共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
A series of polyurethane–poly(methyl acrylate) sequential interpenetrating polymer networks containing 40 wt % polyurethane were prepared. The triol/diol ratio used in the preparation of the first formed polyurethane network was changed so that the average molecular weight between crosslinks ranged from 9500 to 500 g/mol. In addition to decreasing this average molecular weight, changing the triol/diol ratio alters the hard segment content of the polyurethane. The extent of mixing of the components in these IPNs was investigated using electron microscopy, dynamic mechanical analysis, tensile testing, and sonic velocity measurements. The polyurethane networks were also characterized by swelling studies. It was concluded that, as the triol/diol ratio increased, the extent of mixing increased and there was evidence of phase separation of the hard segments of the polyurethane component at high triol/diol ratios. 相似文献
3.
4.
A series of segmented polyurethanes containing 60 wt° of hard segments (HS) was prepared from MDI (4,4-diphenylmethane diisocyanate) ethylene glycol and mixtures of a polyoxyethylene end-capped polyoxypropylene triol and a polyoxyethylene end-capped polyoxypropylene diol. The effects of the content of polyether diol in polyether polyols on phase separation and properties was investigated by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and investigation of tensile properties. The DSC and DMA results indicate that the polyurethane derived from only polyether triol exhibits obvious phase separation and that the HS is immiscible with the SS, but that the HS is compatible with the HS for the polyurethane derived from polyether diol. As the content of polyether diol increases, the compatibility between HS and SS increases. As the content of polyether diol increases, the tensile strength. elongation. toughness and tear resistance of the polyurethanes increases. but their moduli decrease. The modulus-temperature dependence in the temperature region of –30 to 65 °C increases as the polyether diol content increases. 相似文献
5.
Urea-containing polyurethane reaction systems, based on ethylene oxide-capped poly(propylene oxide) polyether diol, 1,4-butyldiol, uretonimine liquefied 4,4′-diphenyl-methane diisocyanate, and a biurea compound, were used to investigate the effect of urea groups on polyurethane bulk polymerization by using Fourier transform infrared spectroscopy. The biurea compound was a liquid biurea-capped poly(propylene oxide) polyether, which can mix well with the polyurethane systems. Catalysis of urea groups was observed clearly regardless of whether organotin catalyst was used. A catalytic mechanism was presented in this paper. © 1996 John Wiley & Sons, Inc. 相似文献
6.
This article deals with the synthesis and properties of poly[(propylene glycol maleate)-co-(propylene glycol phthalate)] diol (PGMPD)/polyester–urethane or polyether–urethane hybrid polymer networks (HPNs). The polyurethane type and the molar ratio of NCO/OH have an effect on their properties. The structure–property relationship is discussed as well. © 1994 John Wiley & Sons, Inc. 相似文献
7.
To achieve a good biocompatibility, two sets of novel segmented polyurethanes, namely, poly(ether urethane)s and poly(carbonate urethane)s, with long side chain fluorinated alkyl phosphatidylcholine polar head groups attached to hard block have been synthesized recently in our laboratory by using a new diol with a long side chain fluorinated alkyl phosphatidylcholine polar head group 2-[2-[2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-10-ethoxy-decyloxy]-N-(2-hydroxy-1-hydroxymethyl-1-methyl-ethyl)-acetamide] phosphatidylcholine, HFDAPC as an extender. These novel polyurethanes have shown a potential to be used as bio-membrane mimicry. In this article we investigated the phase behavior of these materials by Instron, DSC, DMA, and AFM because the phase behavior has a great effect on the surface properties thus the biological-related perspective. Tg decreases first then increases for the poly(carbonate urethane)s, but increases first then decreases for the poly(ether urethane)s with an increasing in fluorinate phosphatidylcholine content. On the other hand, the tensile modulus was found decrease for the poly(carbonate urethane)s but increase for the poly(ether urethane)s with an increasing in fluorinate phosphatidylcholine content. It was found via AFM that the phase separation increases in poly(ether urethane)s but phase mixing increases in poly(carbonate urethane)s, with increasing content of fluorinated phosphatidylcholine side chain. The interaction between hard and soft segment, particularly, the hydrogen bonding was investigated by FTIR. The effect of fluorinated phosphatidylcholine side group on the phase separation of polyurethane was discussed and compared with that of fluorinated polyurethanes containing only fluorinated side chains. Our result demonstrated how the phase behavior of polyurethanes could be controlled by tailoring the interaction between hard and soft segment. 相似文献
8.
