玉米秸秆-PVA复合气凝胶的制备及其吸附性能研究

以玉米秸秆为原料,用溴化锂和聚乙烯醇(PVA)溶液将其溶解,制备玉米秸秆-PVA复合气凝胶。采用正交试验法对制备工艺进行优化,并通过FT-IR、吸附率等手段对气凝胶的相关性能进行表征。结果表明：复合气凝胶的优化制备工艺条件为：固液质量比(秸秆∶混合溶液)为1∶100,PVA添加量与秸秆的质量比为100∶15,PVA浓度为5%,溴化锂浓度为66%,溴化锂溶液和PVA的质量比为13.85∶1。该工艺下所制得的复合气凝胶密度低至0.026 8 g/cm³,比表面积为175.00 m²/g,对废弃机油的最大吸附倍率为35.01 g/g。制备过程中,纤维素的氢键被破坏,PVA与纤维素之间通过氢键连接。复合气凝胶的密度越小,其吸油率越大。复合气凝胶具有全范围内的孔径,且大部分孔径处于介孔范围内,因此有利于对大分子污染物的吸附。     

闪爆稻秆纤维/聚乙烯醇制品热压成型及性能研究

采用连续式螺杆闪爆预处理稻秆,得到闪爆稻秆纤维(SERS)。以聚乙烯醇(PVA)为胶黏剂,将具有一定含水率的SERS与PVA粉末直接混合,热压制备复合制品。探究了SERS含水率、PVA种类和成型温度对制品机械性能的影响。结果表明:稻秆纤维中适当的水分能够增塑PVA,软化稻秆纤维,促进两者在成型过程中的塑性形变能力。以含水率为10%的SERS和PVA0588为原料,在210℃下热压制备的SERS/PVA复合板材,其弯曲强度和弯曲模量分别达到57.92 MPa和6 780 MPa,2 h吸水厚度膨胀率仅为16.7%。基于相同成型工艺可高效制备形状复杂的复合容器,有利于实现植物纤维的高效与高值化利用。     

纤维素/聚乙烯醇复合气凝胶制备及其性能研究

针对纤维素(CE)气凝胶机械回弹性、尺寸稳定性差等问题,基于冷冻干燥工艺和化学气相沉积技术,利用聚乙烯醇(PVA)对CE进行复配,以甲基三乙氧基硅烷(MTES)对CE/PVA进行改性,制备了具有轻质性、高弹性和疏水性的多孔S-CE/PVA复合气凝胶。研究了PVA添加量对S-CE/PVA复合气凝胶力学性能的影响,随着引入PVA质量分数的增加,纤维素气凝胶的压缩强度增加;当PVA添加量为纤维素质量的15%(S-CE/PVA-15%)时,气凝胶压缩应力增加至66 kPa,比纯的硅烷改性纤维素气凝胶提升了6.5倍。同时探究了MTES改性对复合气凝胶微观结构、热稳定性、亲/疏水性、比表面积和物理特性的影响,改性后的S-CE/PVA复合气凝胶具有紧密的片层结构,初始分解温度由284.0℃上升至314.6℃,水接触角高达115°,比表面积为109.42 cm³/g,密度为0.045 g/cm³,孔隙率大于95%。     

纳米纤维素基吸油气凝胶的制备及性能

以竹粉为原料制备纳米纤维素基体材料,以聚乙烯醇(PVA)为增强相,在酸性环境下采用冷冻干燥法制得PVA/CNFs(纳米纤维素)复合气凝胶;采用三甲基氯硅烷(TMCS)对其进行疏水改性处理,随后将其浸渍到还原氧化石墨烯(r GO)悬浮液中,最终制得疏水型r GO/PVA/CNFs复合气凝胶;通过扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)、拉曼光谱(Raman)、接触角(CA)和吸油性能测试,对所制气凝胶的微观形貌、化学结构、疏水性能及吸油性能进行表征。结果表明:制得的复合气凝胶密度为6.78 mg/cm3,具有均匀的三维网状多孔结构,且孔洞结构表面均被石墨烯片层覆盖;经过TMCS疏水处理后,在气凝胶表面形成疏水层结构。FT-IR和Raman分析表明,TMCS疏水改性处理并未改变PVA/CNFs复合气凝胶的化学结构。经疏水处理后气凝胶与水的接触角为138°左右,吸油倍率为78 g/g左右,且吸附过程迅速,饱油后也能悬浮于溶液表面,便于回收再利用。     

