Hydrogel-elastomer composite biomaterials: 3. Effects of gelatin molecular weight and type on the preparation and physical properties of interpenetrating polymer networks

To optimize the preparation of a gelatin-HydroThane^TM Interpenetrating Polymer Network (IPN) and obtain optimum physical properties for its use as a wound dressing, we studied IPN films prepared with two types of gelatin having different molecular weights. The effects of the gelatin molecular weight and type on the IPN film’s structure, morphology, swelling and mechanical properties were determined. While FTIR did not reveal any noticeable differences between the IPNs prepared using different gelatin, light microscopy showed a lesser phase separation of the film prepared with a high-molecular-weight type A gelatin. Furthermore, these films displayed slightly less swelling, higher strength and lower strain, compared to the IPNs prepared with either low-molecular-weight type A or type B gelatin. The IPN prepared with type B gelatin showed higher swelling in serum-containing medium than those prepared with type A gelatin, because of its ionic charges under the condition. Increases in viscosity were observed with increasing molecular weight, type A being more viscous than type B gelatin despite having a lower bloom number. The viscosity of the high-molecular-weight gelatin was in the same magnitude as that of HydroThane^TM, which might lead to less phase separation. A better understanding of the effects of alterations in the gelatin molecular weight and type on the formation and properties of the gelatin-HydroThane^TM IPN should facilitate the development of promising composite biomaterials for wound dressing applications.     

MDI聚氨酯/聚硅氧烷IPN的结构与力学性能

用MDI聚醚氨酯和含少量苯基的聚二甲基硅氧烷合成了一系列的聚氨酯／聚硅氧烷IPN阻尼弹性体，研究了材料的结构与力学性能．结果表明，当聚氨酯与聚硅氧烷的质量比为90：10时。IPN的抗张强度达41．57MPa，断裂伸长率为376％，并具有良好的阻尼性能，玻璃化转变温度范围大于80℃．聚氨酯／聚硅氧烷IPN具有细微的微相分离结构，聚硅氧烷在IPN中的微相尺寸为微米级，并趋向于分布在IPN的表面．     

大豆分离蛋白与明胶蛋白复合膜的制备与性能研究

以大豆分离蛋白为基质,添加明胶蛋白,用溶液铸膜法制备复合膜.研究了成膜液的溶液性能;复合膜的各种性能,包括表观性能、力学性能、阻隔性能.通过扫描电子显微镜观察了膜的微观结构.结果表明,当明胶含量为30%(质量分数)左右,两种蛋白的相容性最佳,复合膜的各项性能达到较佳值,拉伸强度达到31.59MPa,断裂伸长率达到65.96%,并且对氧气和水都有良好的阻隔性.     

接枝和非接枝聚氨酯/环氧树脂互穿网络聚合物的制备及其性能

采用分步法分别制备了接枝和非接枝聚氨酯(PU)/环氧树脂(EP)互穿网络聚合物(IPNs),研究了不同配比对材料力学性能和热性能的影响。红外结果显示接枝聚氨酯/环氧树脂互穿网络聚合物分子间形成了氨基甲酸酯的接枝结构;力学性能测试结果表明,聚氨酯的引入显著地提高了材料的力学性能,当m(PU)∶m(EP)=15∶85时,接枝聚氨酯/环氧树脂互穿网络聚合物的拉伸和冲击强度达到最大值(分别为36.7MPa和22.39kJ/m2),当m(PU)∶m(EP)=10∶90时,非接枝互穿网络聚合物拉伸和冲击强度达到最大值(分别为27.8MPa和19.34kJ/m2);TGA结果证实接枝互穿网络聚合物的热稳定性明显优于非接枝互穿网络聚合物。     

聚氨酯/环氧树脂互穿网络半硬泡沫的力学性能及吸能特性

采用同步法制备了聚氨酯/环氧树脂互穿聚合物网络(IPN)半硬泡沫。通过压缩和拉伸试验研究了泡沫材料密度对力学性能的影响。研究表明,在所研究的密度范围内,泡沫的压缩模量和屈服强度均与密度成指数关系。泡沫的拉伸模量和断裂强度与密度也存在类似的关系。利用这些方程可以很好地预测泡沫力学性能随密度的变化关系。IPN泡沫兼有较好的韧性和较高的拉伸强度。相同形变下,相同密度IPN半硬泡沫拉伸过程的单位体积吸能大于压缩过程的单位体积吸能。     

PDAAM/PU同步互穿网络聚合物的力学性能

利用互穿聚合物网络技术(IPN),将双丙酮丙烯酰胺(DAAM)用于PU胶粘剂的改性.研究了组分比、引发剂用量、固化参数对PDAAM/PU IPN力学性能的影响.结果表明,PDAAM可以提高PU的力学性能.当DAAM的质量分数在40%时,拉伸强度及断裂伸长率都达到最大值.     

