EPM-g-GMA接枝率的测定及其增韧PBT的力学性能和形态结构研究

在同向双螺杆挤出机中通过熔融接枝反应制备了EPM g GMA ,将其与PBT在转矩流变仪中熔融共混可以获得增韧的PBT工程塑料 .实验中EPM g GMA接枝率的测定采用红外工作曲线法 ,选用CCl4 做溶剂以避免溶剂对样品吸收峰的干扰 .随着EPM g GMA接枝率的增加 ,PBT EPM g GMA的缺口冲击强度相应提高 ,共混物中EPM g GMA的粒径尺寸减小 ,当EPM g GMA的接枝率为 4 7mL 1 0 0gEPM时 ,EPM g GMA的粒径尺寸可达 0 5 μm ,PBT EPM g GMA的缺口冲击强度达到 5 1 6kJ m2 ,是纯PBT的 3 1倍     

Physical characterization of blends of isotactic poly(butene-1) with ethylene-propylene copolymer

Melt-mixed blends of isotactic poly(butene-1) (PB) with an ethylene-propylene copolymer (EPM) containing 60 wt% PP were studied over the complete composition range. Phase-contrast polarizing microscopy and dynamic mechanical spectroscopy revealed that the blend is heterogeneous. DSC studies of quenched and annealed blends for both PB modifications indicate that total blend crystallinity decreases linearly with the EPM content. Pure PB crystallinity is enhanced to a small degree in the presence of EPM. Tensile behaviour of the blends was good up to moderate EPM levels. It was also demonstrated that blends containing EPM with increased PP content showed synergism in tensile behaviour not exhibited by blends with EPM of lower PP content. Appropriate mechanical models tested over the complete composition and temperature range suggest that the rubbery phase adheres strongly to the PB matrix. Overall, the experimental results support the contention that the system is mechanically compatible, possibly a result of component miscibility at elevated temperatures as predicted on thermodynamic grounds.     

苯甲酸甲酯促进茂金属催化剂催化SBS加氢反应研究

以苯甲酸甲酯为促进剂,用茂金属催化剂制备了活性丁苯嵌段共聚物(SBS)的选择性催化加氢产物,讨论了苯甲酸甲酯、SBS的数均分子量等因素在几种实验条件下对产物加氢度的影响.结果表明,每百克干胶使用0.15～0.3mmol Ti催化条件下,苯甲酸甲酯在特定添加方式下能较大程度地提高茂金属催化剂的活性.在不加入苯甲酸甲酯的情况下,Mn=6.5×104和Mn=5.5×104两种SBS基础胶加氢反应180min时加氢度均97.0%;加入酯以后,反应60～120min时,基础胶的加氢度≥98%;与已报道的研究结果相比,将加氢反应时间缩短了60～120min.在每百克干胶使用0.15～0.3mmolTi催化条件下,数均分子量的大小也对SBS基础胶的加氢度有影响,反应30min时,Mn=5.5×104的加氢度≥97%,Mn=6.5×104的加氢度90%;随着反应时间的延长,这种差距在逐渐缩小;反应180min时,两者已无明显差距,此时两种基础胶的加氢度都≥98%.对影响的加氢度的机理进行了解释.     

线形苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)的粘弹弛豫与相形态

研究了不同温度下苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)的粘弹弛豫与相形态. DSC分析发现, SBS的相结构特别是其中质量分数较低的PS相畴的大小受热历史影响显著. 用TEM表征了SBS的双相连续形态和两相相畴尺寸. 用动态流变学方法研究了不同温度下SBS嵌段大分子的松弛行为. 结果表明, 在低于PS相玻璃化转变温度时, 嵌段分子中的PB段已可发生运动; 而当高于PS玻璃化转变温度后, 由于PB与PS间的相互作用及PB的链缠结所限制, 体系仍保持较高的弹性模量, 呈现“第二平台”特征流变行为.     

Effect of butadiene/styrene ratio,block structure and carbon nanotube content on the mechanical and electrical properties of thermoplastic elastomers after UV ageing

Thermoplastic elastomers based on a triblock copolymer styrene-butadiene-styrene (SBS) with different butadiene/styrene ratios, block structure and carbon nanotube (CNT) content were submitted to accelerated weathering in a Xenontest, in order to evaluate their stability to UV ageing. It was concluded that ageing mainly depends on butadiene/styrene ratio and block structure, with radial block structures exhibiting faster ageing than linear block structures. Moreover, the presence of carbon nanotubes in the SBS copolymer slows down the ageing of the copolymer. The evaluation of the influence of ageing on the mechanical and electrical properties demonstrates that the mechanical degradation is higher for the C401 sample, which is the SBS sample with the largest butadiene content and a radial block structure. On the other hand, a copolymer derivative from SBS, the styrene-ethylene/butadiene-styrene (SEBS) sample, retains a maximum deformation of ∼1000% after 80 h of accelerated ageing. The hydrophobicity of the samples decreases with increasing ageing time, the effect being larger for the samples with higher butadiene content. It is also verified that cytotoxicity increases with increasing UV ageing, with the exception of SEBS, which remains non-cytotoxic up to 80 h of accelerated ageing time, demonstrating its potential for applications involving exposure to the environment.     

