含规整PMMA支链的共聚物及其离聚体的力学性能

研究了用聚甲基丙烯酸甲酯（ＰＭＭＡ）大单体与丙烯酸丁酯（ＢＡ）共聚制得的接枝共聚物及其与ＢＡ及丙烯酸（ＡＡ）共聚并中和制得的离聚体的力学性能与支链分子量、支链含量、共聚物分子量、羧基含量、中和度及离子种类的关系．结果表明这二种产物均呈现较好的热塑性弹性体行为，而离聚体的性能更为优越。     

含聚氧乙烯支链的三元共聚物及其离聚体

用聚氧乙烯（PEO）大单体与丙烯酸丁酯（BA）及丙烯酸（AA）共聚，合成了三元规整接枝共聚物，并经离子中和生成了离聚体。研究了共聚条件对各单体转化率及共聚物相对分子质量的影响。产物经纯化后用红外光谱仪，膜渗透压计，凝胶渗透色谱仪等进行了表征。研究了共聚物的平均接枝数，结晶度，力学性能及吸水性，还研究了丙烯酸质量分数，PEO质量分数，中和度及不同离子对离聚体力学性能的影响。结果表明，共聚开始大单体的转化速率大于小单体的，后期则相反。大单体转化率随引发剂用量增加而增加，随大单体占总单体的质量分数及大单体相对分子质量增加而下降，共聚物相对分子质量则随聚合时间增加而增加，随引发剂用量增加而降低。共聚物有一定结晶度及100％－200％的吸水率。三元共聚物中和成离聚体后拉伸强度明显增加，呈热塑性弹性体性质。铅或锌离子中和的离聚体拉伸强度最大。     

苯乙烯-环氧丙烷多嵌段共聚物的合成及表征

在端双羟基聚苯乙烯和聚丙二醇中加入偶联剂2,4-甲苯二异氰酸酯(TDI),采用一步法或二步法制备了苯乙烯-环氧丙烷多嵌段共聚物。结果表明,由二步法制备的共聚物较一步法制备共聚物中均聚物的含量少。粗产物可分别用乙醇及十氢萘萃取,以除去未反应的聚丙二醇及端双羟基聚苯乙烯。纯化物经红外光谱法、核磁共振波谱法、凝胶渗透色谱法、膜渗透压法和元素分析法测试表明,试样为聚苯乙烯与聚环氧丙烷的多嵌段共聚物。     

水性聚氨酯胶粘剂性能的影响因素探讨Ⅱ——结构因素的影响

探讨了结构因素包括离子基含量,硬段/软段的物质的量比,低聚物二醇的结构和分子质量,异氰酸酯结构,扩链剂类型和扩链程度,离子基的中和程度或离子对的性质以及溶剂量对水性聚氨酯(WPU)分散液性能和胶膜力学性能的影响。     

离聚体的制备及抗静电研究

乙烯丙烯酸共聚物(EAA)在熔融中和反应下形成离子聚合物,首先测试了不同中和度的钾离聚体的流变性能和抗静电性能,另外测试了K、Na、Mg、Zn四种离子中和两种EAA而得的离聚体抗静电的效果,并讨论了两种羧酸含量的EAA按不同比例复配、中和后对抗静电性能的影响。结果发现,钾离聚体的抗静电性能最为优异,中和度为80%的EAA 5200钾离聚体,其表面电阻率可达2.53×10~9Ω,但是由于原料中羧酸含量较低,复配效果不明显。在表征了不同离子的离聚体吸水能力后,发现钾离聚体的吸水能力和稳定性最高,其平衡吸水率可达20.19%。     

CPVC羧酸型离聚体的合成以及性能研究

采用氯化原位接枝制备的氯化聚氯乙烯接枝丙烯酸(CPVC-g-AA)与Al(OH)3中和,制备羧酸型离聚体.将离聚体纯化后进行傅立叶变换红外光谱(FT-IR)和差示扫描量热仪(DSC)分析,并进行动态机械分析(DMA)测试,讨论了离聚体力学性能和溶胀性能.结果表明,FT-IR谱图显示出现了新的离子特征吸收峰;离聚体的玻璃化转变温度比CPVC-g-AA的有很大提高;Al离子含量和中和度对离聚体的力学性能具有较大影响;Al离子含量高时,离聚体表现出溶胀行为.     

