PDMC),探讨了其与阴离子聚丙烯酰胺(APAM)形成的二元体系中CS-PDMC用量对两种填料(重质碳酸钙(GCC)、高岭土)的首程留着率及浆料滤水性能的影响。当浆料中GCC用量15%时,加入用量0.8%的CS-PDMC(相对于绝干浆,以下同),GCC的首程留着率最高,为79.3%;当浆料中高岭土用量15%时,加入用量1.0%的CS-PDMC,高岭土的首程留着率最高,为88.5%。当浆料中GCC用量10%时,加入用量0.8%的CS-PDMC,浆料滤水速度最快,为0.91 m L/s;当浆料中高岭土用量5%时,加入用量0.8%的CS-PDMC,浆料的滤水速度最快,为0.83 m L/s。     

CPAM-膨润土双元体系在新型硅酸钙加填纸上的应用

比较分析了CPAM-膨润土双元微粒助留体系对新型硅酸钙(FACS)和研磨碳酸钙(Gcc)加填浆料的留着、滤水及纸张性能的影响.实验结果表明,CPAM-膨润土双元体系应用于FACS加填纸中时,CPAM需求量高于GCC加填的;膨润土用量为0.1％时,CPAM用量的增加,能改善FACS加填纸料的留着性能,但对其滤水性能却有不利影响;CPAM用量为0.08％时,随着膨润土用量的增加,FACS加填纸料Zeta电位的下降比GCC加填的更快;膨润土的用量低于0.2％时,膨润土用量的增加对纸料的首程留着率和滤水性能都有利.CPAM用量为o.08％、膨润土用量为0.1％时,FACS加填纸白度与GCC加填纸张相当,但是不透明度比GCC加填纸高;FACS加填纸的抗张指数比GCC加填纸低11.2％,撕裂指数比GCC加填纸低21.0％;FACS加填纸张的松厚度比GCC加填纸高41.7％.加填纸张的扫描电镜对比发现,FACS能够较好地填充在纤维之间的缝隙中,可以看到纤维与填料之间有较好的交织.     

草浆白泥加填特性的研究

研究取自不同厂家白泥碳酸钙的基本物化特性和加填应用性能,并将其与商品沉淀碳酸钙(PCC)和研磨碳酸钙(GCC)填料进行性能对比。实验结果表明,碱回收白泥精制碳酸钙的活性氧化钙和残碱含量与商品碳酸钙相当,但其白度和碳酸钙含量低,杂质含量高。白泥碳酸钙具有较高的比表面积,白泥颗粒呈不规则状且粒径分布较宽,其表面带负电而且具有较高的电导率。白泥加填后成纸的光学性能介于商品PCC与GCC之间,强度性能与商品碳酸钙相当,且白泥加填具有较高的留着率,但是白泥对AKD施胶会产生明显的负面影响,要达到常规填料的施胶度水平,白泥加填纸对AKD的消耗量是商品碳酸钙的2倍甚至更高。     

不同制备方式得到的MFC的增强应用对比

分别采用TEMPO诱导氧化预处理结合机械研磨法和PFI磨精浆法制备了2种微纤化纤维素(分别记作TO-MFC和PR-MFC),比较了TO-MFC和PR-MFC作为增强剂对抄纸过程的影响及对纸张的增强效果。研究表明：加入3%的TO-MFC或PR-MFC后,浆料滤水速度变慢,填料留着率提高,纸张强度性能提高,其中,抗张强度增幅最大,TO-MFC的增强效果略好于PR-MFC。TO-MFC和PR-MFC均为纳米级纤丝交织形成的网络状结构体,与纸浆纤维之间有很强的结合力,提高了纸张的强度性能。     

酸碱两步法改性硅灰石的表征及对纸张性能的影响

研究了经酸碱两步法改性处理后的硅灰石形态结构变化及作为填料对纸张性能的影响。结果表明,先用H2SO4使硅灰石部分溶解,然后调节p H值至碱性,以使溶出物质再沉积到颗粒表面,形成疏松多孔包覆层,在保持硅灰石原有针状形态的基础上,实现了硅灰石颗粒表面结构的重建。与未改性硅灰石相比,改性后硅灰石的粒径有所增加,白度提高;其加填纸的白度高、松厚度好、强度降低少。虽然改性硅灰石在纸张中的留着率低于未改性硅灰石,但高于GCC填料。     

Lignin-containing Microfibrillated Cellulose Prepared from Corncob Residue via Calcium Hydroxide Co-grinding and Its Application in Paper Reinforcement

In this study, lignin-containing microfibrillated cellulose (MFC) was prepared from corncob residue after xylose extraction via co-grinding with calcium hydroxide. The product was then compared with the MFC obtained by direct grinding and applied to strengthen paper. The chemical composition and morphological structure analysis results showed that the corncob residue can be used to prepare lignin-containing MFC and does not require further purification. Moreover, the co-grinding with calcium hydroxide is easier to fibrillate corncob residue. The MFC obtained by co-grinding with calcium hydroxide had a higher aspect ratio, and its surface was coated with calcium carbonate nanoparticles. MFCs obtained by both the methods mentioned above had an obvious strengthening effect on paper. Compared with the paper without MFC, the tensile index, elongation, burst index, and folding strength of the paper with MFC obtained by co-grinding with calcium hydroxide significantly increased by 17.5%, 22.1%, 19.5%, and 157.1%, respectively. This study provides a novel idea for the utilization of corncob residue, which may enhance the value and promote the comprehensive utilization of corn by-products.     