Nanostructured carbon black filled polypropylene/polystyrene blends containing styrene-butadiene-styrene copolymer: Influence of morphology on electrical resistivity

This paper is part of a comprehensive study on using selective localization of carbon black (CB) at the interface of immiscible polymer blends in order to reduce the percolation threshold concentration and enhance the conductivity of the blends. CB was successfully localized at the interface of polypropylene/polystyrene (PP/PS) blend by introducing styrene-butadiene-styrene (SBS) tri-block copolymer to the blend. In CB-PP/PS/SBS blends, CB has higher affinity for the polybutadiene (PBD) section of the SBS copolymer, whereas in CB-PP/PS blends, CB prefers the PS phase. PP/PS interface is one of the preferred locations for the SBS copolymer in the (PP/PS) blend; at which the PBD section of the SBS copolymer forms a few nanometers thick layer able to accommodate the CB nano-particles. The influence of SBS addition on the morphology and electrical properties of various PP/PS blends filled with 1 vol% CB were studied. SBS influence on the conductivity of PP/PS blends was found to be a function of the PP/PS volume ratio and SBS loading. The most dramatic increase in conductivity was found in the (60/40) and (70/30) PP/PS blends upon the addition of 5 vol% SBS. 5 vol% SBS was found to be the optimum loading for most blends. Using 10 vol% of SBS was reported to deteriorate electrical conductivity of the conductive co-continuous PP/PS blends. For all blends studied, SBS addition was found to compatibilize the blends. Finer morphologies were obtained by increasing SBS loading.     

Steady and transient shear flow properties of poly(styrene-B-butadiene)-dioctyl phthalate systems

The viscosity, stress overshoot effect and stress relaxation after cessation of flow of an SBS block copolymer, dissolved in dioctyl phthalate, have been studied at various temperatures and concentrations. Analysis of these functions reveals that there is not a complex flow behaviour, as in SBS melts, and that the mechanism of flow is the same for the whole range of temperatures and concentrations considered.     

Block copolymers as compatibilizers for blends of linear low density polyethylene and polystyrene

Compatibilization of blends of linear low-density polyethylene (LLDPE) and polystyrene (PS) with block copolymers of styrene (S) and butadiene (B) or hydrogenated butadiene (EB) has been studied. The morphology of the LLDPE/PS (50/50) composition typically with 5% copolymer was characterized primarily by scanning electron microscopy (SEM). The SEB and SEBS copolymers were effective in reducing the PS domain size, while the SB and SBS copolymers were less effective. The noncrystalline copolymers lowered the tensile modulus of the blend by as much as 50%. Modulus calculations based on a coreshell model, with the rubbery copolymer coating the PS particle, predicted that 50% of the rubbery SEBS copolymer was located at the interface compared to only 5–15% of the SB and SBS copolymers. The modulus of blends compatibilized with crystalline, nonrubbery SEB and SEBS copolymers approached Hashin's upper modulus bound. An interconnected interface model was proposed in which the blocks selectively penetrated the LLDPE and PS phases to provide good adhesion and improved stress and strain transfer between the phases. © 1995 John Wiley & Sons, Inc.     

乙丙共聚物熔融接枝甲基丙烯酸环氧丙酯

乙丙共聚物熔融接枝甲基丙烯酸环氧丙酯张晓民，尹志辉，殷敬华（中国科学院长春应用化学研究所高分子物理开放实验室长春１３００２２）关键词乙丙共聚物，甲基丙烯酸环氧丙酯，接枝共聚接枝共聚物可作为不相容共混体系的增容剂［１，２］，反应加工法制备乙丙共聚物（Ｅ...     

