Pu Wang Li

Formulation of Vanillin Cross-Linked Chitosan Nanoparticles and its Characterization

Chitosan nanoparticles were successfully prepared by chemical cross-linking with vanillin. The nanoparticles were spherical in shape with smooth surface, and the average particle size of chitosan nanoparticles was 141 nm. The formulation of chitosan nanoparticles is based on Shiff reaction between aldehyde group of vanillin and amino group of chitosan. Chitosan nanoparticles prepared by crosslinking with vanillin are promising vehicle for the drug delivery of various anticancer drugs in the chemotherapy of cancers.

Preparation and Properties Analysis of Slow-Release Microcapsules Containing Patchouli Oil

Abstract: The microcapsules containing patchouli oil were prepared using a complex coacervation with chitosan and arabic gum as wall material, patchouli oil as the core material. The different factors influence on the microcapsule properties were investigated by scanning electron microscope, laser particle size analyzer, infrared spectrum and UV spectra. The best conditions for preparing patchouli oil microcapsules were confirmed as follows: the concentration of chitosan with low viscosity 0.5%, arabic gum 4%, and the ratio of wall material to core material was 2: 1. The pH value of the complex coacervation reaction was 4.5, and stirring speed was 800 r/min. The microcapsules were analyzed by Infrared spectral to confirm the patchouli oil had been successfully embedded in the microcapsules. The drug loading and encapsulation efficiency for patchouli was 20.7% and 67.2%, respectively.

Preparation of Nanoparticles by Crosslinking Folate Conjugated Chitosan with Vanillin and its Characterization

Functionalized chitosan (CS) were widely used as drug delivery system in the chemotherapy of various disease. In this work, folate (FA) was conjugated into chitosan molecular as targeting ligand based on Schiff reaction between –NH2 group of CS and –COOH group of FA. And nanoparticles were made by emulsion method with vanillin novel cross-linking agent. The FA modified CS and its nanoparticles were characterized by Fourier transform spectroscopy (FT-IR), scanning electron microscope (SEM) and Zeta potential. SEM results confirmed the nanoparticles made from FA-CS conjugate were spherical in shape and were about 100 nm in size. Zeta potential analysis revealed that the nanoparticles were negatively charged with charge density of -7.73mV.

Comparison of Kjeldahl and the Elemental Analysis Methods for Determination of Nitrogen Content in Raw Natural Rubber

The nitrogen in raw natural rubber is mainly derived from crude protein of latex. In this study, the nitrogen content of six kinds of raw natural rubber was analyzed for evaluating Kjeldahl and elemental analysis methods. The nitrogen content ranged from 0.43% to 0.66% for Kjeldahl methods and from 0.45% to 0.75% for elemental analysis method. There was no significant difference between the two methods. The coefficient of variation was below 1%. The data of nitrogen content showed a simple linear correlation (r=0.9937) between the two methods. It was concluded that the elemental analysis method could replace Kjeldahl method in nitrogen analysis of raw natural rubber.

The Natural Rubber/Zinc Oxide Nanocomposites: Its Morphology, Mechanical and Thermal Decomposing Properties

Natural rubber /Zinc Oxide (NR/ZnO) nanocomposites are fabricated by blending natural rubber latex with aqueous suspension of nanoZnO particles. Its morphology and thermal/thermooxidative ageing resistance are investigated with scanning electron microscopy (SEM) and thermogravimetric analyzer (TGA). The results show that the mechanical properties of NR is greatly improved by the incorporation of nanoZnO, nanoparticles, which are homogenously distributed throughout NR matrix as nanoclusters with an average size of 80 nm when the ZnO loading is less than 4 wt%. The thermal/thermooxidative aging resistance of NR/ZnO nanocomposites is compared to the pure NR. It is found that the introduction of nanoZnO has no obvious impact to the thermal decomposing properties of NR matrix. ZnO/NR composites possess excellent antibacterial effect.

Development of Ligand Incorporated Chitosan Nanoparticles for the Selective Delivery of 5-Fluorouracil to Colon

Drug delivery systems with active targeting ligand provide improved therapeutic efficiency due to the selectivity towards tumor cells. In this paper we prepared drug loaded nanoparticles (NPs) using folate (FA) incorporated chitosan (FA-CS) based on ionic gelation technology. FA-CS NPs were spherical in shape with an average particle size of 100 nm, while 5-fluorouracil (5-FU) loaded NPs became less circular with average particle size of 100-500 nm. NPs made from FA-CS conjugates exhibited improved capability to encapsulate hydrophilic 5-FU. It was found 5-FU distributed in FA-CS NPs in solid solution state. In vitro release results demonstrated the release of 5-FU from FA-CS NPs was more controllable as compared to that of CS NPs.

Damping Performance of CB Filled NR/ENR, NR/BR and NR/IIR Compounds

Natural rubber (NR)/epoxidized natural rubber (ENR)/carbon black (CB), natural rubber/butadiene rubber (BR)/carbon black and natural rubber/isobutylene-isoprene rubber (IIR)/carbon black compounds were prepared by mechanical mixing method. The mechanical properties, dynamic mechanical properties for the compounds were investigated respectively. The temperature range of tanδ>0.3 of NR/ENR40/CB compound was wider and shifted to high temperature than NR/CB compound. Comprehensive analysis indicated that NR/BR/CB and NR/IIR/CB compounds had no better damping performance than NR/CB compounds, while NR/ENR/CB compound had better damping performance.

Surface Modification and Properties Analysis of Shell Powder with Sodium Stearate Surface Modifier

In this study, shell powder was modified by sodium stearate surface modifier for improving the compatibility of SP with polymer materials. The surface modifiers influence on the physical and chemical properties of SP were studied by scanning electron microscope (SEM), fourier infrared spectrum (FT-IR), surface contact angle meter, XRD diffraction analysis meter and other modern instruments and analysis method. The results showed that the surface modifier was successfully coupled to the shell powder surface. After surface modifier modification, the interfacial compatibility of the shell powder with polymer materials was effectively improved. The contact angle of shell powder surface increased from 73.5 ° to 110.8 ° , along with the dosage of sodium stearate surface modifier was 4.0%. All results suggested that modified shell powder is promising for using as a reinforcement filler in polymer materials.

Effect of Accelerator Type on Dynamic Properties of Natural Rubber Vulcanizates

The influence of accelerator M and accelerator NS on dynamic properties of NR vulcanizate was investigated by using rubber processing analyzer (RPA), flexometer and Nuclear Magnetism Resonance (NMR). The results showed that the degree of crosslinking density of NR vulcanizate by using accelerator NS was higher than NR vulcanizate by using accelerator M, the response of dynamic properties of vulcanizate to frequency and temperature was different, and the NR vulcanizate cured with accelerator NS had lower heat built up than NR vulcanizate cured with accelerator M.

Preparation and Characterization Nano-Cellulose and its Surface Modification by Silane Coupling Agent

Pineapple leaf fiber (PALF) was pretreated by sodium hydroxide, and hydrolyzed by sulfuric acid to obtained nano-cellulose (NC). The SEM showed that size of NC is 30-50nm. Bis[3-(triethoxysilyl)propyl]tetrasulfide (Si-69) was employed to sueface modificate the NC. The results of characterization of particle size, zeta potential, FTIR and contact angle illuminated that particle size of surface modified NC was smaller than NC and zeta potential of -75.8mV was lower than NC’s. The hydrophobicity of surface modifiedNC has been improved.