影响混炼型聚氨酯橡胶性能的因素

介绍混炼型聚氨酯(MPU)橡胶的研究现状,讨论影响MPU橡胶性能的因素。与聚醚型MPU橡胶相比,聚酯型MPU橡胶的耐低温性能好,耐光性能稳定,耐磨性能优异,添加水解稳定剂后耐水性能大大提高。与硫黄硫化的MPU橡胶相比,硫化剂DCP硫化的MPU橡胶压缩永久变形较小。温度升高,MPU橡胶的物理性能、耐老化性能、耐水性能和耐湿性能均下降。添加增塑剂后MPU橡胶的物理性能和耐磨性能下降,耐低温性能改善。     

混炼型聚氨酯橡胶的稳定性

混炼型聚氨酯橡胶是由聚酯或聚醚多元醇、芳香族或脂肪族二异氰酸酯、扩链剂制备而成。聚氨酯橡胶与其他聚氨酯产品相比,具有橡胶的特性,因此聚氨酯橡胶同样需要填料、增塑剂和硫化剂来制备性能合适的聚氨酯产品。聚氨酯橡胶需在通用的橡胶加工设备上加工操作。由混炼型聚氨酯橡胶制作的产品应用在有许多苛刻要求的场所,     

化学结构对混炼型聚氨酯橡胶力学性能的影响

介绍了混炼型聚氨酯橡胶的分类、性能和应用,讨论了化学结构对聚氨酯橡胶力学性能的影响,化学结构包括聚酯结构(聚己二酸酯二醇、聚己内酯二醇),硫化剂(过氧化物、硫黄、异氰酸酯)和补强剂(炭黑、白炭黑)等。表明硫化体系是影响混炼型聚氨酯橡胶力学性能的主要因素之一。     

混炼型耐磨聚氨酯橡胶的配方设计

进行混炼型耐磨聚氨酯橡胶的配方设计。结果表明,采用聚醚型聚氨酯橡胶UR101为主体材料,加入20份炭黑N220或气相法白炭黑,添加适当的硅烷偶联剂、防老剂和碳纳米管等,可得到综合性能良好的硫化胶,其DIN磨耗量可低至30～40 mm^3。     

混炼型聚氨酯橡胶的稳定

混炼型聚氨酯橡胶由聚酯或聚醚多元醇、芳族或肪族二异酸酯以及扩链剂合成。与其他氨基甲酸酯相比,聚氨酯(PU)橡胶的氰酸指数低,所以其具有橡胶性能。这些聚氨酯橡胶需配入填料、增塑剂和硫化剂,以制备适当的聚氨酯部件。PU橡胶必须在标准橡胶加工设备上加工。混炼型聚氨酯制品     

过氧化物硫化聚醚型聚氨酯混炼橡胶力学性能的研究

研究了过氧化物过氧化二异丙苯（DCP）、双叔丁基过氧化异丙基苯（BIPB）和补强剂（炭黑或白炭黑）对聚醚型聚氨酯混炼橡胶力学性能的影响,讨论了DCP和补强剂用量变化及不同硫化条件对混炼橡胶力学性能的影响。结果表明,DCP硫化混炼胶定伸应力高,永久变形小;BIPB硫化混炼胶硬度和强度高;当DCP用量在1．6份时,混炼胶拉伸强度和撕裂强度最高;提高补强剂用量,混炼胶硬度和定伸应力增加,拉伸强度变化不明显,但永久变形变大。     

聚酯型聚氨酯浇注橡胶

五十年代由联邦德国拜耳(Beyer)公司首先研制的聚酯型聚氨酯浇注橡胶,于六十年代获得迅速发展,山西省化工研究所七十年代初研制成功了这种橡胶,这种材料经不断改进,使用范围不断扩大,先后在国内十多个生产厂家推广。     

混炼型聚氨酯橡胶的加工成型

本文详细地介绍了混炼型聚氨酯橡胶所使用的原材料及生产方法。重点阐述了用硫黄、过氧化物和异氰酸酯三种硫化体系进行硫化的方法以及采用上述硫化体系的胶料所适用的几种模压工艺，简要介绍了用三种硫化体系生产的混炼型聚氨酯橡胶的物理性能。     

透明混炼型聚氨酯橡胶的研究

研究了硫化体系、填充剂品种和用量、硫化时间、硫化温度、防水剂以及模具表面光洁度对混炼型聚氨酯橡胶透明度的影响。结果表明,采用硫化剂２,５二甲基２,５叔丁基过氧化己烷、４＃气相法白炭黑和表面光洁的模具,可制得邵尔Ａ型硬度为５０～９０度的透明聚氨酯橡胶     

混炼型聚氨酯橡胶/聚十二内酰胺热塑性硫化胶动态硫化历程与性能

采用动态硫化方法制备了混炼型聚氨酯橡胶（MPU）/聚十二内酰胺（PA 12）热塑性硫化胶（TPV）,通过控制动态硫化时间探究了该TPV的动态硫化历程,同时研究了不同动态硫化阶段共混物的物理机械性能和动态力学性能。结果表明,随着动态硫化时间的延长,MPU/PA 12 TPV逐步完成相转变,在温度和剪切作用下,MPU相由连续相转变为分散相,而PA 12则由分散相转变为连续相;随着动态硫化时间的延长,MPU/PA 12共混物的储能模量升高,损耗模量降低,损耗因子减小。此外,随着动态硫化时间的延长,MPU/PA 12共混物的综合力学性能提高。     

