核壳结构微纳橡胶粒子的可控合成及对PPO/PS共混体系的增韧

采用乳液聚合方法在粒径为100 nm的聚丁二烯(PB)胶乳上接枝聚合苯乙烯(St),合成了核壳比为70/30(PB/PS)的PB-g-PS接枝共聚物,将其与聚苯醚(PPO)、聚苯乙烯(PS)树脂熔融共混,制备出一系列橡胶含量、基体组成不同的PPO/PS/PB-g-PS共混物,并考察了共混物的相容性、力学性能及形态结构。结果发现:PPO与PS为完全相容体系,且PB-g-PS在PPO/PS基体中的均匀分散程度随体系中PPO引入量的增大而明显改善,共混物的冲击强度及屈服强度也随之逐渐增大,进而促使共混物发生脆-韧转变所需的橡胶含量逐渐降低;随着共混体系中橡胶含量的增加,共混物的冲击强度逐渐提高,而屈服强度却逐渐降低,共混物的韧性断裂特征越发显著。     

Controllable Synthesis of Submicrometer Core–Shell Modifier and Its Effect on Toughening Polypheylene Ether/Polystyrene Blends

Core–shell polybutadiene-graft-polystyrene (PB-g-PS) graft copolymers with different ratios of PB to PS are synthesized by emulsion polymerization. Further, the PB-g-PS copolymers are blended with polypheylene ether (PPE) and PS to prepare PPE/PS/PB-g-PS blends. The effects of PB-g-PS copolymer structure and matrix composition on the morphological, mechanical properties, and deformation mechanism of the blends are studied. The results show that the synthesized submicrometer-sized PB-g-PS copolymer has an excellent toughening efficiency, both the copolymer and PS are introduced into PPE resin to produce a ternary blend which is combined with high toughness and processing properties. The optimum toughening effect on PPE/PS matrix is observed at the core–shell weight ratio of 70/30 in PB-g-PS copolymer, and the impact strength of the blends increased from 101 to 550 J m⁻¹. In addition, the dispersion pattern of rubber particles in the matrix gradually changes from uniform dispersion to aggregation as the core–shell ratio of PB-g-PS copolymers increases. On the other hand, with the increase of PPE content, the dispersion of rubber particles in PPE/PS matrix is improved, and the deformation mechanism is changed from cracking to a combination of crazing and shear yielding, which can lead to absorb more energy to achieve better toughness.     

PS/SBR-g-PS共混物的力学性能和形态结构

采用种子乳液聚合技术在丁苯胶乳上接枝聚合苯乙烯 ,合成了一系列丁苯橡胶接枝聚苯乙烯共聚物 (SBR-g-PS)。将其与聚苯乙烯 (PS)树脂共混后 ,考察了 SBR-g-PS的组成 (SBR/ PS)对共混物的力学性能和形态结构的影响。结果发现 ,当 SBR/ PS为 6 7/ 33-5 0 / 5 0时 ,PS/ SBR-g-PS共混物表现出良好的综合力学性能 ,在 SBR-g-PS中随着接枝 PS的增多 ,像胶粒子在基体中的分散状况获得改善 ,在大橡胶颗粒中含有大量的 PS次级粒子。在外负载的作用下 ,共混物中的大橡胶颗粒引发了大量的银纹 ,吸收了断裂应变能 ,从而提高了材料的冲击韧性。     

丁苯橡胶/高岭土纳米复合材料的性能

采用熔融共混法和乳液共混法制备了丁苯橡胶／高岭土纳米复合材料,研究了复合材料的分散性能、力学性能和热稳定性能。结果表明,高岭土在橡胶基体中具有良好的分散性。熔融共混法制备的复合材料的力学性能基本接近白炭黑填充橡胶,其热稳定性能明显优于白炭黑填充橡胶。随着纳米高岭土用量的增大,乳液共混法制备的复合材料的拉伸强度先增大后减小,且当纳米高岭土用量为40质量份时,复合材料的综合性能良好。     

ABS树脂的冲击韧性极限及形变机理的研究

将苯乙烯-丙烯腈共聚物接枝聚丁二烯（PB-g-SAN）与苯乙烯-丙烯腈共聚物（SAN）树脂按照一定比例熔融共混制备具有不同橡胶含量的丙烯腈-丁二烯-苯乙烯共聚物（ABS）树脂。研究了不同橡胶含量对ABS树脂的冲击以及拉伸行为的影响,并通过透射电子显微镜研究了ABS树脂的微观形态及形变机理。结果表明,ABS材料的冲击强度随着橡胶含量的增加先升高后降低;断裂伸长率随着橡胶含量的增大而增大;当橡胶含量较少时,橡胶粒子在基体相中发生聚集现象的可能性较小,分散性较好;随着橡胶含量的增加发生聚集现象的可能性增加,粒子分散性变差;随着橡胶粒子含量的增加,ABS树脂的主要增韧机理是由空洞化到银纹再到剪切屈服的转变。     

