Effect of rubbers on the flame retardancy of EVA/ultrafine fully vulcanized powdered rubber/nanomagnesium hydroxide ternary composites

Two flame retardant ternary composites of ethylene‐vinyl acetate copolymer (EVA)/ultrafine fully vulcanized powdered rubber (UFPR)/nanomagnesium hydroxide (MH) were studied in this article. It has been found that carboxyl acrylonitrile butadiene UFPR (CNB‐UFPR) and acrylonitrile butadiene UFPR (NB‐UFPR) have different effect on the flame retardancy of related materials when they are used together with nano‐MH. CNB‐UFPR is in favor of lowering the material's heat release rate during its combustion, while NB‐UFPR benefits the material on the resistance to ignition. Observation on the microstructure of the composites by transmission electron micrograph revealed that the aforementioned two ternary composites have quite different morphology. EVA/CNB‐UFPR/nano‐MH composite exhibits partial encapsulation structure, while EVA/NB‐UFPR/nano‐MH composite has full separation structure. POLYM. COMPOS., 28:479–483, 2007. © 2007 Society of Plastics Engineers     

Impact behavior and fracture morphology of acrylonitrile–butadiene–styrene resins toughened by linear random styrene–isoprene–butadiene rubber

A novel toughening modifier, styrene–isoprene–butadiene rubber (SIBR), was used to improve the impact resistance and toughness of acrylonitrile–butadiene–styrene (ABS) resin via bulk polymerization. For comparison, two kinds of ABS samples were prepared: ABS‐1 was toughened by a conventional modifier (a low‐cis polybutadiene rubber/styrene–butadiene block copolymer), and ABS‐2 was toughened by SIBR. The mechanical properties, microstructures of the as‐prepared materials, and fracture surface morphology of the specimens after impact were studied by instrumented notched Izod impact tests and tensile tests, transmission electron microscopy, and scanning electron microscopy, respectively. The mechanical test results show that ABS‐2 had a much higher impact strength and elongation at break than ABS‐1. The microscopic results suggested that fracture resistance of ABS‐1 only depended on voids, shear yielding, and few crazing, which resulted in less ductile fracture behavior. Compared with ABS‐1, ABS toughened by linear random SIBR (ABS‐2) displayed the synergistic toughening effect of crazing and shear yielding, which could absorb and dissipate massive energy, and presented high ductile fracture behavior. These results were also confirmed by instrumented impact tests. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

高冲击玻纤增强聚丙烯的研制与应用

利用玻璃纤维、SBS橡胶和高密度聚乙烯增韧聚丙烯。增韧后的聚丙烯冲击强度是只用玻纤增强的2倍以上,而其它性能影响较小。     

SBS nanocomposites as toughening agent for polypropylene

The toughening of polypropylene [PP] with styrene–butadiene–styrene rubber [SBS]/montmorillonite [MMT] nanocomposites was investigated with respect to morphological, thermal, and mechanical properties. The MMT/SBS nanocomposites were prepared in an internal mixer, using an epoxidized SBS [SBSe] to investigate its effect as a compatibilizer. The MMT/SBS nanocomposite was added to PP up to 10 wt%, aiming at material toughening. Transmission electron microscopy (TEM) revealed MMT induced dispersed-phase reductions when compared to typical PP/SBS blends. In addition, changes in the PP crystallization process were observed in the presence of the nanocomposite. Surprisingly, the use of nanofiller, combined with SBSe compatibilizer agent, increased the PP impact strength by about 60%, with no reduction in the tensile module.     

Thermal properties and crystallization behavior of ultrafine fully‐vulcanized powdered rubber particle toughened polypropylene

Thermal properties and crystallization behavior of ultrafine fully‐vulcanized powdered rubber (UFPR) toughened polypropylene (PP) were studied by Differential scanning calorimetry (DSC) and Wide angle X‐ray diffraction (WAXD) measurements. It was found that the fraction of β‐form in the PP crystal increased at first, then sharply deceased up to zero with increasing UFPR content. This trend did not rely on isothermal crystallization temperature. Moreover, DSC measurements implied that UFPR particles addition affected both isothermal and nonisothermal crystallization behaviors, including the crystallization temperature and the half‐time of crystallization. Furthermore, WAXD test results indicated that the addition of UFPR induced the orientation of the crystallites more or less. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

