聚合物/蒙脱土纳米复合材料及其在包装中的应用

纳米技术是一项前沿科学技术,目前,聚合物/蒙脱土纳米复合材料是重要的工程材料之一。由于蒙脱土的特殊结构,对蒙脱土进行有机改性后,聚合物/蒙脱土纳米复合材料的各项性能均得到较大改善。解读聚合物/蒙脱土纳米复合材料的主要制备方法、结构表征与性能,以及聚合物/蒙脱土纳米复合材料在包装领域的应用,并且对将来开发出具有特殊功能的高性能聚合物/蒙脱土纳米复合材料进行了展望。     

水溶性高分子/蒙脱土纳米复合浆料

以钠基蒙脱土、丙烯酸类单体和聚乙烯醇为原料,通过溶液原位聚合法和溶液插层法分别制备出不同蒙脱土含量的丙烯酸系共聚物/蒙脱土纳米复合浆料和聚乙烯醇/蒙脱土纳米复合浆料。用X射线衍射(XRD)法测定纳米复合材料中蒙脱土的层间距,并测定纳米复合浆料对纤维的黏附性和浆纱强力。试验结果表明,当蒙脱土含量较少时,形成了剥离型纳米复合材料,随着蒙脱土含量的增加,形成插层-剥离型和插层型纳米复合材料;丙烯酸系纳米浆料有利于提高对纯棉纤维的黏附性,并提高浆纱的断裂强力,而聚乙烯醇纳米浆料可提高对涤/棉的黏附性,对浆纱强力的影响不大。     

壳聚糖/蒙脱土纳米复合材料对染料废水吸附作用的研究进展

介绍了壳聚糖/蒙脱土纳米复合材料的制备机理、表征手段,对影响壳聚糖/蒙脱土纳米复合材料性能的主要因素作了详细的说明,综述了壳聚糖/蒙脱土纳米复合材料应用于多种染料废水吸附处理的最佳吸附条件、去除率及等温吸附模型等。     

PET/蒙脱土纳米复合材料的制备、结构与性能

通过对蒙脱土的有机化处理 ,利用DMT缩聚方法制备了PET/蒙脱土纳米复合材料 ,分析了蒙脱土的层间距变化及其在纳米复合材料基体中的分散状态 ,并测试了聚合物的结晶性能及力学性能。实验表明 ,采用二次插层法处理所得的有机蒙脱土能很好地分散于PET/蒙脱土纳米复合材料基体中 ,所得复合物的结晶性能与力学性能都有不同程度的提高     

插层处理纳米蒙脱土改性脲醛树脂对胶合板性能的影响

将纳米蒙脱土、十六烷三甲基溴化铵插层处理后的纳米蒙脱土、面粉分别对脲醛树脂进行改性,用改性后的脲醛树脂制备胶合板,并检测其胶合强度和游离甲醛释放量。结果表明:相比面粉,用纳米蒙脱土和插层处理纳米蒙脱土改性的脲醛树脂制得的胶合板均表现出了较好的胶合性能和较低的游离甲醛释放量,且插层处理纳米蒙脱土改性的脲醛树脂性能更优异。     

蒙脱土对水溶性聚合物基蒙脱土纳米复合材料性能的影响

通过自由基水溶液聚合制备了聚二烯丙基二甲基氯化铵-丙烯酰胺-丙烯酸(PDM-AM-AA),将PDM-AM-AA分别与钠基蒙脱土、十六烷基三甲基氯化铵改性蒙脱土(1631-MMT)和二烯丙基二甲基氯化铵改性蒙脱土(DM-MMT)进行复合,制备系列纳米复合材料,采用FT-IR和XRD对其结构进行了表征,并将其分别配合2%铬粉应用于皮革鞣制工艺中,对坯革的耐湿热稳定性和物理机械性能进行了测试。XRD结果表明:PDM-AM-AA/1631-MMT和PDM-AM-AA/DM-MMT纳米复合材料中蒙脱土的衍射峰消失,PDM-AM-AA/Na-MMT纳米复合材料中蒙脱土的层间距为1.5125nm;与聚合物PDM-AM-AA相比,蒙脱土的引入使得纳米复合材料的结晶度不同程度地降低。应用结果表明:PDM-AM-AA/DM-MMT配合2%铬粉应用于制革工艺中,坯革的各项性能较好,能够符合服装用皮革QB/T1872-2004的标准。     

壳聚糖/纳米蒙脱土复合涂膜对枇杷保鲜的研究

采用壳聚糖和纳米蒙脱土作为复合涂膜剂,研究室温条件下对枇杷的保鲜效果。结果表明,壳聚糖/纳米蒙脱土复合涂膜剂能明显延缓水分流失,抑制硬度、VC含量、总糖含量和总酸含量的下降,有效延长枇杷保质期。     