HIPS／SBS共混物的形态结构和性能

通常,高抗冲聚苯乙烯(HIPS)为多相体系,由连续聚苯乙烯(PS)相和分散的聚丁二烯(PB)颗粒组成。PB含量一般为5～15%,粒径范围为0.5～10μm,PB颗粒是交联的,同时含有接枝的PS,其内部结构由制备工艺决定。HIPS力学性能与其制备工艺、PB含量、PB分子结构、相区尺寸及内部结构密切相关。PS和PB嵌段共聚物(SBS)通常为热塑弹性体,由于PS段和PB段的不相容性而呈现微相分离的结构特征。SBS常用于与其它聚合物共混以增加后者的韧性。本工作研究了HIPS/SBS共混物的形态结构和力学性能。     

SBS与甲基丙烯酸丁酯本体接枝反应的研究

本文研究了以过氧化苯甲酰(BPO)为引发剂,甲基丙烯酸丁酯(BMA)既作溶剂又作为单体与苯乙烯-丁二烯嵌段共聚物(SBS)进行接枝共聚反应。用红外光谱、核磁共振谱及透射电镜表征了接枝共聚物(SBS-g-BMA)的组成及结构,讨论了时间、温度及SBS和BPO的用量对接枝的影响。     

Evidences of macromolecular chains confinement of ethylene–propylene copolymer in organophilic montmorillonite nanocomposites

A random ethylene–propylene copolymer (EPM) functionalized with grafted diethylsuccinate groups was melt blended with increasing amount (to 20 wt%) of organophilic montmorillonite (OMMT) to prepare nanocomposites with different morphologies as evidenced by XRD and TEM analysis. All the nanocomposites were treated with boiling toluene that did not extract a significant amount of EPM. The increase of not-extracted EPM with the increasing quantity of OMMT suggested strong interactions of the polymer chains with the inorganic substrate. The DSC measurements of nanocomposites and the corresponding insoluble residues revealed a higher T_g values with larger amount of inorganic particles. The dielectric relaxation analysis confirmed the evidence of strong interactions among montmorillonite and the polar diethylsuccinate groups for the macromolecules trapped due to the presence of the inorganic layers. The results were discussed with reference to their relevance as an evidence of nanoconfinement at polymer clay interface and correlated with the clay basal distance variation due to the intercalation process.     

Ultrasonic absorption and dielectric loss in heterophase block copolymers

A styrene–butadiene–styrene block copolymer (SBS) and a plasticized SBS were studied as a function of temperature by an ultrasonic wave propagation technique at 9 MHz. Two absorption maxima were found for each of these polymers, one being attributable to the primary glass transition of the polybutadiene blocks and the other to that of the polystyrene blocks. The SBS was cast from two different solvents, namely benzene and tetrahydrofuran–methyl ethyl ketone. Parallel dielectric loss measurements were also made of the SBS in the frequency range of 50–10⁵ Hz. Relaxation temperatures determined from the ultrasonic and dielectric loss maxima over a range of measurement frequencies can be correlated by an Arrhenius-type equation. The polystyrene loss peak in the ultrasonic data was found to be much weaker than the polybutadiene loss peak. However, these two peaks were of comparable magnitude in dielectric data. This observation was interpreted as being due to the onset of structured–unstructured (heterophase to homogeneous) transitions at sufficiently high temperatures. Ultrasonic data were also compared with low-frequency dynamic mechanical data (11 Hz) and stress relaxation data (10²–10⁵ sec) through the use of simple time–temperature superposition principle. Considerable discrepancies were found by using this principle, indicating that the heterophase SBS block copolymer was thermorheologically complex.     

丙烯酸接枝乙丙共聚物的结构

丙烯酸接枝乙丙共聚物的结构李丽霞，尹志辉，綦玉臣，殷敬华（中国科学院长春应用化学研究所高分子物理开放实验室长春１３００２２）关键词ＥＰＭ，ＥＰＭ－ｇ－ＰＡＡ，异相成核剂，结晶温度聚烯烃是目前应用最为广泛的塑料之一，但由于它的非极性限制了它与金属和其它...     

Morphology and mechanical properties of styrene–butadiene–styrene/poly(methyl methacrylate–co-n-butyl acrylate) interpenetrating polymer networks

A series of interpenetrating polymer networks (IPNs) based on styrenic triblock copolymer, polystyrene-b-polybutadiene-b-polystyrene (SBS), and random copolymer of methyl methacrylate (MMA) and n-butyl acrylate (nBA) were prepared. Corresponding semi-IPNs of the same composition without a crosslinking agent were also synthesized for comparison, and toluene was used as a common solvent to investigate the influence of the presence of the common solvent during the IPN synthesis. Throughout the compositions of IPNs tested, SBS appears to form a continuous phase and the domain size decreases gradually with the increase in SBS concentration. IPNs are found to have finer domain sizes than semi-IPNs because of the higher intermixing between polymers. The microstructure of SBS could be observed using highly magnified transmission electron microscopy (TEM). The dynamic mechanical behavior of the IPNs shows the inward shifting of two glass transition peaks, corresponding to polybutadiene phase of SBS and p(MMA–co-nBA) phase respectively, which indicates enhanced intermixing. The increase in loss tangent of styrene blocks of SBS by the addition of common solvent indicates the structural change of the microstructure in SBS, and this structural change can also be confirmed through the observation of the morphology of SBS-rich phase with higher magnification. © 1997 John Wiley & Sons, Ltd.     