木质素改性HAp/PVA生物复合材料研究

为实现制浆造纸行业剩余物中木质素的高值化利用,研究了有机溶剂型木质素/纳米羟基磷灰石/聚乙烯醇(EOL/HAp/PVA)复合材料的制备与性质。1)采用化学沉淀法合成HAp,其XRD谱图中发现归属于(002)、(211)、(112)、(202)、(310)晶面的特征峰;其FTIR图中发现归属于PO_4~(3-)基团的特征峰,证实HAp的存在。2)结合超声处理、聚合物共混技术制备出EOL为0、3.5%、7%(质量分数)的EOL/HAp/PVA复合材料。3)复合材料各组分间存在氢键,由此构成了EOL/HAp/PVA体系的有机-无机杂化界面。4)随EOL含量上升,EOL/HAp/PVA外观由白变棕、微观质地更加均匀、柔性有所增强。5)EOL/HAp/PVA复合材料性能良好,表明其具备用于人工关节软骨的潜力。     

聚乙烯醇/三聚氰胺改性脲醛树脂胶黏剂制备芦苇刨花板及性能研究北大核心

为解决普通脲醛(UF)树脂对芦苇材料胶合性能差的问题,以聚乙烯醇/三聚氰胺改性脲醛(PVA/MUF)树脂为胶黏剂制备芦苇刨花板。通过正交试验,研究密度、热压温度、热压时间、施胶量等因素对板材内结合强度(IB)、静曲强度(MOR)以及2 h吸水厚度膨胀率(TS)的影响。结果表明:芦苇刨花板的优化制备工艺为:密度0.85 g/cm3、热压温度160℃、热压时间5 min、施胶量12%。所制得的芦苇刨花板IB和MOR分别为1.00 MPa和21.4 MPa,与木材刨花板相当。未来,使用PVA/MUF树脂改性胶黏剂制备的芦苇刨花板有望替代传统木材刨花板。     

壳聚糖/聚乙烯醇的流变行为及其可纺性研究

采用乙酸(HAc)作为溶剂，配制壳聚糖(CS)/聚乙烯醇(PVA)纺丝液，探究纺丝液稳态流变和动态流变性能并考察其静电纺丝的可行性。研究结果表明：随着CS质量分数的增加，纺丝液的稠度系数、结构黏度指数、表观黏度、储能模量(G′)、损耗模量(G″)和复合黏度(η^*)均相应增加，非牛顿指数相应减小，不利于CS/PVA纺丝液静电纺丝。随着测试温度的增加，纺丝液的稠度系数、结构黏度指数、表观黏度、G′、G″和η^*均相应减小，非牛顿指数相应增加，纺丝液流动性能加强，可纺性提升。当CS质量分数为3.0%时，纺丝液在测试温度30℃下的稠度系数和结构黏度指数均较小，分别为7.978 1和2.16,且非牛顿指数为0.887 7接近于1,表明该纺丝液具有良好的流动性和加工性。结合SEM和流变行为分析，在室温条件下CS质量分数为3.0%的CS/PVA纺丝液呈现优异的可纺性，可以构建连续、均匀且不带珠状连结的纳米纤维。     