Correlation of viscosity ratio,morphology, and mechanical properties of polyamide 12/natural rubber blends via reactive compatibilization

Natural rubber (NR)-modified polyamide 12 (Nylon12/NR) was produced by melt blending Nylon12 and NR in the presence of polystyrene/maleated natural rubber (PS/MNR) copolymer as a reactive compatibilizer. The influence of compatibilizer loading on viscosity ratio, morphology, and mechanical properties of the blends was investigated. As a consequence of the reactive blend between Nylon12 and maleated NR in PS/MNR, the formation of amide and succinimide linkages was set at rubber-Nylon12 interfaces. Thus the dispersion of rubber particles was improved, and the particle coalescence was prevented so that the fine morphology with good interfacial adhesion was stabilized. This also resulted to enhance the blend viscosity and to lower viscosity ratio. The data revealed strong correlation between low viscosity ratio and fine spherical morphology of the compatibilized blends. An optimum PS/MNR compatibilizer content was at 7 phr to produce good dispersion of small rubber domains (size ≤0.3 μm) in Nylon12 matrix. Thermal properties by DSC revealed that crystallization temperature of Nylon12 was lowered by the presence of NR and crystallinity of Nylon12 was slightly affected by the PS/MNR content. An enhancement of mechanical properties, especially the impact energy was observed without suffering the tensile and flexural properties. Compared to the neat Nylon12, the compatibilized blends showed an increase in impact energy by a factor of 5. This large enhancement is successfully interpreted in term of the toughening effect by rubber phase of suitable dispersed size and the interparticle distance.     

基于ABAQUS炭黑填充天然橡胶Mullins效应的分析与比较

以炭黑填充天然橡胶为研究对象,借助有限元软件ABAQUS和MATLAB对炭黑填充橡胶Mullins效应进行了仿真,并探究了材料参数r、m、β对Mullins效应的影响规律,提出了一种计算Mullins效应材料参数的方法.结果表明,炭黑填充天然橡胶的Mullins效应是由r、m、β因素共同决定,Mullins效应的强度随...     

Quantitative characterization of interfaces in rubber–rubber blends by means of modulated‐temperature DSC

Rubber–rubber blends are used widely in industry, for example, in tire manufacture. It is often difficult to characterize interfaces in such rubber–rubber blends quantitatively because of the similarity in the chemical structure of the component rubbers. Here, a new method was suggested for the measurement of the weight fraction of the interface in rubber–rubber blends using modulated‐temperature differential scanning calorimetry (M‐TDSC). Quantitative analysis using the differential of the heat capacity, dCp/dT, versus the temperature signal from M‐TDSC allows the weight fraction of the interface to be calculated. As examples, polybutadiene rubber (BR)–natural rubber (NR), BR–styrene‐co‐butadiene rubber (SBR), SBR–NR, and nitrile rubber (NBR)–NR blend systems were analyzed. The interfacial content in these blends was obtained. SBR is partially miscible with BR. The cis‐structure content in BR has an obvious effect on the extent of mixing in the SBR–BR blends. With increasing styrene content in the SBR in the SBR–BR blends, the interface content decreases. NR is partially miscible with both BR and SBR. The NBR used in this research is essentially immiscible with NR. The maximum amount of interface was found to be at the 50:50 blend composition in BR–NR, SBR–BR, and SBR–NR systems. Quantitative analysis of interfaces in these blend systems is reported for the first time. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1791–1798, 2000     

Crystallization behavior of syndiotactic polystyrene nanocomposites for melt‐ and cold‐crystallizations

Analyses of the effects of montmorillonite (clay) on the crystallinity and crystallization behavior of syndiotactic polystyrene (s‐PS) were investigated by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The dispersibility of the clay in s‐PS nanocomposites was studied by X‐ray and transmission electron microscopy (TEM). The clay was dispersed into the s‐PS matrix by melt blending on a scale of 1–2 nm or few tenths–100 nm, depending on the surfactant treatment. On adding clay, the crystallization behavior of the s‐PS tends to convert into the β‐crystal from the α‐crystal after being cold‐crystallized because the clay plays a vital role in facilitating the formation of the thermodynamically favored β‐form crystal when the s‐PS is cold‐ or melt‐crystallized. This phenomenon leads to a change in a conventional mechanism of molecular packing for the s‐PS. Evidently, the clay significantly affects the crystallinity and crystallization behavior of the s‐PS. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2492–2501, 2002     

