Styrene/butadiene rubber (SBR) was prepared by anionic polymerization using a twin screw extruder as the reactor. To study the relationship between microstructure and phase morphology, three SBRs were synthesized using different initiator complexes. With the addition of tetrahydrofuran (THF), the vinyl content of butadiene increased; the microstructure of SBRs was randomized, simultaneously. Transmission electron microscope and dynamic mechanical analysis showed that the compatibility of the two components became better with the increasing relative mass of the THF. The method used in this paper provides an environmentally friendly way to synthesize SBR, which is always synthesized through anionic solution polymerization.
Styrene/isoprene/butadiene integrated rubber (SIBR) was synthesized using anionic bulk polymerization in a corotating intermeshing twin-screw extruder. In order to study the relationship between microstructure and physical properties, three SIBRs were synthesized using different initiator complexes: n-BuLi (N-butyl lithium), n-BuLi/THF (tetrahydrofuran), and n-BuLi/TMEDA (tetramethylethylenediamine). The microstructure of the rubber products was analyzed by gel permeation chromatography and H nuclear magnetic resonance. SIBR prepared with pure n-BuLi exhibited a multiblock microstructure. With the addition of THF or TMEDA, the vinyl content of the alkadiene increased; and the microstructure of SIBRs was randomized, indicated by the presence of a high weight content of styrene microblocks. Transmission electron microscopy demonstrated similar morphology in both the SIBRs and SSBR2003 (an industrial product). Dynamic mechanical analysis of the vulcanized SIBRs showed that the randomized SIBRs were quite suitable for the preparation of high-performance tires. Tensile and tear test results of SIBRs were equivalent to those of SSBR2003. The low manufacturing cost of reactive extrusion technology will allow the large-scale industrialization of SIBRs. POLYM. ENG. SCI., 55:1163–1169, 2015. © 2014 Society of Plastics Engineers
In this study, styrene–isoprene diblock and multiblock copolymers were synthesized with n-butyllithium as the initiator, in an intermeshing, corotating twin-screw extruder. The diameter (D) of this extruder was 36 mm, and the ratio of length/diameter was 56. The weight content of polyisoprene in these copolymers was above 50% although in the past studies it had not been possible to accomplish levels higher than 30%. Gel permeation chromatography results of samples and their degraded products show that there is only one long block polystyrene in the diblock copolymer chains; while in the multiblock copolymer molecules, there is a long block and large numbers of small blocks. Dynamic mechanical analysis and transmission electron microscopy show that the two phases in the diblock copolymer are completely incompatible, leading to sharp phase separation. In the multiblock copolymer, the two phases are partly compatible without an obvious phase boundary. The successful syntheses of styrene/isoprene diblock and multiblock copolymers with high-isoprene contents provide a novel method to synthesize polystyrene rubbers and styrene–diene–styrene thermoplastic elastomers. Traditionally, these products were mainly synthesized by solution polymerization. The present work in this article provides the possibility to synthesize them with very little or no solvent using bulk polymerization. This method fits the environmentally friendly trend to use low amounts of carbon while allowing commercial profitability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39429.
This work confirmed a novel ligand in the anionic polymerization, lithium phenoxide, which helped to improve the controllability of the polymerization. The stability of n-BuLi against THF at 0°C was effectively improved by adding lithium phenoxide. More than 60% n-BuLi in THF was alive with the presence of lithium phenoxide after stirring at 0°C for 20 min, compared to 2% under same conditions but without lithium phenoxide. The propagation of polymerization of styrene (St) and methyl methacrylate (MMA) were retarded after adding lithium phenoxide. And by adding more than 10 fold lithium phenoxide, completed conversion was achieved in the polymerization of MMA in THF at 0°C. The lithium phenoxide showed both promoting and inhibiting effects in the polymerization of isoprene (Ip): it promoted the formation of 3,4-structure, while mitigated the formation of 1,2- and 1,4-structures. In general, the polymerization rate of Ip was promoted by lithium phenoxide.