低黏度高固含量聚醋酸乙烯酯乳液胶黏剂的制备及应用

聚醋酸乙烯酯(PVAc)具有固化速度快、初粘性好的优点，可作为胶黏剂或增稠剂应用于人造板工业。研究以醋酸乙烯酯(VAc)为单体、聚乙烯醇(PVA)为保护胶体，采用半连续乳液聚合法制备低黏度、高固含量聚醋酸乙烯酯乳液，并考察了PVA种类及其他聚合工艺因素对乳液性能的影响。结果表明：PVA种类对乳液性能影响较大。采用激光粒度分析仪、差示扫描量热仪(DSC)等对不同种类PVA合成的乳液进行表征表明：粒径随PVA醇解度增加而明显增大；PVA聚合度对乳液的玻璃化转变温度(T_g)影响较大。以PVA₀₅₉₉为保护胶体制备的PVAc乳液作为木材胶黏剂时，其拉伸剪切强度达8.62 MPa。     

Ni-P/rGO复合催化剂的制备、表征及其松香加氢性能研究

以鳞片石墨为原料,采用改良后的Hummer s法制备了氧化石墨烯(GO)分散液,然后以化学还原法制备非晶态Ni-P/rGO复合催化剂,并以松香加氢为探针反应考察了催化剂制备条件对催化性能的影响,进一步通过正交试验优化了松香加氢反应的工艺条件。结果表明:在Ni元素与GO质量比为6∶1、溶液pH值为11、n(P)/n(Ni)为5∶1、温度为70℃的优化制备条件下,以及反应时间4.5 h、催化剂用量5%、反应温度200℃和反应压力4.5 MPa的适宜加氢反应条件下,该催化剂对松香加氢具有较高的活性,枞酸型树脂酸转化率达99.37%,且重现性良好,该催化剂重复使用7次仍能保持较高的催化活性。X射线衍射(XRD)、透射电镜(TEM)、X射线光电子能谱(XPS)表征结果表明:非晶态Ni-P/rGO复合催化剂已经成功制备,未与rGO复合的Ni-P粒子颗粒较大且分散性较差,使用7次后复合催化剂中Ni 0含量相对下降,活性组分流失导致催化活性稍有降低。     

酶/磁双驱动果胶/海藻酸钠复合微球的制备及表征

设计构建了酶/磁双驱动的果胶(PET)/海藻酸钠(SA)复合微球机器人药物递送系统,即通过注滴法,以乳酸钙为交联剂,将Fe₃O₄磁性纳米粒子(Mag)、过氧化氢酶(CAT)/葡萄糖氧化酶(GOD)/磷酸锌杂合颗粒、天然喜树碱衍生物(盐酸伊立替康CPT-11)药物同时装载到PET/SA复合微球中,制备得到磁响应的负载双酶驱动载药磷酸锌杂合颗粒的PET/SA复合微球(CPT-11/CAT/GOD-Zn₃(PO₄)₂@Mag/PET-SA)。考察了不同PET与SA复配比及磁性颗粒的加入对复合微球结构、形貌、粒径及药物包封率的影响,采用UV-vis法测定了载药微球机器人在模拟胃液(SGF,pH值1.2)和模拟肠液(SIF,pH值6.8)释放介质中的药物释放曲线。研究结果表明：制备得到的酶/磁双驱动微球载药机器人球形度好,但磁性颗粒的加入使复合微球表面出现大量褶皱,变得粗糙,从而使药物包封率有明显的下降;当m(PET)∶m(SA)为1∶3时,加入磁性颗粒前复合微球的平均粒径为1.658 ...     

Preparation and characterization of wood/montmorillonite nanocomposites

With montmorillonite (MMT) organically modified as organophilic MMT (OMMT) and water-soluble phenol formaldehyde resin (PF) as intermediate, Chinese fir (Cunninghamia lanceolata) wood/MMT nanocomposites (WMNC) were prepared via nano intercalation compounding and characterized by XRD, SEM and FTIR. Results show that: 1) the preparation of OMMT is very successful; 2) the self-made PF can effectively intercalate into MMT to increase markably its gallery distance and even exfoliate its nano silicate laminae; 3) the XRD analysis indicates that some exfoliated MMT enters the non-crystallized region of microfibrils in wood cell walls and the crystallinity degree of wood in WMNC decreases; 4) the SEM graphs show that multiform MMT exists in WMNC. Some grains block in wood cell lumen, some layers adhere to the wood surface of the inner cell wall and some exfoliated nanolaminae even insert into wood cell walls; and 5) the FTIR analysis suggests that MMT and wood in WMNC perhaps interact via certain chemical bonding.     