海藻酸钙/明胶共混膜的制备及性能研究

用蒸馏水溶解海藻酸钠和明胶,将两种溶液混合制得海藻酸钙/明胶复合功能膜,研究海藻酸钠/明胶复合共混膜的相容性、力学性能、透湿性及吸湿保湿性等.实验结果表明,明胶含量较少时,共混膜有良好的相容性和力学性能;海藻酸钙/明胶质量比为1:0.6时,共混膜的透湿性、吸湿保湿性较好.     

Effect of PbS nanocrystal concentration on the physical properties of a polymer–nanocrystal composite

Semiconductor nanocrystals doped in stable matrices such as polymers are of interest due to fundamental scientific aspects as well as their scope for technological applications. In the present investigation, PbS nanocrystals are synthesized in polyvinyl alcohol (PVA) matrix using a simple technique based on colloidal chemistry. Various concentrations of nanocrystalline PbS (with an average size of 4.5 nm) are loaded into the polymer to study the effect of PbS concentration on the optical, thermal and electrical properties of the composite. An increase in PbS content results in decrease in thermal stability and an increase in electrical conductivity, presumably resulting from interactions between the nanofiller and polymer. Considerations for designing composites with desired combinations of electrical, thermal, and optical properties to suit specific device operating environments are studied systematically.     

Morphological, thermal and annealed microhardness characterization of gelatin based interpenetrating networks of polyacrylonitrile: A hard biopolymer

The present paper reports the preparation of full IPNs of gelatin and polyacrylonitrile. Various compositions of gluteraldehyde crosslinked gelatin and N,N′-methylene-bis-acrylamide crosslinked PAN were characterized by SEM and DSC techniques. The IPNs were also thermally pretreated by the annealing process. The effects of annealing temperature on the microhardness of IPNs were studied using the Vickers method. SEM indicates the homogeneous morphological features for IPN. The role of gelatin, AN and crosslinker on the developed hard biopolymer has been described with the help of DSC thermograms and microhardness measurements of annealed specimens and good correlation is observed.     

Au/TiO2复合纤维的制备及其光催化性能研究

采用溶胶-凝胶法制备了TiO2纤维和Au/TiO2复合纤维,利用XRD、SEM、TEM等手段对纤维样品的结晶性能及其表面形貌进行了表征,并以光催化降解甲基橙为模型反应考察了样品的光催化活性。结果表明,热处理后的TiO2呈锐钛矿结构,Au的颗粒尺寸范围为7～15nm,纤维直径范围为5～20μm,长度为5～50cm。Au的掺入可以显著地提高TiO2的光催化活性,且其光催化活性随着Au掺入量的增加而变大。     

Effects of pure and dyed PCE on physical and interfacial properties of remedial solutions

Hydrophobic dyes have been used to visually distinguish dense non-aqueous phase liquid (DNAPL) contaminants from background aqueous phases and soils. The objective of this study was to evaluate the effects of a dyed DNAPL, 0.5 g Oil-Red-O/l of PCE, on the physical properties of remedial solutions: water, co-solvents (50, 70, and 90% (v/v) ethanol), and surfactants (4% (w) sodium dihexyl sulfosuccinate). This study compared the densities, viscosities, and interfacial tensions (IFTs) of the remedial solutions in contact with both dyed and undyed PCE. The presence of the dye in PCE substantially alters the IFTs of water and ethanol solutions, while there is no apparent difference in IFTs of surfactant solutions. The remedial solutions saturated with PCE showed higher viscosities and densities than pure remedial solutions. Solutions with high ethanol content exhibited the largest increases in liquid density. Because physical properties affect the flow of the remedial solutions in porous media, experiments using dyed DNAPLs should assess the influence of dyes on fluid and interfacial properties prior to remediation process analysis.     

