骨架修饰有机-无机杂化二氧化硅膜的研究进展

综述了骨架修饰的有机-无机杂化二氧化硅膜的制备及其在气体分离和渗透汽化方面的应用。在-Si-O-Si-骨架结构中引入有机基团形成有机-无机杂化的二氧化硅膜,提高了膜材料的孔径可调控性和水热稳定性。分析了采用不同有机基团修饰对膜材料性能的影响,综述了近年来这类膜材料在气体分离和渗透汽化方面的应用。     

环氧/二氧化硅杂化涂层研究进展

介绍了环氧/二氧化硅杂化涂层分类、制备及性能,并对其研究方向提出了展望。     

PTFE/CaCO3杂化中空纤维膜制备及其界面孔研究

以聚乙烯醇(PVA)和硼酸(H3 BO3)的凝胶体为纺丝载体,由聚四氟乙烯(PTFE)分散乳液通过凝胶纺丝法制备PTFE/PVA初生中空纤维,经烧结去除载体,得到聚四氟乙烯中空纤维膜.通过在成膜体系中引入纳米无机粒子碳酸钙(CaCO3),经后拉伸得到具有界面微孔结构的PTFE/CaCO3杂化中空纤维膜.研究了PVA和H3 BO3的络合机理,并讨论了CaCO3对杂化中空纤维膜性能及结构的影响.通过对膜的表面形貌观察表明所得PTFE中空纤维膜是一种均质膜,形成的界面微孔结构不同于PTFE双向拉伸产生的纤维-结点状裂隙孔结构,界面微孔的数量和孔径随着后拉伸倍数的增加呈增大的趋势.     

聚氯乙烯/无机粒子复合膜的结构与性能

通过在聚氯乙烯(PVC)铸膜液中引入无机粒子二氧化硅,利用湿法相转化法成膜机理,制得一系列不同粒子含量的PVC/SiO2复合膜。对PVC/SiO2复合膜的形貌进行观察,分析和讨论了无机粒子SiO2含量对PVC/SiO2复合膜产生界面微孔的作用以及添加聚乙二醇(PEG)后PVC/SiO2复合膜性能的变化。结果表明,添加一定含量的二氧化硅可在PVC/SiO2复合膜中产生较明显的界面微孔结构,有效增强PVC/SiO2复合膜的通透性及力学性能,而PEG添加则有利于PVC/SiO2复合膜中界面微孔之间的贯通。     

聚醋酸乙烯酯／二氧化硅杂化纳米纤维膜的制备与性能

采用溶胶一凝胶法将二氧化硅（SiO2）溶胶加入到聚醋酸乙烯酯（PVAc）的丙酮溶液中形成杂化纺丝液,测试了纺丝液的表面张力、粘度、电导率,再采用高压静电纺丝法制备了PVAC／SiO2杂化纳米纤维膜。结果表明,SiO2的加入改善了纳米纤维膜的形貌特征,膜的断裂强力增大,但断裂伸长率却有所降低,而膜的热稳定性也得到了提高。     

聚醋酸乙烯酯/二氧化硅杂化纳米纤维膜的制备与性能

采用溶胶-凝胶法将二氧化硅（SiO₂）溶胶加入到聚醋酸乙烯酯（PVAc）的丙酮溶液中形成杂化纺丝液,测试了纺丝液的表面张力、粘度、电导率,再采用高压静电纺丝法制备了PVAc/SiO₂杂化纳米纤维膜。结果表明,SiO₂的加入改善了纳米纤维膜的形貌特征,膜的断裂强力增大,但断裂伸长率却有所降低,而膜的热稳定性也得到了提高。     