壳聚糖-蒙脱土与壳聚糖-高岭土纳米复合涂料流变性及其对纸张阻隔性能的影响

分析了不同的硅酸盐用量和搅拌速度对壳聚糖-蒙脱土和壳聚糖-高岭土纳米复合涂料流变性的影响;借助原子力显微镜(AFM)观察了涂覆这2种纳米复合涂料后白卡纸的表面形貌,并探讨了这2种涂料对纸张阻隔性能的影响。结果显示,随蒙脱土用量的增加,壳聚糖-蒙脱土纳米复合涂料的黏度增大,但当蒙脱土用量为12%时,涂料黏度下降;蒙脱土的搅拌速度越大,表观黏度对剪切速率的依赖性越大,壳聚糖-蒙脱土纳米复合涂料属于典型的非牛顿假塑性流体,表现出典型的“剪切变稀”现象。随高岭土用量的提高,壳聚糖-高岭土纳米复合涂料的黏度增加,其非牛顿性要大于壳聚糖-蒙脱土纳米复合涂料;随高岭土搅拌速度的提高,壳聚糖-高岭土纳米复合涂料出现了典型的“剪切增黏”现象。相同工艺条件下,壳聚糖-高岭土纳米复合涂料的黏度高于壳聚糖-蒙脱土纳米复合涂料。AFM结果显示,经纳米复合涂料涂布后纸张的粗糙度较原纸显著降低,且壳聚糖-蒙脱土纳米复合涂料对纸张阻隔性能的影响优于壳聚糖-高岭土纳米复合涂料。     

蒙脱土纳米复合材料的制备及应用研究

利用离子交换法对钠基蒙脱土进行了改性。探讨了钠基蒙脱土及改性蒙脱土在处理制革废水方面的应用及有机改性蒙脱土 / Cr3 复合物在鞣制方面的应用 ;对有机改性蒙脱土增强增韧聚合物材料的性能进行了检测。对有机改性蒙脱土的 CEC(cation exchange capacity,离子交换容量 ,mmol/ 10 0 g)、FT- IR(傅立叶变换红外光谱 )及 XRD(X射线衍射 )测定结果表明 :有机阳离子已和钠基蒙脱土发生离子交换作用 ,使蒙脱土的层间距增大 ;蒙脱土及改性蒙脱土可对制革废水进行处理 ,较好地吸附废水中的油脂 ;钠基蒙脱土及有机改性蒙脱土对皮革有一定的鞣制作用 ,与无机鞣剂结合使用可大大减少无机鞣剂的用量 ,使鞣后坯革具有较高的收缩温度 ;有机改性蒙脱土用于聚合物材料的复合物改性 ,能使复合材料的强度和韧性得到较大提高 ,为纳米涂饰剂的开发提供了新的思路。     

蒙脱土的研究与应用综述

蒙脱土(MMT)是一种层状硅酸盐矿物质,具有较大的比表面积,强烈的吸水性,良好的阳离子交换能力和吸附性能。蒙脱土可作为载体,用于吸附以及增强材料的物理性能。为扩大蒙脱土应用范围,可将蒙脱土进行相应的改性。蒙脱土可用于制备良好的纳米复合材料广泛应用于污水处理、石油、药品、汽车制造等方面[1]。本文对近十年关于蒙脱土的研究进行综述,有利于进一步开展蒙脱土的研究与应用。     

改性蒙脱石消减黄曲霉毒素B1的研究进展

真菌毒素污染严重威胁食品、农产品和饲料产业高质量发展和人民生命健康.黄曲霉毒素B1是污染广,毒性最大的一种真菌毒素,具有强致癌性和致畸性.天然蒙脱石可通过离子-偶极子、羰基氧配位及静电引力等方式与黄曲霉毒素B1结合,因此有一定的吸附脱除作用.但天然蒙脱石在吸附黄曲霉毒素的同时可能会影响基质中的矿物质、维生素与其他营养组...     

Clay particles destabilize engineered nanoparticles in aqueous environments

Given the ubiquity of natural clay minerals, the most likely interaction of nanoparticles released into an aquatic environment will be with suspended clay minerals. Thus, the transport of engineered nanoparticles in the subsurface and the water column will most likely be altered by their interaction with these minerals. We studied the interactions of two of the most produced nanoparticles, Ag and TiO(2), and montmorillonite to determine how heteroaggregation can alter the stability of nanoparticle/clay mineral mixtures. Since at low pH montmorillonite has a negatively charged basal plane and positively charged edges, its interaction with these nanoparticles at different pH lead to unusual behaviors. There are six different interactions for each clay-nanoparticle pair. At pH values below the IEP of montmorillonite edge site, montmorillonite reduced the stability of both negatively charged Ag and positively charged TiO(2) nanoparticles. Surprisingly this enhanced coagulation only occurs within an intermediate ionic strength range. The spillover of the montmorillonite basal plane electric double layer to the montmorillonite edge may screen the electrostatic attraction between Ag and the montmorillonite edge at low ionic strength, whereas a repulsion between TiO(2) and montmorillonite face sites may restabilize the mixture.     

