最新刊期
卷 28 ， 期 3 ， 2015
- 摘要：Self-reinforced polymer composite is a peculiar kind of muti-phases material. Its reinforced phase comprises the same chemical structure but different physical properties as the matrix phase being in a great value of application, owe to the significant excellent compatibility and bonding strength at the interphase of the two phases, while it seems significant beneficial for recycling. In this paper, a few preparation methods containing in-situ and out-situ ways for this material are summarized, including hot compact, overheating of constrained fibers, die-drawing, roll-drawing and other ones in details. And we also focus on summarizing the manufacture process and faults for the composite. At last, an overlook of this material’s perspective is made.关键词：Self-reinforced;Composite;Preparation method;Faults
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发布时间：2022-09-18 - 摘要：Poly (β-hydroxybutyrate-co-β-hydroxyvalerate) (PHBV) has been widely used in potential applications due to its biodegradation, biocompatibility, piezoelectric, and optical activity compared to traditional polymers. However, the poor toughness limits its expansion into industry. This paper reviews the toughness modification of PHBV with nanomaterials during these years. The addition of nanomaterials could be acting as an anisotropic nucleating agent, which improving the crystallization of PHBV, and leading to the improved toughness. Nanocellulose would be used as toughening in PHBV polymer because of its lightweight, biodegradation, and superior mechanical properties compared to other nanomaterials. In the end, some barriers are proposed in this paper and the prospect was also outlooked.关键词：Poly (β-hydroxybutyrate-co-β-hydroxyvalerate) (PHBV);Nanomaterials;Nanocellulose;Toughening modification
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发布时间：2022-09-18 - 摘要：Morpholine-2,5-dione derivatives are a kind of cyclic monomers for the preparation of biodegradable materials. This paper summarized the synthesis methods of morpholine-2,5-dione derivatives and their copolymers, as well as their potential applications in medical field. Firstly, three synthesis methods of these derivatives were introduced, also the homopolymerization of morpholine-2,5-dione derivatives to prepare polydepsipeptides was summarized. Secondly, this paper introduced ring-opening copolymerization of morpholine-2,5-dione derivatives with e-caprolactone and lactide to prepare the copolymers based on amino acids. Finally, this paper summarized the synthesis of morpholine-2,5-dione derivatives block copolymers, and the recent development of their applications in drug delivery and gene carriers.关键词：Morpholine-2;5-dione derivatives;Biodegradable;Ring-opening polymerization
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发布时间：2022-09-18 - 摘要：Lignin,one of the most abundant biopolymers on earth, is a polyphenolic macromolecule which is comprised of 9-carbonphenol propane units (p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol) linked together by different types of bonds. Large amounts of lignin have been generated by the pulp and paper industry through kraft process. Lignin is mainly used as a low-grade fuel and its potential is not fully valued. It is economically and environmentally desirable to convert lignin to valuable reinforcing additives for rubbers. Lignin can be used as coupling agent, antiaging agent, fire retardant as well as reinforcing agent, and it could partially replace carbon black in the rubber composites. Modification of lignin, various preparation methods of rubber/lignin composites and recent research progress are systematically reviewed in this article. Lastly, the challenges and future potentials of rubber/lignin composites are proposed.关键词：Lignin;Rubber;Modification;Composites