Processing,microstructure, and physical properties of interpenetrating Al2O3/Ni composites

Abstract

Alumina/nickel composites have been fabricated by hot pressing powder blends of various volume fractions of nickel and alumina. The electrical resistivities and Young's moduli of these composites have been measured and their dependence on the volume fraction of reinforcement has been investigated. Microstructural parameters such as contiguity were measured to quantify the distribution of the phases in these composites, and existing property models based on these data were used to predict the properties of the composites. The percolation threshold of nickel was found to occur at between 7.5 and 15 vol.-%Ni. The Young's modulus decreases as the volume fraction of nickel increases and is dependent on the contiguity of alumina. Composites containing 25, 35, 50, and 65 vol.-%Ni display microstructures with interpenetrating networks of alumina and nickel. The property models were found to fit both the resistivity and modulus data well, although the percolation threshold was predicted at a lower volume fraction than measured experimentally.     

不同结晶性能聚合物/纳米SiO2复合材料的制备与阻隔性能

选取3种偶联剂(KH550、KH560和KH570),将纳米SiO2进行改性,并采用熔融共混法分别与4种结晶性能不同的聚合物(HDPE、PP、PVC和PC)共混制备了一系列纳米复合材料(0～5%(质量分数)SiO2),并吹塑成薄膜。采用红外光谱(IR)、差示扫描量热仪(DSC)及扫描电镜(SEM)对纳米SiO2和复合材料的结构进行了表征,并对复合材料的力学性能、阻隔性能等进行了表征。结果表明,纳米SiO2与偶联剂均形成化学键合,改性后的纳米SiO2在各聚合物中分散较好,且在聚合物中起到异相成核的作用。在相同纳米SiO2含量下,SiO2对结晶性能不同的聚合物的结晶改善情况有差异,且纳米SiO2的异相成核作用在结晶性聚合物中更为明显,能使复合材料的结晶更为完善,结晶性能的改变与复合材料的阻隔性能能够形成一定关系。     

纳米羟基磷灰石/聚乙烯醇/明胶复合水凝胶的结构与性能研究

用溶液共混法制备了纳米羟基磷灰石/聚乙烯醇/明胶三元复合水凝胶材料.测定了材料的含水率,采用TEM、SEM、EDAX、IR、XRD和燃烧实验对材料的结构进行了表征和分析,并研究了材料的吸水性.结果表明,制备的复合水凝胶组成均一,各组份间存在相互作用,并且具有好的吸水和保水性能.本研究制备的纳米羟基磷灰石/聚乙烯醇/明胶复合水凝胶可望作为一种人工软骨材料.     

热氧老化对碳纤维织物增强聚合物基复合材料弯曲性能的影响

为了探索增强体结构对碳纤维增强聚合物基复合材料(CF-PMCs)热氧老化后弯曲性能的影响,对三维四向编织碳纤维/环氧复合材料(简称为三维编织复合材料)和层合平纹碳布/环氧复合材料(简称为层合复合材料)的热氧老化性能进行了研究。利用FTIR、老化失重、弯曲测试和SEM等手段分析了热氧老化前后的试样。结果表明:热氧老化导致基体树脂的氧化断链以及纤维/基体界面结合力的退化是两种复合材料弯曲强度和弯曲模量下降的原因,弯曲强度比弯曲模量更容易受热氧老化的影响。在相同的热氧老化条件下,层合复合材料的热氧老化失重大于三维编织复合材料的,而三维编织复合材料的弯曲强度和弯曲模量保留率均大于层合复合材料的。在140℃下老化1 200h后,层合复合材料的弯曲强度和弯曲模量保留率分别为74.7%和88.3%,而对应的三维编织复合材料的分别为79.4%和91.5%。因此,采用三维编织预制件作为CF-PMCs的增强体是一种有效的提高其热氧稳定性的方法。     

PAMPS/PAA互穿双网络水凝胶的制备及强度研究

通过自由基溶液聚合法和互穿双网络技术(IPDN),合成包含第一网络PAMPS及第二网络PAA的高强度PAMPS/PAA互穿双网络水凝胶(IPDNH),探讨IPDNH的最佳制备条件、抗压缩性能影响因素。结果表明,PAMPS所占比例的提高及PAA交联剂用量的增大都使IPDNH的压缩强度呈现先增大后减小的趋势,而PAMPS交联剂用量的增大,则使压缩强度不断降低。当双网络的单体配比n(AMPS)/n(AA)=3.5/1,PAMPS交联剂用量为2%,引发剂用量为0.2%,PAA交联剂用量为0.5%,引发剂用量0.5%时,IPDNH的抗压缩强度可达58.3MPa,远大于普通水凝胶。     