聚胺/膨润土复合体的制备及其对松香酸的吸附作用

将低分子质量聚胺直接与膨润土在溶液中进行层间结合,形成聚胺/膨润土复合体.结果表明,聚胺的分子大小及带电性质对其与膨润土的复合程度有直接影响.将制备的聚胺/膨润土复合体及相应的聚胺与膨润土的简单混合物对松香酸分散液做吸附实验.研究发现,聚胺/膨润土复合体具有合适的表面带电状态,才能有效地吸附松香酸.此外,实验所用膨润土原土性质是影响聚胺/膨润土复合体的制备及其性能的重要因素.     

Photodegradation of decabromodiphenyl ether adsorbed onto clay minerals, metal oxides, and sediment

The photodebromination of decabromodiphenyl ether (BDE-209) adsorbed onto six different solid matrixes was investigated in sunlight and by irradiation with 350 +/- 50 nm lamps (four lamps at 24 W each). After 14 days of lamp irradiation, BDE-209 degraded with a half-life of 36 and 44 days, respectively, on montmorillonite or kaolinite, with much slower degradation occurring when sorbed on organic carbon-rich natural sediment (t1/2 = 150 days). In late summer and fall sunlight (40.5 degrees N, elevation 600 ft), the half-lives of BDE-209 sorbed on montmorillonite and kaolinite were 261 and 408 days, respectively. Under both irradiation schemes, no significant loss of BDE-209 occurred when sorbed to aluminum hydroxide, iron oxide (ferrihydrite), or manganese dioxide (birnessite). Upon exposure to both lamp and solar light and in the presence of montmorillonite and kaolinite, numerous lesser brominated congeners (tri- to nonabromodiphenyl ethers) were produced. Nearly identical product distribution was evident on montmorillonite and kaolinite. Dark control experiments for each mineral showed no disappearance of BDE-209 or appearance of degradation products. These results suggest that photodegradation of BDE-209 on mineral aerosols during long-range atmospheric transport may be an important fate process for BDE-209 in the environment.     

Clay minerals affect the stability of surfactant-facilitated carbon nanotube suspensions

Carbon nanotubes (CNTs), because of their wide application, will inevitably enter aquatic systems, but the fate and transport of their suspensions in the environment are largely unknown. Clay minerals are expected to interact with CNT suspensions, affecting their fate and bioavailability. This study investigated the influence of clay minerals (kaolinite and montmorillonite) on the stability of surfactant (SDBS, CTAB, and TX100) facilitated multiwalled CNT (MWCNT) suspensions. Adsorption of the surfactants by MWCNTs and clay minerals was also examined. This is a first study on the interaction between clay minerals and surfactant-CNT suspensions. Sorption of SDBS by clay minerals and MWCNTs followed the order MWCNTs > montmorillonite approximately kaolinite; but sorption of CTAB and TX100 followed the order montmorillonite > MWCNTs > kaolinite. For SDBS suspended MWCNTs, introduction of montmorillonite and kaolinite could not change their stability; for CTAB suspended MWCNTs, both montmorillonite and kaolinite greatly deposited the suspended MWCNTs; for TX100 suspended MWCNTs, montmorillonite could partially deposit the suspended MWCNTs, whereas kaolinite showed minimal effect. Two mechanisms of clay minerals affecting MWCNT suspensions are (1) removal of surfactants by clay minerals from solution and MWCNT surface and (2) bridging between clay mineral and MWCNTs by surfactant.     

Internal quality of coated eggs with soy protein isolate and montmorillonite: Effects of storage conditions

The development of the bio-nanocomposite coating materials for eggshells has received more attention because of the decline in interior egg quality. This work evaluated the effects of weight loss, Haugh unit, yolk index, air space and albumen pH, eggshell strength, number of microorganisms on eggshells, contact angle and water vapor permeability of uncoated eggs and eggs coated with soy protein isolate/montmorillonite emulsions (5/0, 5/0.20, 5/0.50, 5/0.80; w/w) during 6 weeks at 25°C. A scanning electron microscope was used to visualize morphologies of soy protein isolate and the soy protein isolate/montmorillonite composite coatings, and the scanning probe microscope was determined. Compared with uncoated and soy protein isolate-coated eggs, the interior egg quality was improved by the increase of Haugh unit, yolk index, air space or eggshell strength, and decrease in weight loss, albumen pH, or the number of microorganisms on eggshells. The higher contact angle indicated the hydrophobicity of coatings. The values of water vapor permeability with 0.2% montmorillonite, 0.5% montmorillonite, and 0.8% montmorillonite were reduced by 21.14, 57.78, and 69.13%, respectively, as compared to those of soy protein isolate coatings. The images by a scanning electron microscope indicated that coatings could cover the cracks of eggshells to preserve the interior egg quality. The experimental values of the scanning probe microscope showed that montmorillonite would not penetrate through the eggshell pores, and it was safe to coat with montmorillonite. This study highlights the use of soy protein isolate/montmorillonite coating to maintain the internal quality and enhance the shelf life of eggs stored at 25°C.     

