无机纳米材料增强尿素和甲酰胺混合塑化热塑性淀粉

用尿素和甲酰胺混合塑化剂制备的热塑性淀粉(UFPTPS)可以有效抑制淀粉的重结晶,用这种热塑性淀粉作为纳米S iO2或纳米CaCO3的基质,制备了无机纳米增强热塑性淀粉(NRTPS)。扫描电镜(SEM)显示了纳米S iO2和CaCO3含量对UFPTPS塑化后微观形貌的影响。红外光谱(FTIR)显示了纳米S iO2或CaCO3和淀粉可以发生作用,淀粉与纳米S iO2的相互作用要大于纳米CaCO3。X射线衍射说明,加入纳米S iO2或纳米CaCO3后,作为基质的UFPTPS仍可以抑制淀粉重结晶。纳米S iO2和纳米CaCO3均对UFPTPS起到增强的作用,在w(H2O)=10%时,S iO2增强UFPTPS的强度由UFPTPS的5.67 MPa增加到9.67 MPa;CaCO3增强UFPTPS的强度由UFPTPS的5.67 MPa增加到8.61 MPa。水含量再增加,增强效应逐渐弱化,w(H2O)>23%后,水分对材料力学性能影响很小。与UFPTPS相比,NRTPS耐水性明显提高,在100%相对湿度下,S iO2增强UFPTPS材料在w(S iO2)=1%时材料耐水性最好,平衡时w(H2O)=45%;CaCO3增强UFPTPS材料耐水性随着CaCO3含量增加而提高,w(CaCO3)=3%时材料耐水性最好,平衡时w(H2O)=41%。     

纤维增强尿素和甲酰胺混合塑化热塑性淀粉

使用尿素和甲酰胺混合塑化剂制备的热塑性淀粉(UFPTPS)可以有效抑制淀粉的回生。用这种热塑性淀粉作为短棉绒纤维的基质,制备的纤维增强热塑性淀粉(FRTPS)可以提高其力学性能和耐水性能。扫描电镜显示了短棉绒纤维较好地分散在UFPTPS中,纤维和淀粉结合良好。X ray衍射说明加入纤维后作为基质的UFPTPS仍可以抑制淀粉回生。纤维质量分数对FRTPS力学性能影响的研究显示,随着w(纤维)=0%提高到20%,FRTPS拉伸强度翻番达到10 16MPa,杨氏模量达到97 85N/mm2;伸长率从105%降到17%,断裂能从2 158N·m降到0 573N·m。随着水质量分数的增加,增强效应逐渐被弱化,在高水含量[w(水)>30%]时,水分和纤维质量分数对强度没有影响。FRTPS与UFPTPS相比,耐水性明显提高。     

高密度聚乙烯／蒙脱土纳米复合材料的制备与性能研究

采用马来酸酐接枝乙烯醋酸乙烯酯（EVA-g-MAH）和马来酸酐接枝低密度聚乙烯（PE-LD-g-MAH）为相容剂，制备了高密度聚乙烯傣脱土（PE-HD／MMT）纳米复合材料。用X射线衍射和扫描电镜对有机蒙脱土和PE-HD／MMT复合材料的结构进行了表征，研究了蒙脱土和相容剂含量对制备的纳米复合材料力学性能及热性能的影响。结果表明，相容剂的加入有利于插层。MMT在复合材料中呈纳米级分散。其层间距可由2．10nm增大至3．85nm。MMT含量为3％（质量分数，下同）、EVA-g-MAH含量为15％时，复合材料的综合力学性能最好，冲击强度和拉伸强度分别较PE-HD提高43．7％和5.8％。     

原位乳液插层法制备丁腈橡胶/蒙脱土纳米复合材料的研究

结合乳液插层蒙脱土的特点，利用原位插层制备了丁腈橡胶（NBR）／改性蒙脱土（HOMMT）纳米复合材料。通过X-射线衍射（XRD）及透射电镜（TEM）证实和分析了蒙脱土的纳米分散相结构。物理性能的研究表明，所制备的复合材料体现了纳米材料的一些特点，填充少量蒙脱土，复合材料的物理机械性能即达到一个较高的水平。     

热塑性塑料/蒙脱土纳米复合材料的研究进展

概述了蒙脱土的结构、有机改性机理和热塑性塑料/蒙脱土纳米复合材料的制备方法,同时介绍了无定型热塑性塑料/蒙脱土和结晶型热塑性塑料/蒙脱土复合材料的最新研究进展和今后研究开发的方向。     