Two types of permanent antistatic agents, polyethylene wax grafted with sodium acrylate (PEW-g-AAS) and polypropylene (PP) wax grafted with sodium acrylate (PPW-g-AAS), were prepared using a solution grafting method and applied to PP to enhance antistatic properties. The grafting degree was determined using back titration method, and structures were confirmed by Fourier transform infrared spectroscopy. The antistatic properties of PEW-g-AAS/PP blends and PPW-g-AAS/PP blends were characterized by surface resistivities (ρs) and volume resistivities (ρv), and a combination of contact angle measurement, scanning electron microscopy, permittivity, and dielectric loss were used to investigate the surface and inner structures of the blends. Results showed that ρs and ρv of PEW-g-AAS/PP blends dropped significantly (four to seven orders of magnitudes) above a critical addition at 10%, where an electrostatic dissipative network formed; PPW-g-AAS revealed an inferior antistatic performance than PEW-g-AAS due to its better compatibility and smaller content of dispersed phase in the matrix. Furthermore, the antistatic blends treated in 80°C water, 80°C air, and room temperature were investigated, and the results were interpreted from surface energy. Moreover, the addition of antistatic agent had little impact on tensile strength of the PP matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
The synergistic mechanism of tetrabutyl titanate (TBT) in the intumescent flame-retardant polypropylene (PP) composites was investigated in this work. The intumescent flame-retardant was composed of pentaerythritol (PER) as a carbonizing agent ammonium polyphosphate (APP) as a dehydrating agent and blowing agent. Five different concentrations (1, 1.25, 1.5, 1.75, 2 wt %) of TBT were incorporated into flame retardant formulation to investigate the synergistic mechanism. The thermal degradation and flammability of composites were characterized by thermogravimetric analysis (TGA), limiting oxygen index (LOI), and UL-94 tests. The morphology and chemical structure of char layer was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive spectrometer (EDS). The results showed that LOI was increased from 27.8 to 32.5%, with the increase of TBT content from 0 to 1.5 wt %. Results from SEM, and FTIR demonstrated that TBT could react with APP and PER to form the stable char layer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4255–4263, 2013
Tween, one type of non-ionic surfactants, was used as inner antistatic agent of polypropylene (PP) and the antistatic performance of PP/Tween sheets were evaluated by surface resistivities (ρs) and water contact angles. The influence factors including hydrophile–lipophile balance (HLB) of Tween, addition amount, process conditions and atmospheric humidity were investigated in detail and the results showed Tween 40 with HLB at 15.7 provided PP an optimum antistatic effect with surface resistivity of 1010 Ω/sq, water contact angle of 57°, and surface energy of 49.5 mN/m. The ρs of PP/Tween sheets declined approximately 1 order of magnitude with 10% increasing of relative humidity. In order to improve the washing endurance of antistatic PP, a combination of T40 and cationic PP (CPP) were blended with PP and PP/CPP/T40 sheets revealed improved washing durability, with ρs below 1011 Ω/sq after ultrasound washing. In addition, T40 with double bonds was synthesized and UV crosslinking of modified T40 on PP surface also presented definite effects on water resistance.
Two types of permanent antistatic agents, polyethylene wax grafted with sodium acrylate (PEW-g-AAS) and polypropylene (PP) wax grafted with sodium acrylate (PPW-g-AAS), were prepared using a solution grafting method and applied to PP for enhancing antistatic properties. The grafting degree was determined using back titration method and structures were confirmed by Fourier transform infrared spectroscopy. The antistatic properties of PEW-g-AAS/PP blends and PPW-g-AAS/PP blends were characterized by surface resistivities (ρs) and volume resistivities (ρv), and a combination of contact angle measurements, scanning electron microscope, permittivity, and dielectric loss were used to investigate the surface and inner structures of the blends. Results showed ρs and ρv of PEW-g-AAS/PP blends dropped significantly (4–7 magnitudes) above a critical addition at 10%, where a electrostatic dissipative network formed; PPW-g-AAS revealed an inferior antistatic performance than PEW-g-AAS due to its better compatibility and smaller dispersed phase in the matrix. Further, the antistatic blends treated in 80°C water, 80°C air, and room temperature were investigated, and the results were interpreted from surface energy. Moreover, the addition of antistatic agent had little impact on tensile strength of the PP matrix. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Living polystyryl lithium was synthesized by anionic polymerization under the protection of argon at normal pressure, and styrene, toluene, tetrahydrofuran, and n-butyllithium were used as a monomer, solvent, polar reagent, and initiator, respectively. Then, polystyrene oligomers containing several pendent epoxy groups with well-defined structures and narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight < 1.1) were prepared by the reaction of polystyryl lithium with glycidyl methacrylate. The prepared oligomers were characterized with gel permeation chromatography, Fourier transform infrared spectroscopy, 1H-NMR, and the hydrochloric acid/dioxane argentimetric method. The effects of the glycidyl methacrylate dosage, molar mass of polystyrene precursors, copolymerization time, and temperature on the content of side epoxy groups were also investigated. The results confirm that 1,1-diphenylethylene-end-capped polystyryl carbanion could initiate glycidyl methacrylate in toluene in the presence of lithium chloride and a small amount of tetrahydrofuran, and the content of the side epoxy groups could be adjusted. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Present work gave a new method for preparing polymethyl(3,3,3-trifluoropropyl)siloxane (PMTFPS) in the mixing chamber of a torque rheometer using sodium silanolate as initiator, and ethyl acetate (EA) and dimethyl sulfoxide (DMSO) as promoters. The promoting effect of EA in the anionic bulk polymerization of 1,3,5-tris(trifluoropropylmethyl) cyclotrisiloxane (F3) was investigated in comparison with DMSO, a common promoter. Results showed that EA exhibited an effective promoting effect as DMSO did. When the polymerization was carried out for 4.0 min at 120°C in the presence of 0.30 mol L−1 EA, the maximum of number average molecular weight (Mn = 2.45 × 105 g mol−1) of PMTFPS was obtained with high yield (89.2 wt%). The back-biting reactions during the polymerization were almost suppressed and less than 0.75 wt% cyclic by-products were obtained by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for EA promoter system. Investigations of differential scanning calorimetry and thermogravimetic analysis showed that PMTFPS could be used in a wide range of operational temperatures. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
The surface compositions of a series of polystyrene-b-polydimethylsiloxane (PS-b-PDMS) and polystyrene-g-polydimethylsiloxane (PS-g-PDMS) copolymers were investigated using ATR-FTIR and XPS technique. The results showed that enrichment of PDMS soft segments occurred on the surface of the block copolymers as well as on that of graft copolymers. And the magnitude order of the enrichment was as follows: PS-b-PDMS > PS-g-PDMS, which was attributed to the facilitating of the movement of the PDMS segments in PS-b-PDMS copolymer. Meanwhile, the solvent type and the contact medium had influence on the accumulation of PDMS on the surfaces. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006
A complex of Eu3+, benzoate (BA), acrylate (AA), and 1,10-phenanthroline (Phen) was synthesized in this work. The structure of Eu(BA)2(AA)(Phen) was characterized with elemental analysis, FTIR, and UV spectroscopy. Copolymers containing rare earth complex were prepared via the copolymerization of Eu3+(BA)2(AA)(Phen) with styrene. Semitransparent, luminescent polymer materials with high fluorescent intensity were obtained. The as-synthesized materials were further characterized by means of IR and UV spectra, which indicated that they were copolymers instead of blends. The fluorescence spectra of the copolymers revealed the intense UV absorption characteristics of the rare earth complex present in the materials, as long as only a small portion of the complex was incorporated into the copolymers. Moreover, thermal analysis showed that the copolymer had excellent heat stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1506–1510, 2006
Polypropylene (PP) foam has been considered as a potential substitute for other thermoplastics foams in industrial applications. However, the key concern is the weak melt strength of PP, which leads to a high content of open-cell structure in PP foams; and, thus, unsatisfactory for a number of applications. In this work, PP was modified by grafting with unsaturated linear polyester (ULP) in a twin-screw extruder in attempt to improve the melt strength of PP. The grafting reaction on PP and the modified PP were characterized using FT-IR, DSC, and TGA. The improved foamability was verified by SEM observation. In addition, the rheological behavior of modified PP was investigated using a Hakke rheometer. The results indicated that the melt strength of grafted PP was significantly enhanced, facilitating the foam formation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4114–4123, 2006
Rare earth (RE) complex photoluminescence films were conventionally prepared by blending. The RE complexes were unevenly dispersed in the polymer matrix, thus readily quenching the fluorescence. An improved approach for preparing photoluminescence films was developed, in which the chemical or covalent bonding between the RE complex and polymer was introduced through melt-grafting polymerization. An RE complex (europium3+-acrylate-1,10-phenanthroline) [Eu(AA)3phen] was synthesized, and then grafted onto polypropylene (PP) in the melt phase to render the resin fluorescently active. The complex and the grafted PP were systematically characterized using various analytical tools including elemental analysis, TGA, IR DSC, WAXS, and fluorescence. The results indicated that the complex possessed favorable fluorescence and thermal stability, and the Eu(AA)3phen complex was successfully grafted onto the PP backbone. The findings from the DSC and WAXS measurements revealed that the complex acted as a nucleating agent, increasing the crystallization rate effectively and destroying the integrity of the crystallinity as well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1547–1552, 2006
![Pentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaene-4,6,10,12,16,18,22,24-octol](/data/chemimg/131300/125748-07-4.png)
![Pentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaene-4,6,10,12,16,18,22,24-octol](/data/chemimg/131300/125748-07-4_b.png)
![Poly[oxy[methyl(3,3,3-trifluoropropyl)silylene]]](http://img.cochemist.com/ccimg/25800/25791-89-3.png)
![Poly[oxy[methyl(3,3,3-trifluoropropyl)silylene]]](http://img.cochemist.com/ccimg/25800/25791-89-3_b.png)
![2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-dihydroxy-,3,9-dioxide](http://img.cochemist.com/ccimg/1000/947-28-4.png)
![2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-dihydroxy-,3,9-dioxide](http://img.cochemist.com/ccimg/1000/947-28-4_b.png)