橡胶增韧苯乙烯与马来酸酐共聚物的方法

对增韧无规苯乙烯/马来酸酐共聚物(SMA)的方法作了分类,并对国内外SMA研究方面的进展作了分析。可以认为,橡胶增韧无规SMA,无论从耐热、冲击性能,还是从价格/性能比而言,是一类值得开发的高分子材料。以不同品种橡胶(如乙丙橡胶、苯乙烯-丁二烯-苯乙烯和丁基橡胶等)作增韧剂,通过不同的增韧方法,可以达到不同的增韧效果,满足不同的需求。     

聚硫橡胶对环氧树脂固化动力学及力学强度的影响

用红外光谱分析了在环氧树脂中加入聚硫橡胶的固化及增韧过程,通过差示扫描量热法研究了增韧体系的反应动力学,探讨了聚硫橡胶用量对固化产物力学强度的影响,并对试样断口形貌进行了扫描电镜观察。结果表明,聚硫橡胶的加入降低了环氧树脂的表观活化能而没有改变反应级数,使得固化反应的总放热量减少、放热过程更加平均。聚硫橡胶对环氧树脂的增韧效果明显,二者通过化学键结合,韧性撕裂的冲击断面形貌验证了这种活性增韧。当聚硫橡胶用量为30份(质量)时,环氧树脂固化物的冲击强度可达到未增韧者的896%。     

Crystallization behavior and spherulite growth rate of isotactic polypropylene in isotactic polypropylene/natural rubber based thermoplastic elastomers

The melting and crystallization behavior of isotactic polypropylene/natural rubber (PP/NR) based thermoplastic elastomers (TPEs) were investigated using differential scanning calorimetry. The samples were scanned at a heating rate of 10°C/min under nitrogen atmosphere. The effects of blend ratio on the melting and crystallization characteristics of the blends were analyzed. Normalized crystallinity is unchanged by the addition of small amount of NR, but as the amount of rubber increases crystallinity increased for the 30/70 NR/PP and lowered for the 50/50 NR/PP blend system. Morphology of the blend was analyzed using scanning electron microscopy (SEM). Blend ratio showed a pronounced influence on the phase morphology of the NR/PP TPEs. As the amount of NR increases more than 50 wt % the system changes from dispersed to cocontinuous structure. Hot‐stage polarizing optical microscopy (POM) was used to study the radial growth of spherulite as a function of blend ratio, cooling rate, and crystallization temperature. Spherulite growth rate is marginally influenced by the rubber inclusions. The spherulite morphology observed under polarized optical microscopy is influenced by the blend morphology. It was found that for the cocontinuous 50/50 blend system, spherulites are much different from the usual appearance under polarized light. Attempts have been made to correlate the crystallization behavior with the morphology of the blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

ABS高胶粉对ABS/PET/SMA合金的增韧研究

采用ABS高胶粉(ABSHR)对丙烯腈-丁二烯-苯乙烯共聚物(ABS)/聚对苯二甲酸乙二醇酯(PET)/苯乙烯-g-马来酸酐(SMA)合金进行增韧改性;探讨了ABSHR对合金体系的力学性能、耐热性和流变性能的影响;同时采用扫描电镜(SEM)对其断面形态进行表征。研究结果表明:ABSHR可以显著提高ABS/PET/SMA合金的冲击强度和断裂伸长率。当ABSHR加入量为20份时,冲击强度从7.7kJ/m2提高到17.6kJ/m2,断裂伸长率从24.6%提高到60.2%;而体系的拉伸强度和弯曲强度有不同程度的降低;维卡软化温度随着ABSHR的增加而逐渐降低;ABSHR增韧体系的剪切黏度和假塑性均得到提高。未增韧的合金断面较平整;而增韧的合金断面产生大量橡胶撕裂带,并伴有应力发白现象。     