蒙脱土对热塑性淀粉结晶和力学性能的影响

用熔融挤出方法制备的甘油塑化热塑性淀粉(GTPS)/蒙脱土(MMT)复合材料,可以有效抑制GTPS长时间放置的结晶行为,提高其力学性能。不同相对湿度下复合材料、GTPS、淀粉的X ray衍射说明,MMT对GTPS结晶有抑制作用;力学测试表明,随着w(MMT)=0%提高到30%,复合材料最大应力达到27 31MPa,应变从85 3%下降到17 8%,杨氏模量达到206 7MPa,断裂能从1 921N·m下降到1 723N·m。红外(FTIR)谱图显示复合材料中淀粉分子的碳氧(C—O)基团向高波数移动,蒙脱土中可反应性羟基(OH)向低波数移动。这表明蒙脱土分子可反应OH和淀粉分子OH之间有氢键形成,使GTPS中淀粉分子之间氢键难以形成,蒙脱土在复合材料中起到阻隔剂的作用,是抑制GTPS结晶的主要原因;扫描电子显微镜(SEM)显示,蒙脱土均匀分散在GTPS中,提高了材料力学性能。     

凝聚共沉法制备的蒙脱土／天然橡胶纳米复合材料及其性能研究

以新鲜胶乳为主体材料,有机改性蒙脱土为填料,用凝聚共沉法制备了蒙脱土／天然橡胶复合材料,研究了复合材料的物理性能、动态力学性能及其热稳定性。结果表明,在天然橡胶中加入少量（3％-5％）的纳米蒙脱土,可以使橡胶的定伸应力、拉伸强度等性能大幅度提高,动态力学性能和耐热稳定性得到明显改善。     

NR/有机蒙脱土/GMA纳米复合材料的制备与性能研究

采用胶乳接枝插层法制备NR／有机蒙脱土／甲基丙烯酸缩水甘油酯(GMA)纳米复合材料，并对其性能进行研究。结果表明，在NR胶乳与有机蒙脱土体系中加入GMA，并使之原位聚合，同时实现对NR的接枝和对有机蒙脱土的插层并与有机蒙脱土层间的基团产生化学结合，可以制备NR／有机蒙脱土／GMA纳米复合材料；采用胶乳接枝插层法制备的NR／有机蒙脱土／GMA纳米复合材料的物理性能和耐热氧老化性能优异，动态力学性能良好，热稳定性与NR胶料相差不大。     

聚丁烯-1/蒙脱土复合材料的制备与性能表征

采用溶液插层法,以正庚烷为溶剂,将有机改性蒙脱土与聚丁烯-1进行复合,制备得到聚丁烯-1/蒙脱土复合材料.对蒙脱土含量不同的纳米复合材料进行红外光谱测试和热失重测试.红外谱图显示PB材料中引入了蒙脱土,热失重曲线和数据显示经有机蒙脱土改性后的聚丁烯-1热稳定性增强.     

聚对苯二甲酸丁二醇酯/聚甲基丙烯酸甲酯季铵盐修饰蒙脱土纳米复合材料的制备与性能

用聚甲基丙烯酸甲酯苄基季铵盐和聚甲基丙烯酸甲酯十八烷基季铵盐修饰蒙脱土,制备出两种有机土（MAPS-B-MMT和MAPS-O-MMT）,通过熔融共混法制备聚对苯二甲酸丁二醇酯/蒙脱土（PBT/MMT）纳米复合材料,考察了有机土含量和修饰剂结构对复合材料性能的影响。TEM结果显示,两类复合材料均为插层型纳米复合材料。热稳定性能研究表明,PBT/MAPS-B和PBT/MAPS-O两个体系热稳定性有较大的改善,材料的初始降解温度均比纯PBT提高,PBT/MAPS-O-2纳米复合材料的初始降解温度提高了20 ℃;热稳定性受到蒙脱土分散性影响,随着黏土含量增加,蒙脱土分散性变差,导致材料初始降解温度下降,质量分数2%为蒙脱土的最佳含量;加入有机土降低了材料的熔融温度,提高了材料的结晶速率和结晶度。     

Effect of urea and formamide plasticizers on starch/PVA bioblend sheets

The starch/polyvinyl alcohol (PVA) bioblend sheets containing urea and formamide as plasticizers were prepared through melt processing in presence of water. The experiments indicated that urea and formamide plasticizers could form strong hydrogen bonds with starch/PVA molecules. Urea exhibited better plasticizing effect than formamide. Urea also could greatly destroy the crystal structures of PVA component in the blends, leading to the decreased crystallinity of the blends. Formamide was a good solvent for urea and could prevent urea separating from the blends, resulting in the improved stability of plasticizing systems. The blends exhibited good flexibility. Therefore, the incorporation of both urea and formamide into starch/PVA blends could exhibit synergistic effects to ensure the blends with both good plasticizing effect and the stability of the plasticizing systems. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42311.     

