具有吸水保水功能的改性魔芋共聚物包膜缓释尿素的制备及其性能研究

以烯丙基硫脲改性魔芋葡甘聚糖为包膜剂制备包膜缓释尿素。对包膜缓释材料进行扫描电子显微镜(SEM)表征,并分析其吸水性能;评价温度及土壤水含量对包膜缓释尿素氮素溶出率的影响,利用土柱淋溶法检测包膜缓释尿素的缓释效果,并分析缓释尿素对白菜的生长影响。结果表明,烯丙基硫脲接枝魔芋葡甘聚糖在接枝率为35%~45%时,吸水性能最好,吸水量高达794 g/g;随着温度和土壤水含量的升高,包膜缓释尿素氮素溶出率逐渐增加;氮素溶出具有典型的缓释肥溶出特征,表现出良好的缓释效果;白菜对缓释尿素中氮素的利用率提高。     

魔芋葡甘聚糖基敷料的研究及其应用进展

魔芋葡甘聚糖因具有良好的生物相容性、吸水性及凝胶性而被广泛应用于医用敷料领域，且魔芋葡甘聚糖含量丰富，又可生物降解，以魔芋葡甘聚糖为基底的医用敷料的部分性能较传统类型敷料有其独特优势，同时通过物理和化学等改性，可以研究出各种性能不同的新型敷料。本文总结了魔芋葡甘聚糖的近年来的研究，和其在敷料领域的应用。最后对魔芋葡甘聚糖敷料的发展做出展望。     

交联羧甲基魔芋葡甘聚糖的合成及阻垢性能研究

将天然产物魔芋粉进行改性,制备了交联羧甲基魔芋葡甘聚糖,通过静态阻垢法对交联羧甲基魔芋葡甘聚糖的阻碳酸钙垢性能进行了评价.结果表明,当温度为70℃、pH≤7.(p)(Ca2+)≤500 mg/L时,交联羧甲基魔芋葡甘聚糖具有良好的阻垢效果.推测其阻垢作用机理主要是晶格畸变作用和螯合增溶作用.     

羧甲基魔芋葡甘聚糖的制备及其对铅的吸附研究

以异丙醇为分散剂,在碱性介质中一氯乙酸(MCA)和魔芋葡甘聚糖(KGM)反应制备了系列羧甲基魔芋葡甘聚糖(CMKGM).研究了反应时间、反应温度、MCA和NaOH量等因素对取代度及反应率的影响,优化反应条件为n(KGM)n(MCA)n(NaOH)=112,反应温度为50℃,反应时间为4 h.将制得的CMKGM用环氧氯丙烷交联,结果表明交联羧甲基魔芋葡甘聚糖(CCMKGM)能有效的吸附水中的Pb2+;且再生后的CCMKGM吸附性能好,解吸附百分率高.     

新型甲硝唑口腔缓释膜的制备及体外释放

以天然多糖魔芋葡甘聚糖和黄原胶为基质,构建了一种新型甲硝唑口腔缓释膜,用于口腔溃疡局部给药.通过紫外分光光度法测定甲硝唑含量和体外累积释放度,所得药膜每片甲硝唑含量为(13.71±0.35)mg,在30 min时体外累积释放度为26.07%,而3 h时达到91.09%,并可维持3～6 h.结果表明,以魔芋葡甘聚糖和黄原胶复配凝胶为基质的甲硝唑口腔膜剂,具有较好的缓释效果,可望进一步深入开发.     

魔芋精粉中葡甘聚糖含量的测定

魔芋中的葡甘聚糖是一种可再生的天然高分子资源,具有流变性、水溶性和凝胶性等理化性质。目前魔芋葡甘聚糖的应用主要是在食品、化工和医疗等行业。能够简单快捷测定魔芋精粉中葡甘聚糖含量具有重要意义,本论文采用分光光度法快速测定魔芋中的葡甘聚糖含量。     

不同分子量磺酰化魔芋葡甘聚糖的制备与生物活性研究

利用纤维素酶降解原始魔芋葡甘聚糖,制得魔芋葡甘低聚糖,以N,N-二甲基甲酰胺为溶胀剂,用吡啶-氯磺酸法制备了一系列分子量不同而取代度相近的磺酰化魔芋葡甘聚糖(KGMS).通过对KGMS分子量的测试,探讨了磺酰化条件对磺酰化衍生物的影响;以红外光谱、元素分析等表征其结构,并通过生物活性测试(包括体外抗凝血时间、体外抗肿瘤活性、抑菌活性等),探讨了不同分子量的磺酰化魔芋葡甘聚糖的生物活性.     

