连续纤维增强热塑性复合材料制备与熔融浸渍机理研究

介绍了4种连续纤维增强热塑性复合材料制备技术及这些方法的优缺点,针对具有工业化前景的熔融浸渍法,根据流体力学理论和Darcy定律,建立了基于物性参数、工艺参数和结构参数的连续纤维束熔融浸渍模型,并对模型进行了求解;结合理论研究和实验研究,分析了物性参数、工艺参数和结构参数对纤维浸渍效果的影响。分析结果表明,聚合物黏度和模具结构参数是影响纤维浸渍效果的关键参数。     

BiOCl/Fe3O4磁性复合结构超薄纳米片的制备及其光催化性能研究

以Fe3O4为磁粒,制备了易于和催化液体分离的磁性光催化剂。采用X射线粉末衍射(XRD)、光催化等手段表征催化剂的表面形貌、晶型组成、化学结构等。结果表明,Fe3O4包覆在BiOCl片的表面,且包覆较为牢固。     

Experimental investigation and stability analysis on dense-phase pneumatic conveying of coal and biomass at high pressure

Conveying characteristics and flow stability are very important for design and control of a conveying system at high pressure. The influences of operating parameters and material properties on conveying characteristics were investigated in an experimental test facility with a conveying pressure up to 4MPa. Wavelet transform and Shannon entropy analysis were applied to analyzing pressure drops through horizontal pipe in order to obtain the stability criterion. Results indicated that the mass flow rate of biomass decreased, while the mass flow rate of pulverized coal increased at first and then decreased with the increase in fluidization velocity. Solid loading ratios for four kinds of powders decreased with the increase in fluidization velocity. Conveying phase diagrams and pressure drops through different test sections of pulverized coal and biomass at high pressure were obtained and analyzed. The influences of coal category, fracture characteristics and particle size on conveying characteristics were determined.     

Crystallization behaviors and foaming properties of diatomite-filled polypropylene composites

The non-isothermal crystallization kinetics and foaming properties of polypropylene (PP) filled with various contents of diatomite were investigated. The results showed that the diatomite had strong effects on the PP crystallization kinetics, which significantly increased the crystallization temperature and reduced crystallite size. These were attributed to the nucleation effect of the diatomite particles and the complex interface properties between the PP chains and diatomite particles. Non-isothermal crystallization can be well described by the Mo’s method. The non-isothermal crystallization activation energy calculated by the Kissinger’s method increased with increased content of diatomite. The foamed PP composites, in particular, the PP composites filled with 10 wt% diatomite had better cell morphology ascribed to the facilitated crystallization and increased polymer melt strength compared with the foamed pure PP.     

PLA复合材料降解性能研究进展

概述了聚乳酸(PLA)的降解理论,重点综述了PLA复合材料水解和热降解的国内外研究进展,并展望了PLA复合材料降解研究的发展方向。     

Formation of ordered microporous films with water as templates from poly(D,L‐lactic‐co‐glycolic acid) solution

Recently a method that uses water droplets at the air–solution interface as an ordered template was reported for the preparation of ordered micrometer‐size honeycomb structures. Here we show that the method can also be used for formation of honeycomb‐like porous films from random copolymers with certain hydrophilicity, besides those polymers with defined structures such as block copolymers, starlike homopolymers, amd amphiphilic polymers. This demonstrates that the stabilization of water droplets is the key factor for the regular structure. Also we indicate that size and structure of the films can be regulated by such variables as concentration and atmospheric humidity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1846–1850, 2003     

Paclitaxel-loaded nanoparticles of star-shaped cholic acid-core PLA-TPGS copolymer for breast cancer treatment

A system of novel nanoparticles of star-shaped cholic acid-core polylactide-d-α-tocopheryl polyethylene glycol 1000 succinate (CA-PLA-TPGS) block copolymer was developed for paclitaxel delivery for breast cancer treatment, which demonstrated superior in vitro and in vivo performance in comparison with paclitaxel-loaded poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles and linear PLA-TPGS nanoparticles. The paclitaxel- or couramin 6-loaded nanoparticles were fabricated by a modified nanoprecipitation method and then characterized in terms of size, surface charge, surface morphology, drug encapsulation efficiency, and in vitro drug release. The CA-PLA-TPGS nanoparticles were found to be spherical in shape with an average size of around 120 nm. The nanoparticles were found to be stable, showing no change in the particle size and surface charge during 90-day storage of the aqueous solution. The release profiles of the paclitaxel-loaded nanoparticles exhibited typically biphasic release patterns. The results also showed that the CA-PLA-TPGS nanoparticles have higher antitumor efficacy than the PLA-TPGS nanoparticles and PLGA nanoparticles in vitro and in vivo. In conclusion, such nanoparticles of star-shaped cholic acid-core PLA-TPGS block copolymer could be considered as a potentially promising and effective strategy for breast cancer treatment.     

Efficiency enhancements in Ag nanoparticles-SiO2-TiO2 sandwiched structure via plasmonic effect-enhanced light capturing

TiO₂-SiO₂-Ag composites are fabricated by depositing TiO₂ films on silica substrates embedded with Ag nanoparticles. Enhancement of light absorption of the nanostructural composites is observed. The light absorption enhancement of the synthesized structure in comparison to TiO₂ originated from the near-field enhancement caused by the plasmonic effect of Ag nanoparticles, which can be demonstrated by the optical absorption spectra, Raman scattering investigation, and the increase of the photocatalytic activity. The embedded Ag nanoparticles are formed by ion implantation, which effectively prevents Ag to be oxidized through direct contact with TiO₂. The suggested incorporation of plasmonic nanostructures shows a great potential application in a highly efficient photocatalyst and ultra-thin solar cell.     

A fluorescent probe for the determination of Ce4+ in aqueous media

A rhodamine-based probe bearing an N,N-dimethylaniline unit was developed as a fluorescent chemodosimeter for Ce⁴⁺ in aqueous media. Importantly, the sensor can selectively respond to Ce⁴⁺ over other commonly coexistent metal ions (such as La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Er³⁺, Tb³⁺, Ho³⁺, Tm³⁺, Yb³⁺, Lu³⁺, Y³⁺) in aqueous media with a rapid response time. The system, which utilizes an irreversible Ce⁴⁺-promoted oxidation reaction, responds instantaneously at room temperature with linear proportionality to the amount of Ce⁴⁺.