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发布时间：2022-09-18 - 摘要：The devulcanization reaction of waste ethylene-propylene-diene monomer rubber (W-EPDM) during melt extruding process mixed with unvulcanized EPDM was investigated through a compound-induced reaction by increasing the screw rotation speed and being in the presence of different subcritical fluids in a twin screw extruder. The effects of subcritical fluids (water, ethanol/water mixture and propanol), screw rotation speed and devulcanizaion accelerators (alkylphenol polysulfides 450 and DADS) on the gel content, mooney viscosity, FT-IR spectra of the sol of devulcanized blends (DEPDM/EPDM) and the mechanical properties of dynamically crosslinked thermoplastic elastomer((DEPDM/EPDM)/PP) prepared by devulcanization blends and PP were measured, and fracture surface morphology of dynamically crossinked thermoplastic elastomer (DEPDM/EPDM)/PP was also observed by SEM. The results show that subcritical ethanol/water mixture or propanol has a better selectivity on S—S bond cleavage, leading to increase of the cleavage reaction of crosslinked S—S bonds and decrease of cleavage reaction of the main bonds in crumb rubber crosslinked network. The size of unmelted particles in dynamically crosslinked thermoplastic elastomer becomes smaller. The mechanical properties of revulcanized material increased significantly. The devulcanization accelerator alkylphenol polysulfides 450 has significant role in promoting devulcanization. The tensile strength and elongation at break of dynamically crosslinked thermoplastic elastomer (DEPDM/EPDM)/PP reaches to 17.1MPa and 443% respectively when the screw rotation speed and devulcanization reaction temperatures exist optimum value (220℃, 600rpm) in the presence of subcritical propanol. The mechanical properties and facture surface morphological structure of it was significantly better than those of the corresponding material obtained by conventional devulcaniztion tank.关键词：Ethylene-propylene-diene monomer rubber (EPDM);Devulcanization;Subcritical fluid;Dynamically crosslinked thermoplastic elastomer
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发布时间：2022-09-18 - 摘要：In this work, biocompatible and biodegradable chitosan nanospheres were successfully prepared by a simple method in water. The nanospheres were well monodispersed and stable in aqueous solution. The physicochemical properties of nanospheres were investigated by using Fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscope, scanning electron microscopy and zeta potential. It was found that the surface structure and zeta potential of nanospheres can be manipulated by changing pH. The obtained chitosan nanospheres provide the functional sites with abundant functional groups for embedding of other active materials. Thus, the chitosan nanospheres were employed as absorbents for removal of nickel(II) ions from aqueous solutions. The adsorption behaviors of nanospheres were investigated including the effects of adsorption time, pH value, temperature and initial concentration by the batch method. The adsorption capacity of the chitosan nanospheres for nickel(II) ions was observed to be as high as 44.41mg/g. Moreover, the adsorption isotherms obeyed the Freundlich equation, and kinetics followed a pseudo-second order model.关键词：Chitosan nanospheres;Nanostrctures;Adsorption;Nickel(II) ions
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发布时间：2022-09-18 - 摘要：In this article, an idea of using multiple conductive networks to improve the conductivity and electromagnetic shielding effectiveness (EMI SE) of the organic silicon rubber composite is described. The composite with multiple conductive networks was fabricated by combining electroless silver plating foam and low conductive fillers with the organic silicon rubber. Scan electron microscope is applied to observing the microstructure of the composites. Resistance tester, vector network analyzer, and thermo-gravimetric analyzer are respectively used for the characterization of the conductivity, EMI SE, and thermal stability of the composite. The effect of the fortifier nano SiO2 on these properties is also discussed. The results show that the resistivity of the multiple composite system 2wt% carbon nanotubes (CNTs)/conductive foam (F)/silicone rubber (SR) decreases 6 orders of magnitude compared to the one-part composite system 2wt% CNTs/SR. The average EMI SE, which has increased from 12dB to 52dB, is 4 times than that of the system 2wt% CNTs/SR. When the filler replaces with carbon black (CB), the resistivity of the multiple composite system 2wt% CB/ F/SR is 7 orders of magnitude lower than that of the one-part composite system 2% CB/SR. The average EMI SE, which has increased from 10dB to 50dB, is 5 times higher than that of the system 2% CB/SR. The conductivity and the EMI SE are significantly enhanced due to the multiple conductive networks. In addition, the thermal stability of each composite system is improved at the presence of the fortifier, but the conductivity and EMI SE has decreased.关键词：Organic silicon rubber;Conductivity;Electromagnetic shielding;Conductive foam
