HPVC与丁腈橡胶共混交联物的分子模拟

采用分子模拟方法,研究了高聚合度聚氯乙烯（HPVC）／丁腈橡胶（NBR）交联共混物的结构。结果发现,NBR呈分散相分散在连续相HPVC中,分散状态与两相的比例无关;共混物交联后形成了网络结构,致使材料力学性能提高。     

HPVC/NBR共混物力学性能的分子模拟的研究

采用分子模拟与实验现象相结合的方法,对高聚合度聚氯乙烯(HPVC)与增塑剂,HPVC/丁腈橡胶(NBR)共混物的力学性能进行了模拟研究。结果发现:偏苯三酸三辛酯(TOTM)增塑的HPVC具有较高的拉伸强度和硬度,邻苯二甲酸二辛酯(DOP)比对苯二甲酸二辛酯(DOTP)增塑的HPVC具有较高的拉伸强度,而DOTP增塑的HPVC具有高的断裂伸长率和较小的永久变形;在HPVC/NBR共混体系中,NBR用量增加,邵氏硬度、拉伸强度以及压缩永久变形将降低,断裂伸长率先增加后降低。共混物交联后,材料的拉伸强度增加,其断裂伸长率和压缩永久变形将降低,硬度略有增加。     

HPVC/BR共混体系的性能研究

采用动态硫化方法制备高聚合度聚氯乙烯／顺丁橡胶(HPVC／BR)共混型热塑性弹性体，考察了单一组分增容剂丁腈橡胶(NBR)、氯化聚乙烯(PE—C)和(氢化苯乙烯／丁二烯／苯乙烯)嵌段共聚物(SEBS)，复合增容剂SEBS／NBR和PE—C／NBR及交联程度对HPVC／BR共温体系相容性的影响。结果表明，使用复合增容剂可明显改善HPVC／BR共混物的性能；动态硫化在改善共混物力学性能方面起主要作用。     

HPVC／NBR合金的制备与研究

本文研究国产高聚合度聚氯乙烯(HPVC)与丁腈橡胶(NBR)共混制备非交联型HPVC/NBR合金。结果表明:当共混比HPVC/NBR=35/65,超细CaCO_340份,白炭黑10份,轻质CaCO_3 25份,其它助剂适量,共混温度150～180℃时,可得到性能良好的HPVC/NBR合金且动态力学数据表明,该共混体系具有较好的相容性。     

丙烯腈含量对NBR/TPU共混物性能的影响

采用熔融共混的方法制备了丙烯腈含量不同的丁腈橡胶(NBR)和热塑性聚氨酯(TPU)的复合材料,探究了丙烯腈含量和填料对NBR/TPU共混物的物理机械性能及阻尼性能的影响.结果表明,随着丙烯腈含量增加,NBR/TPU共混物的拉伸强度和扯断伸长率明显提高,硬度略有增加;NBR/TPU共混物的玻璃化转变温度(Tg)向室温移动...     

NBR/PVC共混物的共混工艺和性能

介绍NBR／PVC共混物的共混工艺和性能。NBR／PVC共混物共混工艺主要有乳液共沉法和机械共混法，其中乳液共沉法共混物性能较好，机械共混法操作简单、成本较低。影响共混物性能的因素主要有NBR的门尼粘度和丙烯腈含量、PVC品种、NBR／PVC共混比、共混温度以及PVC在共混物中的分散程度等。     

橡胶/树脂共混物复合阻尼材料的研究

将三元乙丙橡胶/石油树脂(EPDM/PR)共混物和丁腈橡胶/酚醛树脂(NBR/PF)共混物共混制得新共混物。动态力学分析(DMA)表明,EPDM/PR共混物和NBR/PF共混物在室温附近均有较好阻尼性能,但有效阻尼温域较窄;当两者共混比为50∶50时,新共混物阻尼温域可拓宽至100℃(-17.2℃～83.5℃);改变两者中橡胶与树脂的比例并保持50∶50的共混比不变,新共混物的阻尼行为会发生改变;改变丙烯腈含量,NBR极性随之变化,新共混物的相容性发生变化,阻尼性能受到影响;当丙烯腈质量分数为40%并保持50∶50的共混比不变时,新共混物的阻尼温域可达到127.8℃。     

