PP/纳米ZnO的紫外光老化性能

将纳米ZnO(nano-ZnO)用钛酸酯偶联剂表面处理后制备聚丙烯(PP)/nano-ZnO复合材料。研究了nano-ZnO含量对复合材料耐老化性能的影响。nano-ZnO可明显改善PP树脂的紫外光老化性能。当w(nano-ZnO)为3%时,复合材料老化前后的性能差和纯PP树脂老化前后的性能差分别为:拉伸强度1.9 MPa和3.1 MPa、断裂伸长率为29.0%和66.7%、缺口冲击强度为1.1 kJ/m~2和2.9 kJ/m~2、无缺口冲击强度为1.5 kJ/m~2和3.2 kJ/m~2、球压痕硬度为4.8 MPa和5.8 MPa、维卡软化温度为3.3℃和7.0℃。     

纳米TiO2协同纳米ZnO/SBS复合改性沥青耐紫外光老化性能评价

高海拔地区强烈紫外光辐照易使沥青路面老化,特殊环境因素要求沥青路面中黏结料须具有良好耐老化性,纳米材料以其独特优点已成为改性沥青研究的重要方向,而纳米材料在沥青中易发生团聚是制约该发展的重要瓶颈.以纳米ZnO、纳米TiO2、聚合物SBS为改性剂,运用硅烷偶联剂(KH-560)对纳米材料表面进行修饰,在此基础上研究基质沥青、SBS改性沥青、纳米ZnO/SBS改性沥青、纳米ZnO/纳米TiO2/SBS复合改性沥青紫外光老化前后物理性能演变规律,利用场发射扫描电镜结合能谱分析(SEM/EDS)研究老化前后纳米ZnO/纳米TiO2/SBS复合改性沥青中Zn、Ti特征元素含量变化及纳米材料分布形态,揭示耐光老化机理.结果显示:经过修饰后的纳米材料在沥青中分散均匀,纳米材料和沥青相容性得到明显改善,在制备过程中两者发生化学反应;紫外光老化后,纳米ZnO/纳米TiO2/SBS复合改性沥青延度保留率为87.72％,软化点增量降幅61.32％,耐老化性能最佳,其老化机理是纳米TiO2对波长为365 nm紫外光波具有良好吸收作用,而纳米ZnO在该波长辐照下易发生光分解,活性降低.     

HIPS/纳米TiO2的分散及光老化性能研究

研究了纳米TiO2粒子在高抗冲聚苯乙烯(HIPS)／纳米TiO2复合材料中的分散及纳米TiO2对复合材料光老化性能的影响，探讨了复合材料的光老化机理。结果表明，通过两步法熔融共混，可得到纳米粒子均匀分散的复合材料；纳米TiO2质量分数为1.O％时，复合材料的综合力学性能最好，纳米TiO2对HIPS具有一定的增韧效果；经氙灯加速光老化后，HIPS／纳米TiO2复合材料的力学性能明显优于纯HIPS样品。纳米TiO2可显著提高复合材料的抗光老化能力。     

纳米TiO2/PP复合材料的研究

研究了纳米TiO2／PP复合材料的力学性能和耐老化性能，实验结果表明，添加1％－2％的纳米TiO2可以明显改善PP材料的抗冲击性能；纳米质量分数在1％－4％范围内对复合材料的拉伸强度几乎没有影响；而添加少量的纳米TiO2可以大大提高PP材料的耐紫外光老化性能，说明纳米TiO2对紫外光有极强的吸收能力。TiO2/PP复合材料具有良好的耐候性，可以提高其户外制品的使用寿命。     

纳米TiO2/高抗冲聚苯乙烯耐候型复合材料研究

利用金红石型纳米TiO2优异的紫外线屏蔽性能,采用熔融共混法制备了纳米TiO2/高抗冲聚苯乙烯(H IPS)复合材料。经过672 h的氙灯气候加速老化后,缺口强度保持率比未改性H IPS提高了约20%,颜色变化幅度只有未改性H IPS的10%,抗色变能力大幅度提高;质均相对分子质量在整个加速老化期间未发生明显变化,老化672 h后下降幅度只有未改性H IPS的10%,FTIR分析表明,由于纳米TiO2与光稳定剂的协同作用使改性H IPS的光老化速度得到有效抑制,其羰基和羟基吸收峰的振动特征在672 h的老化期间内均未发生明显变化。     

纳米TiO2表面改性以及增韧聚苯乙烯的研究

实验采用钛酸酯偶联剂对纳米TiO2进行了表面改性,通过熔融共混法制备聚苯乙烯/TiO2纳米复合材料,借助FTIR、DTA-TG等手段分析了纳米TiO2的改性效果。实验表明,纳米TiO2的加入提高了PS/TiO2纳米复合材料的冲击强度,改性后纳米TiO2的增韧效果更好。     

