Synthesis of polymer materials by low energy electron beam. I. Polyurethane–acrylate materials prepared by the EB and the UV solid-state polymerization

Structure and properties of films obtained by the electron beam (EB) and the ultraviolet light (UV) solid-state polymerization of polyurethane–acrylate prepolymer were examined to reveal the characteristics of these radiation polymerizations. The prepolymer was synthesized by the reaction of poly(butylene adipate)diol, 4,4′-diphenylmethane diisocyanate, and 2-hydroxyethyl acrylate. EB polymerization behaviors of the prepolymer produced a unique polymer film different from that obtained by UV irradiation. Although polyurethane–acrylate films from the EB and the UV solid-state polymerizations consisted mainly of amorphous and crystalline phases, it was proved that the film from 10 Mrad of EB irradiation at 25°C had higher crystallinity and larger crystallite size than the film from UV irradiation. This is assumed to be due to the reason that EB irradiation below the melting point of the polyurethane–acrylate can lead to crosslinking without the destruction of the original crystalline structure. On the other hand, the UV polymerization proceeded with the melting of the crystalline structure by absorbing other lights than the UV absorbed by a photoinitiator. The EB-polymerized film which was crosslinked more densely than the UV-polymerized film showed higher mechanical strength than the latter film.     

Polymeric reaction of polymer-monomer system irradiated by low energy electron beam. III. Adhesive property of pressure sensitive adhesive

Application of low-energy electron beam to nonsolvent-type pressure-sensitive adhesive is investigated. Adhesive properties such as peel strength, dead load strength, and ball tack were closely related to the reaction behavior (gel fraction and graft efficiency) of the acrylate polymer-monomer system. The reaction behavior is eluciadated by combining the measurements of gel fraction, infrared spectrum of gel, and molecular weight distribution detected by gel permeation chromatogrophy. It was found that the adhesive property of electro beamcured adhesives depends on the molecular weight of added polymer, monomer concentration, and irradiation dose. Graft polymerization and moderate crosslinking by electron beam irradiation especially contribute to superior high adhesive properties.     

Effects of atomic oxygen and ultraviolet in low earth orbit on low surface energy polymer film

Effects of atomic oxygen (AO) and ultraviolet (UV) on a polymer film with surface energy of 8.0 mJ m⁻² derived from poly(1H,1H‐perfluorooctyl methylacrylate) were investigated by contact angle measurements, X‐ray photoelectron spectroscopy, and atomic force microscope. The film was exposed to AO with a flux of 6.73 × 10¹⁵ atoms cm⁻² s⁻¹ and UV with intensity of 15.8 mW cm⁻² at wavelength of 200–450 nm, respectively. It is found that AO and UV irradiation resulted in the reduction of film thickness, change of wettability, and increase of surface energy, and AO exhibited more serious effects than UV on the fluorinated polymer film. Reduced rate of thickness of the film was almost proportional to the AO exposure time. After exposed to AO and UV irradiation, the surface energy of the film increased to 17.3 mJ m⁻² and 11.0 mJ m⁻², respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

低热固相氧化反应合成二氧化铅纳米片

以硝酸铅为铅源,以过硫酸钾为强氧化剂,在碱性条件下,采用阴离子表面活性剂十二烷基磺酸钠（SDS）辅助低热固相氧化法,首次成功制备了片状纳米二氧化铅。在反应过程中,二价铅盐首先与碱发生一步低热固相反应,生成橘红色的一氧化铅中间产物,该中间产物在碱性条件下进一步与过硫酸钾发生低热固相氧化反应,得到目标产物二氧化铅。SDS的引入对产物片状结构的形成起到了决定性作用。进一步借助XRD和TEM测试手段对所制备的纳米材料的晶型、形貌及大小进行了表征。XRD测试结果证实,所得样品为二氧化铅。TEM测试结果表明,所得二氧化铅纳米片的平均尺寸为300nm×200nm。     

Polymeric reaction of acrylic polymer–monomer system irradiated by low energy electron beam. I. Effects of molecular weight of polymer and polymer-to-monomer ratio

