马来酸酐熔融接枝二元乙丙橡胶的研究

在转矩流变仪中,以过氧化二异丙苯(DCP)为引发剂,采用多单体熔融接枝技术,研究了二元乙丙橡胶(EPM)熔融接枝马来酸酐(MAH),考察了MAH含量、DCP用量、反应温度、反应时间、转子转速以及第二单体苯乙烯(St)的用量对接枝反应的影响,并用红外光谱(FTIR)对接枝产物进行了表征.研究结果表明:对于EPM-g-MAH体系,MAH和DCP最佳用量分别为3.0 phr和0.22 phr,最佳反应温度为170℃,反应时间8 min,转子转速60 r/min,此时接枝率最高达到0.46％;加入第二单体St后,当n(St) /n(MAH)为1/1时,EPM-g-(MAH-co-St)的接枝率为0.64％,接枝率明显提高.     

反应增容型马来酸酐/丁腈橡胶接枝共聚物的制备

以过氧化苯甲酰(BPO)为引发剂、马来酸酐(MAH)为接枝单体、四氢呋喃为溶剂,采用溶液接枝法制备了MAH/丁腈橡胶(NBR)接枝共聚物(MAH-g-NBR),考察了MAH及BPO的用量、反应温度对接枝率的影响,并通过傅里叶变换红外光谱和热重分析法对接枝产物进行了表征。结果表明,接枝产物有2个明显的热失重阶段,第1阶段发生在152℃左右,为接枝共聚物的脱羧阶段,第2阶段发生在360℃左右,为NBR分子链的断裂,证明了MAH-g-NBR的存在;在NBR用量为1 g、MAH用量为1.3 g、BPO用量为0.08 g、反应温度为65℃的条件下,MAH-g-NBR的接枝率最高可达4.12%。     

高剪切应力诱导引发乙丙橡胶与马来酸酐官能化反应的研究

采用在熔融挤出过程中提高双螺杆挤出机螺杆转速的高剪切应力诱导引发方法和采用添加引发剂与提高螺杆转速的应力诱导复合引发方法,研究了乙丙橡胶(EPR)与马来酸酐(MAH)的官能化反应;采用化学分析、熔体流动速率测定、FT IR、SEM观测和材料力学性能测试等方法考察了官能化产物(EPR-g-MAH)性能及其对PA66/EPR-g-MAH共混材料力学性能的影响。结果表明:双螺杆挤出机的螺杆转速和官能化反应温度对产物的接枝(嵌段)率和熔体流动速率具有重要影响;与热引发方法相比较,270℃条件下螺杆转速由80 r/m in提高至800 r/m in时,产物的接枝(嵌段)率由0.26%提高至0.47%;与引发剂引发方法相比较,产物熔体流动速率由每10 m in约0.07 g提高至1.80 g,抑制或避免了官能化过程中的交联副反应;所得产物的接枝(嵌段)率和熔体流动速率易于控制,对于PA66的增韧作用,存在最佳接枝(嵌段)率(约0.66%)和最佳熔体流动速率(每10 m in约2.0 g)。     

Impact toughened blends of styrene-maleic anhydride copolymer,polyethylene, and ethylene-propylene copolymer

Impact-toughened, compatibilized binary blends of styrene-maleic anhydride (SMA) copolymer/amine functionalized ethylene-propylene (amine-EP) polymer and ternary blends consisting of SMA/amine-EP/high density polyethylene (HDPE) are described. In both blends 0.02 to 4 μm range rubbery inclusions, which toughen the SMA matrix, are formed. SMA sub-inclusions exist in the amine-EP phase. In the ternary blend substantially all of the polyethylene is embedded in the EP phase. Compatibilization of the SMA and the commingled polyolefin phase is promoted by a graft copolymer formed by the reaction of amine groups on the EP with the maleic anhydride groups on the SMA. We describe the morphology, rheology, aging characteristics and impact properties of these blends. SMA modification by SMA-g-(amine-EP) polymers formed in situ in the melt, with HDPE, has not been previously reported.     