Preparation of Chinese fir wood/MMT nanocomposites and the factors affecting it

The nano intercalation compounding of wood and MMT has important implications for the modification of wood and for the development of new materials. With water-soluble phenol formaldehyde resin as an intermediary, the nanocomposites of Chinese fir (Cunninghamia lanceolata) wood and montmorillonite (MMT) were prepared via three impregnation methods, i.e. normal pres-sure, once and twice vacuum methods. Based on the weight percent gain (WPG) of impregnated wood, the effects of compounding wood and MMT in term...     

Properties of Wood/Montmorillonite Nanocomposites

INTRODUCTIONWood possesses many special properties, such asbeautiful grain, natural color, high strength-to-weightratio, good electricity and heat insulation; and it can beeasily processed, glued or dyed. It is biodegradable,recyclable and environmental-friendly (Wang Tianminet al. 2002). But as a biomaterial, it also has intrinsicdefects as easy decaying, burning and deforming,which largely limits its usage. Nano science andtechnology opens a completely new way to developwood composites…     

Structure and characterization of Chinese fir (Cunninghamia lanceolata) wood/MMT intercalation nanocomposite (WMNC)

With water-soluble phenol-formaldehyde resin as an intermediate, Chinese fir (Cunninghamia lanceolata) wood/montmorillonite nanocomposite (WMNC) was prepared through vacuum impregnation and characterized with XRD, SEM, FTIR and TG-DTA analyses. The XRD analysis indicated that the wood crystallinity of WMNC decreased, the MMT exfoliated and some nano silicate layers entered into the non-crystallized microfibrillar region of the wood cell wall. Wood structure is anisotropic and its impregnation is anisotropic. Due to the nonuniformity of the MMT organic modification, PF intercalation and wood impregnation, the MMT configuration and distribution in wood were diverse. The SEM graphs of WMNC showed that some silicate grains were blocked in the wood cell lumen, some silicate layers adhered to the inner surface of the wood cell wall, and some exfoliated MMT layers even penetrated the wood cell wall. The obtained hydroxyl of WMNC increased and its ether linking decreased. It was considered that MMT and wood interacted not only with hydroxyl bonds, but also involved some chemical linking. Compared with untreated wood and the PF-impreg, the pyrolysis process of WMNC changed; its starting decomposing temperature decreased and its pyrolysis weight loss at high temperatures greatly decreased. The WMNC indicated certain nanoeffects of the composition of the inorganic MMT nanolamellae. __________ Translated from Journal of Beijing Forestry University, 2007, 29(1): 131–135 [译自: 北京林业大学学报]     

Design of wood/montmorillonite (MMT) intercalation nanocomposite

Studying new wood composites through nano science and technology (NSC) will develop new compounding theory of wood, and accelerate the combination of new technology, wood science, material science and other disciplines. The compounding of wood and inorganic MMT on nanoscale molecular level has high potential to greatly improve the mechanical properties, fire retardance, abrasion resistance, decay resistance, dimensional stability and other properties of wood. Based on the great achievements of polymer/montmorillonite (MMT) nanocomposites, this paper reviewed nano intercalation compounding methods (i.e. in-situ intercalative polymerization and direct polymer intercalation), and discussed the structure, properties and modification of montmorillonite (MMT). According to the main chemical components and particular structure of wood, the authors discussed the liquefaction and plasticization of wood, compared the dissolvability and meltability between wood and polymer, and then systematically put forward the basic idea, technological processes and schematic diagram to prepare wood/MMT nanocomposites (WMNC). The key technology to prepare WMNC is either to introduce delaminated MMT nanolayers into wood with the help of some intermediate polymers, or to obtain liquefied wood or plasticized wood from the complicated natural composite. It is applicable and effective to realize wood/MMT nanoscale compounding with the help of proper intercalation agent and medium polymer through the proposed “one-step” or “two-step” impregnating processes.     