壳聚糖渗透汽化复合膜的研究

用聚丙烯腈（ＰＡＮ）超滤膜为底膜制成的壳聚糖（ＣＳ）复合膜，对乙醇／水溶液的渗透汽化分离性能具有较好的稳定性复合膜用于运行低浓度的乙醇溶液后，再运行质量分数为９５％的乙醇溶液，膜的性能变化不大，稳定性优于均质膜研究了用多种试剂来代替硫酸交联剂处理膜，表明有些可有效地提高膜的渗透选择性，特别是用聚苯乙烯磺酸钾（ＰＳＳＫ）处理，膜的渗透通量达３１０～３３５ｇ／（ｍ２·ｈ），比硫酸处理膜提高近一倍同时还进行了薄分离层复合膜的研制，实验表明，薄分离层ＣＳ复合膜，膜分离系数虽有所下降，而渗透通量显著提高，比原来ＣＳ复合膜提高近５倍     

原位ZrB2p/Al复合材料的制备及其力学性能研究

以Al-10%(质量分数)Zr和Al-3%(质量分数)B合金为原料,在高能超声作用下采用熔体直接反应法成功地制备了ZrB2p/Al复合材料。利用X射线衍射仪、扫描电镜等分析了复合材料的物相和显微组织,并测试了其力学性能。结果表明,经过高能超声处理后,复合材料中的ZrB2颗粒尺寸更小,分布也更均匀。复合材料的抗拉强度、屈服强度和伸长率分别达到94、81MPa和14.5%,较未施加高能超声场的复合材料分别提高了10.6%、15.7%和16.0%。     

HIPS/nano-TiO2复合材料的吸光及光老化性能研究

研究了高抗冲聚苯乙烯／纳米TiO2（HIPS／nano—TiO2）复合材料的吸光及光老化性能,以紫外-可见光（UV—Vis）吸收光谱表征吸光性能,以傅里叶红外（FT—IR）及熔体流动速率（FMI）表征老化样品的结构．结果表明,与钛白粉相比,锐钛矿nano—TiO2对紫外光的吸收加强,但对可见光的反射率咯低．复合材料对250-400nm区域的紫外光有较强吸收,且随纳米质量含量的提高而增强．钛白粉也可提高复合材料的紫外吸收性能,且能大幅度提高对可见光的反射能力．锐钛矿nano—TiO2在老化样品中发挥了刚性粒子增韧作用．光老化后复合材料的力学性能明显优于HIPS老化样品,冲击强度可提高30％以上．光老化集中于HIPS的聚1,4-丁二烯（PB）相,老化以断链方式为主．     

服役低温老化对铝合金-玄武岩纤维增强树脂复合材料粘接接头力学性能的影响及失效预测

为了给铝合金-玄武岩纤维增强树脂(BFRP)复合材料粘接结构在汽车工业中的应用提供参考和指导,加工了铝合金-BFRP复合材料粘接接头。结合汽车服役中的温度区间,选取?10℃和?40℃的低温老化环境,对接头进行0、10、20、30天的老化。对老化后的粘接接头进行准静态拉伸试验和剪切试验,得到不同老化时间下铝合金-BFRP粘接接头的准静态失效强度。结合DSC和FTIR分析低温老化对BFRP复合材料的影响,并对粘接接头的失效断面进行宏观分析和SEM分析。结果表明:在低温老化环境中,胶粘剂与BFRP复合材料的化学性质受低温老化作用影响不大,BFRP中的官能团与玻璃化转变温度(T_g)没有发生明显的变化,接头的失效强度和失效模式主要受胶粘剂与粘接基材的热应力影响。对于拉伸接头,随着低温老化时间的增加,BFRP复合材料纤维与树脂基体间的结合力降低,铝合金-BFRP复合材料接头的失效断面中纤维撕裂的比例逐渐减少,拉伸接头失效强度逐渐下降。老化后剪切接头仍为内聚失效,BFRP复合材料的低温老化对铝合金-BFRP复合材料剪切接头的失效强度几乎没有影响,剪切接头失效强度的下降主要是胶粘剂与粘接基材热膨胀系数不一致引起的热应力的影响。采用二次应力准则公式对?10℃和?40℃低温环境下,拉应力、剪应力值随老化时间的变化规律进行了拟合,在此失效准则的基础上,根据响应面原理,建立接头失效强度随老化时间变化的三维曲面,为粘接技术在车身结构中的工程应用提供参考。