The reaction of polypropylene with maleic anhydride

An addition reaction of maleic anhydride with polypropylene takes place in the presence of radical reagents or sunlight. The initial rate of the reaction was proportional to the concentration of polypropylene and maleic anhydride, and one-half power of the concentration of the radical reagents. The increase in the temperature from 80 to 120°C increased the rate of the reaction and di-cumyl peroxide was effective as a radical reagent for this reaction. Ionic crosslinked rubber-like polymers were obtained from the reaction of maleic polypropylene with some alkali metal compounds. They showed the characteristic absorption band due to ? COO^? in their infrared spectra.     

马来酸酐接枝天然橡胶的制备及应用研究

以过氧化二异丙苯(DCP)为引发剂,在转矩流变仪中以马来酸酐(MAH)单体对天然橡胶(NR)进行接枝改性。通过傅里叶变换红外光谱对接枝物进行了定性表征;采用化学滴定法测定了反应产物中MAH的接枝率和接枝效率。研究了MAH单体用量、DCP用量、反应温度、转子转速等因素对反应产物接枝率和接枝效率的影响,研究结果表明,以转矩流变仪作为反应器,NR为100份(质量份数,以下同此),MAH和DCP分别为5份、0.75份,温度为130℃,转子转速为50 r/min的条件下反应3min,产物接枝率和接枝效率较高,分别为1.45%和30.63%。将所制备的马来酸酐接枝天然橡胶(NR-g-MAH)应用于尼龙短纤维增强天然橡胶复合材料(NR/SF)体系中,可有效改善尼龙短纤维与NR基体间的界面结合。     

Functionalization of styrene-butadiene-styrene (SBS) triblock copolymer with maleic anhydride

Summary The thermoplastic elastomers have been widely used in polymer blends to improve their mechanical properties. This work is about the study of chemical modification of styrene-butadiene-styrene (SBS) with maleic anhydride (MA) by radical reaction. The functionalization reaction was carried out in a mixer Haake Rheomix 600 and the torque variation was monitored during the process. The products were characterized by Infrared Spectroscopy (FTIR) and crosslinking was evaluated by extraction. A calibration curve was plotted to determine the functionality. The results showed that it is possible to accomplish the functionalization reaction avoiding the crosslinking. Received: 26 February 2001/Revised version: 25 June 2001/Accepted: 25 June 2001     

Influence of triblock copolymer interfacial modifiers on fracture behavior of polystyrene/ethylene-propylene rubber blends

In a previous study, two triblock copolymers of styrene/ethylene-butylene/styrene (SEBS), of different molecular weights, were used to compatibilize a blend of 80 vol% polystyrene (PS) and 20% ethylene-propylene rubber (EPR). The emulsification curve, which relates the average minor phase particle diameter to the concentration of interfacial agent added, was used to quantify the effect of the interfacial agents on the blend morphology. Links between morphology, interface, and properties were established by combining the emulsification curve with a fracture mechanics approach. The aim of this work is to foster the understanding of the effects of these two triblock copolymers on the fracture behavior of the blend over various loading rates and temperatures. The focus is on the brittle-ductile transition in fracture behavior, which is a critical condition for the application of these materials. It has been found that adding an interfacial agent lowers the temperature at brittle-ductile transition. However, this effect is much more pronounced for the copolymer with a lower molecular weight. The time-temperature dependence of fracture performance of the blend is also affected by the interface and morphology. When loading rate increases, the shift of the temperature at brittle-ductile transition is less significant for the blend with an interfacial agent having a lower molecular weight. The effect of loading rate and temperature on the brittle-ductile transition in fracture performance of the blends is controlled by an energy activation process. Adding the interfacial agents results in a plasticizing effect of the polystyrene matrix and a reduction in the energy barrier controlling the fracture process. With the addition of interfacial agent, the yield stress slightly increases at low concentration, attains a maximum value, and then decreases. The increase in yield stress confirms the coupling role of the copolymer and is in agreement with the observed emulsification curves. The reduction of yield stress and increase in ultimate strain with the copolymer concentration demonstrate the plasticizing effect of the interfacial agent. The result of stress relaxation tests also confirms the above effects of the interfacial agent.     