A series of multiblock polyurethanes, containing various poly(ethylene oxide) (PEO; number‐average molecular weight = 400–3400) contents (0–80 wt %) and prepared from hexamethylene diisocyanate/PEO/poly(dimethylsiloxane) diol/polybutadiene diol/1,4‐butanediol, were used as modifying additives (30 wt %) to improve the properties of biomedical‐grade Pellethene. Different molecular weights of PEO were used to keep poly(ethylene glycol) at a fixed molar content, if possible, although the PEO content, related to the PEO block length in the multiblock polyurethanes, was varied from 0 to 80 wt %. The hydrophilic PEO component was introduced through the addition of PEO‐containing polyurethanes and dicumyl peroxide as a crosslinking agent in a Pellethene matrix. As the PEO content (PEO block length) increased, the hydrogen‐bonding fraction of the crosslinked Pellethene/multiblock polyurethane blends increased, and this indicated an increase in the phase separation with an increase in the PEO content in the crosslinked Pellethene/multiblock polyurethane blends. According to electron spectroscopy for chemical analysis, the ratio of ether carbon to alkyl carbon in the crosslinked Pellethene/multiblock polyurethane blends increased remarkably with increasing PEO content. The water contact angle of the crosslinked Pellethene/multiblock polyurethane blend film surfaces decreased with increasing PEO content. The water absorption and mechanical properties (tensile modulus, strength, and elongation at break) of the crosslinked Pellethene/multiblock polyurethane blend films increased with increasing PEO content. The platelet adhesion on the crosslinked Pellethene/multiblock polyurethane blend film surfaces decreased significantly with increasing PEO content. These results suggest that crosslinked Pellethene/multiblock polyurethane blends containing the hydrophilic component PEO may have potential for biomaterials that come into direct contact with blood. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2348–2357, 2004 相似文献
9.
10.
双组分聚氨酯嵌缝密封剂的制备与性能研究 总被引:1,自引:1,他引:0
以TDI(甲苯二异氰酸酯)、N-220(聚醚二元醇)和N-330(聚醚三元醇)等为主要原料合成PU(聚氨酯)预聚体,并以此作为PU密封剂的甲组分;以MOCA(3,3′-二氯-4,4′-二氨基二苯甲烷)、EP330N(聚醚三元醇)、增塑剂邻苯二甲酸二辛酯(DOP)、轻质碳酸钙和辛酸亚锡等作为PU密封剂的乙组分。研究结果表明:以D3(PU类)为底涂剂,当R=n(-NCO)/n(-OH)=1.05~1.10、混合固化剂中n(MOCA中-OH)∶n(EP330N中-OH)=2∶1和w(DOP)=40%时,室温固化双组分PU密封剂具有良好的拉伸性能和定伸粘接性能,并且满足大变形、高位移量水泥伸缩缝的嵌缝工艺要求。 相似文献
11.
12.
13.
以聚氧化丙烯二醇(N-210)、甲苯二异氰酸酯(TDI)和二羟甲基丙酸(DMPA)为原料,采用内乳化法合成了无纺布增强用水性聚氨酯乳液。研究了R值(nNCO:nOH)、DMPA用量、不同二醇扩链剂和乳液扩链剂间苯二胺的用量对水性聚氨酯乳液外观、粘度和稳定性以及对乳胶膜的强度、硬度和耐水性的影响。结果表明:R值=3.7、nDMPA:nN-210=0.7、采用新戊二醇和间苯二胺扩链,合成的水性聚氨酯乳液储存稳定、耐水性好,用于无纺布增强,制造树脂抛光轮。 相似文献
14.
Effect of crosslinking density on resilient performance of low‐resilience flexible polyurethane foams
下载免费PDF全文
![点击此处可从《Polymer Engineering and Science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Low‐resilience flexible polyurethane foams (FPUFs) with varying crosslinking densities, were synthesized from polyols, 4, 4′‐diphenyl methane diisocyanate (MDI‐100), and water. The effects of crosslinking agent content, the molecular weight (Mw) of polyether diol, and the ratio of (polyether triol)/(polyether diol) on the resilience performance of FPUFs were investigated. Results indicate that higher crosslinking density was beneficial to the increasing of recovery time. The recovery time of the FPUF using polyether diol with Mw of 400 was 24.3 s. It was 3.2 times longer compared with FPUF using polyether diol with Mw of 3000. Dynamic mechanical analysis (DMA) results showed that, FPUFs with high crosslinking density displayed viscoelasticity in a wider range of temperature. However, when molecular chains were longer enough, FPUFs with low crosslinking density also demonstrated significant viscoelasticity, which is owing to the excess of physical crosslinking points. The results in stress–strain cycling and recovery time experiments were consistent with the results of DMA. POLYM. ENG. SCI., 55:308–315, 2015. © 2014 Society of Plastics Engineers 相似文献
15.