Study on blending of millable polyurethane derived from castor oil with natural rubber

A millable polyurethane prepared from castor oil was blended with natural rubber in a two-roll mill and sulfur-cured. It was observed that blending of more than 50/50 (by weight) of the polyurethane with natural rubber was not feasible. Blends were found to have improved tensile modulus and abrasion resistance compared to pure natural rubber. Curing studies on the blends revealed that blending with urethanes enhanced the reversion resistance of natural rubber. The gel contents, measured by Soxhlet extraction using tetrahydrofuran, were above 90%.     

蓖麻油基双键封端聚氨酯预聚物/混炼型聚氨酯可降解密封材料的制备与性能

以蓖麻油、甲苯二异氰酸酯和甲基丙烯酸羟乙酯为原料制得双键封端聚氨酯预聚物(DTPUP),再将混炼型聚氨酯(MPU)与DTPUP、炭黑及其他橡胶助剂共混制备出新型可降解聚氨酯密封材料,研究了DTPUP用量对复合材料力学性能、降解行为及热稳定性的影响。结果表明,随着DTPUP用量的增加,复合材料的拉伸强度和扯断伸长率均先增大后减小,100%定伸应力、撕裂强度和邵尔A硬度均逐渐增大;复合材料在100℃清水中浸泡的降解效应随DTPUP用量的增加而减弱,当MPU与DTPUP质量共混比为70/30时,复合材料浸泡120 h后拉伸强度保持率最高可达16.1%;复合材料的初始分解温度、硬段和软段的最快分解速率对应的温度随着DTPUP用量的增加均有所提高,即其热稳定性得以改善。     

Rheological properties and thermal transitions in millable polyurethane fluoroelastomers

A series of segmented polyurethane fluoroelastomers based on dimethylol‐terminated perfluoropolyethers (PFPEs), aliphatic diisocyanates and allyl functionality is presented. Depending on the type of diisocyanate monomer used, it was found that quite different prepolymer molecular weights were achieved. Thermal analysis by differential scanning calorimetry showed formation of polyphasic copolymers, either amorphous or semi‐crystalline depending on the monomer structure. Rheological measurements showed that much higher zero‐shear viscosity, a shorter Newtonian plateau and more marked shear thinning behaviour were achieved with polyurethanes based on hexamethylene diisocyanate (HDI) or H₁₂‐MDI monomers. Isothermal viscosity curves were fitted with either three‐ or two‐parameter empirical models, and relaxation times of the structures were estimated at the temperature of 120 °C. Copyright © 2004 Society of Chemical Industry     

Effect of nAl(OH)3 on thermal, mechanical and morphological properties of millable polyurethane (MPU) rubber

Aluminium hydroxide nanoparticles [nAl(OH)₃] were synthesized using continuous ultrasonic cavitation technique. The size and shape of synthesized nanoparticles were confirmed using X-ray diffraction and transmission electron microscopy, which was found to be ~55 nm in diameter with needle shape. Millable polyurethane (MPU) rubber nanocomposites were prepared with nAl(OH)₃ as a filler (0.5–2.5 wt% loading) using two-roll mill and moulded on compression moulding machine. Dicumyl peroxide was used as a curing agent. Mechanical property and abrasion resistance was determined using universal testing machine (UTM) and abrasion resistance tester, respectively. Physical (hardness and swelling index) and thermal (flammability and stability) properties were also studied on shore A hardness tester, flammability tester and thermo gravimetric analyzer, respectively. The extent of dispersion of nAl(OH)₃ in MPU matrix was studied using scanning electron microscope (SEM) and atomic force microscope (AFM). MPU rubber:nAl(OH)₃ nanocomposites show improved mechanical, physical and thermal properties compared to pristine MPU composite. This dramatic improvement in properties was due to very small grain size of nAl(OH)₃, which facilitates uniform dispersion of nanoparticles within the chains of MPU rubber. This improvement in properties were up to 2 wt% and decreases subsequently (2.5 wt%) due to agglomeration. nAl(OH)₃ behaves like an ordinary filler at higher wt% loading.     

Effect of crosslinking agents on the structure and properties of polyurethane millable elastomer composites

A study of the effect of crosslinking agents on the structure and properties of the millable polyurethane (PU) elastomer is reported here. Effects of the conventionally used dicumyl peroxide (DCP) and tolylene disocyanate dimer (TDID) on the curing characteristics, mechanical properties, and relative thermal stabilities of the PU composites have been compared. Use of X-ray diffraction as a supportive evidence helps in understanding the nature of crosslinking. The mixture of DCP and TDID is also evaluated as crosslinking agents. A dramatic improvement in the mechanical properties and thermal stability is observed because of the mixed type of crosslinking obtained by the combined use of DCP and TDID. Effect of carbon black loading shows an increase in the mechanical strength with a decrease in the elongation. The results obtained from various properties measurements have been satisfactorily explained with a general model of crosslinking.     