Design of Wood/Montmorillonite (MMT) Intercalation NanocompositeCollege of Material Science and Technology, Beijing Forestry University, Beijing 100083, P.R.China

Studying new wood composites through nano science and technology (NSC) will develop new compounding theory of wood, and accelerate the combination of new technology, wood science, material science and other disciplines. The compounding of wood and inorganic MMT on nanoscale molecular level has high potential to greatly improve the mechanical properties, fire retardance, abrasion resistance, decay resistance, dimensional stability and other properties of wood. Based on the great achievements of polymer/montmorillonite (MMT) nanocomposites, this paper reviewed nano intercalation compounding methods (i.e. in-situ intercalative polymerization and direct polymer intercalation), and discussed the structure, properties and modification of montmorillonite (MMT). According to the main chemical components and particular structure of wood, the authors discussed the liquefaction and plasticization of wood, compared the dissolvability and meltability between wood and polymer, and then systematically put forward the basic idea, technological processes and schematic diagram to prepare wood/MMT nanocomposites (WMNC). The key technology to prepare WMNC is either to introduce delaminated MMT nanolayers into wood with the help of some intermediate polymers, or to obtain liquefied wood or plasticized wood from the complicated natural composite. It is applicable and effective to realize wood/MMT nanoscale compounding with the help of proper intercalation agent and medium polymer through the proposed "one-step" or "two-step" impregnating processes.     

聚乙烯醇/纳米纤维素晶体复合膜热学性能

以微晶纤维素(MCC)为原料,通过硫酸水解得到纳米纤维素晶体(NCC),再将纳米纤维素晶体与聚乙烯醇复合共混制备聚乙烯醇/纳米纤维素晶体复合膜,研究复合膜的热学性能,同时采用场发射透射电镜(FETEM)、场发射扫描电镜(FE-SEM)、原子力显微镜(AFM)、热重分析(TG)、差示扫描量热仪(DSC)等仪器对纳米纤维素晶体及其复合膜进行表征与分析。结果表明:所制得的纳米纤维素晶体直径约2～24nm,50～450nm长,呈棒状;由FE-SEM图可观察到纳米纤维素晶体与聚乙烯醇具有良好的界面相互作用,但在较大添加量7%时,NCC出现部分团聚,与基体的相容性下降;由TG和DSC分析说明NCC与PVA基体可较好相容,形成了热稳定性较好的复合膜,但当NCC添加量较大时,由于团聚使复合膜热稳定性下降。     

木材/蒙脱土(MMT)纳米插层复合材料的制备构想

基于聚合物 蒙脱土纳米插层复合材料的研究成果 ,综述了插层复合方法的原理、工艺过程和产品性能 ,分析比较了单体插层原位聚合和聚合物直接插层等方法。从木材与蒙脱土的结构和组成特性出发 ,分析比较了木材与聚合物溶解、熔融性的不同 ,讨论了利用插层复合原理制备木材 蒙脱土纳米复合材料的基本构想 ,并进一步提出了相应的技术路线和工艺流程概念图。     

聚苯胺/竹炭复合材料的制备及性能研究

利用竹炭(BC)的导电性和特殊的多孔结构,结合聚苯胺(PANI)的导电性,通过原位溶液聚合法制备了具有导电性能的聚苯胺/竹炭(PANI/BC)复合材料,考察了各种反应条件对复合材料电导率的影响.利用四探针、红外光谱、扫描电镜对复合材料的导电性能、分子结构、微观形貌进行表征测试.结果表明:当苯胺用量为1mL,引发剂过硫酸...