Thermal stability of copolymer acrylamide–maleic anhydride

The thermal degradation of copolymer acrylamide–maleic anhydride prepared in various solvents (benzene, dioxane, methylethyl ketone) and different monomer ratios was investigated. The techniques of thermogravimetry (TG and DTG) and differential scanning calorimetry (DSC) were used. The IR spectra of degraded copolymers are discussed.     

Functionalized polystyrene maleic anhydride copolymer/ZnO nanocomposites for enhanced electrochemical performance

Novel functionalized polymeric materials incorporated with metal oxide nanoparticles are of paramount importance in the field of supercapacitors. These materials provide the advantage of enhanced specific capacitance coupled with efficient energy storage characteristics. In the present study, a new electrode material has been prepared by modifying the polystyrene maleic anhydride copolymer with 4,4-diaminodiphenylmethane (DDM). Chemically synthesized zinc oxide nanoparticles were incorporated into the polymer matrix at different weight percentages to form polymer nanocomposites (SMA–DDM–zinc oxide (SDZ)). The effect of increasing the weight percentage of nanoparticles on the modified copolymer was studied in details. The samples were characterized using ultraviolet–visible, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and thermogravimetric analysis. SDZ was drop casted on the surface of the glassy carbon electrode and the electrochemical properties were studied. Cyclic voltammetry studies were conducted at various scan rates, and the characteristic curves were observed to be pseudorectangular in nature. The specific capacitance values were measured using the chronopotentiometry technique. SDZ 15% nanocomposite shows an enhanced specific capacitance of 313 F g⁻¹ at a current density of 0.05 A g⁻¹ with a power density of 629 W kg⁻¹. The superior performance of the SDZ nanocomposite electrodes renders it as a promising material for supercapacitor applications. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48945.     

Molecular motion in a copolymer of styrene and maleic anhydride

Dielectric and mechanical relaxation techniques have been applied to the study of the molecular motions exhibited by an alternating copolymer of styrene and maleic anhydride. Three major relaxations were detected by these techniques and shown to correspond to motions already defined in homopolymers of substituted maleimides. A fourth relaxation was detected but insufficient evidence for assignment was obtained. The α relaxation is attributed to gross main chain motion (T_g～475K), the β relaxation (activation energy 103kJ) to local motion about the backbone and the δ relaxation (activation energy 51kJ) to deformation of the substituted succinic anhydride ring.     

Acrylonitrile–maleic anhydride copolymer membranes with different molecular weights

The structure and performance of acrylonitrile–maleic anhydride copolymer membranes with different molecular weights were investigated. The results showed that the water flux of the membrane decreased gradually with increasing molecular weight of the copolymer; the rejection increased only when there was an obvious increase of molecular weight. The addition of an additive (polyvinylpyrrolidone) largely decreased the water flux and rejection of the membrane when the concentration of the copolymer remained unchanged. The higher the molecular weight, the thicker were the transition layer and the wall of the support pore and the better was the anticompactness of the membrane. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2521–2527, 2002     

氯化聚丙烯及其马来酸酐接枝物的氯含量研究

通过氧瓶燃烧法测定的氯化聚丙烯及其马来酸酐接枝物的氯含量,可以对接枝反应机理和马来酸酐在接枝物中的存在状态进行估计。根据实验所测得的氯含量和接枝率(马来酸酐含量),可以求得接枝物的结构单元。根据结构单元可以计算接枝物结构单元的相对分子质量,这种方法要比用仪器法测定分子质量简单明确。     

Modification of cellulase by synthesized copolymer with polyethylene oxide and maleic acid anhydride