催化剂预加载Fenton氧化法微纤化纤维素的制备

以溶解浆为原料,采用催化剂预加载Fenton氧化协同高压均质法制备微纤化纤维素(MFC)。探讨了过氧化氢用量、催化剂七水硫酸亚铁用量、反应温度和反应时间对氧化效率的影响,并对氧化后纤维的微观形貌、化学结构变化及MFC微观结构、结晶度、热稳定性进行了表征。结果表明,催化剂预加载Fenton氧化法可显著提高氧化纤维中的羧基和醛基含量,降低纤维素聚合度和Zeta电位,增大纤维之间的静电斥力,利于后续的均质处理。在浆浓25%、过氧化氢用量0.15 g/g浆、七水硫酸亚铁用量1.5 g、pH值3、反应温度45℃、反应时间120 min条件下,氧化纤维中羧基和醛基含量分别为85.43μmol/g和57.32μmol/g,聚合度为154,Zeta电位为?34.72 mV。傅里叶变换红外光谱(FT-IR)表明Fenton氧化纤维成功制备,扫描电子显微镜(SEM)、X射线衍射(XRD)、热重分析(TG)表明MFC尺寸分布比较均匀,直径在200nm左右,结晶度为81.3%,热稳定性有所降低。     

The Young's Modulus,Fracture Stress,and Fracture Strain of Gellan Hydrogels Filled with Whey Protein Microparticles

Texture modifying abilities of whey protein microparticles are expected to be dependent on pH during heat‐induced aggregation of whey protein in the microparticulation process. Therefore, whey protein microparticles were prepared at either pH 5.5 or 6.8 and their effects on small and large deformation properties of gellan gels containing whey protein microparticles as fillers were investigated. The majority of whey protein microparticles had diameters around 2 μm. Atomic force microscopy images showed that whey protein microparticles prepared at pH 6.8 partially collapsed and flatted by air‐drying, while those prepared at pH 5.5 did not. The Young's modulus of filled gels adjusted to pH 5.5 decreased by the addition of whey protein microparticles, while those of filled gels adjusted to pH 6.8 increased with increasing volume fraction of filler particles. These results suggest that filler particles were weakly bonded to gel matrices at pH 5.5 but strongly at pH 6.8. Whey protein microparticles prepared at pH 5.5 showed more enhanced increases in the Young's modulus than those prepared at pH 6.8 at volume fractions between 0.2 and 0.4, indicating that microparticles prepared at pH 5.5 were mechanically stronger. The fracture stress of filled gels showed trends somewhat similar to those of the Young's modulus, while their fracture strains decreased by the addition of whey protein microparticles in all examined conditions, indicating that the primary effect of these filler particles was to enhance the brittleness of filled gels.     

超声处理对制备竹浆微纤化纤维素的影响

以漂白竹浆为原料,采用中性2,2,6,6-四甲基哌啶-氮-氧化物(TEMPO)微波氧化预处理,然后在浆浓0.6%下结合超声波处理将竹浆纤维素分离解纤为微纤化纤维素(MFC)。通过表观分散性观察、透射电子显微镜(TEM)、傅里叶变换红外吸收光谱(FI-TR)和X射线衍射仪(XRD)对不同超声时间所制备的MFC的分散特性、形态特征、化学结构、结晶度和晶型结构进行表征分析。结果表明,超声2 h可以得到分散性好、完全透明的MFC,其直径分布均一(5~15 nm),而长度在微米级;超声处理不会改变纤维素的化学结构和晶体类型,但对其结晶度有一定的影响,超声1.5 h其结晶度最高66.97%,超声2.5 h后其结晶度剧烈下降至39.16%。     

重质碳酸钙的表面改性及其在造纸中的应用

研究重质碳酸钙表面改性的影响因素,确定了最优改性剂。对最优改性剂和淀粉对重质碳酸钙改性的工艺进行了研究,并探讨了改性剂用量、糊化温度、糊化时间、保温时间等因素对重质碳酸钙改性的影响,优化了其操作工艺条件。把制备淀粉-碳酸钙复合物加填到手抄片中,并对手抄片的物理性能进行检测,检测结果表明改性的碳酸钙对纸张的物理性能有很大的提高。     