Structure and mechanical properties of nanodispersed fibrous silicate‐reinforced ethylene–propylene–diene monomer nanocomposites

In this study, ethylene–propylene–diene monomer (EPDM)/fibrillar silicate (FS) nanocomposites were successfully prepared by mechanically blending EPDM with FS, which was modified by silane coupling agent KH570 containing methacryloxy group. The effects of silane content and modified FS on the dispersion of FS and mechanical properties of the composites were investigated. The impact of water in FS on mechanical properties of the composites was also evaluated. The results showed that modified FS could be dissociated into nanofibers dispersing evenly in the EPDM matrix by increasing substantially the loading of silane through the mechanical blending. The optimum loading level of silane coupling agent was up to 24 phr/100 phr FS. Silane KH570 could improve the dispersion of FS and strengthen nanofibers–rubber interfacial adhesion even at the loading of as high as 50 phr FS, making FS to exhibit excellent reinforcement to EPDM. Too much FS could not be completely dissociated into nanofibers, slowing down further improvement. The EPDM/FS composites exhibited the similar stress–strain behavior and obvious mechanical anisotropy with short microfiber‐reinforced rubber composites. With the increase in silane coupling agent and modified FS, the number of nanofibers increased because of the exfoliation of FS microparticles; thus, the mechanical behaviors would become more obvious. It was suggested that the free water in FS should be removed before mechanically blending EPDM with FS because it obviously affected the tensile properties of the composites. Regardless of whether FS was dried or modified, the EPDM/FS composites changed little in tensile strength after soaked in hot water. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Deformation mechanism of polystyrene toughened with sub‐micrometer monodisperse rubber particles

Core–shell polybutadiene‐graft‐polystyrene (PB‐g‐PS) rubber particles with different ratios of polybutadiene to polystyrene were prepared by emulsion polymerization through grafting styrene onto polybutadiene latex. The weight ratio of polybutadiene to polystyrene ranged from 50/50 to 90/10. These core‐shell rubber particles were then blended with polystyrene to prepare PS/PB‐g‐PS blends with a constant rubber content of 20 wt%. PB‐g‐PS particles with a lower PB/PS ratio (≤70/30) form a homogeneous dispersion in the polystyrene matrix, and the Izod notched impact strength of these blends is higher than that of commercial high‐impact polystyrene (HIPS). It is generally accepted that polystyrene can only be toughened effectively by 1–3 µm rubber particles through a toughening mechanism of multiple crazings. However, the experimental results show that polystyrene can actually be toughened by monodisperse sub‐micrometer rubber particles. Scanning electron micrographs of the fracture surface and stress‐whitening zone of blends with a PB/PS ratio of 70/30 in PB‐g‐PS copolymer reveal a novel toughening mechanism of modified polystyrene, which may be shear yielding of the matrix, promoted by cavitation. Subsequently, a compression‐induced activation method was explored to compare the PS/PB‐g‐PS blends with commercial HIPS, and the result show that the toughening mechanisms of the two samples are different. Copyright © 2006 Society of Chemical Industry     

Effect of acrylic core–shell rubber particles on the particulate flow and toughening of PVC

Different types of acrylic core–shell rubber particles with a poly(butyl acrylate) (PBA) core and a grafted poly(methyl methacrylate) (PMMA) shell were synthesized. The average size of acrylic core–shell latex particles ranged from 100 to 170 nm in diameter, having the core gel content in the range of 35–80%. The melt blending behavior of the poly(vinyl chloride) (PVC) and the acrylic core–shell rubber materials having different average particle sizes and gel contents was investigated in a batch mixing process. Although the torque curves showed that the particulate flow of the PVC in the blends was dominant, some differences were observed when the size and gel content of the particles varied. This behavior can be attributed to differences in the plasticizing effect and dispersion state of various types of core–shell rubber particles, which can vary the gelatin process of the PVC in the mixing tool. On the other hand, the highest toughening efficiency was obtained using core–shell rubber particles with the smallest particle size (i.e., 100 nm). The results showed that increasing the gel content of the core–shell impact modifiers with the same particle size improved the particle dispersion state in the PVC matrix. The toughening efficiency decreased for the blends containing 100 and 170 nm rubber particles as the gel content increased. Nevertheless, unexpected behavior was observed for the blends containing 140 nm rubber particles. It was found that a high level of toughness could be achieved if the acrylic core–shell rubber particles as small as 100 nm had a lower gel content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

