高沸醇木质素辐射接枝苯乙烯

利用辐射接枝共聚操作简单易行的优点,研究高沸醇木质素在γ-射线辐射下与苯乙烯的辐射接枝反应,并用红外光谱对接枝产物进行表征。结果表明,γ-射线辐射下高沸醇木质素易与苯乙烯发生辐射接枝反应,其最佳接枝条件是:辐射剂量30 kGy,苯乙烯单体与木质素质量比为3∶10,所用木质素为芒秆高沸醇木质素。     

聚丙烯纤维共辐射接枝苯乙烯的研究

以60Co γ射线为辐射源,在氮气保护下对聚丙烯(PP)纤维和苯乙烯-二乙烯苯在甲醇介质中进行共辐射接枝。结果表明,当接枝液中苯乙烯质量分数为20％-30％,辐射总剂量为25-50 kGy时,PP纤维的接枝率高。二乙烯苯相对苯乙烯的质量分数为2％时,纤维的接枝率和玻璃化转变温度最高,分别为701％和161.5℃。接枝反应离开辐射源后存在一定程度的后效应,放置一定时间和接枝液中加入适量无机酸均可有效提高PP纤维的接枝率。在相同条件下,用乙醇替代甲醇可以达到相近的接枝率。     

环氧树脂与苯乙烯对马来酸酐接枝聚乙烯性能的影响

实验通过工艺优化制备聚乙烯接枝马来酸酐(PE-g-MAH),研究了添加不同含量环氧(EP)、苯乙烯(St)制备的PE-g-MAH的熔融指数、接枝率和红外光谱性能。阐述了环氧、苯乙烯加入接枝体系的接枝机理。结果显示红外光谱显示加入环氧的接枝体系中马来酸酐(MAH)基团反应形成了酯,部分环氧接枝到了大分子链上。环氧树脂的加入大大增加了聚乙烯的交联,苯乙烯加入马来酸酐接枝聚乙烯体系后能得到很好的接枝率和熔体流动性。     

聚四氟乙烯与苯乙烯辐射接枝共聚

含氟高聚物具有耐热、耐寒、耐化学介质、电绝缘性好和摩擦系数低等许多优异性能,而聚四氟乙烯的性能居于含氟高分子材料的首位,故有塑料王之称。接枝共聚是高分子材料改性和合成新高聚物的重要途径,目前高能射线辐射接枝的方法发展很快。本工作研究了聚四氟乙烯与苯乙烯辐射接枝共聚,着重研究室温、空气等预辐射和共辐射接枝条件。探讨了预辐照和共辐照的剂量、剂率、时间、温度对接枝率的关系,并作了比较,对接枝产物作了分析鉴定和性能测试。     

电子束辐射接枝对PAN基碳纤维的表面改性

采用电子束加速器辐射接枝方法对聚丙烯腈(PAN)基碳纤维进行表面改性,研究了接枝单体种类对接枝率及其环氧树脂基复合材料力学性能的影响,分析了辐射接枝前后PAN基碳纤维的表面形貌与化学结构以及其复合材料界面断口的形貌变化。结果表明:电子束辐射接枝改性的PAN基碳纤维表面粗糙度增加,表面活性官能团增多,与树脂的机械锲合作用增强,其树脂基复合材料断口表而较为平整;乙二胺/水溶液体系是辐射接枝改性的理想溶液,在200 kGy的电子束辐射下,PAN基碳纤维表面的接枝率为6.66%,复合材料的层间剪切强度提高了45.1%。     

水性环氧树脂乳液的合成及性能研究

探讨了高分子质量环氧树脂(HMW)、中等分子质量环氧树脂(MMW)的制备方法,并用一定比例的HMW、MMW混合溶解后,用丙烯酸和苯乙烯为接枝单体、以BPO为引发剂,进行接枝反应,然后用N,N-二甲基乙醇胺中和即得水性环氧树脂乳液.通过红外光谱分析了各步产物的结构,讨论了接枝反应温度、丙烯酸与苯乙烯比例、丙烯酸用量、中和程度、环氧树脂分子质量等对乳液性能的影响.     

