Papers by Keyword: Oligomer

Abstract: In this paper, fluorosilicone oligomer and its curing agent are used as the main film-forming materials, and fluorosilicone POSS is added to reduce the surface energy of the composites to prepare a coating with certain anti-sticking effect. The changes of molecular structure before and after the reaction were obtained by infrared spectroscopy. The contact angle and anti-sticking property of the coating surface were studied by changing the content of POSS containing fluorine. It was found that the contact angle of fluorine-containing POSS reached 98.7° when the content of fluorine-containing POSS was 3 Wt.%. With the increase of POSS content, the anti-sticking force of composites changed little, but with the increase of the contact time of tape, the anti-sticking force showed an increasing trend.

Abstract: Dynamic Time Sweep of Rotational Rheometer has been Used to Study the Variation in Rheological Properties of Polymers with Time. Polycarbosilane (PCS) is a Solid Oligomer at Room Temperature and Becomes Melt at its Softening Temperature. Bubbles are Unavoidably Produced by Gasification of Low Molecular Weight Part of PCS, which Significantly Disturbs the Subsequent Rheological Measurement. however, the Rheological Data of PCS Melt Cannot Be Repeated on Conventional Dynamic Time Sweep Test even after Reducing the Bubble. in this Work, a Series of Oscillatory Rheological Measurements were Carried out by Temperature Control to Improve the Data Reliability. the Axial Force Data of PCS Melt were Manually Recorded and Compared before and during the Test, which Reflected the Response of PCS Melt to Temperature Change. the Results Confirmed that the Shear Stress of PCS Melt was Readily Affected by Temperature Alteration. the Data Repeatability of the Rheological Test was Evidently Improved for PCS Melt with the Temperature Control.

Abstract: As an important precursor in preparation of silicon carbide ceramic fibers by polymer precursor-derived method, it is very difficult to find the zero shear viscosity through the conventional steady test for the oligomer-like polycarbosilane (PCS) because of the possible oxidation and a prolonged time required to attain a steady state of the samples. In this work, a steady test and a series of transient tests were performed for the PCS melts. The limitation of the steady test is discussed. An averaging method based upon data from the transient tests is developed to determine the zero shear viscosity for the melt. The reliability of the results from the method is discussed and the zero shear viscosity of the pretreated PCS melt was obtained.

Abstract: Formation of epoxy composite material with microfilling agent Al₂O₃ was investigated. Physical and chemical aspects of formation of external surface layers around disperse filler particles during structure formation of epoxy composites was proposed.

Abstract: A kind of novel multifunctional ene bio-based oligomer has been successfully synthesized, which based on the renewable resource of the rapeseed oil and the 10-undecylenic acid. The structure of this novel oligomer was confirmed through proton nuclear magnetic resonanace (NMR). The result shows that the goal product has been produced successfully.

Abstract: In this paper, polyaniline (PANI) fibres were prepared by electrochemical polymerization from the solutions of aniline and hydrochloric acid in the presence of different concentrations of aniline oligomer. The influences of adding a small amount of aniline oligomeric additives, such as p-aminodiphenylamine (PADPA), p-phenylenediamine (PPDA) to the electrochemical polymerization system of aniline on polyaniline fibres have been investigated. Change in fibre diameter with the concentration of aniline oligomer were investigated. Morphologies of PANI fibres were characterized by scanning electron microscopy (SEM). Electrochemical behaviors of PANI fibres were studied by cyclic voltammetry (CV). The results show that with the addition of PADPA, PPDA to aniline polymerization system, the rate of polymerization increases greatly, and more lower potentials can be applied to generate electroactive PANI fibres with more finer and uniform structure.

Abstract: A feasible and effective method of thermal hydrolysis to prepare poly (lactic acid) (PLA) oligomers with different controlled molecular weight from PLA is presented in this paper. The thermal hydrolytic reaction was carried out by immerging PLA resin pellets in boiling distilled water for a certain period of time. Ester groups in PLA chains are hydrolytically degraded in the presence of water and thermal, so PLA oligomers with different molecular weight were prepared. The structures and properties of PLA oligomers were characterized by FT-IR, GPC, DSC, etc. The results showed that thermal hydrolytic reaction could effectively reduce the molecular weight of PLA, which declines with the increase of the thermal hydrolytic reaction time. Meanwhile, the content of terminal hydroxyl group, glass transition temperature, melting point of PLA oligomers prepared from thermal hydrolytic reactions exhibit gradual changes with the extension of the thermal hydrolytic time.

Abstract: A castor oil-based UV-oligomer bearing benzophenone side chains (LU-5)was synthesis through two-step partial esterification reaction of polyacrylic acid with 4-hydroxy benzophenone and castor oil in the presence of N, N-diisopropyl carbodiimide and 4-(dimethylamino) pyridinium 4-toluenesulfonate(DPTS), then LU-5 was cured by UV irradiation with trimethylolpropane triacrylate(TMPTA) without any photoinitiator. The structure of the productions of the esterification reaction was characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance(NMR) and ultraviolet and visible spectrophotometer (UV-Vis), and the properties of UV cured polymer(FUV) has been studied. The results show that LU-5 has a certain light initiator activity, and it can be used as a macromolecular photoinitiator, the film of polymer has a certain degree of crosslinking.

Abstract: In this article, the damping mechanism of organic hybrids consisting of Nitrile Butadiene Rubber (NBR) and phenolic oligomer 4-methyl-pheno reaction products of both dicyclopentadiene and isobutylene (MPDI) were investigated by dynamic mechanical analysis (DMA). It was shown that NBR/MPDI blends exhibit only one damping peak, which shifted to higher temperature with the increase of MPDI content, and the maximum of tan δ peak decreased slightly when the ratio of NBR/MPDI was no more than 100/20, and then increased when the ratio rised from 100/20 to 100/80. Fourier transform infrared spectrum (FT-IR) showed that the hydrogen bond were formed between -OH of MPDI and a-H of NBR. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) measurements indicated that MPDI exhibit amorphous features, which was compatible with the blends. These may imply that much more stable damping material with both higher tan δ peak and controllable damping peak position can be achieved.

Abstract: The electronic structures of oligomers of pyrrole have been calculated using the extended Hückel tight-binding program. The energy diagrams are shown for oligomers as the number of the repeating unit in the oligomers increases from 1 to 16. The relationship between the energy gap of the oligomers and the number of the repeating unit in the oligomers is established. Blue-green photoluminescence and electroluminescence from one-dimensional polypyrrole are predicted.