蓖麻油聚氨酯/聚甲基丙烯酸甲酯交联共聚物中氢键对性能的影响

本文在蓖麻油聚氯酯/聚甲基丙烯酸甲酯交联共聚物体系中,加入不同含量的丙烯酸共聚,详细考察了氢键对力学性能、相容性及形态结构的影响。结果表明:丙烯酸含量为7.5％时,材料的相容性最差,微区尺寸在几十纳米,这时的增韧效果最好。丙烯酸含量在5％和lO％时相容性最佳。     

硅垢的抑制方法

介绍了用选择的低分子量（甲基）丙烯酸或马来酸基二地共聚物或三元共聚物，镁离子或选择的二元共聚物或三元共聚物与铝离子或镁离子的混合物，或聚丙烯酸或聚马来酸与铝离子或镁离子的混合物来抑制含水系统中硅垢形成的方法。     

丙烯酸—2—硝基乙酯—丙烯酸丁酯—丙烯酸共聚物的合成

对丙烯酸－２－硝基乙酯－丙烯酸丁酯－丙烯酸共聚物的合成进行了研究，从而改进了低温力学性能，所得聚合物在溶剂下用全氟醋酸铬可室温固化，得到表面光滑，机械强度较好的弹性体。     

淀粉与聚丙烯共混体系的相容剂

采用丙烯酸十八酯-马来酸酐的共聚物(OA-MA)作为聚丙烯(PP1330)／淀粉／无机填料共混体系的相容剂,制成的共混材料,代替聚苯乙烯发泡体作为可降解的一次性餐饮具。通过DSC和力学性能、流变性能等测试,结果表明OA-MA共聚物作为PP1330／淀粉/CaCO3共混体系相容剂的效果与通用的偶联剂相差无几。     

Ionomers made from copolymers with uniform grafts

Summary Carboxylic acid-containing graft copolymers with uniform polystyrene grafts were synthesized by copolymerization of methacrylate-terminated polystyrene macromers, acrylic acid and butyl scrylate. The graft copolymers were neutralized with metal ions in solution or in melt to form ionomers, which were characterized by IR, TEM and dynamic mechanical analysis. TEM photographs showed that there appeared three phases in the ionomers, namely polystyrene domains, ion clusters and continueous phase of polybutyl acrylate, while dynamic mechanical analysis indicated the phase separation of polystyrene and ion-containing polyacrylate.     

Ionomers made from terpolymers with uniform poly(methyl methacrylate) grafts

Terpolymers with uniform poly(methyl methacrylate) (PMMA) grafts were prepared by terpolymerization of PMMA macromonomer, butyl acrylate, and acrylic acid in benzene using AIBN as initiator. During terpolymerization the macromonomer polymerizes faster than the monomers at the beginning but slower at the latter stage. The terpolymers were purified by solvent extraction and fractional precipitation. The average grafting number per chain of the terpolymers was determined to be 3–8. Ionomers were obtained by neutralization of the terpolymers with alkali hydroxide or metallic acetate. Dynamic mechanical spectrum of the ionomer shows the existence of two T_g's, which implies the occurence of microphase separation. The ionomer exhibits high damping over a temperature range from ?25 to 100°C. Both PMMA grafts and metallic carboxylate content raise the tensile strength of the ionomer and lower the ultimate elongation. The tensile strength of ionomers neutralized with different metallic ions decreases in the following order: Pb²⁺ > Zn²⁺ > Na⁺ > Ca²⁺ > Mg²⁺ > K⁺. The ionomers with uniform PMMA grafts show much better mechanical properties than the terpolymer without neutralization or the ionomer without PMMA grafts.     

