羧甲基甲壳素与丙烯酸钠溶液接枝共聚反应研究

以过硫酸铵为引发剂,制备了羧甲基甲壳素接枝丙烯酸钠共聚物,讨论了反应温度、反应时间、引发剂用量、单体用量对接枝率的影响。红外光谱分析说明接枝反应是由过硫酸铵和羧甲基甲壳素上存在的氨基组成的氧化还原引发体系引发的。     

Enhancement of Physico-mechanical Properties of Plywood Surface with Urethane Acrylate (M-1200) by UV Curing Method

Several UV-curable formulations containing urethane acrylate (M-1200) oligomer with a trifunctional monomer, trimethylol propane triacrylate (TMPTA), and photoinitiator Irgcure-369 were developed to improve the surface of plywood. Thin polymer films were prepared on glass plate with these formulated solutions and finally applied on polished plywood surface to modify the surface, and both were cured under UV-radiation. The properties of UV-cured thin films were studied as a function of UV-radiation intensities. Pendulum hardness (PH) and gel content were found to increase with the increase of TMPTA concentration up to a certain level and with further increase of monomer concentration the physical properties were decreased. The polymer-coated surface yielded enhanced physico-mechanical properties compared to that of unmodified surface.     

导电高分子与丙烯酸酯的接枝共聚反应研究

通过β-噻吩丙烯酸甲酯的自由基聚合，获得了聚（噻吩丙烯酸甲酯）（P-TAc）。GPC测得其数均分子量为2．4×10^4。化学氧化（P—TAc）获得聚丙烯酸甲酯-聚噻吩接枝共聚物。用FTIR光谱和Raman光谱确定了结构。材料的电导率为0．15S·cm^-4。     

过硫酸铵引发丙烯酸甲酯接枝羧甲基甲壳素共聚

以过硫酸铵为引发剂,制备了羧甲基甲壳素接枝丙烯酸甲酯共聚物,讨论了反应条件对接枝率和接枝效率的影响.确定最佳反应条件为:羧甲基甲壳素0.4 g,丙烯酸甲酯2.0 g,水50.0 mL,过硫酸铵60.0 mg,在50℃反应3.0 h.接枝共聚物具有水溶性.接枝反应是由过硫酸铵和羧甲基甲壳素上存在的氨基组成的氧化还原引发体系引发的.     

Role of Photoinitiators in the UV Curing of Urethane Acrylate

Polymeric films were prepared under UV radiation with tetraacrylated urethane oligomer in combination with N-vinyl pyrrolidone (NVP) using a set of four photoinitiators (Irg 907, Irg 651, Irg 369, and Irg 184). The study evaluates optimum photoinitiator concentration and radiation dose. Various film properties such as gel content, swelling ratio in acetone, pendulum hardness, tensile strength, and elongation at break were determined. These formulated solutions were coated on wood substrates, and gloss and hardness of the film cured on the wood substrate were determined. Some of these properties are compared with those of the films cured on the glass plates. Irg 369 is found to be the best photoinitiator to produce better films, both on glass plate and on wood substrate.     

Graft Copolymerization of Methyl Acrylate onto Oil Palm Empty Fruit Bunch (OPEFB) Fiber

Graft copolymerization of methyl acrylate (MA) onto OPEFB fiber has been successfully carried out using hydrogen peroxide and ferrous ammonium sulfate as initiators in an aqueous medium. The effects of reaction temperature, reaction period, and amount of monomer and initiators on the percentage of grafting were investigated. The results show that the percentage of grafting depends on reaction period and temperature as well as concentration of monomers and initiators. With 33.36 mmol of MA, the optimum percentage of grafting was obtained when the reaction was carried out using 6.00 mmol of H₂O₂ and 0.191 mmol of Fe²⁺ for 210 min at 75°C. The presence of the functional group in the grafted polymers was characterized by FTIR spectroscopy. Scanning electron microscopy was used to study the surface morphology. Thermogravimetric analysis indicated that the grafted OPEFB is thermally stable than the OPEFB     

紫外辐照引发PF-g-SAN接枝共聚反应的研究

以二苯甲酮（BP）为引发剂,通过紫外光辐照引发苯乙烯（St）、丙烯腈（AN）在纸浆纤维（PF）表面共聚,生成苯乙烯/丙烯腈共聚物（SAN）并接枝PF生成SAN接枝纸浆纤维（PE-g-SAN）,研究了引发剂BP浓度、St/AN质量比、辐照时间、反应温度对PF-g-SAN的接枝率和接枝效率的影响,用红外光谱仪和扫描电子电镜表征接枝产物,得出最佳反应条件为St/AN质量比2∶1,BP浓度2%,反应时间20 min,反应温度40℃。     