聚丙烯共混增韧研究进展

从塑料增韧聚丙烯（PP）体系，橡胶或热塑性弹性体增韧PP体系、PP／弹性体／塑料三元共混体系以及无机刚性粒子增韧PP体系4个方面详细论述了国内外PP共混增韧改性的研究进展。采用塑料类作为改性剂增专心PP，虽可增韧，但是由于体系的不相容性，往往要大量使用改性剂或添加相容剂。使用橡胶或者热塑性弹性体与PP共混增韧效果最为明显，但由于随着弹性体用量的增加，体系在冲击强度大幅度提高的同时也出现了刚性等性能的损失。PP弹性体／塑料三元共混体系可均衡改善力学性能及降低成本。此外，还就近年发展起来的无机刚性粒子增韧PP的研究工作进展和机理研究情况作了介绍。     

聚丙烯/超细丁苯胶粉/纳米碳酸钙三元复合材料的制备与性能

采用喷雾干燥方法得到丁苯橡胶／纳米碳酸钙复合粉末橡胶(RPS),探讨了RPS中苯甲酸钠用量以及丁苯橡胶与纳米碳酸钙质量比对聚丙烯(PP)力学性能、耐热性和结晶性能的影响。结果表明,苯甲酸钠最佳用量为丁苯橡胶和纳米碳酸钙总用量的10％;随着纳米碳酸钙用量的增加,体系中分散相粒径减小,结晶速率加快,材料的韧性、刚性和耐热性能提高。RPS对于不同熔体流动指数的PP具有不同的增韧增强效果。熔体流动指数越小,越有利于RPS在PP中的分散,体系韧性越高。此外。动态流变学研究表明,PP／RPS三元复合材料的熔体流变行为与纯PP类似,RPS的加入增加了PP的黏度．流动性能变差。     

端氨基丁腈橡胶增韧环氧-聚酰胺胶粘剂的研究

通过DSC,扫描电镜分析及剪切和剥离强度性能测试研究了端氨基液体丁腈橡胶(ATBN)改性环氧-聚酰胺体系的固化动力学,粘接性能及增韧相态。结果表明,根据Ellerstein法和峰值法计算得到的固化反应活化能分别为为73.6 kJ/mol和65.7 kJ/mol,体系最佳固化温度为41～97℃。固化体系中橡胶相粒径大小对胶粘剂性能有较大影响,60℃和室温固化体系分散相粒子平均粒径分别为1～2μm,0.5μm。粒径1～2μm时体系的增韧效果最佳,粘接性能优异。     

Synergistic effect of dual rubber system in toughening styrene maleic anhydride copolymers

Styrene maleic anhydride (SMA) copolymers were toughened by blending with two distinctly different rubber modifiers: styrene‐butadiene‐styrene (SBS) block copolymer and methacrylated butadiene‐styrene emulsion‐made graft copolymer (MBS). The modifiers were used both individually and in combination for the examination of their roles in toughening SMA. SMA was miscible with poly(methylmethacrylate) shell of MBS, whereas it was partially miscible with the polystyrene (PS) phase of SBS. When 40–50% of SBS was used in blends, the PS phase of SBS became immiscible with SMA. SBS did not improve the Izod impact strength of SMA appreciably. A prominent synergistic toughening effect was experimentally observed when SBS and MBS were used in combination in brittle SMA. This effect may be attributed to the fact that the large SBS particles initiate crazes and small MBS particles with good adhesion to SMA matrix improve the ligament thickness, which may play a critical role in craze growth and termination. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2260–2267, 2003     

Toughened polypropylene with balanced rigidity. IV. Morphology,crystallization behavior,and thermal properties

The morphology of toughened polypropylene with balanced rigidity (TRPP) was characterized by using transmission electron microscopy and polarizing light microscopy. The crystallization behavior and thermal properties were investigated by differential thermal analysis and thermogravimetric analysis. The PP component in the polymer blend was realized as the continuous phase and the elastomer component as the dispersed phase with a cellular structure (salami structure) containing some PP. The particles of the dispersed phase were small and regular. The cellular structure of the TRPPs resulted from the introduction of toughening master batches and was similar to the morphology of acrylonitrile‐butadiene‐styrene and high‐impact polystyrene synthesized by graft copolymerization. By gradually cooling from the melt, crystallization of TRPPs was nucleated heterogeneously and the crystallization temperature was slightly higher than that of PP whereas the crystallite size was remarkably reduced. For the samples with different compositions, the number, shape, and size of the cellular dispersed particles and the crystallite size were different. Considering the toughening theories and our experimental data, it was concluded that the samples with more regular and small cellular dispersed particles generally had better mechanical properties and the remarkably reduced crystallite size of PP was favorable for toughness improvement. The melting point, thermal oxidation temperature, and thermal oxidation onset temperature of the TRPPs were all a little lower than those of PP and the processability remained good. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1351–1358, 2001     