HPVC/NBR并用透明鞋底的研制

研究了采用高聚合度聚氯乙烯(HPVC)与丁腈橡胶(NBR)并用制造透明鞋底的过程,讨论了材料折光率、稳定剂、HPVC/NBR并用比、补强剂和硫化体系等因素对鞋底的透明性和力学性能的影响。实验结果表明:选择共混比HPVC/NBR=70/30(质量比)、TS_3白炭黑30份、超细CaCO_3 3～5份及适量助剂.可制得透明性和力学性能较好的耐油透明鞋底;含铅类稳定剂不能在硫黄硫化的HPVC/NBR透明鞋底中使用;硫化体系对透明鞋底的力学性能影响不大。     

丁腈橡胶增容丁苯橡胶/聚氯乙烯共混体系

采用一系列结合丙烯腈质量分数不同的丁腈橡胶(NBR)作为丁苯橡胶(SBR)／聚氯乙烯(PVC)不相容共混物的增容剂,研究了SBR／PVC／NBR硫化胶的力学性能,并用扫描电子显微镜、傅里叶变换红外光谱仪和动态黏弹仪研究了该硫化胶的形态结构与相容性。结果表明,结合丙烯腈质量分数为20％～26％的NBR是SBR／PVC的优良增容剂,可提高共混物的力学性能,使SBR相和PVC相达到微细均匀化分散,并在两相之间形成了界面层,使得增容效果达到最佳。     

NBR/HPVC热塑性弹性体的性能研究Ⅱ

选用丁腈橡胶(NBR)和高聚合度聚氯乙烯(HPVC)为主体材料,用动态硫化法制备了一类性能优异的材料—丁腈橡胶/高聚合度聚氯乙烯共混型热塑性弹性体(TPE),研究了共混方法,硫化温度,硫化体系,硫化剂用量,硫化时间等因素对动态硫化NBR/HPVC热塑性弹性体力学性能的影响。     

HPVC/SBR共混体系相容性的研究

采用动态硫化方法制备高聚合度聚氯乙烯（ＨＰＶＣ）／ＳＢＲ共混型热塑性弹性体,考察了单一组分相容剂「相容剂分别为ＮＢＲ２７０、ＮＢＲ Ｐ６５、ＣＰＥ和氢化苯乙烯－丁二烯、苯乙烯嵌段共聚物（ＳＥＢＳ）」、复合相容剂（ＳＥＢＳ／ＮＢＲ和ＣＰＥ／ＮＢＲ）及交联程度对ＨＰＶＣ／ＳＢＲ共混体系相容性的影响。结果表明,使用复合相容剂可明显改善ＨＰＶＣ／ＳＢＲ共混物的性能;动态硫化在改善共混物力学性能方面起主要作     

Study on compatibilization-crosslinking synergism in PVC/LDPE blends

Influences of nitrile rubber (NBR, acrylonitrile content 33.5 – 36.5 wt.-%) on the structure and mechanical properties of poly(vinyl chloride) (PVC)/low density polyethylene (LDPE) blends and its synergism with crosslinking agent have been studied. The addition of NBR to the blend is accompanied by a decrease in domain size and improvements in mechanical properties of the blend. When dicumyl peroxide (DCP) is added to the blend together with NBR, good synergism is caused and mechanical properties will improve dramatically. It is concluded that NBR can promote the phase dispersion of PVC and LDPE and their interfacial adhesion. Then, the probability of DCP existing at the interface will increase and more co-crosslinked products will form. Therefore, compatibilization and crosslinking are both exerted sufficiently.     