基于魔芋葡甘聚糖阳离子聚合物的合成及表征

首先以魔芋葡甘聚糖为原料,制备羧甲基化魔芋葡甘聚糖(CKGM),然后在水介质中,以过硫酸钾为引发剂,引发羧甲基魔芋葡甘聚糖(CKGM)与甲基丙烯酰氧乙基三甲基氯化铵(DMC)接枝共聚,制备系列含阳离子季铵盐基团的CKGM-gPDMC接枝共聚物,系统考察了反应条件对接枝共聚物接枝率(GR)和取代度(DS)的影响,与此同时,用FTIR对接枝共聚物结构进行了表征。     

魔芋葡甘聚糖溶胶流变特性及应用研究进展

主要综述了魔芋葡甘聚糖和改性魔芋葡甘聚糖溶胶流变特性．以及各种改性方法对其溶胶流变特性的影响．魔芋葡甘聚糖流变特性的多样性．未改性的魔葡甘聚糖是极为典型的假塑性流体．而改性后的魔芋葡甘聚糖开始呈现出较为明显的牛顿流体行为,且其流变特性受诸多因素的影响．葡甘聚糖经改性后．其透明度、粘度、冻融稳定性均明显改善。此外还总结了魔芋葡甘聚糖溶胶的应用。     

天然高分子魔芋葡甘聚糖的复配产物成膜研究

魔芋葡甘聚糖是日用化学工业潜在的廉价原料之一。以魔芋葡甘聚糖为原料,分别加入卡拉胶、卡拉胶和黄原胶、黄原胶等其它高分子多糖后进行复配。利用红外光谱法地葡甘聚糖及复配产物的成膜机理进行了探讨,并对膜的性能进行了分析研究,提出了制膜方法。文中成膜速度控制容易,制作方法简便锭为开发多种具有凝胶成膜性的日用化学产品提供了依据。     

Influence of glyoxal on curing of urea-formaldehyde resins

In the present paper, the effect of glyoxal on the gel formation within the adhesive systems based on urea-formaldehyde (UF) resins is shown. A reduction of formaldehyde content in wood-based panels by decreasing the formaldehyde/urea molar ratio in the UF resins leads to increasing of the UF resin gel time, and impairing the qualitative characteristics of the UF-based wood materials. Glyoxal is shown to speed up the crosslinking of the macromolecules as well as significant reduction of gel time of adhesive composition. The first reason is the result of reaction between glyoxal and ammonium ion leading to protons releasing. Another reason is that glyoxal and its interaction products react with macromolecules of the UF resin forming a three-dimension cross-linked structure. The gel time and the pot life of the UF resin are measured by the oscillatory viscometer. Formation of the UF cross-linked resin structure with glyoxal and a curing catalyst (ammonium sulfate) is studied using dispersion Raman scattering spectroscopy. Particleboards (PB) are produced using different amount of glyoxal and formaldehyde/urea molar ratio in the UF resin. The properties are evaluated according to the European Standards and include density, internal bond, thickness swelling moisture content and formaldehyde content.     

包埋尿素的葡甘聚糖/黄原胶复合凝胶的制备及其释放特性

尿素的高效利用一直是环保型农业的一个非常重要的研究课题。本工作利用两种天然多糖魔芋葡甘聚糖（KGM）与黄原胶（XG）在形成凝胶过程中的协同作用以及简单的包埋工艺,制备了包埋尿素的KGM/XG复合凝胶,并系统地研究了不同组成的复合凝胶在不同温度和pH环境中尿素的释放特性。结果表明,不同组成的包埋尿素的复合干凝胶在中性水介质中的尿素释放行为表现出3个具有不同特征的阶段。在释放的初期,释放速率较快,尿素的累积释放率随时间显著上升;在第二阶段,尿素的释放与包埋达到基本平衡,期间尿素的累积释放率无明显增加;在释放时间达22～24 h后,进入第三阶段,溶胀的复合凝胶出现崩解,释放速率再度加快,并在32～45 h后达到释放平衡。各阶段的持续时间与复合凝胶的载药量、m_KGM/m_XG和介质的温度有关。介质的pH相似文献   

聚合物凝胶堵漏剂的研究与应用进展

聚合物凝胶堵漏剂是近年来逐步完善和发展起来的一种堵漏材料。简要介绍了聚合物凝胶堵漏剂特点及作用机理,并对国内外聚合物凝胶堵漏剂的研究及应用进行了评述。聚合物凝胶堵漏剂包括地下交联聚合物凝胶和可吸水膨胀交联聚合物凝胶,交联聚合物凝胶强度较低,必须与其他刚性材料配合才能很好地发挥作用。在堵漏施工中,交联聚合物凝胶不受漏失通道的限制,能够通过挤压变形进入裂缝和孔洞空间,最终达到封堵漏层的目的。现场应用表明,聚合物凝胶堵漏剂与其他材料配合使用,能很好地解决钻井过程中的恶性漏失,堵漏成功率高,对碳酸盐岩、裂缝发育地层及孔洞漏失特别有效。     

Synthesis of a Mullite Precursor from Aluminum Nitrate and Tetraethoxysilane via Aqueous Homogeneous Precipitation: An 27Al and 29Si Liquid- and Solid-State NMR Spectroscopic Study