淀粉-硬脂酸改性碳酸钙的制备及在造纸中的应用

针对造纸常用填料碳酸钙加填量较大时纸张强度严重下降的问题,利用淀粉-硬脂酸反应形成复合物包覆在碳酸钙表面的方法对其表面改性,研究改性碳酸钙制备工艺及改性前后碳酸钙对纸张物理性能的影响。结果表明：当淀粉用量为碳酸钙质量的20%,搅拌速度500r/min,搅拌时间20min,反应温度40℃,淀粉浓度3.0%,脂肪酸用量为碳酸钙质量的4.0%时,制得的改性碳酸钙性能较好。相同加填量下,加填改性碳酸钙的纸张与加填未改性碳酸钙和传统工艺加填的纸张相比具有良好的性能。     

龙眼果肉多糖超微粉碎-酶解提取工艺优化及其免疫活性

依据Box-Benhnken中心组合原则,分别选取超声时间、酶添加量和提取时间3个因素对超微粉碎纤维素酶辅助提取工艺进行优化。通过分析多糖基本成分、分子质量、黏度、溶解度等比较热水浸提法、超微粉碎辅助法和超微粉碎纤维素酶辅助法3种方法制得的龙眼果肉多糖(LP、LP-S、LP-SE)的理化特性。通过分析对巨噬细胞分泌细胞因子的刺激作用,比较3种龙眼果肉多糖的免疫活性。结果表明:①最佳的提取工艺参数为:超微时长2 min,酶添加量140 U/g,pH值5,料液比1∶40,提取温度50℃,提取时长90 min,在此条件下,多糖提取率为38.49%;②LP-SE与LP和LP-S相比,具有得率高,分子质量小,糖醛酸含量低,鼠李糖和阿拉伯糖含量高,低黏度和高溶解性的特性;③LP-SE激活巨噬细胞分泌NO、TNF-α、IL-6、IL-1β的能力显著高于LP和LP-S。不同提取工艺制备的龙眼果肉多糖的理化性质和免疫活性存在显著性差异,超微粉碎-纤维素酶辅助提取法制备的龙眼果肉多糖表现出较好的免疫调节活性。     

响应面法优化机械砂磨辅助提取婆枣中原花青素工艺

为了优化深州婆枣中原花青素提取工艺。以深州婆枣为研究对象,利用机械砂磨辅助提取婆枣中原花青素,通过单因素实验和响应面实验优化提取工艺。研究结果表明,机械砂磨辅助提取婆枣中原花青素优化工艺条件为:研料粒径3 mm、研磨时间16 min、研料用量(体积比)30%、研磨温度62 ℃,液料比25 mL/g、乙醇体积分数61%,在优化工艺条件下婆枣中原花青素得率为1.942%±0.001%。实际验证实验表明,预测回归方程模型预测最大得率与验证试验得率相对误差为0.052%,拟合函数模型是可用的。实验证明机械砂磨波提取深州婆枣中原花青素的工艺是可行的。     

微切变—助剂互作技术辅助提取柑橘皮总黄酮的工艺研究

目的研究以氯化钾为助剂的微切变—助剂互作技术辅助提取柑橘皮中总黄酮的最佳工艺条件。方法以柑橘皮为主要原料,氯化钾为助剂,乙醇为提取溶剂。采用单因素试验和正交试验,以柑橘皮中总黄酮的提取率为考察指标,对助剂添加量、研磨时间、乙醇浓度和料液比等4个因素进行研究,优化了微切变—助剂互作技术辅助提取柑橘皮总黄酮的最佳工艺条件。结果在最佳工艺条件即助剂氯化钾添加量为4%(W:W),研磨时间为35 min,乙醇浓度为40%(V:V),料液比为1:50(m:V)的条件下,总黄酮提取率为2.87%,比传统的热回流法提高了54.30%。结论微切变—助剂互作技术具有提取率高、提取周期短、乙醇用量少、无需加热等特点,是提取柑橘皮总黄酮的一种有效方法。     

慈竹置换蒸煮对己烯糖醛酸含量的影响

研究了慈竹置换蒸煮过程中预浸渍段、温充段、热充段NaOH用量及硫化度对置换蒸煮和蒸煮过程中己烯糖醛酸(HexA)产生的影响,通过合理控制工艺可降低纸浆中HexA含量,不仅有利于纸浆Kappa值的测定,而且可以减轻对后续ECF漂白的不良影响。研究结果表明:当预浸渍段NaOH用量从2g/L到10g/L变化时,HexA的含量从4.278μmol/g增加到了6.515μmol/g;温充段的NaOH用量对置换蒸煮中HexA含量影响较小,当NaOH用量从5g/L增加到15g/L时,HexA的含量仅降低了0.85μmol/g;热充段NaOH用量对HexA含量的影响最为显著,当热充段NaOH用量从20g/L增加到40g/L时,HexA的含量从14.14μmol/g下降到4.28μmol/g。硫化度对HexA含量影响较小。当预浸渍段NaOH浓度为10g/L、温充段NaOH用量为15g/L、热充段NaOH用量为30g/L,硫化度为23%时,浆料中HexA的含量仅为6.51μmol/g,去除HexA的影响后,浆料卡伯值为12.0,得率为44.21%。