高保水性淀粉接枝聚丙烯酸钠高吸水性树脂合成研究

以过硫酸铵为引发剂,N,N'-亚甲基双丙烯酰胺为交联剂,聚合与干燥一步合成淀粉接枝丙烯酸钠超强吸水剂,其生理盐水加压保水率达75%～90%。     

Synthesis of cellulosic graft copolymers and their analysis by ultra-violet and infra-red spectroscopy

Two types of graft copolymer were prepared by irradiating regenerated cellulose and hydroxyethylcellulose, both in film form, in the presence of styrene. Dioxane was used as solvent for the styrene and water as swelling agent for the substrate. The rate and extent of grafting was investigated gravimetrically and through ultra-violet and infra-red spectroscopy. Spectroscopic techniques are shown to be valuable aids in kinetic studies of grafting reactions under otherwise difficult conditions. Excellent correlation between gravimetric and spectroscopic analysis occurs. Grafting to regenerated cellulose exhibits steady state kinetics whereas anomalies exist in grafting to hydroxyethylcellulose film. Such anomalies are explained in terms of the changing nature of the grafting medium.     

Mechanism and kinetics of hydrochloric acid initiated ɛ-caprolactam polymerization

Summary A mechanistic scheme is suggested for lactam polymerisation initiated by hydrochloric acid on the basis of the general mechanism put forward earlier by Bertalan et al. According to this mechanism during the polymerization conditions are created which can initiate further polymerizations resulting in a characteristic inflection type kinetic curve. Experimental results can be well interpreted qualitatively on the basis of this mechanism, and therefore it can serve as a starting point also for a quantitative kinetic model.Presented at 31st IUPAC macromolecular symposium, 30 June 1987, Merseburg, German Democratic Republic, I/43     

高锰酸钾引发聚酯纤维接枝共聚改性研究

研究了用KMnO_4/H_2SO_4作为引发剂,聚酯(PET)纤维与丙烯酸接枝共聚的改性方法,探讨了间甲酚浸泡时间和温度、KMnO_4浓度、H_2SO_4浓度、丙烯酸(AA)浓度等对接枝率的影响。结果表明:间甲酚浸泡时间2h、浸泡温度60℃、KMnO_4浓度3.0×10~(-3)mol/L、H_2SO_4浓度0.02mol/L、AA浓度2.66mol/L、反应时间2h时,PET纤维的接枝率较高;同时,用红外光谱证明了聚丙烯酸接枝支链的存在。     

Study of thermal and dyeing behavior of isotactic polypropylene fiber graft copolymerized with acrylate monomers using preirradiation method

In an attempt to modify isotactic polypropylene (IPP) fiber, grafting of acrylate monomers such as methyl acrylate (MA) and ethyl acrylate (EA) onto IPP has been carried out by preirradiation method in aqueous medium. Percentage of grafting has been determined as a function of various reaction parameters. Rate of grafting (R_g) and induction period (I_p) have been evaluated as a function of total initial monomer concentration. Methyl acrylate was found to be more reactive than ethyl acrylate toward grafting. Thermogravimetric analysis (TGA) indicates that the thermal stability of polypropylene fiber is significantly improved upon grafting. While polypropylene fiber could not be dyed by crystal violet, the grafted fiber was dyed with crystal violet, and the dye uptake has been quantitatively determined by spectrometric method. © 1994 John Wiley & Sons, Inc.     

Ce(IV)‐initiated graft polymerization of acrylic acid onto poly(ethylene terephthalate) fiber

Graft copolymerization of acrylic acid onto poly(ethylene terephthalate) (PET) fiber by a redox system using ceric (IV) initiator was studied with regard to various parameters of importance: acrylic acid concentration, ceric (IV) concentration, nitric acid concentration, reaction temperature, and reaction time. Based on the morphology of the PET fiber, it could be concluded that ceric (IV) in dilute nitric acid is a redox initiator for the surface graft copolymerization of the acrylic acid/PET system. The grafted PET fiber showed an increase in improved moisture regain to reach 900% at 39.5% graft yield. The dyeability with the basic dye and disperse dye significantly increased by 100 and 22%, respectively, as a result of the grafting onto PET fiber. Both tenacity and elongation gradually decreased by 51.2 and 28.9%, respectively, with increasing graft yield, which reduced the fiber service lifespan. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1952–1958, 2003     