茂金属化合物对苯乙烯丁二烯嵌段共聚物SBS催化加氢的研究

合成了一系列茂金属催化剂（C5H4R)2TiCl2[R=H(1),Me(2),C6H11(3)]和（C5H4R)2TiAr2[R=H,Ar=C6H5(4),p-MeC6H4(5),m-MeC6H4(6);R=Me,Ar=C6H5(7),p-MeC6H4(8);R=C6H11,Ar=C6H5(9),p-MeC6H4(10)],研究了这些催化剂对苯乙烯丁二烯嵌段共聚物SBS的催化加氢,考察了催化剂种类、用量及催化剂各组分之间的比例对加氢效果的影响,得到了较佳的条件,可使聚合物加氢度达到98%以上,钛催化剂用量为0.001-0.003mmol/g聚合物。     

Chemical initiation mechanism of maleic anhydride grafted onto styrene-butadiene-styrene block copolymer

The mechanism of grafting styrene-butadiene-styrene (SBS) tri-block copolymer with maleic anhydride (MAH) initiated by benzoperoxide (BPO) or 2,2^′-azo-bis-isobutyronitrile (AIBN) was studied by FTIR and ¹H NMR spectroscopies. The variation of CC (double bond) content in SBS-g-MAH was used to verify the different graft mechanisms of BPO and AIBN, indicating that the chemical initiation mechanisms of MAH grafted onto SBS of AIBN is different from that of BPO. The graft reaction occurs by addition on CC for AIBN, while by removal of an allylic hydrogen atom from SBS and by addition on CC at the same time for BPO. The graft efficiency of AIBN is higher than that of BPO in this system.     

Unexpected consequences of block polydispersity on the self-assembly of ABA triblock copolymers

Controlled/"living" polymerizations and tandem polymerization methodologies offer enticing opportunities to enchain a wide variety of monomers into new, functional block copolymer materials with unusual physical properties. However, the use of these synthetic methods often introduces nontrivial molecular weight polydispersities, a type of chain length heterogeneity, into one or more of the copolymer blocks. While the self-assembly behavior of monodisperse AB diblock and ABA triblock copolymers is both experimentally and theoretically well understood, the effects of broadening the copolymer molecular weight distribution on block copolymer phase behavior are less well-explored. We report the melt-phase self-assembly behavior of SBS triblock copolymers (S = poly(styrene) and B = poly(1,4-butadiene)) comprised of a broad polydispersity B block (M(w)/M(n) = 1.73-2.00) flanked by relatively narrow dispersity S blocks (M(w)/M(n) = 1.09-1.36), in order to identify the effects of chain length heterogeneity on block copolymer self-assembly. Based on synchrotron small-angle X-ray scattering and transmission electron microscopy analyses of seventeen SBS triblock copolymers with poly(1,4-butadiene) volume fractions 0.27 ≤ f(B) ≤ 0.82, we demonstrate that polydisperse SBS triblock copolymers self-assemble into periodic structures with unexpectedly enhanced stabilities that greatly exceed those of equivalent monodisperse copolymers. The unprecedented stabilities of these polydisperse microphase separated melts are discussed in the context of a complete morphology diagram for this system, which demonstrates that narrow dispersity copolymers are not required for periodic nanoscale assembly.     

Dynamic mechanical behaviour of styrene/butadiene copolymers and their blends

The dynamic mechanical behaviour of high impact polystyrene (PS-HI), styrene/butadiene/styrene block copolymer (SBS) and PS-HI + SBS blends were investigated. Dynamic mechanical analysis (DMA) was performed in the temperature range −100°C to 100°C. The primary viscoelastic functions were determined. The copolymers PS-HI and SBS as well as PS-HI+SBS blends were investigated in creep-fatigue regime and relaxation at temperatures 25, 30, 35, 40 and 45°C. Dynamic mechanical behavior of PS-HI, SBS and PS-HI + SBS blends depends on the copolymer and blends composition, the hard phase content, time and temperature. With the decrement of the hard phase PS concentration, the loss tangent of the soft phase increases while the loss tangent of the hard phase and the storage modulus decrease. All samples have a single T_g of the hard phase and a single T_g of the soft phase. The glass transition temperatures decrease as the content of the PS phase decreases. At the constant load the creep values increase and those of creep modulus decrease over a period of time, for all examined samples. These effects are more pronounced in samples with lower content of hard phase and at higher temperatures. The time-temperature correspondence principle was applied to create master curves for the reference temperature 25°C for the creep modulus of PS-HI, SBS and PS-HI + SBS blends on a time scale far outside of the range measured by DMA experiments. These results enable us to predict the useful life of our copolymers and their blends in a wide range of time and temperature.