高间同聚丁二烯/聚苯乙烯原位共混聚合物的合成与表征(Ⅰ)共混物的合成及微观结构

聚苯乙烯(PS)复合材料主要由弹性体、聚烯烃、纳米材料等采用机械共混法制得,因性能优异而屡见报道,但两相分散不均、相容性差。用结晶聚合物改性PS．国内外研究较少。高问同1,2-PB(聚丁二烯)因熔融温度高,机械共混加工困难,本实验将原位聚合的概念引入到双烯烃聚合,即在PS基体中采用“原位生成(in—situ fom)”s—PB方法,制备了s—PB／PS原位共混聚合物,降低了加工难度,简化了工艺,傅立叶红外光谱和差示扫描量热法分析初步表明：体系是部分相容体系,s—PB分子链的集结和排列受到了PS分子链的阻碍．PS抑制了s—PB的结晶．随着PS含量的增加,s—PB结晶的完善程度降低,导致了s—PB的结晶温度及结晶度都随之下降。     

Synergistic effect of multiwalled carbon nanotubes and an intumescent flame retardant: Toward an ideal electromagnetic interference shielding material with excellent flame retardancy

To shield undesirable electromagnetic waves caused by electronic devices and simultaneously resolve the flame safety of the electronic components, an electromagnetic interference (EMI) shielding material with excellent flame‐retardant properties is urgently needed. The synergistic effect of the intumescent flame retardant (IFR) and multiwalled carbon nanotubes (MWCNTs) for polystyrene (PS) nanocomposites prepared by melt blending was investigated. The results show that addition of certain amounts of IFRs facilitated the dispersion of MWCNTs in the PS matrix, and the percolation threshold of the MWCNTs in the PS matrix also decreased from 1.67 ± 0.05 to 1.29 ± 0.04 wt %. Moreover, the EMI shielding efficiencies (SEs) of the PS–MWCNT–IFR composites were consistently higher than those of the PS–MWCNT composites without the addition of the IFRs at the same MWCNT content; this indicated that the synergistic effect of the MWCNTs and IFRs effectively improved the EMI SE of the PS–MWCNT–IFR composites. Furthermore, the limiting oxygen index (LOI) testing results show that the LOI values of the PS–MWCNT composites were consistently higher than 27%; this indicated that the PS–MWCNT composites effectively met the needs of flame safety; this indicated that the PS–MWCNT–IFR composite is a novel and promising candidate for an ideal EMI shielding material with excellent flame‐retardant properties for today's electronic devices. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45088.     

The effect of reactive compatibilization of carboxylated polystyrene on morphology and toughness of polyamide-1010/polystyrene blends

The morphology and notched impact behaviour of polyamide-1010/polystyrene (PA1010/PS) (90/10) blends compatibilized by carboxylated polystyrene (CPS) have been studied. It is found that the addition of CPS has a beneficial effect upon the morphology of the resulting blends which leads to a finer dispersion of the PA1010 spherulites and of the PS particles in the PA1010 matrix. However, with increasing CPS content, the shape of the PS domains appears less regular, which may be due to the cracking of the PS spherical domains. Infrared analysis was performed to confirm the formation of PS–PA1010 graft copolymer during the blending process. The notched impact toughness of the compatibilized blends shows a maximum which is almost triple that of the binary blend at approximately 5 wt% of the CPS addition based on the amount of PS. © 1999 Society of Chemical Industry     

玻璃微珠在填充聚丙烯基复合材料中分散效果的分形定量表征

用熔融共混法将玻璃微珠(GB)填充到聚丙烯(PP)中制备PP/GB复合材料,通过冲击试验获得复合材料的冲击强度及其断面,采用扫描电子显微镜观察了断面中GB在PP基体中的分散形态,应用分散分形维数(D_d)的分形模型和图像处理软件测算了GB在PP中的D_d。结果表明,GB在PP中的分散形态具有显著的分形特征,D_d可以定量表征GB在PP基体中的分散效果;GB的D_d先随体积分数(φf)的增加而减小,当φf为11%时,D_d达到最小值,其中改性GB的D_d为1.474,未改性GB的D_d为1.503;随后则随φf的增加而增大;在相同的φf条件下,经硅烷偶联剂改性的GB有较小的D_d;D_d越接近1.5,则GB在PP基体内的分散越均匀,其填充的PP复合材料的冲击强度越高,韧性越好。     