Nanoclay plating of cellulosic fiber surfaces

A basic problem in making cellulose‐reinforced composites is achieving a dispersion of cellulosic fibers in an often olephinic polymer matrix. Drying cellulosic fibers results in the formation of fiber flocs/nodules because of their strong interfiber bonding, and this makes the hydrophilic cellulosic fibers difficult to disperse in a hydrophobic matrix material. One common approach to alleviate floc formation is to adsorb cationic surfactant onto anionically charged cellulose, which reduces the interfiber bonding, decreases floc formation and gives better compatibility with the matrix. In this report, a different approach is taken, namely to adsorb nanoclays onto the cellulosic fibers, and thereby reduce the natural hydrogen‐bonding affinity between fibers. In a second report, the same technology will be shown to be advantageous to decrease floc formation in oleophinic composites reinforced with cellulosic fibers. This article summarizes experiments aimed at optimizing the chemistry of deposition of montmorillonite clay onto fiber surfaces. The aim was to optimize the chemical conditions for the heterodeposition of the anionic clay onto cationically charged fluff pulp. The experiments were designed to provide a theoretical framework for the deposition of the nanoclay onto the pulp fibers. High M_w p‐DADMAC and an exfoliated clay (achieved by passing the clay through a homogenizer) were used. As expected, a certain degree of charge overcompensation by adding an electrolyte was necessary to bring about deposition. The adsorbed amount of clay could be calculated from the charge balance between the overcompensated charge and the net clay charge, constituting the theoretical framework for nanoclay heterodeposition. As expected, montmorillonite clay greatly destroyed the joint strength between fibers (determined by evaluating the strength of paper made from treated fibers). The surface coverage (determined by ESCA) was shown to be a linear function of the attached amount of clay, and ～3% clay was required to fully cover the fiber surfaces. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

L-抗坏血酸-2-棕榈酸酯钠的合成工艺研究

以L-抗坏血酸和棕榈酰氯为基本原料，以5，6-D-异亚丙基也-抗坏血酸为中间产物，在无水吡啶中进行酯化反应，经成盐和脱保护反应，制得最终产品。总收率为47％-51％。     

制备接枝共聚羟丙基瓜胶的新工艺

以可聚合的甜菜碱功能单体和羟丙基瓜胶为主要原料,分别使用均相反应法(原工艺)和非均相反应法(新工艺)制备了接枝共聚羟丙基瓜胶。探讨了新工艺的操作条件对反应过程和目标物性能的影响。结果表明,新工艺中m(功能单体)∶m(羟丙基瓜胶)=1∶1,引发剂用量0.12%,溶剂中m(乙醇)∶m(水)=4∶1时,新工艺反应过程较平稳,所得目标物的耐盐性能最好。新工艺目标物符合SY/T 5764—2007《压裂用植物胶通用技术要求》。与原工艺相比,新工艺在不改变目标物主要性能的前提下,能够大幅提高产量、降低生产成本,为实现大规模工业化生产积累了一定经验。     

Degradation kinetics of ascorbic acid during ohmic heating with stainless steel electrodes

Ascorbic acid degradation experiments were performed in buffer solution at pH 3.5 using a batch ohmic heater with uncoated stainless steel electrodes. The electrical conductivity of the buffer solution was adjusted using sodium chloride. The concentration of ascorbic acid was found using an HPLC technique. Kinetics of degradation can be described adequately by a first order model for both conventional and ohmic treatments, but unlike conventional heating, the temperature dependence of degradation for some ohmic treatments cannot be represented by the Arrhenius relation. During ohmic heating, power, temperature and NaCl content affect the degradation rate. A number of reactions, including electrode reactions, electrolysis of the solution, as well as reactions between electrode materials and electrolysis products may influence the reaction mechanism as well as kinetic parameters. At the highest power and salt content, citrate complexation and a significant loss of buffering capacity were noted, resulting in an increase in pH. The results underline the importance of inert electrode coatings, or the use of high frequency power for control of electrochemical reactions.     

制备接枝共聚羟丙基瓜胶的新工艺

以可聚合的甜菜碱功能单体和羟丙基瓜胶为主要原料,分别使用均相反应法(原工艺)和非均相反应法(新工艺)制备了接枝共聚羟丙基瓜胶。探讨了新工艺的操作条件对反应过程和目标物性能的影响。结果表明,新工艺中m(功能单体)∶m(羟丙基瓜胶)=1∶1,引发剂用量0.12%,溶剂中m(乙醇)∶m(水)=4∶1时,新工艺反应过程较平稳,所得目标物的耐盐性能最好。新工艺目标物符合SY/T 5764—2007《压裂用植物胶通用技术要求》。与原工艺相比,新工艺在不改变目标物主要性能的前提下,能够大幅提高产量、降低生产成本,为实现大规模工业化生产积累了一定经验。     

丙烯酸接枝改性PET纤维的结构与性能

采用丙烯酸接枝改性聚对苯二甲酸乙二酯(PET)纤维,探讨了接枝率对PET纤维结构、回潮率、染色性能以及力学性能的影响。结果表明:随着接枝率的增加,PET纤维密度变化不大,双折射率略为下降,纤维的吸湿性、抗静电性和染色性能提高,拉伸性能有所下降。当接枝率为10.78%时,PET纤维经0.03 mol/L的Na_2CO_3溶液处理后,其质量比电阻为1.34×10~6Ω·g/cm~2,回潮率为5.05%,纤维拉伸强度为3.31 cN/dtex,上染率达93.8%。     

Synthesis and properties of synthetic polymer latexes with copolymerized emulsifiers

The synthesis and properties of latexes with an emulsifier monomer (surface-active monomer-SAM) were examined. It was found that the polymerization rate in the presence of the emulsifier monomer was two times higher than in the presence of a saturated emulsifier. The stability of the latexes with SAM was much higher than for latexes with saturated emulsifiers, which is especially valuable in creating compositions containing a large amount of electrolytes and fillers. After separation of the polymer from the latexes with SAM, the emulsifier does not pollute wastewaters. The article is based on data from a report read at the memorial conference dedicated to the 100th birthday of Z. A. Rogovin (Moscow, 2005). __________ Translated from Khimicheskie Volokna, No. 5, pp. 13–17, September–October, 2006.     