Formulations for rigid polyurethane foams (RPUFs) based on crude 4,4′‐diphenylmethane diisocyanate, polyether polyol, triethylenediamine, 1,4‐butane diol, poly(siloxane ether), methylene chloride, and water were studied. The stoichiometric ratios of various foam ingredients and their effects on physical properties such as the cream time, gel time, tack‐free time, and density of the RPUF samples were studied. The results indicated that the rate of RPUF formation increased with the catalyst (triethylenediamine and tin) and water content. The density of the RPUF samples blown with water, methylene chloride, and a mixture of water and methylene chloride decreased from 240.1 to 33.4 kg/m3 with an increase in the blowing agent contents. However, the RPUF density increased with increasing contents of 1,4‐butane diol. The cell morphology and thermal properties of the RPUF samples were investigated with scanning electron microscopy, thermogravimetric analysis, derivative thermogravimetry, and differential thermal analysis. Scanning electron microscopy results revealed an average increase in the cell size of the RPUF samples from 162 to 278 μm with increased water content. A thermal behavior study indicated that the RPUF samples decomposed in nitrogen and degraded in air through two and three weight‐loss stages, respectively. Foam pyrolysis in nitrogen and combustion in air led to 15 and 0% char residue, respectively. The results indicated that the thermal stability of the RPUFs was better in nitrogen than in an air atmosphere. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
16.
预聚体法制备聚醚聚氨酯胶粘剂 总被引:3,自引:0,他引:3
以四氢呋喃-环氧丙烷共聚醚三醇、甲苯二异氰酸酯、1,4-丁二醇、白炭黑为原料,合成了聚醚预聚体,以四氢呋喃-环氧丙烷共聚醚三醇为固化剂,制备了双组分无溶剂聚氨酯胶粘剂。研究了硬段比例,NCO质量分数、白炭黑用量、预聚体贮存时间等因素对预聚体和胶粘剂性能的影响,测试了预聚体的粘度和NCO质量分数,以及胶粘剂固化物的力学性能,粘接强度。测试结果表明,将1,4-丁二醇(BG)和四氢呋喃-环氧丙烷共聚醚三醇(JF)的羟基摩尔比值控制在1.5,NCO质量分数控制在5.6%左右,白炭黑用量为10g,可以获得工艺性能和贮存性能良好的聚醚预聚体,与聚醚固化剂配制,可以获得比较高而且稳定的力学性能和粘接强度。 相似文献
17.
以聚醚多元醇、亲油性二元醇、有机磷阻燃剂10-(2,5-二羟基苯基)-10-氢-9-氧杂-10-膦杂菲-10-氧化物(DOPO-HQ) 、甲苯二异氰酸(TDI)等为原料制备了阻燃型聚氨酯吸油泡沫,并研究了DOPO-HQ用量对阻燃型聚氨酯泡沫的拉伸强度、吸油性能、阻燃性能的影响。结果表明,随着DOPO-HQ用量的增加,阻燃型聚氨酯泡沫的拉伸强度先增大后减小;吸油性能逐渐下降;随着阻燃剂DOPO-HQ的用量从0增加到12份(质量份,下同),阻燃型聚氨酯泡沫的极限氧指数由18.2 %提高到27.2 %,达到难燃级别。 相似文献
18.
This paper described the synthesis of four types of polyurethanes by using diisocyanato dicyclohexylmethane (H12MDI) as the hard segment and poly hexamethylene carbonate diol, polybutylene adipate diol, poly(hexamethylene diol/neopentyl glycol)-based copolyester diol, or poly hexamethylene diol/hexamethylene carbonate)-based copolyester/carbonate diol as the corresponding soft segment. The spectral analysis, thermal studies (differential scanning calorimetry and dynamic mechanical analysis), tensile strength-elongation relationship, and water vapor permeability of these samples were investigated. The results of these studies showed that the phase separation extent of the four types of polyurethanes displayed the following order: ESBA (polybutylene adipate-based polyurethane) > ECHH (co-polyester / carbonate-based polyurethane) > ESHN (copolyester diol-based polyurethane) > CAHC (polyhexamethylene carbonate-based polyurethane). The water vapor permeability of the cast films increased with the increase of the phase separation extent, in which the polyester-based polyurethane (sample ESBA) displayed the highest water vapor permeability. In terms of tensile strength-elongation property, the polycarbonate diol based polyurethane displayed higher tensile strength but lower elongation than polyester-based polyurethanes. 相似文献
19.