Urea and formamide as a mixed plasticizer for thermoplastic starch

Mixtures of urea and formamide were tested as plasticizers for thermoplastic starch (TPS). The hydrogen bonding interactions between urea/formamide and starch were investigated by using Fourier‐transform infrared spectroscopy (FT‐IR). The thermal stability, mechanical properties and starch retrogradation behavior were also studied by thermogravimetric analysis (TGA), tensile testing and X‐ray diffraction (XRD), respectively. TPS plasticized by urea (20 wt%) and formamide (10 wt%) showed better thermal stability and water resistance than conventional TPS plasticized by glycerol. Moreover, the tensile stress, strain and energy at break, respectively, reached 4.83 MPa, 104.6 % and 2.17 N m after storing in an atmosphere of relative humidity (RH) of 33 % for one week. At the same time, this mixed plasticizer could effectively restrain the retrogradation of starch. Copyright © 2004 Society of Chemical Industry     

Structure and properties of bio-based polyurethane coatings for controlled-release fertilizer

Two kinds of bio-based polyurethane coatings for controlled-release urea were prepared by in-situ polymerization used castor oil and liquefied starch as raw materials, respectively. Scanning electron microscopy (SEM) showed that the section morphology of castor oil based polyurethane (Castor-PU) coating was uniform and dense, and that of liquefied starch based polyurethane (Starch-PU) coating had certain proportion of microporous. Infrared spectroscopy (IR) showed that the two coatings had typical urethane characteristic structure, but the difference was that the Starch-PU had obvious unreacted isocyanate structure. Differential scanning calorimetry (DSC) showed that the glass transition temperature of the two coatings was around 58°C, but the Castor-PU had a crystallization domain with obvious crystallization melting peak at 130°C. Thermogravimetric analysis (TG) showed that the thermal stability of Castor-PU was significantly higher than that of Starch-PU. The controlled-release property test showed that when the coating ratio was 2.8%, the nutrient release longevity of urea coated with Castor-PU was 49 days and that of urea coated with Starch-PU was 14 days. The reasons for the poor controlled-release performance of Starch-PU were analyzed, which probably caused by concentrated sulfuric acid and hydrophilic dispersant added in the liquefied starch.     

Formamide as the plasticizer for thermoplastic starch

As a novel plasticizer, formamide was tested in thermoplastic starch (TPS), in which native cornstarch granules were proved to transfer to a continuous phase by scanning electron microscope (SEM) and the hydrogen bond interaction between plasticizer and starch was proved by Fourier transform infrared (FTIR) spectroscopy. Mechanical tests showed that tensile strength and Young's modulus of formamide‐plasticized TPS (FPTPS) were lower than glycerol‐plasticized TPS (GPTPS) and elongation at break and energy break were higher. The effect of formamide and glycerol on the retrogradation of TPS was studied using X‐ray diffractometry. Formamide could effectively restrain the starch retrogradation at three different relative humidity (RH) environments, because it could form the more stable hydrogen bonds with the starch hydroxy group than glycerol. From these results, we found that the elongation at break, energy break, and the retrogradation of TPS were ameliorated by formamide. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1769–1773, 2004     

Preparation and characterization of compatible thermoplastic dry starch/poly(lactic acid)