壳聚糖与MA、MMA接枝共聚研究

以硝酸铈铵(CAN)为引发剂,使壳聚糖与丙烯酸甲酯(MA)、甲基丙烯酸甲酯(MMA)二种乙烯类混和单体接枝共聚,用红外和综合热重法对其结构和热性能进行了分析。研究了反应温度、反应时间、引发剂含量以及壳聚糖和单体的用量对接枝率的影响,确定了合成高接枝率产物的优化工艺条件。结果表明,接枝率随上述实验条件的增加均呈现先增加后减小的趋势。当反应温度为80°C,反应时间为120 min,壳聚糖、硝酸铈以及单体(VMA∶VMMA=2∶3)的用量分别为0.80 g0、.08 g和5 mL时,接枝率最高。     

Jute Reinforced Polymer Composite by Gamma Radiation: Effect of Surface Treatment with UV Radiation

Jute (Hessian cloth) reinforced polymer composites were prepared with a mixture of 2-hydroxy ethyl methacrylate (HEMA) and aliphatic urethane diacrylate oligomer (EB-204), and then cured under gamma radiation. Thick pure polymer films (2 mm thickness) were prepared by using the same monomer and oligomer at different weight ratios, and 500 krad of total gamma radiation dose at 600 krad/hr was selected for the curing of all composites. Total radiation dose, jute content, and monomer concentration were optimized with the extent of mechanical properties. Among all resulting composites, the composite of 38% jute content at monomer:oligomer = 50:50 (w/w) ratios showed the better mechanical properties, such as 108% increase in tensile strength (TS), 58% increase in bending strength (BS), 138% increase in tensile modulus (TM), and 211% increase in bending modulus (BM) relative to pure polymer film. The gel content values were also found to increase with the increase of jute content in the composite. But the elongation at break (Eb) for both tensile and bending was found to decrease with increasing jute content. The best mechanical properties were obtained when jute fibers were pre-irradiated with UV radiation, such as 150% increase in TS, 90% increase in BS relative to polymer film, 19% increase in TS, and 15% increase in BS relative to untreated jute-based composites. A water uptake behavior investigation of the resulting composites was also performed and composites based on UV-treated jute showed the minimum water uptake value.     

制备氯引发PE接枝苯乙烯/顺丁烯二酸酐

为提高氯化原位接枝过程中聚乙烯(PE)接枝顺丁烯二酸酐(MAH)的接枝率,加入了第二单体苯乙烯(St).以FTIR,1H-NMR、GPC及凝胶含量研究PE氯化原位接枝MAH/St接枝共聚物(PE-cg-(MAH/St)的结构.实验结果表明:第二单体St的加入可以明显提高MAH的接枝率,同时没有交联结构的产生.研究了反应温度、单体配比、单体总质量分数、氯气流速等对接枝产物PE-cg-(MAH/St)接枝率的影响,并对接枝物的热性能进行了探索.当反应温度控制在80～90℃,MAH/St单体比例为9:7,单体总量16份,氯气流速29 mmol/min,MAH的接枝率可达3.56％.     

Ce4+引发丙烯酸甲酯在玉米淀粉上接枝共聚反应的研究

淀粉与乙烯基单体接枝共聚是淀粉化学改性的重要方法，该聚合物具有合成和天然高分子的优良性能，在生物降解塑料中有很好应用。本文以硝酸铈铵为引发剂，引发丙烯酸甲酯与玉米淀粉的接枝共聚反应，重点研究了引发剂浓度、单体浓度、反应温度、反应时问对接枝共聚反应的影响规律。用红外光谱来测定反应产物的结构，α淀粉酶测定接枝共聚物的生物降解性能。实验结果表明：丙烯酸甲酯的浓度为1．20mol／L，引发剂硝酸铈铵的浓度为3．5mmol／L，最佳反应温度为34℃，反应时间在3．0-3．5h。     

Graft Copolymerization of Chitosan with Butyl Acrylate and Application of the Copolymers to Cotton Fabric

Graft polymerization of butyl acrylate (BuA) onto chitosan using potassium persulfate (KPS) as initiator was studied under different conditions. The grafting percentage (G%) and the grafting efficiency (GE%) increase by increasing KPS concentration up to 40 mmol/L then decrease thereafter. Another trend was observed with BuA concentration where G% increases significantly as BuA concentration increases within the range studied, i.e., 10%–100%, based on weight of chitosan sample (ows), meanwhile GE% exhibits a maximum at BuA concentration of 50% ows. Temperature acts in favor of grafting up to 65°C where maxima for both G% and GE% could be achieved. The grafting reaction is characterized by an initial fast rate during the first 60 minutes then levels off thereafter. Poly (BuA)-chitosan graft copolymers were applied to cotton fabric in presence and absence of low formaldehyde cross-linking agent. Introduction of the copolymer and the cross-linking agent to cotton fabric enhances the performance of the latter to a great extent provided that the copolymer and the cross-linking agent are applied in two subsequent steps. Fabric performance was assessed through monitoring, nitrogen content, crease recovery angle, tensile strength and elongation at break.     

