聚乙烯醇-甲醛-脲三元共聚物的合成及其粘接性能的研究

本文研究了聚乙烯醇-甲醛-脲在酸性介质中的共聚反应，三元共聚物的粘接性能及影响因素。     

Electrochemical copolymerization of aniline with m-aminophenol and novel electrical properties of the copolymer in the wide pH range

A copolymer, poly(aniline-co-m-aminophenol), has been synthesized using repeated potential cycling. The monomer concentration ratio, acid concentration and applied potential strongly affect the copolymerization rate and the properties of the copolymer. The optimum conditions for the copolymerization are that the scan potential range is controlled between −0.10 and 0.95 V (vs.SCE), and a solution consists of 0.34 M aniline, 0.012 M m-aminophenol and 2 M H₂SO₄. The IR spectra of the copolymers demonstrate that the m-aminophenol units are included in the copolymer chains. The cyclic voltammograms of the copolymers in 0.3 M Na₂SO₄ solution with various pH values were performed at the potential ranges from −0.20 to 0.80 V and at a scan rate of 60 mV s⁻¹. The results indicate that the copolymer still hold 41.7% of the electrochemical activity when the copolymer electrode was transferred from a solution of pH 5.0 to a solution of pH 11.0 in the potential range of −0.20 to 0.80 V. An impedance plot of the copolymer in a solution with pH 12.0 and at 0.40 V is constructed of a semicircle and a Warburg line with a slope of 1. This means that the electrode reaction of the copolymer at pH 12.0 is also under mass transfer control. The conductivity of the copolymer prepared under the optimum conditions is 1.42 S cm⁻¹, and slightly depends on the pH value. Thus, the pH dependence of the electrical properties of the copolymer is improved compared with poly(aniline-co-o-aminophenol), and is much better than that of the parent polyaniline.     

Macromolecular anchoring layers for polymer grafting: comparative study

Comparative study of efficiency of macromolecular anchoring layers in the grafting of end-functionalized polymers to a surface was conducted. Poly(glycidyl methacrylate) (PGMA) and epoxydized polybutadienes (EPB) were utilized as the primary anchoring films. Amount of the epoxy moieties introduced to the surface was varied via thickness of the modifying polymer layer or amount of epoxy groups in the polymer backbone. Comparison between the grafting of polystyrene and poly(ethylene glycol) to the various macromolecular anchoring layers indicated that grafting ability of a layer was mostly governed by thickness of the interpenetration zone between the two polymers (anchoring and being grafted). In case of low level of the interpenetration, only functional groups at the periphery of the primary polymer layer were available for the grafting. Then, amount of grafted polymer did not increase with total number of epoxy groups in the anchoring film. However, as the thickness of the interpenetration zone increased, higher amount of the functional groups become available for the grafting.     

Graft copolymerization of 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid onto carboxymethylcellulose (sodium salt) by H2O2/Fe+2 redox pair

The effect of the reaction conditions on the grafting parameters during grafting of 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid onto sodium carboxymethylcellulose using H₂O₂/Fe⁺² redox pair are studied at 30°C. The grafting ratio, add on, and conversion initially increase with the H₂O₂ concentration in the range of (10.0–15.0) × 10^?2 mol dm^?3. Thereafter, these parameters decrease with the H₂O₂ concentration. The grafting ratio, add on, and conversion increase when increasing the ferrous ion concentration from (0.5 to 4.0) × 10^?2 mol dm^?3 and decrease with a further increase in the concentration. It is observed that the grafting ratio and add on increase with the monomer concentration, whereas the conversion decrease. The hydrogen ions seem to be facilitating the grafting reaction up to a certain concentration and after this concentration seem to be retarding the process. The grafting ratio, add on, and conversion decrease with the sodium carboxymethylcellulose concentration. When increasing the time period from 60 to 90 min, the grafting parameters increase but decrease thereafter. Similarly, when increasing the temperature from 25 to 30°C, the grafting parameters increase and decrease thereafter. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4819–4825, 2006     

