电子束辐照聚乳酸-聚乙二醇共聚物的结构及热性能研究

本文首先通过直接熔融缩聚法制备了聚乳酸-聚乙二醇共聚物(PLEG),并采用FTIR和1 H NMR对其结构进行表征。然后在辐射剂量0～100kGy范围下,利用衰减全反射红外(ATR-FTIR)、差示扫描量热(DSC)和热失重分析(TGA)研究了电子束辐照对PLEG结构及热性能的影响。结果表明:加入3%的三聚氰酸三烯丙酯(敏化剂TAC)后,由于交联结构的形成,PLEG的凝胶率、玻璃化转变温度(Tg)和热稳定性均随辐射剂量的增加而有所提高,且其热转变行为也发生变化。     

微波法合成新型双酚A二苯醚型双马来酰亚胺研究

本文采用微波辐射方法,以顺丁烯二酸酐(MA)和2,2′-双[4-(4-氨基苯氧基)苯基]丙烷(BAPP)为原料,合成了2,2′-双[4-(马来酰亚胺基苯氧基)苯基]丙烷(BPA-BMI),并通过红外光谱、核磁共振、质谱等对产物结构进行表征.经过正交试验确定了微波法合成BPA-BMI的最佳工艺条件为n(MA):n(BAPP)=2.3:1,催化剂用量为10％(wt％),辐射功率为450W,辐射时间为30min,产率可达67.26％.结果表明:与传统制备双马来酰亚胺的方法相比,微波法不仅可行,并且具有反应时间大大缩短、效率高、操作简单、环境友好等特点.     

γ辐射对交联聚乙烯结构和性能的影响

研究了空气中60Coγ射线对交联聚乙烯(XLPE)结构和性能的影响.采用傅立叶红外光谱仪、万能材料试验机、差示扫描量热仪和热失重等对辐照前后的XLPE进行了分析.结果表明:XLPE在空气中辐照后,表面出现羧基和羰基.随辐照剂量的增加,材料的氧化程度、凝胶含量和拉伸强度均逐渐增大,而断裂伸长率、熔点和结晶度则逐渐降低.低...     

双马来酰亚胺树脂/碳纳米管复合材料的性能研究

制备了接枝N-苯基马来酰亚胺基团的碳纳米管(PMI-MWNT),并采用原位聚合法制备了双马来酰亚胺-二烯丙基双酚A(BMI-BA)/PMI-MWNT复合材料.研究了PMI-MwNT用量对复合材料力学性能、动态热力学性能的影响.结果表明,随着PMI-MwNT用量的增多,体系的反应活性呈上升趋势,且热力学性能显著提高;当PMI-MWNT的质量分数为1.5%时,复合材料的冲击强度和弯曲强度比BMI树脂分别提高了近291%和50%.     

含醚酮结构的新型双马来酰亚胺树脂的合成

4,4′-双(3-氨基苯氧基)二苯甲酮(443BAPDBP)和马来酸酐(MA)在N,N′-二甲基甲酰胺(DMF)溶剂、催化剂和共沸剂的作用下,一步法合成了新型醚酮双马来酰亚胺树脂,对其进行了进一步的表征,并对其应用作了初步探索研究。结果表明,合成得到的443BMIPOBP树脂熔点为88～90℃,纯度为98．2%,用443- BMIPOBP/DABPA/HTPPI预聚物比BDM/DABPA/HTPPI体系对铜材具有更高的黏接强度,其剪切强度为17．5 MPa。     

PA6/SMA/N-PMI复合材料的热性能和力学性能研究

采用熔融共混法制备了聚酰胺6/苯乙烯-马来酸酐共聚物/N-苯基马来酰亚胺复合材料(PA6/SMA/N-PMI),利用差示扫描量热法(DSC)、热重分析(TGA)及力学性能测试等手段研究了N-PMI用量对PA6/SMA/N-PMI复合材料熔融结晶行为、热性能以及力学性能的影响。结果表明:复合材料的最大分解温度较纯PA6有所提高;随着N-PMI用量的增加,复合材料的结晶温度、结晶度以及熔融焓均逐渐降低;当N-PMI用量为15份时,复合材料的弯曲强度、弯曲模量、拉伸强度以及热变形温度均达到最大值,分别为101.0、2 892、71.6 MPa以及56.6℃,较纯PA6分别提高了11.0%、21.3%、3.1%和10.0%。     

N-对甲苯基马来酰亚胺与丙烯腈共聚动力学及共聚物的热性能

以AIBN为引发剂,研究了不同配比的丙烯腈(AN)与N-对甲苯基马来酰亚胺(NPTMI)在80℃的自由基溶液共聚合 ,并根据FTIR谱图确证了共聚物的存在。根据元素分析的结果,用FR法得到竞聚率的值rAN=0.57,rNPTMI=1.47。用GPC测定了共聚物的分子量并分别用DSC、TGA对其玻璃化温度和热失重情况进行了研究,发现共聚物具有良好的热性能。     