聚丙烯/纳米TiO2复合材料的紫外老化研究

对聚丙烯(PP)／纳米TiO2复合材料的紫外老化进行了研究。力学性能、熔体粘度、熔融温度、红外光谱和扫描电镜对比试验的结果表明：PP／纳米TiO2复合材料的耐紫外老化性能比纯PP的大大提高,纳米TiO2是一种性能优异的PP抗老化剂。     

纳米二氧化钛在水处理中的研究进展

介绍了纳米TiO2制备方法及光催化氧化还原机理,概述了纳米TiO2光催化技术在降解农药废水、含油废水、染料废水、造纸废水及自来水处理中的应用,提出了纳米TiO2在水处理应用中存在的问题及解决措施,并对TiO2光催化材料在水处理中的发展趋势进行了展望。     

Enhanced thermal properties of PS nanocomposites formed from inorganic POSS-treated montmorillonite

We have prepared polystyrene/clay nanocomposites using an emulsion polymerization technique. The nanocomposites were exfoliated at up to a 3 wt% content of pristine clay relative to the amount of polystyrene (PS). We used two different surfactants for the montmorillonite: the aminopropylisobutyl polyhedral oligomeric silsesquioxane (POSS) and the ammonium salt of cetylpyridinium chloride (CPC). Both surfactants can intercalate into the layers of the pristine clay dispersed in water prior to polymerization. Although the d spacing of the POSS-intercalated clay is relatively smaller than that of the CPC-intercalated clay, PS more easily intercalates and exfoliates the POSS-treated clay than the CPC-treated clay. IR spectroscopic analysis further confirms the intercalation of POSS within the clay layers. We used X-ray diffraction (XRD) and transmission electron microscopy (TEM) to characterize the structures of the nanocomposites. The nanocomposite prepared from the clay treated with the POSS containing surfactant is exfoliated, while an intercalated clay was obtained from the CPC-treated surfactant. The molecular weights of polystyrene (PS) obtained from the nanocomposite is slightly lower than the virgin PS formed under similar polymerization conditions. The value of T_g of the PS component in the nanocomposite is 8 °C higher than the virgin PS and its thermal decomposition temperature (21 °C) is also higher significantly. The presence of the POSS unit in the MMT enhances the thermal stability of the polystyrene.     

国内外PS/PE共混改性研究新进展

综述了国内外采用接枝共聚物,嵌段共聚物以及反应性共混提高PS／PE相容性的研究方法。并提出应继续开发PS／PO合金的途径,并将其转化为工业产品。     

PS/MMT溶液插层复合材料的制备及流动性能研究

研究了溶剂种类和混合时间对聚苯乙烯(PS)在溶液中与不同种类蒙脱土的插层行为的影响以及所制备的复合材料的流动性能。结果表明:PS分子链在溶液中能够插入有机蒙脱土(OMMT)片层之间形成插层型复合材料,而与钠基蒙脱土(Na-MMT)只能形成填充型复合材料,溶剂种类和混合时间对插层效果没有影响;两种复合材料的流动性能与纯PS相比显著改善,其中PS/Na-MMT的流动性能优于PS/OMMT。     

PS/POSS复合材料的阻燃性能和流变性能研究

通过熔融共混法制备了聚苯乙烯(PS)/八苯基多面体低聚倍半硅氧烷(OPS)复合材料。采用氧指数仪和毛细管流变仪测试了复合材料的阻燃与流变性能。结果表明:PS/OPS复合材料为典型的假塑性流体;在较低的剪切速率下,复合材料的表观黏度随着OPS含量的增加而降低,但在较高的剪切速率下,其表观黏度随着OPS含量的增加而增大;与纯PS相比,PS/OPS复合材料的黏流活化能随OPS含量的增加而略有增加;OPS的加入有助于提高PS的阻燃性和热稳定性。     

Studies on thermal properties of PS nanocomposites for the effect of intercalated agent with side groups

Polystyrene-layered silicate nanocomposites were prepared from three new organically modified clays by emulsion polymerization method. These nanocomposites were exfoliated up to 3 wt% content of pristine clay relative to the amount of polystyrene (PS). The intercalated agents C₂₀, C₂₀-4VB, and C₂₀-POSS intercalated into the galleries result in improved compatibility between hydrophobic polymer and hydrophilic clay and facilitate the well dispersion of exfoliated clay in the polymer matrix. Results from X-ray diffraction, TEM and Fourier transform infrared spectroscopy indicate that these intercalated agents are indeed intercalated into the clay galleries successfully and these clay platelets are exfoliated in resultant nanocomposites. Thermal analyses of polystyrene-layered silicate nanocomposites compared with virgin PS indicate that the onset degradation temperature ca. 25 °C increased and the maximum reduction in coefficient of thermal expansion (CTE) is ca. 40% for the C₂₀-POSS/clay nanocomposite. In addition, the glass transition temperatures of all these nanocomposites are higher than the virgin PS.     