Morphology and properties of blends of polypropylene with ethylene-propylene rubber

Great attention has been paid to the toughening of isotactic polypropylene (PP) in recent years in order to make full use of this plastic. This paper presents the results of our study on the compatibility of PP with ethylene-propylene-diene rubber (EPT), polybutadiene rubber (PB) or styrene-butadiene rubber (SBR) through characterization of the blends' morphology, and on. the morphology and properties of binary blends of PP with EPT (EPT/PP) and ternary blends of PP, EPT, and polyethylene (PE) (EPT/PE/PP). Morphological structure of solution blends and the great improvement in low-temperature impact strength and other properties of the mechanical blends have shown the difference among EPT, PB, and SBR in compatibility with PP, the effectiveness of using EPT as PP's toughening agent, and the effect of EPT on EPT/PP blend as both toughening agent and compatibilizer. Addition of EPT to EPT/PP made interesting changes in morphology but no effect on properties was observed.     

磺酸钠基苯乙烯-丁二烯-苯乙烯嵌段共聚物离聚体的力学性能及其应用

由环氧化苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)与NaHSO3开环反应合成了磺酸钠基SBS离聚体。研究了离聚体力学性能的影响因素、离聚体对SBS/氯醇橡胶(CHR)的增容作用、质量比对离聚体/聚丙烯(PP)共混物性能的影响。结果表明:硬脂酸锌能提高离聚体的力学性能;随着离聚体离子含量的增加,拉伸强度及扯断伸长率增加。加入少量离聚体,使离聚体/CHR共混物的力学性能提高,扫描电镜显示两者的相容性增加;离聚体与PP共混,在拉伸强度方面呈现协同效应。质量比各为1/1的离聚体增容SBS/CHR和离聚体/PP共混物的耐油性均较SBS大为改善。     

热塑性弹性体增韧PP研究进展

热塑性弹性体增韧聚丙烯(PP)材料在常温下显示橡胶的弹性,在高温状态下可采用树脂的方式进行加工,因加工方式简便,扩展了PP材料在工程领域的应用。从单一弹性体增韧、弹性体协同增韧、刚性粒子/弹性体协同增韧、成核剂/弹性体协同增韧几方面对热塑性弹性体增韧PP材料进行阐述,并指出弹性体协同增韧、刚性粒子/弹性体协同增韧、成核剂/弹性体协同增韧将是今后的发展方向,新型的动态硫化加工技术及设备也是今后的研发重点。     

Toughening mechanism of SAN resin

SAN resin poly(styrene-co-acrylonitrile) combine, the gloss and transparency of PS with added chemical resistance, high heat distortion temperature, dimensional stability and stiffness characteristics. However brittleness restricts its wider application. The morphology, impact behavior and toughening mechanism of four rubbers toughened SAN resin were investigated in this study.     

超细全硫化粉末丁腈橡胶在聚氯乙烯改性塑料中的应用

介绍了超细全硫化粉末丁腈橡胶及其在硬质聚氯乙烯和软质聚氯乙烯两种材料共混增韧改性中的应用进展。与普通粉末丁腈橡胶P83的增韧性相比,采用少量的超细全硫化粉末橡胶即能够在保持较高强度和耐热温度的基础上,大幅度提高PVC改性材料的韧性。     

乙丙橡胶增韧聚丙烯共混物中橡胶相形态

通过电子扫描电镜(SEM),研究了乙丙橡胶增韧聚丙烯共混物中作为分散相的橡胶粒子的形态。结果表明,在交联剂等助剂的作用下进行过动态硫化的共混物中橡胶相的粒子形状、粒径、粒径分布以及橡胶粒子与连续相聚丙烯所形成的界面形态与单纯的橡塑共混物和PP/EPDM反应器共混物相比有着截然不同的区别。正是由于这些区别,提高了经过动态硫化的共混物的冲击性能。