硅橡胶γ—辐射效应对其结构—流变性能的影响

本文用光学显微镜、电子显微镜、流变等方法研究了硅椽胶γ－射线辐射效应对其结构——流变性能的影响。实验结果表明，试样结构变化不仅与辐射效应有关，也与辐射剂量有关。     

硅橡胶γ—辐射效应对其结构—流变性能的影响

本文用光学显微镜、流变等方法研究了硅橡胶γ－射线辐射效应对其结构－流变性能的影响。实验结果表明，试样结构变化不仅与辐射效应有关，也与辐射剂量有关。     

羧基化改性对PAN热交联膜孔结构及性能的影响

作为热塑性材料，聚丙烯腈不对称膜在热交联的过程中会发生热熔融，导致孔融并。以非溶剂相转化(NIPS)法制备了聚丙烯腈基不对称(PAN)膜，采用NaOH碱性水解工艺，经过羧基化改性和热交联制得具有丰富海绵状孔及指状孔结构的羧基化PAN基热交联(H-TPAN)膜，研究了NaOH浓度对PAN及后处理膜结构与性能的影响。结果表明，羧基化对PAN膜进行改性处理，能够在热交联阶段促进氰基团环化和氧化反应，提高H-TPAN膜的交联程度，避免膜孔在高温下的热融并，保持PAN热交联膜通量。PAN膜在热交联过程中性能最优的羧基化条件为：NaOH浓度0.4 mol·L^-1、羧基化时间1 h、羧基化温度60℃。同时，羧基化改性膜表现出优异的热稳定性和良好的耐溶解性。     

适于电子束固化双马来酰亚胺树脂体系的研究

研究了１种适于电子束固化的双马来酰亚胺树脂体系。在４,４’－二苯甲烷双马来酰亚胺和双酚Ａ－二苯醚双马来酰亚胺的低熔点混合物中加入适量的活性稀释剂、催化剂,经３００ｋＧｙ的电子束辐射,所得树脂浇铸体的玻璃化转变温度为２６０℃;室温模量为４．２ＧＰａ。用红外光谱分析法测定了电子束辐射固化之后官能团的转化率。用热重法测定了树脂的热分解温度。     

Radiation Crosslinking of Poly(ethylene‐co‐octene) with Electron Beam Radiation

Films of ethylene‐co‐octene copolymer are irradiated in air after moulding between Mylar® films with electron beam at different doses. To correlate the change in structure with properties, the irradiated and unirradiated samples are characterised by FTIR spectroscopy, swelling and mechanical measurements. Obtained changes are dependant on the radiation dose of the incident electron beam. Irradiation induces trans‐vinylene double bonds detected by FTIR spectroscopy in transmission mode. No hydroxyl (OH) and carbonyl (C?O) groups were recorded by FTIR spectroscopy. More drastic changes are observed with swelling method and by mechanical properties showing the crosslinking effect. Based on the results obtained by analytical techniques used in this study, free radicals mechanism involving mainly the pendant chains of the PE‐co‐O is proposed.

Strain at break versus gel fraction.     

Mechanical Properties of Electron Beam Cured Monomer and Monomer/Liquid Crystal Films

This article reports on mechanical properties of electron beam cured tripropylene glycol diacrylate (TPGDA) and propoxylated glycerol triacrylate (GPTA) films. This study has been motivated by the need to have direct access to those properties for analyzing the thermo‐mechanical behavior and electro‐optical properties of polymer dispersed liquid crystal systems in general, and systems made either of TPGDA or GPTA and low molecular weight liquid crystals in particular. Representative examples of these systems are considered in this work. The effects of the degree of crosslinking on the mechanical strength of the polymer network are analyzed by considering different doses of the electron beam irradiation. As the radiation dose increases, the mechanical strength of the film is enhanced. Addition of a small amount of liquid crystals leads to remarkable plasticizing effects.

Young modulus and rubbery state modulus as a function of EB dose for cured TPGDA films. The filled symbols represent the Young modulus and the open symbols represent the rubbery state modulus. Circles are for pure TPGDA and squares are for TPGDA/E7 mixture with 15 wt.‐% E7.     