Polymeric reaction of the poly(n-butyl acrylate) (PBA)–benzyl acrylate (BzA) system induced by a low-energy electron beam was investigated. In order to elucidate the reaction behavior of the PBA–BzA system, the gel fraction, molecular weight of soluble part, and molecular weight distributions were examined by means of gel permeation chromatography (GPC) equipped with both ultraviolet (UV) and refractive index (RI) detectors. RI-detected GPC curves represented the molecular weights and their distributions of the total polymers, graft polymer, homopolymer, and unreacted PBA, while UV-detected curves only corresponded to the benzyl groups of graft polymer and homopolymer. Thus, the reaction behavior of the system was able to be followed by GPC. The molecular weight of the added PBA and the mole ratio of PBA/BzA were varied. The crosslinking, the graft reaction and the homopolymerization of BzA proceeded competitively during the polymeric reaction. The proportions of BzA unit incorporated into the crosslinked, graft and homo polymers were estimated by combining of measurement of gel fraction, UV-detected GPC curves, and infrared (IR) spectrum of gel. It was revealed that in the system containing PBA with high molecular weight, the grafting, and the crosslinking reactions predominated. The main reaction was the grafting in the system with a high mole ratio of PBA/BzA, while it was the homopolymerization in the systems with the low mole ratio of PBA/BzA. The reaction mechanism is discussed on the basis of reactivity and mobility of polymer radicals.     

低温相变储能材料研究进展

介绍了国内外低温相变储能材料及其载体的研究进展,结合本课题组的研究结果和文献报道,对低温无机相变材料、低温有机相变材料中的一元、二元及多元相变材料和无机-有机相变材料进行了阐述和分析,针对不同储能材料存在的问题,提出了相应的策略,最后对低温相变储能材料的研究重点及应用领域作了展望。     

Synthesis and characterization of nanometric gadolinia powders by room temperature solid-state displacement reaction and low temperature calcination

Nanometric-sized gadolinia (Gd₂O₃) powders were obtained by applying solid-state displacement reaction at room temperature and low temperature calcination. The XRD analysis revealed that the room temperature product was gadolinium hydroxide, Gd(OH)₃. In order to induce crystallization of Gd₂O₃, the subsequent calcination at 600 ∼ 1200 °C of the room temperature reaction products was studied. Calculation of average crystallite size (D) as well as separation of the effect of crystallite size and strain of nanocrystals was performed on the basic of Williamson-Hall plots. The morphologies of powders calcined at different temperatures were followed by scanning electron microscopy. The pure cubic Gd₂O₃ phase was made at 600 °C which converted to monoclinic Gd₂O₃ phase between 1400° and 1600 °C. High-density (96% of theoretical density) ceramic pellet free of any additives was obtained after pressureless sintering at 1600 °C for 4 h in air, using calcined powder at 600 °C.     

Effects of high‐energy electron beam on low‐density polyethylene materials containing EVA

A series of low‐density polyethylene (LDPE) blends with different amounts of ethylene–vinyl–acetate (EVA) was prepared and irradiated with 10 MeV electron beam in the range of 0–250 kGy at room temperature in air. EVA was used as a compatibilizer and softener in four different amounts: 5, 10, 20, and 30 wt %, based on polyethylene (PE). The crosslinking of the samples was studied on the basis of gel‐content measurements as well as some thermal and mechanical properties of the specimens. The results indicated that the LDPE and LDPE–EVA blends could be crosslinked by a high‐energy electron beam, of which their thermal and mechanical properties changed effectively, however, because of EVA content of the polymer; the blends were more sensitive to lower doses of radiation. These studies were carried out to obtain a suitable compound for heat‐shrinkable tubes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1049–1052, 2004     

Heat sealing of semicrystalline polymer films. III. Effect of corona discharge treatment of LLDPE

The effects of corona-discharge treatment (CDT) of commercial polyethylene (PE) Linear low-density PE (LLDPE) were studied with special emphasis on the heat-seal behavior of treated films. A range of treat levels, representative of those used in industry, was obtained by varying the applied power to a commercial, on-line treater. Film surfaces were characterized by XPS and wetting-tension measurements. The primary effect of CDT on the heat-sealing behavior of LLDPE films is a transition in the failure mode of heat seals from a normal tearing or inseparable bond to a peelable seal. In addition, CDT increases the seal initiation temperature 5–17°C and decreases the plateau seal strength 5–20% as the treat level, or wetting tension, increases from 31 to 56 dynes/cm. These effects are attributed to cross-linking during corona treatment, which restricts polymer mobility near the surface and limits the extent of interdiffusion and entaglements across the seal interface. Results of heat-sealing studies with electron-beam-irradiated PE, chemically oxidized PE, and CDT polypropylene (PP) provide indirect evidence for the proposed surface cross-linking mechanism. The effect of commercial levels of slip additives on the heat-seal behavior was also investigated. © 1994 John Wiley & Sons, Inc.     

