Papers by Keyword: PU

Abstract: Energy-saving and emission-reducing must be achieved based on the reliable performance of fire safety. External thermal insulation material is the main component of external thermal insulation system, and also the main combustion participants when a fire occurs; the combustion performance is an important factor affecting the fire scale of external thermal insulation system. The main material and heat release principle was introduced in this paper, tests were carried out, and fire hazard was analyzed based on large amount of test data. The research will provide theoretical support for external insulation material choice, system construction, fire prevention and rescue.

Abstract: Wear-resistant polyurethane (PU)-based materials were prepared through addition of chemically modified aramid and PE fibers. The morphologies of PU-based materials were examined. We observed that treated fibers can be added to 10%, resulting in useful materials with very stable properties. Besides, bending strength of the materials increased from the 10 ~ 15 to 55 MPa, which greatly broadens the range of its applications. In this research, we also examined volume wear, heat resistance, and surface grinding marks morphology and observed very good performances.

Abstract: As an outstanding class in smart materials of particular interest, shape memory polymers (SMPs) and their composites are drawing more and more attentions due to their potential applications in fields like biomedical and spacecraft industry. In this paper, shape memory behaviors of polyurethane (PU) in stress-controlled situations are simulated on the basis of the generalized Maxwell model and the time-temperature superposition principle. The free recovery cycles under three different imposed stresses and the influence on shape memory behaviors caused by changing heating rate are discussed. As the results reveal, the generalized Maxwell model can be used to describe the PU shape memory performance, and the shape recovery temperature increases with the increase of heating rate.

Abstract: The flame retardants used for the rigid PU foam material were studied systematically in this paper and a series of experiments were carried out to test the oxygen index (OI) of it. The synergistic effect in the different flame retardants also be verified to achieve a well flame retardancy performance. The best ingredients were found out by an orthogonal experiment which can give the PU foam maeterial a difficult combusted degree with the oxygen index higher than 34.

Abstract: Effect of the amount of Channel Black on underwater property of PU material is researched by adding Channel Black into PU material. The results show that the amount of Channel Black has most effect on underwater property of PU material. In one atmospheric pressure, the underwater property of PU material is worst when the amount of Channel Black is 60, while the underwater properties are not evident when the amount of channel is 30 and 45. In lower underwater pressure, effect of the amount of Channel Black on underwater property of PU material is almost difference. In higher underwater pressure, the underwater property of PU material is best when the amount of Channel Black is 45, while 30 is second, and 60 is lowest.

Abstract: Effect of carbon nanotube(CNT) on structure, strength and tribological behavior of CNT/PU composites is studied in the filler range of 5 vol%. It is found that differences in filler content used to determine the type of structure evolved and patterns of variation of mechanical properties, friction and wear in response to increasing filler content. It is found that wear of low-filled CNT/PU composites is dominated by delamination mechanism and wear resistance changes correlate with structural transformations of the composites. The maximum increase in wear resistance of the PU composites is reached at 2 vol% filling.

Abstract: A polyurethane/clay (PU/clay) composite was synthesized. The microstructure of the composite was examined by scanning electron microscopy. The impact properties of the composite were characterized by impact testing. The study on the structure of the composite showed that clays could be dispersed in the polymer matrix well apart from a few of clusters. The results from mechanical analysis indicated that the impact properties of the composite were increased greatly in comparison with pure polyurethane. The investigation on the mechanical properties showed that the impact strength could be obviously increased by adding 20 wt% (by weight) clay to the matrix.

Abstract: By mixing PEG or LiCl respectively into the casting solution, the polyurethane (PU)/SiO2 hybrid membranes were prepared by means of immerged phase inversion process. The method of NMR relaxation time T1 value was used to determine effect of the segmental movement of PU macromolecule in the casting solution on the microporous structure of membrane. The membrane section photos of SEM and properties of the PU hybrid membranes were investigated respectively. The results showed that blending SiO2, and with LiCl or PEG into the PU solution system, the T1 value synchronistically decreased. That was relaxed of PU chain winding and ease to move. The additives of PEG could influence the casting solution of PU, it enhanced the distribution of SiO2 in the casting solution, and formed fine interfacial micropores, meanwhile the retention of the membranes were increased to certain degree whereas the pure water flux could kept at a higher level. Similarly, adding some quantity of LiCl could obtain the membrane with higher retention under the condition of slightly loss of pure water flux. Even thought that there were equivalent quantities of finger pores in section of membrane, mixing PEG or LiCl in the casting solution, the SEM section photos indicated that there were more micropores in the wall of pore.

Abstract: Stab resistance compound fabric is frequently used in daily life, industry, military and aerospace. In this study, Nylon 6 and Polyester short fibers were mixed in ratio of 70:30. The mixture was needle punched at speed 300 needle/min to form a stab resistant fabric. The non-woven fabric matrix, non-woven fabric/grid matrix, non-woven/water-bone polyurethane (PU), and matrix/grid/water-bone PU, were put to test their tensile stress, tear stress, and stab resistance. Latter, the most stab resistant compound matrix was constructed in lamination structures to examine the relationship between thickness and stab resistance. The result showed that stab resistance of the non-woven/grid/water-bone PU compound fabric was 115 N; the triple-layered sample D was 208 N.