Exploring the Combined Effect of Electron Beam and Conductive Carbon Black on the Mechanical,Dynamic Mechanical,Thermal, and Electrical Properties of Ethylene Acrylic Elastomer

The electron beam-crosslinked and conductive carbon black-reinforced ethylene acrylic elastomer composites have been developed for various applications. The inter-connectivity of conductive carbon black agglomerates are clearly observed from the high-resolution transmission electron photo micrographs. The tensile strength of the composites has remarkably increased with increasing conductive carbon black loading up to 350 radiation dose. The dielectric permittivity (?′) and AC conductivity (σ_ac) increase with an increase in conductive carbon black loading. The electron magnetic shielding interference of the developed composites has been measured using X-band frequency range, and the electron magnetic shielding interference increases with an increase in conductive carbon black loading.     

含乙烯基有机硅树脂的电子束固化行为研究

以八甲基环四硅氧烷、四甲基四乙烯基环四硅氧烷为单体,六甲基二硅氧烷为封端剂,碱胶为催化剂,合成了含乙烯基有机硅树脂;并研究了电子束辐射剂量对其固化行为的影响和固化涂层的热性能。红外谱图及凝胶率测试结果表明,有机硅树脂中的碳碳双键吸收峰强度随辐射剂量的增加而减弱,辐射诱导交联网络结构的形成导致固化涂层的凝胶率随剂量的增加而显著增加;辐射剂量为30 kGy时,凝胶率为46.2%;辐射剂量增加至60 kGy时为70.1%和100 kGy时为85.9%。差示扫描量热分析和热质分析结果表明,固化涂层具有优良的耐低温性和热稳定性。     

Influence of Electron Beam Irradiation on the Mechanical Properties of Vegetable‐Oil‐Based Biopolymers

The influence of electron beam (EB) irradiation on the mechanical properties of biopolymers from modified linseed oil is studied. The thermoset is prepared by copolymerizing norbornenyl‐functionalized linseed oil and dicyclopentadiene (DCPD) by ring‐opening metathesis polymerization (ROMP). EB irradiation of the bulk polymer results in a substantial increase in the crosslinking density. The residual carbon‐carbon double bonds remaining after ROMP are expected to act as further crosslinking sites upon exposure to the high‐energy electrons. The increase in the crosslinking density is studied by DMA and sol/gel fraction measurements from Soxhlet extraction. Tensile testing reveals that Young's modulus and tensile strength are enhanced after EB irradiation.

     

Electron Beam Crosslinking of Atactic Poly(propylene): Development of a Potential Novel Elastomer

Atactic amorphous poly(propylene) of various molecular weights has been modified with high energy electrons over an irradiation dose range of 0–200 kGy. Tri‐ and tetrafunctional monomers in varied concentrations have been used as crosslinking additives. A correlation between the original molecular weight and crosslinking behavior of the polymer was observed. A higher gel content is obtained with the tetrafunctional acrylate as compared to that with the trifunctional one, under the same treatment conditions. Electron irradiation treatment at elevated temperature gives rise to an increased gel content over that at room temperature. Similarly, the mechanical properties also enhance with gel content. Moreover, the stress‐strain behavior of the electron modified systems indicates a more pronounced elastomeric nature.

     

Engineering properties of electron beam‐crosslinked ethylene methyl acrylate copolymer

Effect of electron beam on mechanical, thermal, and morphological properties of ethylene methyl acrylate copolymer, grade Elvaloy 1335 has been investigated. The copolymer was subjected to varying doses of electron beam radiation with different proportion of the sensitizer trimethylolpropane trimethacrylate (TMPTMA). It was observed that with increase in electron beam dose, the physicomechanical properties of the crosslinked copolymer improve, reaches an optimum level and subsequently deteriorates. The thermal properties as envisaged from thermogravimetric analysis and differential scanning calorimetric studies revealed stability of the crosslinked irradiated samples over that of the unirradiated ones. The thermal stability was also found to attain the maximum at the same level of radiation and sensitizer. The morphological studies showed consistency with the mechanical properties. Based on the overall study, it may be concluded that ethylene methyl acrylate copolymer with 1 phr TMPTMA at 60 kGy radiation dose is the optimum condition within the range studied in this investigation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and Properties of a Novel Linear Alkylated Diphenylmethane Sulfonate Gemini Surfactant

The linear alkylated diphenylmethane sulfonate (C₁₂‐DSDM) was synthesized by a four‐step reaction with lauric acid, diphenylmethane and chlorosulfonic acid as raw materials. The structure of the final product was characterized by MS. The air–liquid surface tensions at various temperatures and salt solutions (NaCl) were measured by using the drop‐volume technique and the thermodynamic parameters of the micellization were calculated. The results show that the critical micelle concentration (CMC) and γ_CMC of the surfactant are 1.452 mmol L^?1 and 38.49 mN m^?1 at 298 K. With an increase in temperature, the CMC gradually increases, the γ_CMC and the maximum surface adsorption capacity Γ_max decrease. The free energy of micelle formation is negative (?51.2 to ?60.5 kJ mol^?1).