Change of cathodoluminescence spectra of diamond with irradiation of low energy electron beam followed by annealing

We have reported previously that cathodoluminescence (CL) spectra of type II diamond change with irradiation of 20 kV electron beam using a scanning electron microscope (SEM), although it is known that diamond has high resistance against radiation beams. Following the previous paper, the diamond irradiated with the electron beam was annealed at 500 °C, and the CL spectra were measured. It was found from the annealed sample that the CL spectra which changed with the irradiation are partially recovered, namely, the lines at 420 nm and 540 nm formed with the irradiation are annealed out, and the lines at 485 nm, 535 nm and 545 nm which disappeared with the irradiation are recovered. However the 420 nm broad band that appeared with the irradiation does not change with the heat treatment. The effect of the heat treatment suggests that the CL peaks which changed with the irradiation are related to ionization of defects.     

Atom transfer radical polymerization of graft chains onto polyethylene film initiated at tribromomethyl unit introduced by electron beam irradiation

A novel process for graft polymerization onto a polyethylene (PE) film using atom transfer radical polymerization (ATRP) was examined. First, a PE film irradiated with an electron beam was treated with carbon tetrabromide, thereby introducing tribromomethyl groups. The number of tribromomethyl groups introduced onto the film could be controlled by adjusting the electron beam irradiation dose. Methyl methacrylate (MMA) was then graft‐polymerized by ATRP in the initiator‐introduced PE film in the presence of a copper catalyst. Based on FTIR spectra from the PMMA grafted films, the behavior of graft polymerization reactions on the film surface and inside the film are discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

RAFT聚合方法合成自由基聚合物PTMA

以苄基三硫代碳酸酯基丙酸(BSPA)为链转移试剂,采用RAFT聚合方法合成了分子量分布较窄的聚(4-甲基丙烯酰氧基-2,2,6,6-四甲基哌啶醇酯)(PTMPM-RAFT),并用氧化剂间氯过氧苯甲酸(m CPBA)氧化PTMPM-RAFT为聚(4-甲基丙烯酰氧基-2,2,6,6-四甲基哌啶氮氧自由基) PTMA。1H NMR、傅里叶红外光谱仪、紫外-可见分光光度计、凝胶渗透色谱以及X光电子能谱等证实了PTMPM-RAFT的结构及其分子量,并得到了氧化产物PTMA。     

概述低温等离子体技术及其改性高分子材料研究进展

低温等离子体技术作为清洁、高效的改性技术,赋予材料表面优异性能的同时,并不改变材料基体的整体性质,在高分子材料表面改性中有着越来越广泛的应用前景。综述了低温等离子处理、聚合、诱导接枝聚合等表面改性技术方法,并重点介绍了其在高分子材料亲水性、吸附性、粘结性和生物相容性等方面的改性应用研究进展。     

New coating materials and their preparation by radiation polymerization. III. Antifogging coating composition

Compositions for good antifogging and mar-resistant coatings were investigated. A mixture of hydrolyzed aminoalkylalkoxysilane and hydrophilic vinyl monomer was the best combination. Control of suitable viscosity for coating was carried out conveniently by irradiation. The prepolymer was coated and cured by heating to form an antifogging membrane on various base materials such as inorganic glass, CR-39 resin, and poly(methyl methacrylate). These conditions were studied in relation to some physical properties of the membrane. It was found that antifogging and mar-resistant properties were inconsistent in many cases. A possible way to achieve the best balance between the two properties is discussed.     

Ignition of a thin film by a beam of radiant energy

The problem of destruction of a thin polymer film due to heating by a beam of radiant energy is studied. The multistage nature of chemical conversion and dependence of optical properties on depth of decomposition is considered. Analytical estimates are given for the time characteristics of film ignition and its dependence on beam thickness and heating intensity. Optical phenomena related to the chemical reactions are observed by a numerical method.Tomsk. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 6, pp. 3–10, November–December, 1991.     