In the presence of glycerol and formamide, one‐step extrusion processing was used to prepare poly(lactic acid) (PLA)/thermoplastic dry starch (DTPS) blends (50/50 wt%) in a single‐screw extruder. The rheological study proved that formamide could improve the fluidity of DTPS and DTPS/PLA blends. With increasing the fluidity of DTPS, a highly dispersed and compatible DTPS/PLA could be achieved by scanning electron microscope (SEM). It was also certain that the plasticization of DTPS was improved. At the same time, Fourier transform infrared (FT‐IR) spectroscopy proved that formamide not only weakened the interaction of starch molecules, but also improved the interaction between DTPS and PLA. So that the blend could achieve more thermal stability in a compatible blend, as shown in TGA. The improvement of compatible in DTPS/PLA blends was also proved by tensile test and Dynamic mechanical thermal analysis (DMTA) in this article. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Effects of adding nano-clay (montmorillonite) on performance of polyvinyl acetate (PVAc) and urea-formaldehyde (UF) adhesives in Carapa guianensis,a tropical species

The aim of this study was to improve the bond strength resistance of polyvinyl acetate (PVAc) and urea-formaldehyde (UF) adhesives modified with nano-clay (montmorillonite) with a tropical species of wood known to exhibit adhesion related problems. These adhesives were evaluated with 1.0 and 1.5 wt% nano-clay concentrations with lap shear strength (SS), and the percentage of wood failure (PWF) in dry and wet conditions being evaluated. An additional aim of this study was to observe the presence of nano-clay within both adhesive types using Atomic Force Microscopy (AFM) and the Transmission Electron Microscopy (TEM). Color, viscosity and the thermostability of these adhesives with nano-clay were also evaluated. First, AFM and TEM studies showed adequate dispersion and impregnation of nano-clay. The viscosity of PVAc adhesive was not affected by the incorporation of nano-clay, whereas the UF adhesive was. With both PVAc and UF adhesives, the presence of nano-clay increased the L^⁎ and b^⁎ color parameters, especially when 1.5 wt% nano-clay was used. The incorporation of the nano-clay improved thermostability, as determined by thermogravimetric analysis (TGA). Finally, it was shown that the nano-clay incorporation improved SS and PWF. The highest values of SS were obtained when nano-clay was added at 1.5 wt% concentration in the PVAc adhesive under dry conditions. SS was not affected by nano-clay addition in the UF adhesive under dry conditions. However, under wet conditions, both 1.0 and 1.5 wt% loadings of nano-clay increased SS with both adhesive types. The addition of nano-clay in both proportions increased PWF by approximately 15% and between 20–30% in dry and wet conditions, respectively, for the PVAc adhesive. For the UF adhesive, PWF increased by approximately 10% under dry conditions and 25–50% in wet conditions.     

炭黑/纳米粘土/甲基丙烯酸锌并用对NBR硫化胶的协同补强效应

采用正交试验法．研究了炭黑、纳米粘土和甲基丙烯酸锌3种补强剂并用对丁腈橡胶（NBR）综合性能的影响。优选了补强剂的并用配比，当炭黑／纳米粘土／甲基丙烯酸锌的质量比为1／0．7／0．3时，NBR的综合性能较好。进一步研究了炭黑／纳米粘土／甲基丙烯酸锌补强剂并用对NBR硫化胶的协同补强效应。NBR硫化胶补强性的提高，一方面需要粒子与大分子之间有较强的结合力，另一方面也需要粒子表面上的分子产生滑移。     

Investigation of the effect of nano-clay type on the non-isothermal crystallization kinetics and morphology of poly(3(R)-hydroxybutyrate) PHB/clay nanocomposites

PHB is a thermoplastic biopolymer produced by fermentation of renewable resources. Secondary crystallization during storage leading to an increased degree of crystallinity is a principal reason of PHB brittleness. In addition, pure PHB has no residues of catalysts, meaning low nucleation density and slow crystallization rates, leading to the formation of large spherulites with cracks and brittleness. To overcome the brittleness of PHB, polymer composites based on PHB, plasticizers, and nano-clays A and B were prepared by solvent casting. The addition of plasticizer decreases T _g from 5 to ?13 °C in all composites. Furthermore, the addition of nano-clays acts as a nucleating agent to PHB. The effect of nano-clays A and B on spherulites morphology, thermal behavior, and crystal structure of PHB composites were tested by several techniques. Differential scanning calorimetry analysis shows that the addition of nano-clay A does not change the crystallization temperature and the crystallization half-time (t _1/2) of the PHB matrix but that nano-clay B accelerates the crystallization process. Thermogravimetric analysis revealed an increase in thermal stability of composites containing nano-clay B. Polarized optical microscopy showed that nano-clays serve as nucleating agents in PHB matrix. Therefore, the spherulites become smaller and the nuclei density increases at the selected crystallization temperature, compared to pure PHB.