水性环氧树脂的合成与性能

以酯化开环后的环氧树脂为基体,过硫酸铵为引发剂,乙酸乙酯为溶剂,通过自由基接枝聚合将改性单体甲基丙烯酸、丙烯酸丁酯、甲基丙烯酸甲酯、苯乙烯和N-羟甲基丙烯酰胺接枝到环氧树脂上,脱除溶剂及中和乳化后得到了水性环氧树脂,研究了酯化率和溶剂脱除对水性环氧树脂吸水率、附着力的影响,软、硬单体的配比对体系性能的影响。结果表明:当酯化率为50%时,水性环氧树脂的附着力为1级,吸水率为5.69%;脱除溶剂能使水性环氧树脂乳液在固含量相同的情况下黏度降低,当软、硬单体质量比为1∶0时,所制水性环氧树脂稳定性好、性能优、粒径小。     

硅橡胶共辐射接枝甲基丙烯酸甲酯

西南科技大学的索晋玄等人利用^60Coγ-射线共辐射接枝方法，研究了硅橡胶与甲基丙烯酸甲酯（MMA）接枝共聚反应。结果表明，辐射剂量和单体浓度埘接枝率影响较大，其最佳用量分别为20kGy；MMA与硅橡胶的质量比为0．6时，接枝效果较好。接枝后硅橡胶的热性能和亲水性得到明显改善。     

γ-射线辐照碳纤维对其复合材料力学性能的影响

利用高能射线(60Coγ-射线)辐照接枝技术对碳纤维(CF)表面进行处理。对辐照处理前后的CF分别利用SEM观察其复合材料层间剪切断口;比较了吸收剂量对碳纤维增强环氧树脂复合材料层间剪切强度(ILSS)的影响。结果表明:辐照处理后的,碳纤维增强环氧树脂复合材料的界面明显得到改善,辐照接枝技术在一定的剂量范围内能够有效地提高复合材料的ILSS,但是过大的辐照剂量和接枝率不利于复合材料的界面改性。     

聚丙烯无纺布预辐射固相接枝丙烯酸的研究

以聚丙烯(PP)无纺布为基材,以丙烯酸为单体,进行预辐射固相接枝聚合,考察了外部环境、辐射剂量、温度、反应时间、单体用量、介质、阻聚剂、交联剂对接枝率的影响。结果表明,通过预辐射固相接枝聚合方法,可将丙烯酸单体接枝在PP无纺布上,辐射剂量增大可提高接枝率;反应时间对接枝率的影响在低、高温阶段有所不同。最佳反应条件为:氮气环境,辐射剂量大于50 kGy,反应温度65℃,反应时间3 h,单体浓度30%,反应介质为水,阻聚剂0.8 g,交联剂用量为5 mL。     

基于电子束辅助固化的木塑复合材料的研究

在辐射剂量为56kGy的双面电子束辐照工艺条件下，制备了苯乙烯(St)、苯乙烯与不饱和聚酯树脂(St／UPE)混合物以及苯乙烯与环氧丙烯酸酯树脂(St／EA)混合物浸渍的冬瓜木和松木系列木塑复合材料，研究了木材和浸渍液体种类以及电子束辐射对浸渍液体的聚合和固化程度以及所得木塑复合材料性能的影响。结果表明在电子束辅助固化工艺条件下，浸入木材的St、St/UPE和St／EA的聚合率以及St／UPE和St／EA的固化率均可大于90％。木塑复合材料的硬度和压缩强度较原木材可提高2～6倍，其1昼夜吸水率则从原木材的64．6％和52．8％分别降低到8．9％～12．9％和7．0％～7．9％。     

Preparation and reticulation of styrene acrylic/epoxy complex latex

The styrene acrylic/epoxy (SA/EP) complex latex with high content of epoxy resin was successfully prepared through emulsion polymerization initiated by both water-soluble and oil-soluble initiators. The resulting complex latex demonstrated regular spherical morphology with a diameter ranging 150–300 nm and with a narrow size distribution. The compatibility between epoxy and styrene acrylic improved due to the styrene acrylic grafting epoxy formation during grafting copolymerization. The factors influencing the structure and storage time of the complex latex were investigated and the corresponding mechanism was revealed. The SA/EP complex latex can form crosslinking structure with epoxy curing agent at room temperature. The crosslinked complex latex film shows good mechanical properties and excellent chemical resistance. These SA/EP complex latexes show great potential in developing high-performance aqueous paints and adhesive.     

