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。     

高性能混炼型聚氨酯

为了探索聚氨酯的特性,通过对高性能混炼型聚氨酯的性能、配合、加工及应用的研究,发现混炼型聚氨酯具有优异的机械性能、耐油性及气密性,适用于制备密封件、膜片、胶管、胶辊覆盖层及各种胶带。     

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。     

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%.     

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.     

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.     

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.     

聚氨酯改性聚硫橡胶的合成研究

采用二异氰酸酯和低聚多元醇为原料合成预聚物,通过巯基与预聚物的异氰酸酯基反应将聚氨酯链段引入到聚硫橡胶的骨架中,制得聚氨酯改性聚硫橡胶。研究了反应溶剂、催化剂、原料、反应时间及反应温度等因素对改性聚氨酯性能的影响。改性聚硫橡胶的最佳反应条件:所选溶剂为邻苯二甲酸丁苄酯,质量分数为30%～50%;催化剂为对甲苯磺酸,质量分数为0.1%～1.0%;反应温度为(80±5)℃,反应时间为10 h。将制成的改性聚硫橡胶按特定配方制成密封胶,使用效果良好。     

Hygroscopic-aging behavior of pure and NaCl-filled polyurethane rubber

The aging phenomenon of highly filled rubber in humid environment was investigated. HTPBD was reacted with MDI and mixed with salt at the same time. The mixture was then hot-pressed for 24 h at 90°C to prepare the sample. The changes in mechanical properties and glass transition temperature of the sample were followed when they were subjected to different humidity at 30°C for 7 days. Furthermore, the effects of humidity on chemical structures were studied with IR. The results showed that unfilled rubber suffered no changes in mechanical properties after 7 days in environment of high humidity (RH 97). However, for NaCl-Filled rubber, its strength decreased because of a loss of stiffness of salt after salt deliquesced. The glass transition temperature of unfilled rubber seems not to be affected by various humid conditions, but the T_g of filled rubber decreased slightly. From SEM pictures, we observed that interior holes were left after salt deliquesced. This was the main cause for the reduction in mechanical properties of filled rubber.     

Adhesion between polyurethane coating and EPDM rubber compound

The effect of the bulk modification of the EPDM rubber compound on the adhesion performance with polyurethane coating (PU) was studied. Ethylene propylene diene monomer (EPDM) was bulk modified using maleated EPDM, polynorbornene (PNR) or different curatives to improve adhesion to polyurethane coating. The coating–rubber composite adhesion performance was examined by peel, crack and abrasion tests followed by microscopic investigation of fracture surfaces and their chemical nature. The adhesion between the coating and the rubber substrate was improved using maleated EPDM or PNR, as well as different curing systems. The crack stress for the delamination of the polyurethane coating from the flexible bulk-modified rubber surface follows the trend: maleated EPDM > PNR > different curing systems > control.     

Thermoplastic elastomers-based natural rubber and thermoplastic polyurethane blends

Thermoplastic elastomers based on the blends of thermoplastic polyurethane (TPU) and natural rubber were prepared by a simple blend technique. The influence of the two different types of natural rubber (i.e., unmodified natural rubber (NR) and epoxidized natural rubber (ENR)) on properties of the blends was investigated. The main aim of this study was to improve heat resistance and damping properties, and also to prepare the TPU material with low hardness by blending with various amounts of natural rubber. It was found that the TPU/ENR blends exhibited superior modulus, hardness, shear viscosity, stress relaxation behavior and heat-resistant properties compared to the blends with TPU and unmodified NR. This was attributed to higher chemical interaction between the polar functional groups of ENR and TPU by improving the interfacial adhesion. It was also found that the ENR/TPU blends exhibited finer grain morphology than the blends with unmodified NR. Furthermore, lower tension set, damping factor (Tan ??) and hardness, but higher degradation temperature, were observed in natural rubber/TPU blends compared to pure TPU. This proves the formation of TPU material with high heat resistance, low hardness and better damping properties. However, the blends with higher proportion of natural rubber exhibited lower tensile strength and elongation at break.     

聚氨酯橡胶密封件在煤矿设备上的应用

通过实际数据及应用情况，阐述了在煤矿设备上使用聚氨酯橡胶密封件替代丁腈橡胶密封件具有很好的综合效益及经济效益。