Determination of degradation rate of acrylonitrile polymers

Low‐temperature degradations of acrylonitrile homopolymers and acrylonitrile/acrylamide copolymers in air were investigated by IR and thermogravimetry. The degradation rates of acrylonitrile polymers were determined by measurement of normalized absorbance of ? C?N band and effects of the degradation temperature, time, and comonomer on the rate of degradations were discussed. It was found that the polymers start to degrade as the temperature increased to 150°C. In the temperature range of 180–210°C, values of the rate of polymer degradation were maximal and the rate of degradation of acrylonitrile/acrylamide copolymers was higher compared with that of acrylonitrile homopolymers. At 150°C, acrylonitrile homopolymers had an induction period of about 0.5 h. The rate of degradation of acrylonitrile/acrylamide copolymers showed an obvious trend of increase along with acrylamide concentration, and changes of the rate became less prominent as the weight ratio of acrylamide/acrylonitrile went beyond 5/95. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1511–1514, 2006     

Effect of crosslinkers on the preparation and properties of ETFE‐based radiation‐grafted polymer electrolyte membranes

This study concerns a comparative study of three crosslinkers, divinylbenzene (DVB), 1,2‐bis(p,p‐vinylphenyl)ethane (BVPE), and triallyl cyanurate (TAC) crosslinked poly(ethylene‐co‐tetrafluoroethylene) (ETFE)‐based radiation‐grafted membranes, which were prepared by radiation grafting of p‐methylstyrene onto ETFE films and subsequent sulfonation. The effect of the different types and contents of the crosslinkers on the grafting and sulfonation, and the properties such as water uptake, proton conductivity, and thermal/chemical stability of the resulting polymer electrolyte membranes were investigated in detail. Introducing crosslink structure into the radiation‐grafted membranes leads to a decrease in proton conductivity due to the decrease in water uptake. The thermal stability of the crosslinked radiation‐grafted membranes is also somewhat lower than that of the noncrosslinked one. However, the crosslinked radiation‐grafted membranes show significantly higher chemical stability characterized in the 3% H₂O₂ at 50°C. Among the three crosslinkers, the DVB shows a most pronounced efficiency on the crosslinking of the radiation‐grafted membranes, while the TAC has no significant influence; the BVPE is a mild and effective crosslinker, showing the moderate influence between the DVB and TAC crosslinkers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4565–4574, 2006     

Role of mixing parameters in the preparation of poly(ethylene vinyl acetate) nanocomposites by melt blending

Polymer/layered‐silicate nanocomposites have gathered momentum as cost‐effective and versatile materials since the middle of the 20th century. Many publications discuss the chemistry of organomodification and properties of nanocomposites, but relatively few deal with the significance of processing conditions. This article takes into account three mixing parameters and discusses the contribution of each toward nanocomposite formation. Organomodified natural sodium‐type bentonite clay was used in this study. The nanocomposites formed were characterized by X‐ray diffraction and mechanical property tests. Response surface regression was used to optimize the tensile modulus. The analysis shows that nanocomposite formation is promoted by a diffusion mechanism and that the interactions of parameters are as important as individual parameters. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2652–2658, 2006     

Non-Cp type titanium precatalysts for ethylene/norbornene copolymerization

Ethylene/norbornene monomers were homo- as well as copolymerized using titanium-based non-Cp precatalysts [2-(2,6-dialkylphenylamino)-1-phenylethoxy TiCl₂] in the presence of methylaluminoxane. The precatalysts polymerized ethylene with moderate activities that increased with increase in temperature reaching a maximum yield of polyethylene at 70 °C. However, these catalysts showed relatively low activity towards norbornene homopolymerization. Precatalysts 1ATiCl₂ and 3ATiCl₂ were used for ethylene/norbornene copolymerization. The microstructural analysis of these copolymers suggests that these are alternating copolymers with meso (major) and racemic (minor) sequences. Higher norbornene incorporation in the copolymer was obtained with precatalyst 3ATiCl₂, which is a more “open” catalyst system. The reactivity ratios for ethylene/norbornene copolymerization suggest that these precatalysts show lesser tendency towards norbornene homopropagation in the copolymerization reactions.     

力化学法制备金属－NR硫化粘合用CSM－NR接枝聚合物

用开炼机，通过力化学方法，将ＮＲ／ＣＳＭ（质量比为１０／９０）制成４５￣＃钢－ＮＲ硫化粘合剂用接枝聚合物。当橡胶本体１００％破坏时，１８０°剥离强度为２３．６～２４．６ｋＮ／ｍ。     

MMA－ST乳液共聚合成核阶段的数学模型

研究了ＭＭＡ－ＳＴ乳液共聚合动力学规律，提出了成核阶段数学模型，进行了计算机模拟，并对模型预计结果与实验数据进行了比较和讨论