丙烯酸接枝改性环氧树脂的研究

用溶液聚合法制备环氧树脂，丙烯酸类接枝改性物，研究了酸量、MAA/AA的比、引发剂BPO的用量、环氧树脂型号、反应时间等对接枝率和环氧值的影响。最后研究发现：酸量与环氧树脂的质量比为1：1，MAA：AA物质的量比为0．12：0．42，环氧树脂型号为E-20，反应时间为3．5h，该条件下制备出来的接枝改性物接枝率最大，且环氧基发生开环的量较少。     

Laboratory investigation of the properties of asphalt modified with epoxy resin

Epoxy asphalts were prepared by mixing styrene–butadiene–styrene (SBS) modified asphalt with epoxy resin. The curing process and morphology of epoxy asphalts were characterized by infrared spectroscopy and fluorescent microscope, respectively. The effects of epoxy resin contents, ratio of curing agent to epoxy resin and curing temperature on properties of epoxy asphalt were investigated. Results indicated that epoxy resin and epoxy asphalt showed similar curing efficiency. Epoxy asphalts can be cured at 120 or 60°C and its viscosity at 120°C can meet the demands of asphalt mixture mixing and paving. The chemical reaction of epoxy resin in epoxy asphalt is slow and reaction occurs not only with the curing agent but also carboxylic acid in epoxy asphalt. The microstructure of epoxy asphalt transforms from the dispersed structure to networks structure with epoxy resin content increasing and phase transition starts when 30 wt % epoxy resin present in asphalt. The softening point and tensile strength of epoxy asphalt increased with epoxy resin contents increasing. The softening point and tensile strength of epoxy asphalt were markedly improved when epoxy resin content was more than 30 wt %, which is attributed to formation of continuous structure of epoxy resin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Radiation grafting of vinyl monomers onto wood pulp cellulose. Part I

The effect of dose, dose rate, monomer type, and monomer concentration on the water transport behavior in grafted cellulose pulp and hand sheets was studied. At low dose rates, grafting rates of styrene onto wood pulp were less with hand sheets than with the pulp itself. Grafting was also found to be decreased by increasing the dose rate. Grafting mixtures of styrene and acrylonitrile gave better yields than styrene alone. Excellent grafting yields were obtained by treating the pulp or hand sheets with water before adding vinyl monomers. In this way, solvents such as dioxane could be eliminated from the grafting mixture. The hand sheets, grafted with mixtures of acrylonitrile and styrene, had good mechanical properties although less than the corresponding ungrafted sheets. Grafting decreased the moisture regain in pulp and hand sheets. Gamma irradiation of wood pulp under ambient conditions without additives reduced the water sorption considerably.     

Photoinitiated surface grafting of synthetic fibers,I. Photoinitiated surface grafting of ultra high strength polyethylene fibers

Photoinitiated surface grafting of acrylic monomers has been carried out onto high strength polyethylene (HSPE) yarn by means of a continuous process. The grafting reaction is initiated by UV irradiation of the yarn after presoaking in an acetone solution of initiator and monomer. Four initiators, benzophenone (BP), 4-chlorobenzophenone (4-CBP), 2-hydroxy-2-cyclohexylacetophenone (HHA), and 2,2-dimethoxy-2-phenylacetophenone (DMPA), and two monomers, acrylic acid (AA) and acrylamide (AM), have been used. After short irradiation time (10 to 20 s) successful grafting is obtained, as shown by ESCA and IR-ATR spectra, dye adsorpotion from aqueous solution, and measurements of adhesion of single filaments to epoxy resin. Grafting efficiency of 74% has been reached for AA as monomer (26% is homopolymer). The tensile strength and modulus of the HSPE yarn are retained in the grafting process. The degree of surface grafting is mainly a function of structure and concentration of monomer and photoinitiator in the presoaking solution and of the irradiation conditions used. Increasing irradiation time gives increasing amounts of grafted polymer up to a certain limiting value. The reactivities of the four initiators have been compared showing the highest grafting yields of AA with BP and of AM with 4-CBP as photoinitiator. AA grafted HSPE yarn can be dyed to rather deep color by dipping in an aqueous solution of Crystal Violet. Increased dye absorption by a factor of up to seven has been measured for yarn grafted with AA to the maximum level obtained. The filaments of the grafted yarn show increased adhesion to epoxy resin by a factor of up to five compared with the ungrafted filaments.     

