Zong Qiang Zeng

Preparation and Properties of Interpenetrating Polymer Network Films from Prevulcanized Natural Rubber Latex/Chitosan Blends

The acidfied sulfur-prevulcanized natural rubber (NR) latex was mixed with 1～20 parts per hundred rubber (phr) of a 2wt% solution of chitosan (CS) in 1wt% acetic acid, then cast to preapare a series of NR/CS semi-interpenetrating polymer network (semi-IPN) films; the NR/CS semi-IPN films were further treated with 0.5wt% glutaraldehyde（GA）solution for respectively 1, 3 and 6h to obtain NR/CS IPN films. The mechanical properties and swelling behavours in various media of water, toluene and reference olis of IRM901 and IRM 903 of these films were studied and compared with those pure sulfur-prevulcanized natural rubber latex (SNRL) film. Results showed that, NR/CS IPN films with better mechanical properties could be obained by treating the 24h-leached NR/CS semi-IPN films than by treating directly the unleached ones with 0.5wt% GA solution; the tear strength, 300% modulus, Shore A hardness, hydrophilicity and resistance to non-polar solvents and oil of the SNRL films increased with the incorporation of CS, while the NR/CS IPN films exhibited better than the NR/CS semi-IPN films, especially in tear strength enhancement; the tensile strength and elongation at break of NR/CS semi-IPN and IPN films gradually decreased with the increase in CS content. However, most of the elasticity of pure NR vulcanizate could be reserved, when the CS content was not greater than 15 phr.

Structure and Thermal Properties of RHA/NR Composite

The rice husk ash/natural rubber (RHA/NR) composites were prepared by latex blending process using the RHA modified with silane coupling agent. The structure and morphology of modified RHA were studied. The dispersing performance of modified RHA in the composites was evaluated from the structure and thermal properties. The results indicate that silane coupling agent KH-570 can react with the carboxyl of the RHA surface, leading to a significant decrease in carboxyl absorption intensity and the obvious improvement in the dispersion of RHA particles in rubber matrix. As the modified RHA having grafted onto NR molecular chains can increase the interface force between RHA and rubber matrix, the thermal stability of RHA/NR composites thus can be improved. The RHA/NR composite of highest thermal stability can be prepared with RHA load of 5% shows the best.

Optimization for Extraction of Astaxanthin from Shrimp Shell Using Response Surface Method

In this work, the extraction of astaxanthin i.e. bioactive substance in the shrimp head and shell was studied. The extraction method of astaxanthin was established: the alkali method and organic solvents method were combined to extract astaxanthin, the solvent of the alkali solution was ethanol:water =4:1, dichloromethane was selected as the extractant. The best extraction conditions for astaxanthin were optimized: the concentration of sodium hydroxide was 1.4mol / L, the optimum extaction process was at 54°C for 24 h, and the ration of solid to liquid was 8:1. In this condition, the absorption value of astaxanthin was 1.2048, the concentration of astaxanthin was 3.26μg/mL, which was equivalent to 32.6 μg/g dry shrimp shell.

Analysis of Stinky Components in Natural Rubber Latex

The reason for the natural rubber latex giving out stink during long-term storage or transportation was studied. The stinky component in the latex detected by gas chromatography-mass spectrometry was phenol, the generated content of which increases as the storage temperature rising. It is most possible that the phenol was generated from the decomposition of the inwall coating of iron bucket which loading the natural rubber latex in the strong alkaline during the long-term and high-temperature storage.

Surface Modification of Natural Rubber Latex Film by N-Vinypyrrolidone Graft Copolymerization

The surface modification of natural rubber (NR) latex film by argon plasma pretreatment and subsequent UV-induced graft copolymerization of N-vinypyrrolidone (NVP) was carried out to improve the hydrophilic behavior. The effects of plasma pretreatment time and UV irradiation time on the graft yields were studied. The peroxide functionalities formed by the oxidations in air after plasma pretreatment are the activated species for the subsequent UV-induced graft copolymerization of NVP. ATR-FTIR and XPS analyses indicate that the PVP molecules have covalently bonded onto the surface of NR latex film. The argon plasma pretreatment time of 2min and UV irradiation time of 10min are the proper conditions for the graft polymerization of NVP onto NR latex film, which can reduce the water contact angle value of NR latex film from 95o to about 57o.