Morphology, structure and properties of conductive PS/CNT nanocomposite electrospun mat

The morphologies and properties of Polystyrene (PS)/Carbon Nanotube (CNT) conductive electrospun mat were studied in this paper. Nanocomposite fibers were obtained through electrospinning of PS/Di-Methyl Formamide (DMF) solution containing different concentrations and types of CNTs. The dispersion condition of CNTs was correlated to morphologies and properties of nanocomposite fibers. A copolymer as an interfacial agent (SBS, Styrene-butadiene-styrene type) was used to modify the dispersion of CNTs in PS solution before electrospinning. The results showed that the presence of the copolymer significantly enhances CNT dispersion. The fiber diameters varied between 200 nm and 800 nm depending on CNT type, polymer concentration and copolymer. The final morphological study of the fibers showed that CNT addition caused a decrease in beads formation along fiber axis before percolation threshold. However, addition of CNTs above percolation increased the beads formation, depending on the dispersion condition. The presence of SBS modified the dispersion, reduced the fiber diameter and the number of bead structures. Electrical conductivity measurements on nanocomposite mats of 15-300 μm in thickness showed an electrical percolation threshold around 4 wt% MWCNT; while the samples containing SBS showed higher values of conductivities below percolation compared to the samples with no compatibilizer. Enhancement in mechanical properties was observed by the addition of CNTs at concentrations below percolation.     

聚苯乙烯的溴化及其与聚苯乙烯的共混

以通用聚苯乙烯(GPPS)为原料,液溴为溴化试剂,无水三氯化铝–铝粉为复合催化体系,采用溶液法合成了溴化聚苯乙烯(BPS)。讨论了溴化时间、主链卤代抑制剂(BHSA)、液溴、催化剂等对聚苯乙烯(PS)溴化的影响。结果表明,BPS的溴含量随溴化时间的增加而提高,但也使BPS的摩尔质量显著下降,而主链溴代抑制剂则可改善BPS的断链。增加液溴量和三氯化铝的用量,虽BPS中溴含量增加了,但主链骨架上的溴化使产物颜色加深。提高溴化反应温度,BPS的摩尔质量大为下降1。H NMR分析表明,增加溴化时间、增加液溴量和主链抑制剂量可有效增加苯环上溴代含量,而增加催化剂用量和升高溴化温度却使苯环上的溴代含量减少。BPS在300℃的热失重低于5%。通过溶液共混制备了GPPS/BPS的共混膜,用原子力显微镜观察了共混物的表面形貌。由结果可知,GPPS和BPS的共混体系相容性差,当共混质量比达1∶1时,BPS仍自成一相分散在连续的PS相中。     

再生可发性聚苯乙烯工艺研究

本文介绍一种用回收废PS泡沫塑料制成再生可发性PS颗粒的方法。是采用可发性凝胶缩孔剂使废PS泡沫凝胶化,再经挤出造粒(粒径≤2mm),然后将粒料风干至溶剂含量为6～10%,即制得再生可发性PS(EPS)。用该再生料所制PS发泡制品的主要性能已达到轻工部标准:密度0.0258g/cm~3、吸水量0.0075kg/m~2、弯曲强度0.314MPa,50%压缩强度0.214MPa。文中还对几种PS泡沫缩孔消泡的方法和造粒方法进行了比较,对凝胶化用溶剂的组成进行了选择,并对混合溶剂的配比、鼓风和温度对所制EPS颗粒干燥速率的影响进行了探讨。     

Comparative study on phase and properties between rPET/PS and LCP/PS in situ microfibrillar-reinforced composites

Microfibrillar-reinforced composites based on two dispersed phases, liquid crystalline polymer (LCP) and recycled poly(ethylene terephthalate) (rPET), and polystyrene (PS) were prepared using extrusion process. The rheological behavior, morphology, and thermal stability of LCP/PS and rPET/PS blends containing various dispersed phase contents were investigated. All blends and LCP exhibited shear thinning behavior, whereas Newtonian fluid behavior was observed for rPET. The incorporation of both LCP and rPET into PS significantly improved the processability. The potential of rPET as a processing lubricant by bringing down the melt viscosity of the blend system was as good as LCP. The elongated LCP domains were clearly observed in as-extruded strand. Although the viscosity ratio of rPET/PS system was lower than that of LCP/PS system, most rPET domains appeared as small droplets. An addition of LCP and rPET into PS matrix improved the thermal resistance in air significantly. The obtained results suggested the high potential of rPET as a processing aid and thermally stable reinforcing-material similar to LCP. The mechanical properties of the LCP-containing blends were mostly higher than those of the corresponding rPET-containing blends when compared at the same blend composition.