Transition of phase continuity induced by crosslinking and interfacial reaction during reactive processing of compatibilized PVC/SBR blends

Blends of 50 wt% of poly(vinyl chloride) (PVC) and 40 wt% of styrene butadiene rubber (SBR) with 10 wt% of acrylonitrile butadiene rubber (NBR) as the compatibilizer were prepared in a Haake mixer. An inversion of phase continuity was observed when the sulfur concentration was changed from 0.0 to 2.0 parts per hundred parts of resins (phr) in the blends containing an NBR with an acrylonitrile content of 29.5 wt% (NBR-29). The SBR phase, which is continuous in the unvulcanized blend, changes progressively into the dispersed phase as sulfur concentration increases. This is explained by the viscosity increase of the rubber caused by crosslinking. There is no phase inversion as a result of increasing sulfur concentration when the compatibilizer NBR-29 was replaced by an NBR with an acrylonitrile content of 40 wt% (NBR-40). The SBR phase is discrete in the unvulcanized blend with NBR-40 as the compatibilizer.

A change in phase continuity occurs during processing of the vulcanized PVC/NBR-29/SBR (50/10/40) blends. A torque peak in the torque curve during processing is correlated to the transition of the PVC phase continuity. There is a gradual increase in the torque curve after the torque peak. The rubber particle size decreases as a result of such a post-peak increase in the torque. The torque peak and the post-peak increase in the torque are absent in the case of the binary blends (PVC/NBR and PVC/SBR). The post-peak increase in the torque is attributed to the interfacial reaction between SBR and NBR that resides in the PVC phase.

A novel method developed recently was applied to study the interface development during processing. An interface with a higher rubber concentration develops during processing of the compatibilized blends.     

Thermal properties and morphology of isotactic polypropylene/acrylonitrile–butadiene rubber blends in the presence and absence of a nanoclay

A thermoplastic elastomer (TPE) nanocomposite based on polypropylene (PP), acrylonitrile–butadiene rubber (NBR), and a nanoclay (NC) was prepared in a laboratory mixer with a 54/40/6 weight ratio. The effects of NC on the thermal properties, crystalline structure, and phase morphology of the TPE nanocomposite were studied in this work. The results obtained from the nonisothermal crystallization of PP, PP/NBR, and PP/NBR/NC, which was carried out with differential scanning calorimetry, revealed that the overall rate of crystallization of PP decreased with the addition of NBR to PP and increased when NC was incorporated into the nanocomposite. In addition, the crystallite size distribution was more uniform for the PP phase crystallized in the nanocomposite versus the PP itself. Also, although the PP in the reference blend (PP/NBR) crystallized only in the α form, the crystalline structure of the PP incorporated into the nanocomposite was a mixture of α‐ and γ‐crystalline forms. The effects of NC on the phase morphology of PP/NBR blends prepared with three different cooling methods (quenching in liquid nitrogen, cooling between two metal plates at room temperature, and molding at a high temperature in a hot press) were studied. For the samples quenched in liquid nitrogen or cooled between metal plates, a particulate–cocontinuous morphology formed. However, for the samples prepared under a hot press, a laminar‐like morphology was observed. In all three cases, a similar particulate–cocontinuous morphology formed for the reference blend, but the rubber inclusions were always smaller than those of the TPE nanocomposite. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

High density polyethylene/acrylonitrile butadiene rubber blends: Morphology,mechanical properties,and compatibilization