Fabrication of Rice Husk Ash/Natural Rubber Composite

The preparation of rubber-based composite from agricultural by-product is the main trend to upgrade the performance of rubber and reduce the cost. In this work, the rice husk ash/natural rubber (RHA/NR) composites were prepared by latex mixing process using the RHA modified with rare earth coupling agent. The mechanical properties, dynamic mechanical properties, thermal stability and morphology of RHA/NR composites were analyzed by universal testing machine, dynamic mechanical analyzer, thermo gravimetric analyzer and scanning electron microscope. The results indicate that previous modification of RHA with rare earth coupling agent can improve the dispersion of RHA in NR matrix significantly and increase the interaction between RHA particles and NR matrix and thus upgrade the mechanical properties and anti-oxidative behaviors of RHA/NR composite. The RHA/NR composite of highest mechanical properties and anti-oxidative behaviors can be obtained with a RHA loading of 4 per hundred rubber.

Extraction and Purification of Astaxanthin from Shrimp Shell with Alkaline-Organic-Solvent Method

The Alkaline-organic-solvent Method was employed to extract astaxanthin from shrimp shell in this work. The results demonstrated that the optimum extraction temperature was 20°C, the optimum ratio of extraction agent to sample is 1:3. Centrifugal thin layer chromatography was used to purify the astaxanthin and the optimum developer was petroleum, acetone and methanol (14:5:1). The FT-IR spectra and the HPLC analysis both demonstrated the purified substance was identical with standard astaxanthin and the content of astaxanthin account for 55.4%.

Structure and Thermal Stability of Natural Rubber Reinforced with In Situ Generated Zinc Sorbate

In situ prepared zinc disorbate (ZDS) in natural rubber (NR) by the reaction of zinc oxide and sorbic acid was used to reinforce the dicumyl peroxide-cured NR vulcanizate. The changes in mechanical properties of NR vulcanizates after ageing and were determined and the structures and thermal stability of vulcanizates were also analyzed using scanning electron microscope and thermal gravimetric analyzer. The change ratios in tensile strength and elongation at break of NR vulcanizate with theoretic formation of ZDS of 21phr can be increased to -33 from -44 and -27 from -38 after ageing and the initial weight loss temperature of NR vulcanizate can be increased for about 7°C as compared to un-reinforced NR vulcanizate, indicating that the antioxidative behavior and thermal stability of NR can be improved significantly with theoretic formation of ZDS of 21phr.

Viscoelastic Properties of Constant Viscosity Natural Rubber with Mercaptan

2-mercaptobenzothiazole was used to deal with natural rubber (NR) latex to prepare constant viscosity natural rubber (CV-NR) in this research. The dynamic viscoelastic behavior of CV-NR of raw rubber, rubber compound and vulcanized rubber was studied through strain and frequency scanning on rubber processing analyzer, and then it was compared with the response curve of NR.

Study on Natural Rubber Quality of Micro-Cut Tapping with Gas-Stimulation

The natural rubber samples produced by conventional tapping methods were used as a control, then analyzed the dry rubber property of natural rubber, the dynamic property and Physical & mechanical property of vulcanized rubber using Rubber processing analyzer and Thermogravimetric Analyze the difference between the properties of dry rubber and vulcanized rubber produced by Micro-cut Tapping with Gas-stimulation. The results indicated that the tensile strength, tear strength elastic modulus of dry rubber that produced by Micro-cut Tapping with Gas-stimulation are respectively 20%, 7% lower than the control. The protein content of dry rubber materials produced by Micro-cut Tapping with Gas-stimulation is 16.7% higher than control group.