聚四氟乙烯/二氧化硅杂化材料的性能研究

为解决纳米粒子在聚四氟乙烯(PTFE)树脂中难分散均匀的问题,使用PTFE乳液通过原位溶胶-凝胶法(Sol-Gel)制备了聚四氟乙烯/二氧化硅(SiO2)杂化材料,并对其性能进行了表征与研究.研究表明:杂化材料的拉伸强度在SiO2含量为1.05%(记为FS-2)时达到最大值20.96 MPa,为纯PTFE的两倍;断裂伸长率随着SiO2含量的增加而降低,硬度逐渐升高,接触角由121°降至79°.由SEM结果发现,试样FS-2中SiO2的粒径仅为100 nm左右,但随着SiO2含量的增加,粒径变大.杂化材料的耐热性较PTFE有一定提高,当杂化材料中SiO2含量达到5.00%时,热分解温度由纯PTFE的503℃上升至528℃.     

脉冲激光法原位制备纳米二氧化硅杂化聚苯胺研究

用脉冲激光轰击法连续制备聚苯胺原位修饰的纳米二氧化硅,通过溶剂转换的方法,制备得到聚苯胺/纳米二氧化硅杂化薄膜材料,用标准四探针电性能测试,TEM、UV-Vis、TG、XRD、XPS等手段对其进行表征,探讨了纳米二氧化硅的加入对聚苯胺热、电方面产生的影响,结果表明,用本方法制备的纳米二氧化硅具有较小粒径,不团聚,能较好地分散于聚苯胺中与之形成杂化材料,纳米二氧化硅与聚苯胺分子链存在强烈的相互作用,破坏了聚苯胺的规整堆积,导致其热分解温度下降,导电载流子的浓度及迁移率减少,电导率值下降,而抗氧化性有所提高。     

木材／二氧化硅原位复合材料的界面研究

通过引入偶联剂对木材／二氧化硅原位复合材料及其界面的状态的生成和界面状态影响的研究。探讨了木材与二氧化硅无机相间的化学键性能及其对复合尺寸稳定性的改善效果。     

用图象分析仪研究碳酸钙填充硬质聚氯乙烯材料

本文报道了用图象分析仪研究超细CaCO_3填充硬质聚氯乙烯材料。实验结果表明:图象分析仪可定量表征填料在基体中的分散程度,观察填料在基体中聚集的精细结构,对填充材料性能差异的变化可作出满意的解释,是研究填充高分子材料的有效手段。     

聚氯乙烯/聚醚砜共混小孔超滤膜的研制

聚氯乙烯与聚醚砜属部分相容体系。采用溶胶-凝胶相转化法,改变聚合物共混比例、混合溶剂、添加剂用量,制备了一系列聚氯乙烯/聚醚砜(PVC/PES)共混超滤膜。通过调配铸膜液中聚合物共混比例,可大大提高共混膜的强度和韧性。其水通量和截留率与同类日本产高分子分离膜相比,均有较大提高。     

接枝共聚改性型医用聚氯乙烯

本文对增塑剂渗出性小或亲水性、生物相容性优异的接技共聚改性医用聚氯乙烯的研究进展进行了综述     

Plastic fracture in poly(vinyl chloride)

The strain fields around diamond-shaped cavities in cold-drawn rigid PVC have been determined by the application of fine grids to the specimen surface. An element of material adjacent to the diamond tip deforms predominantly in simple shear with a direction of strain parallel to the draw direction. Each element attains a maximum shear strain before the next element begins to shear. This process, possibly analogous to neck propagation in tensile tests, produces the characteristic diamond shape. Simple extension and simple shear tests on cold-drawn PVC confirm that under the stress system around a cavity, simple shear in the draw direction is a favourable mode of deformation.     