Synthesis of sulfonyl fluorinated macro emulsifier for low surface energy emulsion polymerization application

Fluorinated acrylate emulsions have been extensively applied for hydrophobic surface coatings. To obtain fluorinated emulsions of low surface energy, amphiphilic sulfonyl macro emulsifiers consisting of 2‐(perfluorohexyl) ethyl acrylate (PFHEA) and 2‐acrylanmido‐2‐methylpropanesulfonic acid (AMPS) were designed via radical polymerization and subsequently used for the emulsion copolymerization of PFHEA, methyl methacrylate (MMA), and methyl butyl acrylate (MBA). Under optimum synthesis conditions, the emulsifier displayed superior emulsification properties such as high monomer conversion, small particle size, and excellent stability compared with conventional emulsifiers. The corresponding emulsions with sulfonyl macro emulsifiers exhibited extreme low surface energy (9.8 mN/m) and outstanding hydrophobicity due to high contents of fluorinated chains, as well as thimbleful hydrophilic sulfonyl groups, which shows the great potential in water repellent modification application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44921.     

High solids content emulsions. III. Synthesis of concentrated latices by classic emulsion polymerization

Two different methods of producing bi‐ and trimodal latices of a mixture of methyl methacrylate, butyl acrylate, and small amounts of acrylic acid were tested. It is shown that a combination of concentrating blends of seed particles by semibatch reaction, followed by a nucleation of small particles plus a second semibatch phase allowed us to obtain stable latices with solids contents over 65% and viscosities of below 2500 mPa s^?1 with little coagulum formation. The key parameter in determining latex stability, coagulum formation, and viscosity appears to be the the particle size distribution, and especially its modification attributed to secondary nucleation. Because it is not possible to eliminate water‐soluble monomers from the polymerization recipe, secondary (homogeneous) nucleation must be minimized by careful addition of the free‐radical initiator and choice of monomer feed flow rates. The nucleation of the third population in the trimodal latices is best accomplished with a mixed surfactant system because renucleation by anionic surfactant alone leads to detrimental changes in the particle size distribution (PSD) resulting from excessive flocculation of particles. In addition, it was found that the viscosity of the final products was not sensitive to small changes in the ionic strength of the latex, although neutralization to a pH of 6 effectively doubles the final latex viscosity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1916–1934, 2002; DOI 10.1002/app.10513     

Casting of organic glass by radiation-induced polymerization of glass-forming monomers at low temperatures. III. Casting and polymer properties of monomer systems including inner-plasticizing comonomers

Previously, it was found that organic glass material having no optical strain could be cast efficiently in a very short time by radiation-induced cast polymerization of glass-forming monomers. In this report, practical useful monomer systems having glass-forming property and good physical properties were investigated. Several inner plasticized comonomer systems of excellent impact resistance were found which could be glassified and applied to radiation casting. These systems included butyl acrylate or hexanediol monoacrylate as inner plasticized component. Physical properties other than impact resistance were tested. The casting polymerization was studied, and it was found that polymers without optical strain could be obtained in a remarkably short time.     

Graft polymerization of acrylic acid onto polyethylene film by preirradiation method. I. Effects of preirradiation dose,monomer concentration,reaction temperature,and film thickness

Low-and high-density polyethylenes were irradiated by electron beams with dose of 2–50 Mrad and then immersed in aqueous solution of acrylic acid (monomer concentration from 30 to 100 wt %) for 10 min?5 h at a temperature of 25–40°C. The degree of grafting increases with time and levels off. High density polyethylene shows lower grafting rate and higher final % grafting in compared with low-density polyethylene. Both grafting rate and final % grafting increase with total dose of preirradiation, but show some saturation at high doses. The highest grafting rate was observed at 60 wt % of monomer concentration where the grafted polyethylene swells to the largest extent in the monomer mixture. Apparent activation energies for the grafting are 19.6 and 27.3 kcal/mol for low- and high-density polyethylenes, respectively, reflecting the proces of monomer diffusion in the film. Grafting rate decreases with increasing film thickness. Graft polymerization starts on the surface of the film and proceeds to the inner part with monomer diffusion through the grafted layer.     

微波合成甘薯淀粉基高吸水树脂

以N,N’-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂,利用微波辐射接枝甘薯淀粉-丙烯酸共聚合成高吸水树脂。研究了单体配比、丙烯酸中和度、交联剂与引发剂用量、微波功率等因素对所制备的树脂吸水率的影响,并对该数值在不同条件下的保水率进行了研究。结果证明,所制备的树脂吸取去离子水的量为873 g/g,吸取1%NaCl溶液的量为57 g/g,70℃12 h的保水率60%,110℃12 h的保水率18%,5000 r/min离心30 min条件下的保水率96.3%。