Copolymer containing functional groups such as polyethylene oxide (PEO) and maleic acid anhydride (MA) was synthesized to modify cellulase. MA was attached to the PEO allyl ester, which was the product formed by the reaction between PEO allyl alcohol and lauric acid. The number of ethylene oxide (EO) units in one PEO chain was varied from 10 to 40, and MA formed the chemical bond with the amino acid groups of the cellulase for the modification reaction. When cellulase was modified with synthesized copolymer, activity of the modified cellulase decreased slightly as the degree of modification increased. The modified enzyme showed high remaining activity regardless of a high degree of modification. At the maximum modification degree of 52%, the modified cellulase activity retained more than 65% of the unmodified native cellulase. Modified cellulase retained higher reactivity than native cellulase in an organic solvent and at various pH values. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 368–373, 2000     

丁腈橡胶/乙丙橡胶并用胶性能的研究

研究丁腈橡胶(NBR)/三元乙丙橡胶(EPDM)并用比对力学性能、老化性能和耐油性能的影响以及增容剂对共混胶性能的影响.结果表明,在NBR/EPDM共混胶中随EPDM用量的增加,硫化胶的硬度、拉伸强度、撕裂强度和定伸应力呈现下降趋势、拉断伸长率及耐低温性能有所改善,降低了NBR的耐汽油性能,但提高了耐含乙醇汽油性能.随着增容剂CM用量的增加,硫化胶拉伸强度、撕裂强度、100％定伸应力及硬度都呈增大趋势,采用扫描电镜可以清晰的看到添加CM改性后NBR/EPDM共混胶相容性得到显著改善.     

聚乙烯 -醋酸乙烯酯共聚物与马来酸酐的熔融接枝

在双螺杆挤出机中进行了聚乙烯－醋酸乙烯酯共聚物与马来酸酐的接杆反应，通过红外分析证实了接枝产物的存在，研究了醋酸乙烯酯质量分数、引发剂种类及接枝单体和引发剂用量地接枝反应的影响。结果表明，相对于100份乙烯醋酸乙烯酯，接枝单体和引发剂用量分别为2和0．3份较为适宜。     

马来酸酐对聚酰胺6短纤维/天然橡胶复合材料的增容作用

将马来酸酐直接与天然橡胶混炼，得到的马来酸酐-天然橡胶接枝物既能与聚酰胺6短纤维也能与天然橡胶形成良好的结合，有助于提高短纤维增强橡胶复合材料的物理机械性能。     

马来酸酐接枝乙烯-辛烯共聚物对聚对苯二甲酸丁二醇酯的增韧作用

研究了马来酸酐接枝乙烯-辛烯共聚物(POE—g—MAH)和POE—g—MAH／聚丙烯(PP)共混物对聚对苯二甲酸丁二醇酯(PBT)的增韧作用。结果表明,POE—g—MAH／PP共混物对PBT的增韧效果优于POE—g—MAH的,POE—g—MAH和PP并用具有显著的协同增韧作用。扫描电镜照片表明,POE—g-MAH／PP共混物增韧PBT具有软壳-硬核结构。     

Crosslinking and ozone degradation of thermosetting resins based on maleic anhydride/diene copolymer and polyfunctional alcohols

Crosslinking and de‐crosslinking reactions of an alternating copolymer of maleic anhydride (MAn) and 2,4‐dimethyl‐1,3‐pentadiene (DMPD) by thermal curing with polyfunctional alcohols as the crosslinkers and subsequent ozone degradation are reported in this article. The ring‐opening reaction of an anhydride group by polyfunctional alcohols produces network polymers with an ester linkage. The rate of crosslinking reaction depends on the curing conditions, i.e. the structure of the used alcohols and the curing temperature and time. The crosslinking density of the alcohol‐cured copolymers is low due to a slow reaction between the anhydride and hydroxy groups, being different from the corresponding epoxy‐cured copolymer with a dense network structure reported in a previous article. The insoluble resins are readily de‐crosslinked and solubilized by ozone degradation. The polymer surface modification by ozone is also investigated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42763.