Cationic graft polymerization of polymers from carbon fiber initiated by acylium perchlorate groups introduced onto the surface

The cationic graft polymerization of several monomers initiated by acylium perchlorate groups introduced onto the carbon fiber surface was investigated to modify the surface. The introduction of acylium perchlorate groups was successfully achieved by the reaction of silver perchlorate with acyl chloride groups, which were introduced by the reaction of surface carboxyl groups with thionyl chloride. It was found that the cationic polymerization of styrene is initiated by acylium perchlorate groups on the carbon fiber. In the polymerization, polystyrene was grafted onto the carbon fiber surface through the propagation of polystyrene from the surface. Ungrafted polymer was also formed by the chain transfer reaction of growing polymer cation to the monomer. The acylium perchlorate groups have the ability to initiate cationic ring-opening polymerization of tetrahydrofuran (THF) and ε-caprolactone (CL), polyTHF and polyCL being grafted onto the carbon fiber surface, respectively. Polyacetals, such as poly(1,3-dioxolane) and polyoxymethylene, were able to graft onto the carbon fiber by cationic ring-opening polymerization of the corresponding monomers.     

Synthesis and characterization of polysaccharide based graft copolymer by using potassium peroxymonosulphate/ascorbic acid as an efficient redox initiator in inert atmosphere

Polysaccharide based graft copolymer (xanthan gum‐g‐4‐vinyl pyridine) was synthesized using potassium peroxymonosulphate/ascorbic acid redox initiator in inert atmosphere at 40°C. By studying the effect of the concentration of monomer, peroxymonosulphate (PMS), ascorbic acid (AA), xanthan gum (XOH), hydrogen ion along with effect of time and temperature on grafting characteristics: grafting ratio (%G), add on (%A), conversion (%C), efficiency (%E), homopolymer (%H), and rate of grafting (Rg), the reaction conditions for optimum grafting were determined. The optimum concentration of AA, H⁺ ion, 4‐VP for maximum grafting were found to be 10.0 × 10^?3 mol dm^?3, 2.5 × 10^?2 mol dm^?3, 10.0 × 10^?3 mol dm^?3, respectively. Maximum %G was obtained at minimum concentration of xanthan gum i.e., at 40.0 × 10^?2 g dm^?3 and at maximum concentration of PMS i.e., at 10.0 × 10^?3 mol dm^?3. The optimum temperature and time duration of reaction for maximum % of grafting were found to be 45°C and 120 min respectively. The synthesized graft copolymer was characterized by FTIR analysis. Thermogravimetric analysis showed that the xanthan gum‐g‐4‐vinyl pyridine is thermally more stable than pure gum. A probable mechanism was suggested for the graft copolymerization. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Ability of cellulosic materials to initiate graft copolymerization by photo-irradiation

The ability of various kinds of cellulose samples to initiate graft copolymerization of methyl methacrylate by photo-irradiation was examined. Untreated samples (absorbent cotton, sulfite pulp, dissolving pulp, and semichemical pulp), extracted samples (1% sodium hydroxide, methanol, and ethanol-benzene mixture as extraction solvent), oxidized samples (periodic acid, sodium hypochlorite, hydrogen peroxide, and nitrogen dioxide), a reduced sample, an oximated sample, and a ferric ion-adsorbing sample were used for the experiments. It was found that impurities in the sample as well as the oxidized states affect the initiation reaction remarkably. It was also noted that the contribution of these factors was remarkable in an irradiation system with a light of wavelength longer than 300 nm, although in the systems using sensitizers or irradiation with a light of shorter wavelength, initiation took place almost indifferent to the cellulose characteristics.     

含噁唑环支链的苯氧型共聚聚酰亚胺的合成与表征

以3,5-二硝基苯甲酰氯和邻氨基苯酚为原料合成了含苯并噁唑基团的二胺,然后将其与二氨基二苯醚(ODA)和二苯醚四甲酸二酐(ODPA)进行常温共聚合成聚酰胺酸,最后采用两步法合成了含苯并噁唑支链的可溶性聚酰亚胺(PI)。采用红外光谱(FT-IR)、差示扫描量热法(DSC)和热重分析(TGA)等测试手段分析了该PI的结构、热性能和在各溶剂中的溶解性能。实验结果表明,经300℃热处理1h后,聚酰胺酸转化为酰亚胺化比较完全;引入苯并噁唑支链基团可以提高PI的耐热性,其玻璃化转变温度(Tg)在300℃左右,初始热分解温度为552.5℃;该PI在强极性溶剂中溶解性能良好,但不溶于一般的极性溶剂中,说明其在提高加工性能的同时仍能保持耐一般溶剂的性能。