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。 相似文献
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.
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. 相似文献
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 (σac) 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. 相似文献
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.
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.
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 γCMC 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 γCMC and the maximum surface adsorption capacity Γmax decrease. The free energy of micelle formation is negative (?51.2 to ?60.5 kJ mol?1). 相似文献