Comparative study of the radiation‐induced grafting of styrene onto poly(tetrafluoroethylene‐co‐perfluoropropylvinyl ether) and polypropylene substrates. I: Kinetics and structural investigation

A comparative study has been made of the radiation grafting of styrene onto poly(tetrafluoroethylene‐co‐perfluoropropyl vinyl ether) (PFA) and polypropylene (PP) substrates, using the simultaneous irradiation method. Effects of grafting conditions such as monomer concentrations, type of solvent, dose rate and irradiation dose on the grafting yield were investigated. Under the same grafting conditions it was found that a higher degree of grafting of styrene was obtained using a mixture of dichloromethane/methanol solvents for PFA and methanol for PP and the degree of grafting was higher in PP than in PFA at all doses. However, the micro‐Raman spectroscopy analysis of the graft revealed that, for the same degree of grafting, the penetration depth of the grafted polystyrene into the substrate was higher in PFA than in PP substrates. In both polymers the crystallinity was hardly affected by the grafting process and the degree of crystallinity decreased slightly with grafting dose. The dependence of the initial rate of grafting on the dose rate and the monomer concentration was found to be 0.6 and 1.4 order for PFA and 0.15 and 2.2 for PP, respectively. The degree of grafting increased with increasing radiation dose in both polymers. However, the grafting yield decreased with an increase in the dose rate. The increase in the overall grafting yield for PFA and PP was accompanied by a proportional increase in the penetration depth of the graft into the substrates. Copyright © 2003 Society of Chemical Industry     

Surface modification of mesoporous silica by radiation induced graft polymerization of styrene and subsequent sulfonation for ion-exchange applications

In this study, the fabrication of silica-grafted-sulfonated styrene (S-g-SSt) resin by grafting of styrene onto silanized silica via gamma radiation-induced polymerization and subsequent sulfonation of the grafted styrene is described. The grafting was strongly affected by the reaction conditions; absorbed dose, monomer concentration, and the type of solvent used. The structural analysis of the silica and all the relevant products were carried out by FTIR, SEM, TGA, XRD, and BET. FTIR analysis confirmed the presence of styrene onto silica and subsequent sulfonation. The BET nitrogen adsorption–desorption isotherms indicated that grafting occurs on the surface as well as inside the pores. Finally, the ion exchange capacity (IEC) of the fabricated S-g-SSt was evaluated by ion exchange titrations (back titration method). The IEC was found to be in the range of 0.43–2.97 meq/g depending on the degree of grafting. The facile fabrication method and high IEC value (2.97 meq/g) could lead to potential application of the fabricated S-g-SSt resin in ion exchange resin in waste water treatment and metal recovery. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48835.     

Proton exchange membranes prepared by simultaneous radiation grafting of styrene onto poly(tetrafluoroethylene‐co‐hexafluoropropylene) films. I. Effect of grafting conditions

The simultaneous radiation grafting of styrene onto poly(tetrafluoroethylene‐co‐hexafluoropropylene) (FEP) films was studied at room temperature. The effects of grafting conditions (type of solvent, irradiation dose, dose rate, and monomer concentration) were investigated. The degree of grafting was found to be dependent on the investigated grafting conditions. The dependence of the initial rate of grafting on the dose rate and the monomer concentration was found to be of 0.5 and 1.3 orders, respectively. The results suggest that grafting proceeds by the so‐called front mechanism in which the grafting front starts at the surface of the film and moves internally toward the middle of the film by successive diffusion of styrene through the grafted layers. Some selected properties of the grafted films were evaluated in correlation with the degree of grafting. We found that the grafted FEP films possess good mechanical stability, which encourages their use for the preparation of proton exchange membranes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 220–227, 2000     

Preparation and performance of new antifouling resins containing BIT group

New acrylate grafting epoxy antifouling resins containing benzoisothiazoline ketone (BIT) group were successfully synthesized, and their structures and performances were determined. Experimental data indicated that the new acrylate grafting epoxy antifouling resins have a strong bonding to the cured epoxy resin coating through chemical reaction and self-stratifying. And the paint prepared by using the new resin as matrix has excellent self-polishing and antifouling properties. Especially its antifouling period could be modified by changing the weight ratio of the usage of the mixed monomers and epoxy resin in the preparing process of the acrylate grafting epoxy antifouling resins.