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发布时间：2022-09-18 - 摘要：The semi-interpenetrating polymer network (semi-IPN) of PAM/PVP hydrogels were synthesized by one-pot radical polymerization with PVP interpenetrated in chemical crosslinked polyacrylamide (PAM) hydrogel network which was initiated by ammonium potassium. The research was focused on the mechanical properties of PAM/PVP semi-IPN hydrogels. The results of FTIR, TGA coupled with tensile experiments demonstrate that hydrogen bond occurred between PAM and PVP. The tensile experiments show that tensile strength of hydrogel was improved through introducing PVP into PAM. Compared to pure chemical crosslinked PAM hydrogel, a 64.67% increase in tensile strength improvement was achieved with the addition of 7.51% of m(PVP)/m(AM). The mechanical properties were better in presence of AM 6mol/L with n(MBA)/n(AM) and m(PVP)/m(AM) of 1.67×10-4 and 7.51% respectively, showing tensile strength of 1.84MPa and elongation of 3327%. With the increase of water content in hydrogel, both tensile strength and elongation were reduced.关键词：Hydrogen bond;Semi-IPN;Mechanical properties;Acrylamide;Polyvinylpurrolidone
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发布时间：2022-09-18 - 摘要：In this paper we discuss the research on the rheological behavior of several typical fluoropolymers, such as Polyvinylidene fluoride (PVDF), fluorinated ethylene propylene copolymer (FEP), ethylene tetrafluoroethylene alternative copolymer(ETFE) and perfluorosulfonyl fluoride resin(PFSF). FEPs possess quite narrow stable flow region and very poor processability, results were fitted by using Carreau equation. ETFE is thermo rheology simplicity polymer, and ETFE holds wider stable region and superber processability. At very low shear rates,PVDF melt was Newtonian fluid, however it was non-Newtonian fluid at higher shear rates,and its melting viscosity decreased with the increase of shear rates. The apparent viscosity of PFSR and PFCR melt is decreased with increase of shear rate and temperature, and non-Newtonian index is less than 1 in the range of test temperature. The viscosity curves indicates that the PFSR and PFCR melt exhibits a pseudo plastic nature.关键词：ETFE;FEP;PVDF;PFSA;PFCR;Rheological
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发布时间：2022-09-18 - 摘要：The course of the value-added utilization of plant fiber focused mainly on the plant fiber material, especially the separation and value-added utilization of the three natural polymers, i.e., cellulose, hemicelluloses and lignin, which is an important fundamental course for the majors of chemical processing of forestry products, pulp and paper-making, bio-energy, etc. With respect to the characteristics and the reform of the course, this paper explores the following measures for teaching:(1) addressing the core knowledge of the content; (2) focusing on the development of the discipline and updating the material; (3) visualizing knowledge to promote understanding and heuristic teaching to enlighten thinking; (4) initiating the scientific way of thinking and conducting seminars; and (5) combining the theoretical teaching with the practice and reforming the assessment methods to test the comprehensive ability.关键词：Natural polymer;Plant fiber;Educational reform;Practical teaching
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发布时间：2022-09-18 - 摘要：The polymerization process design is the one of the important specialized course of polymer material and relatives. Based on the detail analysis of the problems existing in polymerization process design course and its relatives, the teaching content and method were updated. Aiming at the problems of teaching process, the content of relative courses was associated with the design course. The teaching content of the chemical software foundation, the polymerization production equipment and the chemical engineering practice was combined with the original course. Through the multiple teaching methods, such as the close coordination of the design course and its relatives, the enhancing activeness of students and them interaction with teachers, the theoretical and practical knowledge were organic fused together. Through this way, the better teaching results were obtained, and then the anticipated instructional objectives were achieved.关键词：Polymer polymerization technology;Teaching;Method
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发布时间：2022-09-18
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