肝素化水性聚氨酯改性医用聚氯乙烯表面的研究

以N 甲基二乙醇胺为扩链剂合成了阳离子水性聚氨酯 (ACPU) ,将其固定在医用聚氯乙烯管内壁并对其进行肝素化。通过全血凝固时间实验证明 ,改性后的医用聚氯乙烯管的抗凝血性明显提高。另外使用红外光谱分析了阳离子水性聚氨酯的结构及其肝素化处理后聚合物结构的变化 ,并考察了MDEA含量对阳离子水性聚氨酯乳液及其涂膜性能的影响。     

Electrical conductivity of modified poly(vinyl chloride)

Chemical modification of poly(vinyl chloride) (PVC) by dehydrochlorination with ethanolic KOH is found to yield modified PVC with conjugated polyene sequence. The semiconducting nature of ethoxide-modified PVC is illustrated with temperature dependence of conductivity (σ). The relative ratios (r) of conductivity,σ _modifiedpvc /σ _{unmodifiedpvc} , are greater than unity in the temperature range 50° to 180°C,r being maximum in the vicinity of glass-transition temperature (T _g).T _g inferred from conductivity-temperature profiles is found to be greater for modified PVC relative to unmodified PVC, which is explicable in terms of restricted free rotation limiting segmental motion. For comparison with the conductivity andT _g of ethoxide-modified PVC, LiCl-modified PVC and (aniline + S₂O ₈ ²⁻ )-modified PVC have also been studied.     

Fatigue crack growth in poly (vinyl chloride)

Our measurements on fatigue cracks grown in PVC under plane-strain conditions shows that the width of the observed arrest lines is in agreement with the theoretical results obtained from the Dugdale-Muskhelishvili model.Further, we have shown that the fatigue of one arrest line before rupture requires a large number of loading cycles this number of cycles is constant for every arrest line of a given specimen.Brittle fracture of the specimen occurs when the stress-intensity factor K first introduced by Irwin reaches a given value.     

Optical properties of poly(vinyl chloride)/poly(ethylene oxide) blend

The relatively high dielectric constant poly(vinyl chloride) (PVC) was blended with poly(ethylene oxide) (PEO) polymer electrolytes to improve their electrical conductivity from the optical spectra of the given polymeric system. The optical properties in the UV–visible region of PVC polymer containing 0%, 20%, 50% and 70% by weight PEO are reported. The optical results obtained were analyzed in terms of the absorption formula for non-crystalline materials. The absorption coefficient and the optical band energy gap (E_opt) have been obtained from direct allowed transitions in k-space at room temperature. The width of the tail of localized states in the band gap (ΔE) was evaluated using the Urbach-edges method. It was found that both (E_opt) and (ΔE) vary with the concentration of the PEO complex in the polymer matrix. In addition, a correlation between the energy gap and the ac-conductivity as a function of PEO complex concentration is also reported.     

Development of amorphous carbon protective coatings on poly(vinyl)chloride

The great versatility of polymers has promoted their application in a series of ordinary situations. The development of specific devices from polymers, however, requires modifications to fit specific stipulations. In this work the surface properties of thin films grown onto polyvinylchloride (PVC) were investigated. Hydrogenated amorphous carbon films were deposited onto commercial PVC plates from acetylene and argon plasmas excited by radiofrequency (13.56 MHz, 70 W) power. The proportion of acetylene in the gas feed was varied against that of argon, keeping the total pressure constant at 2.5 Pa. Deposition time was 1800 s. Film elemental composition was analyzed by X-ray photoelectron spectroscopy, XPS. Water contact angle measurements were performed using the sessile drop technique. The root mean squared roughness was derived from 50 × 50 µm² surface topographic images, acquired by scanning probe microscopy. Nanoindentation and pin-on-disk techniques were employed on the determination of film hardness and sliding wear, respectively. Oxidation resistance was obtained through the etching rate of the samples in oxygen radiofrequency (1.3 Pa, 50 W) plasmas. From XPS analysis it was detected oxygen and nitrogen contamination in all the samples. It was also found that sp³/sp² ratio depends on the proportion of argon in the plasma. At lower argon concentrations, hardness, wear and oxidation resistances were all improved with respect to the uncoated PVC. In such conditions, the surface wettability is low indicating a moderate receptivity to water. This combination of properties, ascribed to a balance between the ion bombardment and deposition processes, is suitable for materials exposed to rigorous weathering conditions.