Cilâine Verônica Teixeira Yuri Alencar Marques Márcia Carvalho de Abreu Fantini Diomar da Rocha Santos Bittencourt Cristiano Luís Pinto Oliveira 《Journal of surfactants and detergents》2021,24(5):783-800
Solution behavior of two commercially used polyether glycols with poly(oxyethylene) (PEO)-poly(oxypropylene) (PPO)-poly(oxyethylene) (PEO) triblock composition—Diol (linear) and Triol (star-like)—was studied, concerning the concentration and temperature effects until the cloud point (CP). 2-(2-butoxyetoxy) ethanol (DB) increased their miscibility with water. The structural study was performed with 25% DB in water, which produced isotropic solutions at room temperature at all polymer concentrations. Micelle's formation was only observed above 40% of polymer, when reversed micelles were formed. The solvent nuclei of the reversed micelles increased with increasing polymer concentrations, caused by dehydration of the PPO chains, then decreased at further higher concentrations, with completely dehydrated hydrophobic chains. When CP is reached, the solvent nuclei are separated by large polymer domains, without phase separation. Neither ordered nor gel phase was formed, probably due to a combination of high miscibility and short hydrophobic segments. The study was performed by Small-Angle X-ray scattering (SAXS) and complemented by Fourier-transformed infrared spectroscopy (FTIR) and dynamic light scattering (DLS). The main contribution of this work is based on the fact that the knowledge of the solubility behavior of Diol and Triol, by changing the solvent or temperature, opens up new possibilities of their use to phase separation processes in industrial applications and delivery systems. Moreover, the elucidation of mechanisms of solubility allows for the design of novel polyether glycols with tailored solution behavior for efficient performance in its target use. All applications rely on their solution behavior and can be benefited from the present results. 相似文献
20.
The plasticization of poly(vinyl chloride) (PVC) by polyurethanes made from polycaprolactone (PCL) diol and p.p′-diphenylmethane diisocyanate (MDI) was investigated. By varying the PCL chain length and substituting with polyether chains such as poly(tetramethylene ether) (PTME) or poly(ethylene oxide) (PEO), also of various chain lengths, the efficiency of plasticization was changed. High urethane content, such as obtained with PCL-530/MDI, decreased the miscibility of the polyurethane and PVC. Plasticizing efficiency of the polyurethanes, as indicated by transparency, flexibility, and engineering properties of the blend, increased on increasing the initial PCL chain length. However, polyurethanes containing very high-molecular-weight PCL (e.g., PCL-3000) slowly crystallized from a 50:50 blend with PVC. PVC/polyurethane ratio also had a significant effect on crystallization, as indicated by the rapid crystallization of PCL-2000/MDI polyurethane when it exceeded 50 wt % in the blend. The transparency and flexiblity of 50:50 blends were lowered by systematically replacing PVC-miscible PCL-2000 segments in the polyurethane with PTME-2000, PEO-200, and PEO-1500 segments. The polyurethanes became highly immiscible in PVC beyond the limiting mole fraction replacements of 0.6 for PTME-2000, 0.8 for PEO-200, and 0.4 for PEO-1500. Such chemical modification gave controlled and temperature-dependent miscibility in PVC and consequently blends with broadened glass transitions and high damping properties over a wide temperature range. Decreased miscibility in the blend gradually decreased elongation at break and tensile strength, but increased the modulus. A general correlation of the viscoelastic and tensile properties of the 50:50 blends with the weight fraction, rather than mole fraction, of the PCL content in the polyurethane composition was found; replacement of PCL beyond a limiting weight fraction by polyethers and MDI produced PVC-immiscible polyurethane. These limiting weight fractions are 0.6, 0.5, and 0.4 with PTME-2000, PEO-200, and PEO-1500, respectively, which denotes the order of decreasing miscibility of these polyurethanes in PVC. Viscoelastic and engineering properties of the blend with a particular polyurethane could also be controlled by varying the PVC/polyurethane ratio. Many of these semimiscible blends showed evidence by lower critical solution temperature (LCST) behavior at about ?30°C, but complete cloud and point curves were not constructed. 相似文献