Studies on effect of ethyl 4-amino cinnamate functionalized multiwall carbon nanotubes (f-MWCNTs) on properties of millable polyurethane rubber (MPU) nanocomposites

Multiwall carbon nanotubes (MWCNTs) were prepared using chemical vapor deposition (CVD) technique in presence of nano Co/Mo-MgO as an efficient catalyst. Further the as-synthesized MWCNTs were functionalized using ethyl 4-amino cinnamate (f-MWCNTs) to improve its wettability or compatibility with the chains of polymer. The as-synthesized MWCNTs and f-MWCNTs were subjected to various characterization techniques Raman spectroscopy, X-ray diffraction, FTIR, FESEM and TGA to investigate its size, presence of functional groups and stability. It was observed that diameter of f-MWCNTs were found to be ~ 45 nm with thermally more stable. Further, f-MWCNTs (0 to 1 %) were reinforced in MPU rubber using two roll mill and molded on compression molding machine. The dumbbell shape specimens were then subjected to mechanical and thermal study. It was observed that both the tensile strength and % elongation at break of MPU nanocomposites increases significantly up to 0.8 wt loading and decreases thereafter. This improvement in properties was due to uniform dispersion of f-MWCNTs into the chains of MPU rubber with homogeneity in bonding, while the decrement in properties at 1wt % loading was due to agglomeration of f-MWCNTs at some places. Also the functionalization using ethyl 4-amino cinnamate increases the compatibility of MWCNTs with MPU rubber chains. Besides this, functionalization makes the surface of MWCNTs smooth with enhancement in bonding between the two surfaces that is filler as well as matrix counterpart. Significant improvement in mechanical and thermal properties are achieved due to modification MPU with functionalized MWCNT.     

Exploring the effect of electron beam on swelling,gel fraction,mechanical and thermal properties of ethylene acrylic elastomer/millable polyurethane rubber blends

ABSTRACT

Ethylene acrylic elastomers (AEM) and millable polyurethane (MPU) blend have been prepared successfully using dicumyl peroxide (DCP) system and the blend ratio is optimised on the basis of the tensile results. The optimised unvulcanised blend ratio (60:40) is subjected to different electron beam (EB) dose to obtain uniform three dimensional crosslinking networks. The characteristic shifting of?=?CO vibration in the Fourier-Transform Infrared spectra confirms the formation of hydrogen bonding between the two phases. The phase morphology of the two phases in the optimised blend has been captured in SEM and the results show the successful integration of MPU in AEM phase. It is found that the swelling of the irradiated blend decreases with increase in EB dose, whereas the increase in gel fraction and the crosslink density is due to the irradiation-induced crosslinking. The thermal stability of the irradiated blend has been improved in compression to the pristine form of individual phase.     

Preparation and characterization of carbonyl iron powder/millable polyurethane elastomer microwave absorbing patch

A microwave absorbing patch (MAP) was prepared by compounding millable polyurethane elastomer (MPU) and carbonyl iron powder (CIP). Surfaces of CIP were modified using silane coupling agents (SCA). The effects of different types and amounts of SCA, the amount of vulcanizing agent and the amount of CIP on the microstructure and mechanical properties were investigated. SCA was found to improve the interface compatibility between MPU and CIP and also reinforced the mechanical properties of MAP. The KH550 was the best modifier, and the optimal dosage of KH550 was 2% of the mass of CIP based on a comparison of tensile properties. The optimal dosage of the vulcanizing agent DDPH was 3% of the mass of MPU. However, a large number of CIP could be filled into MPU. The maximum filling content of CIP increased with the increasing Mooney viscosity of MPU, and the maximum filling content of CIP was 1200% of the mass of MPU. The electromagnetic parameters and reflection loss of MPU absorbers and MPU filled with CIP absorbers were measured in the 1–18 GHz frequency range. The absorbers of MPU filled with CIP had excellent microwave absorbing properties compared with the absorbers of MPU. POLYM. COMPOS., 35:1318–1324, 2014. © 2013 Society of Plastics Engineers     

Modified rubber seed oil based polyurethane foams

In this work, rubber seed oil (RSO) was extracted with cyclohexane at room temperature for 24 h. The yield of RSO was about 40 %. The RSO was purified by using sodium hydroxide to eliminate some free fatty acids. Then the RSO was modified by simultaneous epoxidation and hydroxylation. Hydroxylated RSO (HRSO) had the hydroxylation extents 120 and 230 mgKOH/g with 2 h and 4 h reaction times, respectively. The chemical structures of the oils were studied by FT-IR and ¹H-NMR, and they were characterized also in other ways. Polyurethane foam samples based on the HRSOs were successfully prepared, and their physico-mechanical and thermal properties were also studied, with varied NCO index and water content in the formulations. The PUF230 had better thermal stability and compressive strength but lower density than the PUF120. Both the NCO index and the water content had large effects on density, cell size, and compressive strength of the polyurethane foams.