Polymer blends based on high-density polyethylene (HDPE) and acrylonitrile butadiene rubber (NBR) were prepared by a melt blending technique. The mixing parameters such as temperature, time, and speed of mixing were varied to obtain a wide range of properties. The mixing parameters were optimized by evaluating the mechanical properties of the blend over a wide range of mixing conditions. The morphology of the blend indicated a two-phase structure in which NBR phase was dispersed as domains up to 50% of its concentration in the continuous HDPE matrix. However, 70 : 30 NBR/HDPE showed a cocontinuous morphology. The tensile strength, elongation at break, and hardness of the system were measured as a function of blend compostion. As the polymer pair is incompatible, technological compatibilization was sought by the addition of maleic-modified polyethylene (MAPE) and phenolic-modified polyethylene (PhPE). The interfacial activity of MAPE and PhPE was studied as a function of compatibilizer concentration by following the morphology of the blend using scanning electron micrographs. Domain size of the dispersed phase showed a sharp decrease by the addition of small amounts of compatibilizers followed by a leveling off at higher concentrations. Also, more uniformity in the distribution of the dispersed phase was observed in compatibilized systems. The tensile strength of the compatibilized systems showed improvement. The mechanical property improvement, and finer and uniform morphology, of compatibilized systems were correlated with the improved interfacial condition of the compatibilized blends. The experimental results were compared with the current theories of Noolandi and Hong. © 1995 John Wiley & Sons, Inc.     

Effect of rubber content on morphology and thermal and rheological behaviors of acrylonitrile-butadiene rubber/poly(ethylene-co-vinyl acetate)/organoclay nanocomposites

Thermoplastic elastomer nanocomposites based on acrylonitrile butadiene rubber (NBR) and poly(ethylene-co-vinyl acetate) (EVA) with different weight ratios (20, 40 and 60 wt% of NBR) and 5 wt% of organocaly (OC) were prepared in an internal mixer. The results obtained from X-ray diffraction and transmission electron microscopy (TEM) micrographs showed that due to the OC–EVA interaction, nearly all of the clay platelets were exfoliated. Scanning electron microscope (SEM) was used to investigate the particle size and phase morphology. SEM images for the unfilled blends revealed a two-phase structure in which the NBR domains were dispersed into the EVA phase. However, for the blend containing 60 wt.% of NBR, a co-continuous morphology was exhibited. The addition of OC decreased the NBR domain size significantly in which NBR remained as a dispersed phase even for the blend having the highest amount of NBR studied. Young's modulus and yield stress increased, but elongation at break and stress at break decreased for the nanocomposites in comparison with that of the unfilled materials. Thermal studies indicated that although OC decreased the degree of crystallinity and crystallization temperature of EVA slightly, it showed no effect on EVA melting temperature in comparison with that of the unfilled samples. It was also found that the nanocomposites behaved as shear thinning fluids over the entire range of angular frequency and the values of storage modulus and stress relaxation modulus of the nanocomposite containing 20 wt% of NBR was even higher than that of the NBR alone.     

Morphology and dynamic mechanical properties of natural rubber/nitrile rubber blends containing trans‐polyoctylene rubber as a compatibilizer

The use of trans‐polyoctylene rubber (TOR) as a compatibilizer for blends of natural rubber (NR) and acrylonitrile‐butadiene rubber (NBR) was investigated using atomic force microscopy (AFM) and dynamic mechanical analysis (DMA). The NR/NBR blends containing varying proportions of TOR were prepared in an internal mixer. AFM micrographs of NR/NBR blend at 50/50 (w/w) composition showed heterogeneous phase morphology with NR as a matrix and NBR as a dispersed phase. Inclusion of TOR in the NR/NBR blend altered the phase morphology by reducing the size of the NBR phase. DMA of NR/NBR/TOR showed reduction in tan δ peak height of NBR and an increase in storage modulus E′ in the rubbery region for the NR/NBR blends. A comparison of the E′ obtained from experimental data with that from theoretical models was made to deduce the location of TOR in the blend. Based on the fittings of calculated and experimental values of E′, it was inferred that TOR was incorporated into the NR phase at lower proportion as well as at the interfacial region at higher proportion. The Cole–Cole plot illustrated the compatibilizing effect of TOR. Copyright © 2004 Society of Chemical Industry