A simple aqueous process is described for the preparation of aluminosilicate colloids and chemically homogeneous mullite precursor gel. Starting from a solution of aluminum nitrate and silicic acid, aluminum is slowly hydrolyzed at 80–100°C by in situ generation of ammonia. A silica gel is rapidly made, probably by a catalytic effect of urea, the base generator. This gel is then slowly digested by partially hydrolyzed aluminum species which break the Si-O-Si bonds and link to the gel by Si-O-Al bonds. Progressively a clear colloidal sol is obtained and the colloidal particle size continues to decrease toward aluminosilicate species where the silicon atoms are in a single environment and may be linked to three hexacoordinated aluminum atoms and a hydroxyl group, by reference to natural imogolite. When the hydrolysis of aluminum is nearly complete, these particles are cross-linked and a final gel precursor of mullite is obtained. This gel is chemically very homogeneous and crystallizes to mullite at 980°C. The structural evolution, from the first gel to the ceramic, has been followed by ²⁷Al and ²⁹Si liquid- and solid-state MAS NMR spectroscopy.     

Cross-linking super-growth carbon nanotubes to boost the performance of bucky gel actuators

Chemical cross-linking of super-growth carbon nanotubes was performed to increase bucky gel actuators efficiency in transferring motion from the nano-scale to the micro-scale. The modification was achieved by a three-step reaction i.e. first an oxidation with nitric acid, then a chlorination process with thionyl chloride and finally the cross-linking with an aromatic diamine. The use of cross-linked nanotubes in bucky gel results in a threefold increase of the charge transfer capability of the composite material and an increase up to ten times of the strain generated by the resulting actuators. To our knowledge, such bucky gel actuators, prepared using cross-linked super growth carbon nanotubes, outperform any other electrochemical carbon nanotube actuator presented so far.     

Thermal, mechanical, and rheological properties of poly(propylene carbonate) cross-linked with polyaryl polymethylene isocyanate

In this study, cross-linked poly(propylene carbonate) (PPC) was prepared using polyaryl polymethylene isocyanate (PAPI) as a cross-linking agent. The gel content, thermal behaviors, mechanical and rheological properties of the cross-linked PPC were investigated. FTIR results showed that the chemical reactions took place between PPC and PAPI and the interactions demonstrated that PPC may be cross-linked with the PAPI. The results of gel content revealed that PPC was partially cross-linked with the PAPI. The cross-linked PPC showed higher glass transition temperature and decomposition temperature compared with pure PPC. Accordingly, the melt flow index gradually decreased and complex viscosity increased with increasing PAPI content. Moreover, the mechanical properties proved also to be enhanced as evidenced by tensile tests. The introduction of small amount of cross-linkable moiety provides an efficient and convenient method to improve the properties of PPC and extend its application area.     

部分水解聚丙烯酰胺有机交联剂的研制

以部分水解聚丙烯酰胺( HPAM)为主体,添加合成的酚醛树脂水溶液交联,形成的聚合物凝胶体系在不同质最浓度配比下粘度随时间的变化趋势,从而找到最佳的配比条件.结果表明,部分水解聚丙烯酰胺与酚醛树脂最佳的浓度比为2.5∶1,聚合物成胶后体系粘度在3h后达到最大值,胶液粘度稳定后与未交联的胶液相比粘度大为提高.     

形状记忆聚合物的研究进展

综述了形状记忆聚合物的研究进展,重点介绍互穿网络聚合物凝胶、共聚合凝胶和物理交联的形状记忆聚合物和化学交联的形状记忆聚合物,并对形状记忆聚合物的未来发展方向进行了展望.     

Cross-linkable and thermally stable aliphatic polycarbonates derived from CO2, propylene oxide and maleic anhydride

Poly(propylene carbonate maleate) (PPCMA) was successfully synthesized from carbon dioxide with propylene oxide and maleic anhydride using supported zinc glutarate as catalyst. The PPCMA can be readily cross-linked using dicumyl peroxide (DCP) as a cross-linking agent. The gel content, thermal performance and mechanical properties of the cross-linked PPCMA were then investigated. The results showed that the gel content increased with increasing DCP content and reaction temperature. The as-prepared PPCMA showed higher glass transition temperature (T _g) and decomposition temperature compared with uncross-linkable poly(propylene carbonate) (PPC). The introduction of small amount of cross-linkable moiety provides a very effective way to improve the thermal stability and to extend the molecular weight of PPC, consequently extending its application area.     

交联电缆用LDPE树脂性能及其应用

利用拉伸试验、红外光谱、凝胶渗透色谱、差示扫描量热法、流变表征等方法，对交联电缆用QLT17 LDPE树脂的性能进行了表征分析，研究了以QLT17 LDPE为基础树脂分别制备的硅烷交联和过氧化物交联聚乙烯电缆绝缘料的性能，并介绍了QLT17 LDPE在交联聚乙烯电缆绝缘料中的工业化应用。结果表明，QLT17 LDPE是一种性能优异的交联聚乙烯电缆绝缘料基础树脂。