Rubber toughening of polystyrene through reactive blending

Acrylonitrile-butadiene rubber having carboxylic acid groups (XNBR) and polystyrene having oxazoline groups, were melt blended in a Rheomix mixer under optimized conditions, The ratio of rubber to polystyrene phase was kept constant at 1:4 by weight. The concentration of the reactive oxazoline groups in the polystyrene phase was varied by mixing polystyrene (PS) with a copolymer of styrene and vinyl oxazoline (OPS). A torque rise observed during blending was found to be related to the concentration of oxazoline-carboxylic acid pairs. This torque rise, and independently measured increases in viscosity, both indicate inter-polymer crosslinkihg. Scanning electron microscopy was used to observe the morphology of the blends. Improved rubber phase dispersion was observed with increasing oxazoline concentration. Instrumented impact strength measurements were made using an unnotched Charpy technique. The plastic yielding was then quantified with the use of a ductility ratio. The impact strengths and ductility of the reactive blends are found to be up to 73% greater than those of the corresponding non-reactive blends. Increasing the OPS concentration beyond 5% results in decreasing impact strength, for as the compatibility increases, the rubber particle size decreases below an effective size for rubber toughening. Similar impact improvement is observed when the major PS phase is substituted with high impact polystyrene (HIPS) containing some OPS.     

Synthesis of sub‐micrometer core–shell rubber particles with 1,2‐azobisisobutyronitrile as initiator and deformation mechanisms of modified polystyrene under various conditions

BACKGROUND: Sub‐micrometer core‐shell polybutadiene‐graft‐polystyrene (PB‐g‐PS) copolymers with various ratios of polybutadiene (PB) core to polystyrene (PS) shell were synthesized by emulsion grafting polymerization with 1,2‐azobisisobutyronitrile (AIBN) as initiator. These graft copolymers were blended with PS to prepare PS/PB‐g‐PS with a rubber content of 20 wt%. The mechanical properties, morphologies of the core‐shell rubber particles and deformation mechanisms under various conditions were investigated. RESULTS: Infrared spectroscopic analysis confirmed that PS could be grafted onto the PB rubber particles. The experimental results showed that a specimen with a ‘cluster’ dispersion state of rubber particles in the PS matrix displayed better mechanical properties. Transmission electron micrographs suggested that crazing only occurred from rubber particles and extended in a bridge‐like manner to neighboring rubber particles parallel to the equatorial plane at a high speed for failure specimens, while the interaction between crazing and shear yielding stabilized the growing crazes at a low speed in tensile tests. CONCLUSION: AIBN can be used as an initiator in the graft polymerization of styrene onto PB. The dispersion of rubber particles in a ‘cluster’ state leads to better impact resistance. The deformation mechanism in impact tests was multi‐crazing, and crazing and shear yielding absorbed the energy in tensile experiments. Copyright © 2009 Society of Chemical Industry     

Comparison of polystyrene,poly(styrene/acrylonitrile), high-impact polystryrene,and poly(acrylonitrile/butadiene/styrene) with respect to tensile and impact properties

The tensile behaviors of polystyrene (PS), poly(styrene/acrylonitrile) (SAN), high-impact polystyrene (HIPS), and poly(acrylonitrile/butadiene/styrene) (ABS) were examined systematically in the wide range of strain rate, 1.7 × 10^?4–13.1 m/s. When glassy and brittle PS was a criterion, the incorporation of a polar group (SAN) only strengthened the hardness, and the fracture mode was the same as for PS. The introduction of dispersed rubber particles (HIPS) weakened the hardness a little but offered a new deformation mechanism, i.e., microcrazing (whitening), and contributed to the improvement of impact strength. In the heterogeneous system, the enhancement of matrix strength [e.g., preorientation or blending with poly(phenylene oxide) for HIPS] makes possible another deformation mechanism, i.e., shear band formation (cold drawing), which is superior to microcrazing for achieving higher impact strength. ABS, which incorporates concurrently two factors (polar group to matrix phase and dispersed rubber particles), can be regarded as an enhancement of the matrix strength of HIPS. In spite of the remarkable magnitude of its impact strength compared with that of the other three polymers, the deformation mechanism of ABS was limited to microcrazing. This indicated that only the introduction of a polar group (as nitrile group) could not strengthen the matrix as much as preorientation or blending with poly(phenylene oxide).     

天然短纤维增强橡胶复合材料的研究进展

介绍了短纤维的预处理方法,总结了短纤维在橡胶中的混合、分散及取向状态,综述了短纤维-橡胶复合材料在轮胎、胶带和胶管中的应用进展,并提出了复合材料的研究方向.