载锆蒙脱石对蔗糖溶液中没食子酸的吸附特性分析

该研究以氧氯化锆和蒙脱石为原料,通过共沉淀法制备载锆蒙脱石。通过扫描电镜（SEM）、傅里叶红外光谱（FT-IR）、X射线衍射（XRD）、X射线光电子能谱（XPS）和比表面积分析（BET）研究改性和吸附对载锆蒙脱石表观结构和表面基团的影响,并考察了载锆蒙脱石对蔗糖溶液的吸附特性。表征结果显示,载锆蒙脱石相较于蒙脱石表面更加粗糙,比表面积达到了204.47 m2/g,是改性前的3.39倍;表面有纳米小颗粒堆积,FT-IR和XPS结果证明氧化锆成功负载到蒙脱石表面,载锆蒙脱石等电点为7.39。吸附试验表明载锆蒙脱石吸附量相较于蒙脱石吸附量提高了102.54%,载锆蒙脱石对蔗糖溶液中没食子酸吸附的最佳pH为7.0,时间为300 min时达到平衡。吸附过程可以准二级吸附动力学模型和Langmuir等温吸附模型准确描述,饱和吸附量达到129.87 mg/g;热力学研究表明吸附过程为吸热过程,能自发进行。经过5次再生后,载锆蒙脱石可以保持初次吸附量的80%以上。吸附过程主要通过静电引力和氧化锆的配位离子交换吸附没食子酸。综上所述,载锆蒙脱石对蔗糖溶液中没食子酸具有良好的吸附性能,是一种有前景的糖用吸附剂。     

壳聚糖/蒙脱土复合糖用澄清剂的制备工艺及优化

以壳聚糖(chitosan,CTS)、蒙脱土(montmorillonite,MMT)为原料进行复合改性制得糖用CTS/MMT复合澄清剂,将糖汁的脱色效果作为指标,分别考察CTS/MMT材料制备的反应温度、反应时间、壳聚糖的用量和乙酸浓度等因素对其糖汁脱色的影响,并采用正交试验进一步优化其制备工艺,获得最优条件为:反应温度40℃、反应时间4 h、壳聚糖的用量2.5 g、乙酸浓度1.5%。通过扫描电镜、红外光谱、X射线衍射和热重数据分析对CTS/MMT进行结构表征,结果证明壳聚糖较均匀分布于蒙脱土的表面,负载量为28%,CTS/MMT仍保持蒙脱土的多孔结构。     

壳聚糖改性蒙脱石对蔗糖溶液中酚酸的吸附性能研究

通过共沉淀法制备壳聚糖改性蒙脱石并用于蔗糖溶液中酚酸的吸附。通过SEM、FT-IR、XPS和BET对其进行表征,由表征结果可知:改性过程成功地将壳聚糖负载到蒙脱石表面,制备出壳聚糖改性蒙脱石;改性蒙脱石等电点为7.84,主要通过静电力和胺基吸附蔗糖溶液中的没食子酸。吸附试验结果表明改性后的蒙脱石对没食子酸吸附性能提高,壳聚糖改性蒙脱石对蔗糖溶液中没食子酸吸附的最佳pH为7.0,平衡时间为600 min。壳聚糖改性蒙脱石对没食子酸的吸附过程更加符合Freundlich模型和准二级吸附动力学方程,吸附过程主要为多分子层吸附和化学吸附,饱和吸附量达到58.82 mg/g。壳聚糖改性蒙脱石具有良好的再生性能,且对蔗糖溶液中酚酸吸附效果良好,是一种有前景的糖用澄清剂。     

肠道菌群与特殊环境关系的研究进展

肠道菌群的动态平衡是维持人体健康的重要标志之一,许多疾病证实与肠道菌群失调有关.环境是影响肠道菌群的重要因素,进一步可分为常规环境和特殊环境,其中关于特殊环境与肠道菌群之间相互联系的研究少之又少,而两者之间的相互作用对在特殊环境下工作的特殊人群健康具有十分重要的意义.因此,本文从特殊环境入手,重点探讨高原、航空航天、航...