Miscibility and mechanical properties of poly(styrene-co-4-vinylpyridine) and poly(butyl acrylate-co-acrylic acid) ionomer blends

The miscibility of polystyrene with poly(butyl acrylate) is very poor. Ionic interactions have been utilized recently as miscibility enhancers. In this paper, dynamic mechanical studies indicate that ion pair–ion pair interactions can be utilized to achieve miscibility in blends of polystyrene and poly(butyl acrylate). The styrenes contain 0–15mol% quaternary ammonium salt of 4-vinylpyridine, while the butyl acrylates contain 0–15mol% potassium acrylate groups. The miscibility increases with increase of ion content. When the ion content exceeds 11mol%, the polymers can be completely miscible. The mechanical properties of the ionomers and their blends were also studied. The results indicate that the tensile strength of ionomer blends is higher than that of corresponding poly(butyl acrylate-co-potassium acrylate)s (PBA-AA-K). The elongation at break of ionomer blends is higher than that of the corresponding poly(styrene-co-N-methyl-4-vinylpyridinium iodide) (PS-4VP-Q). © 1998 SCI.     

Synthesis of acrylate modified vinyl chloride and vinyl isobutyl ether copolymers and their properties

With acrylic acid, butyl acrylate and methyl methacrylate as the monomers, acrylate modified vinyl chloride and vinyl isobutyl ether copolymers were prepared by solution polymerization. Firstly, vinyl chloride and vinyl isobutyl ether copolymers were grafted with acrylic monomers to obtain a product containing acrylate grafted vinyl chloride and vinyl isobutyl ether copolymers and polyacrylate, which was then neutralized by triethylamine and dispersed into water to get a self-emulsified emulsion. The acrylate modified vinyl chloride and vinyl isobutyl ether copolymers were characterized by Fourier transform infrared spectroscopy. The mean molecular weight of grafted polymer was determined by gel permeation chromatography, and the particle sizes and their distributions of the dispersions were measured by laser light scattering. The influences of initiator concentration, acrylate content, acrylic acid content and neutralization degree upon the properties of the modified copolymers were discussed. The results show that the emulsion will be with good storage stability, and the modified polymer will be with high water resistance, impact resistance and excellent adhesion when initiator concentration is 1.5%, acrylate content is 50%, acrylic acid content ranges from 9% to 11%, and neutralization degree is between 80% and 100%.     

聚苯乙烯大单体/丙烯酸辛酯规整接枝共聚物的结构、性能与增容作用

用傅里叶变换红外光谱、透射电子显微镜和差示扫描量热仪表征了聚苯乙烯大单体和丙烯酸辛酯规整接枝共聚物(POA-g-PS)的结构,测定了其物理机械性能,并研究了POA-g-PS作为聚苯乙烯/丙烯酸酯橡胶体系的共混增容剂时,共混物组成、接枝物用量及接枝物组成对共混物物理机械性能的影响。结果表明,POA-g-PS属于两相态,存在微观相分离结构;当聚苯乙烯大单体的质量分数在40%左右时,POA-g-PS是一种具有较大拉伸强度、较大扯断伸长率及较小永久变形的热塑性弹性体;扫描电镜和差示扫描量热分析表明接枝共聚物促进了聚苯乙烯/丙烯酸酯橡胶共混体系的互容,起到了增容剂的作用。     

自乳化法制备水性上光油用核壳苯丙乳液

以苯乙烯(St)、甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、丙烯酸(AA)等为主要原料,采用自乳化法制备具有核壳结构的无皂苯丙乳液。研究了丙烯酸用量、中和度、核单体用量及引发剂用量等因素对制备过程、乳液及涂膜性能的影响,并用FT-IR、TEM对聚合物和胶粒结构进行了表征。研究表明:当丙烯酸用量为15%～20%、中和度为90%、核单体用量为30%时,乳液的粒径小,自乳化性、稳定性达到最佳,且由此乳液配制的水性上光油具有较高的光泽,良好的耐水性和耐磨性。     