Effect of Ultraviolet Radiation on the Mechanical and Dielectric Properties of Hessian Cloth/PP Composites with Starch

Hessian cloth (jute fabrics) reinforced poly(propylene) (PP) composites (45 wt% fiber) were prepared by compression molding and the mechanical properties were evaluated. Jute fabrics and PP sheets were treated with UV radiation at different intensities and then composites were fabricated. It was found that mechanical properties of the irradiated jute and irradiated PP-based composites were found to increase significantly compared to that of the untreated counterparts. Irradiated jute fabrics were also treated with aqueous starch solution (1–5%, w/w) for 2–10 min. Composites made of 3% starch-treated jute fabrics (5 min soaking time) and irradiated PP showed the best mechanical properties. Tensile strength, bending strength, tensile modulus, bending modulus and impact strength of the composites were found to improve 31, 41, 42, 46 and 84% higher over untreated composites. Water uptake, thermal degradation and dielectric properties of the resulting composites were also performed.     

聚氨酯-丙烯酸酯共聚物动力学的研究

以偶氮二异丁腈为引发剂,合成了以丙烯酸丁酯和甲基丙烯酸甲酯为主链,以聚氨酯为侧链的共聚物,考察了聚合温度、引发剂用量、溶剂含量及大分子单体用量对聚合速率的影响。结果表明,丙烯酸酯封端的聚氨酯预聚体的加入对自由基溶液聚合有一定的影响,共聚体系的表观活化能为39．93kJ／mol,聚合速率同引发剂质量分数的0．278次方成正比,聚合速率在20％溶剂含量时最大。     

PVC氯化接枝聚合制备CPVC-g-VDF接枝共聚物的研究

通过将聚氯乙烯（PVC）氯化原位接枝共聚含氟单体生成氯化聚氯乙烯接枝偏氟乙烯（CPVC-g-VDF）,当配比为VDF占CPVC-g-VDF量的4％时,接枝聚合的效果最好,所得接枝聚合物的综合性能优于聚氯乙烯.     

辐射法合成高强吸水剂交联聚丙烯酸钠

利用^60Co辐照引发丙烯酸钠聚合,制得高强吸水剂交联聚丙烯酸钠。研究了单体浓度,中和度．交联剂,辐照剂量等因素对交联聚丙烯酸钠吸水性的影响。结果表明,辐射剂量为20kGy,中和度为70％。单体浓度为16．7％时．交联聚丙烯酸钠具有较高的吸水率,吸生理盐水(0．9％NaCl水溶液)可达128倍．吸自来水可达干重的252倍,吸去离子水可达干重的2096倍。     

纤维素接枝共聚研究

本文论述了天然纤维素纤维的生产方法包括铜氨溶液、NMMO及LiCl/极性溶剂等对生态环境和纤维性能的影响 ,重点介绍了纤维素在LiCl/极性溶剂体系中溶解机理及各种溶解条件对溶解性能的影响。对纤维素接枝共聚及其产物也作了相应介绍。     

八甲基环四硅氧烷与丙烯酸酯乳液共聚反应的研究

研究了八甲基环四硅氧烷（Ｄ４）与丙烯酸酯等的乳液共聚反应，当温度为８３℃，时间３ｈ，转化率为８０％以上。共聚乳液的综合性能，尤其是胶膜耐甲苯性能（２５℃时膨胀率为７５％）及耐烫性（１２０℃）明显优于丙烯酸树脂。     

乳液共聚法制备膨润土无机凝胶改性丙烯酸酯聚合物

将膨润土无机凝胶(SMP)制成水分散液,加入含有丙烯酸的可聚合性单体,通过乳液共聚法可以制得稳定的SMP改性丙烯酸酯聚合物乳液。它具有极好的抗电解质能力,并体现出了与乳液中直接掺混SMP明显不同的性质。含3%SMP改性的聚合物乳液,可以在保持聚合物弹性和柔韧性不变的前提下,将拉伸强度提高20%左右,但SMP的加入增大了聚合物材料的吸水性。     

淀粉接枝共聚合成吸水树脂工艺研究

以淀粉为原料,丙烯酸和丙烯酰胺为共聚单体,过硫酸铵为引发剂,N,N‘-亚甲基双丙烯酰胺为交联剂,采用接枝共聚法制备吸水树脂。研究了引发剂用量、交联剂量、单体与淀粉质量比以及丙烯酸和丙烯酰胺质量比对产品的吸水率的影响。实验结果表明：当引发剂占干物料质量的0．6％,交联剂质量占单体质量的0．8‰,单体与淀粉质量比为4,丙烯酸与丙烯酰胺质量比为1．33,产品的吸水率可超过550。