ShengLin Yang

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Name: 杨胜林; ShengLin Yang

Organization: Donghua University , China

Department: State Key Laboratory of Modification Chemical Fibers and Polymer Materials

Title: Associate Researcher/Professor(PhD)

TOPICS

Material Chemistry

Chemicals
References

Effects of light stabilizer on the ultraviolet stability of poly-p-phenylenebenzobisoxazole (PBO) fibers

Co-reporter:Junhong Jin;Guang Li;Jianming Jiang

Iranian Polymer Journal 2012 Volume 21( Issue 10) pp:739-745

Publication Date(Web):2012 October

DOI:10.1007/s13726-012-0078-2

A UV-resistant PBO fiber containing light stabilizer OB-1(2,2′-(1,2-ethenediyldi-4,1-phenylene) bis-benzoxazole) is reported. OB-1/PBO Fiber, which had excellent mechanical properties as PBO was prepared via in situ polymerization and dry-jet wet-spinning technique. Effects of the light stabilizer (OB-1) on UV stability of PBO fiber and possible degradation mechanism were investigated by tensile testing, intrinsic viscosity measurement, SEM, and ATR-FTIR analysis. Under UV-accelerated aging, the tensile strength of PBO fiber declined sharply. After exposed to UV 340-nm light for 310 h, the strength retention was only 44.17 %. SEM analysis showed the smooth and compact surface with well-oriented microfibrils was damaged. Meanwhile, the photostability of PBO fiber could be enhanced greatly by adding a small amount (0.05–0.2 %) of OB-1. Under the same conditions, the strength retention of 0.2 %OB-1/PBO fiber increased to 64.84 %, which was 47 % higher than that of PBO fiber. SEM observation showed the surface of OB-1/PBO fiber was also damaged, but it was not as so severe as PBO fiber. After UV irradiation, the intrinsic viscosity of PBO and OB-1/PBO fiber decreased which implies that mild chain scissions occurred. ATR-FTIR analysis revealed that oxazole rings in PBO and OB-1/PBO backbone were disrupted and formed amide linkages. These results indicated the loss of strength is mainly due to the break of microfibrils and fiber morphology, mild chain scission, and the disruption of oxazole rings.

The complicated influence of branching on crystallization behavior of poly(ethylene terephthalate)

Co-reporter:Guang Li;Jianming Jiang;Junhong Jin ;Chengxun Wu

Journal of Applied Polymer Science 2008 Volume 110( Issue 3) pp:1649-1655

Publication Date(Web):

DOI:10.1002/app.28809

Abstract

The randomly branched poly(ethylene terephthalate) (BPET) was prepared by bulk polycondensation from dimethyl terephthalate (DMT) and ethylene glycol (EG), with 0.4–5.0 mol % (with respect to DMT) of glycerol (GL) as a branching agent. The glass transition and crystallization behavior was studied by differential scanning calorimetry (DSC). It was found that the glass transition temperature of BPET reduced with the increasing content of GL until 1.2 mol %, and then increases a little at high degrees of branching. When compared with a linear PET, the crystallization temperature of BPET from the melt shifted to higher temperature as GL content was smaller than 1.2 mol %, and then became lower while GL load was added. Nonisothermal crystallization kinetics was studied through the modified Avrami analysis. It was revealed that the overall crystallization rate parameter of BPET became larger when the GL content was less than 1.2 mol %, then turned to lower at higher branching degree. This indicated that low degree of branching could enhance the overall crystallization of poly(ethylene terephthalate) (PET), whereas high degree of branching in the range of 3.5–5.0 mol % would block the development of crystallization. On the basis of Hoffman's secondary crystallization theory, the product σσ_e of the free energy of formation per unit area of the lateral and folding surface was calculated. According to the change of the product σσ_e with the degree of branching, a possible explanation was presented to illuminate this diverse effect of different degrees of branching on crystallization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Electrical and structural analysis of conductive polyaniline/polyacrylonitrile composites

Co-reporter:Wei Pan, Sheng Lin Yang, Guang Li, Jian Ming Jiang

European Polymer Journal 2005 Volume 41(Issue 9) pp:2127-2133

Publication Date(Web):September 2005

DOI:10.1016/j.eurpolymj.2005.04.003

Conducting composites of polyacrylonitrile (PAN) copolymer containing 10% mass ratio methylacrylate and dodecylbenzene sulfonic acid doped polyaniline (PANI–DBSA) were prepared by solution blending. Electrical properties of the blends were characterized by means of electrical conductivity measurements and the phase structures were investigated via scanning electron microscopy (SEM), X-ray diffraction (XRD), FT-IR spectroscopy, differential scanning calorimetry (DSC) and dynamical mechanical analysis (DMA). It was found that the electrical conductivity of the composites increased with the increase of PANI–DBSA content and the percolation threshold lay around 3.2 wt%. DSC and DMA measurements showed that there was only one Tg for each blend and the values of Tg varied with the PANI–DBSA content, implying that the PANI–DBSA/PAN blend was at least partially compatible. The formation of the hydrogen bonding between the carbonyl groups in PAN copolymer and the imine groups in PANI–DBSA was identified by the FT-IR spectra. XRD demonstrated that the intrinsic layered arrangement of PANI–DBSA was disaggregated in the blends. Nanosize network structure of PANI–DBSA dispersing in PAN matrix and the so-called phase reverse occurring in the skin layer of the film samples at low PANI–DBSA loading were observed by SEM.

A mathematical model of heat transfer of a PU-based intumescent flame-retardant coating during combustion in a cabinet

Co-reporter:Wang Jincheng;Yang Shenglin;Li Guang;Jiang Jianming

Polymer International 2003 Volume 52(Issue 12) pp:

Publication Date(Web):11 NOV 2003

DOI:10.1002/pi.1375

This paper reports studies on the heat transfer of a PU-based intumescent flame-retardant coating. A three-dimensional model has been developed to describe the various physical processes of the system when testing the flame-retardant (FR) properties, such as char index and weight loss, by the cabinet method. The accuracy of the model was evaluated by comparing predicted and experimental temperature profiles. Copyright © 2003 Society of Chemical Industry