Some properties of styrene‐based ionomers II

Some properties of styrene‐based ionomers obtained from copolymers styrene (S) and acrylic acid (AA) or methacrylic acid (MA) obtained in emulsion containing alkali metal salts have been investigated. A study has been conducted to examine the influence of the acid content and nature (acrylic or methacrylic) and nature of alkali metal salt on the glass transition temperature, density, melt index, and activation energy of flow of the styrene‐based ionomers. The present studies have indicated that the temperature of glass transition (T_g) of sodium ionomers increases as the sodium content rises, but the increase is lower than in the case of the ionomers based on copolymers obtained in bulk. The density of films rises with the content of alkali metal salt introduced to the polystyrene chain, and it is higher than in the case of the ionomers based on copolymers obtained in bulk containing almost the same content of alkali metal salts. Styrene ionomers containing alkali metal acrylates have higher densities than those containing alkali metal methacrylates. The melt index of the investigated ionomers depends on the amount and type of introduced acid and salt, as well as on the molecular weight of the initial copolymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 268–275, 2005     

Effect of ethylene ionomers on the properties of crosslinked polyethylene

Most premature failure of underground crosslinked polyethylene (XLPE) cables in service, a matter of great concern, is due to aging induced by water treeing. To improve the water‐tree resistance, sodium‐neutralized poly (ethylene‐co‐acrylic acid) (EAA–Na) ionomers were blended with XLPE; the EAA–Na ionomers were prepared through the neutralization of sodium hydroxide and poly(ethylene‐co‐acrylic acid). A series of XLPE/EAA–Na ionomer blends were investigated through the measurement of the water absorption ratio, water treeing, and mechanical and dielectric testing; the results strongly suggested that EAA–Na ionomers could improve the water‐tree resistance of XLPE, and the XLPE/EAA–Na blends retained excellent mechanical properties and dielectric properties. Moreover, through the characterization of XLPE/EAA–Na blends with Fourier transform infrared spectrometry, dynamic mechanical analysis, and scanning electron microscopy, it was found that the neutralization reaction could be achieved completely; the XLPE and EAA–Na ionomers were partially compatible, so the EAA–Na ionomers could be dispersed well in the matrix with the process examined in this study. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3483–3490, 2007     

Surface modification of ultra-high molecular weight polyethylene fibers by γ-radiation-induced grafting

A technique for grafting acrylic polymers on the surface of ultra-high molecular weight polyethylene (UHMWPE) fibers utilizing ⁶⁰Co gamma radiation at low dose rates and low total dose has been developed. Unlike some of the more prevalent surface modification schemes, this technique achieves surface grafting with complete retention of the exceptional UHMWPE fiber mechanical properties. In particular, poly(butyl acrylate) and poly(cyclohexyl methacrylate) were successfully grafted onto UHMWPE fibers with no loss in tensile properties. The surface and tensile properties of the fibers were evaluated using Fourier transform infrared/photoacoustic spectroscopy (FTIR/PAS), X-ray photoelectron spectroscopy (XPS), and tensile tests. The reinforcement efficiency of untreated, polymer-grafted, and plasma-treated UHMWPE fibers in polystyrene and a poly(styrene-co-butyl acrylate-co-cyclohexyl methacrylate) statistical terpolymer was characterized using mechanical tensile tests. The thermoplastic matrix composites were prepared with 4 wt% discontinuous (10 mm), randomly distributed UHMWPE fibers. An approximate 30% increase in composite strength and modulus was observed for poly(cyclohexyl methacrylate)-grafted fibers in the terpolymer and polystyrene matrices. A comparable improvement was realized with the plasma-treated fibers. On the other hand, poly(butyl acrylate) grafts induced void formation, i.e. energy dissipation through plastic deformation and volume expansion at the fiber/matrix interface in terpolymer composites. The latter resulted in a 75% increase in the elongation to failure. The effect of polymer grafts on fiber/matrix adhesion is discussed in terms of the graft and matrix chain interactions and solubility, graft chain mobility, and fracture surface characteristics as determined by scanning electron microscopy (SEM).