利用FTIR光谱仪研究PU／PMMA IPN初期反应动力学

本文用FTIR光谱仪研完聚醚聚氨酯/聚甲基丙烯酸甲酯(PU/PMMA)互穿聚合物网络(IPN)的初期反应动力学.实验结果表明:该体系IPN在生成过程中动力学不同步是造成相容性较差的原因之一,提高反应温度和增加PMMA的引发剂用量有利于反应同步进行.增加PMMA的含量,使PU反应速度加快是PMMA"溶剂效应”的结果;增加PU含量,使PMMA反应速度减慢是PU的“笼壁效应”结果.聚醚聚氨酯及聚甲基丙烯酸甲酯初期反应均属一级反应动力学.     

网络间含离子键的聚氨酯/接枝乙烯基酯树脂互穿聚合物网络 研究

分别以双酚-A型环氧树脂E-51和聚醚型环氧树脂E-46为原料合成了两种二乙胺-环氧树脂和加成多元醇(分别命名为AE-51,AE-46),将其和甲基丙烯酸一起用于合成聚氨酯/接枝乙烯基酯树脂(PU/接枝VER)互穿聚合物网络(IPN),使之在两个网络间形成离子键。实验结果表明,这类新型的IPN材料中两个网络间的互穿程度与相容性进一步提高,从而导致刚性的接枝VER对弹性的PU网络有更好的增强效果。DSC和FTIR的测定结果表明,在含AE-51的IPN中,由于离子键的作用使PU网络硬段的有序结构遭到很大程度的破坏,与AE-51和PU网络中的硬段以及VER网络有较好的相容性有关,因此这类IPN材料具有较好的力学性能。     

EP-g-PU IPN结构阻尼材料

采用-NCO封端的聚氧酯(PU)预聚物,制备了环氧树脂-聚氨酯互穿网络(EP-g-PU IPN);通过添加受阻酚四[β-(3,5-二叔丁基-4-羟基苯基)丙酸]季戊四醇(AO-60)制备了AO-60/EP-g-PU IPN.通过FT-IR、DMA、SEM分别研究了改性分子链的基团变化、改性体系的动态性能及断裂面的形态,...     

蓖麻油聚氨酯／乙烯类聚合物交联共聚物的动态力学性能

本文研究了蓖麻油聚氨酯(COPU)/聚甲基丙烯酸丁酯(PBMA)交联共聚物(简称ABCP)的动态力学性能,并将其与COPU/PBMA,IPN的动态力学性能作了比较。发现在ABCP中两组份的阻尼峰互相叠加,形成半相容体系,而在IPN中阻尼峰有个宽的平台。透射电镜照片表明,IPN具有更大的相区结构。这些结果证明,化学交联比物理缠结具有更大的强迫互容性。通过对COPU/乙烯类聚合物(VP)交联共聚物相容性的研究,可知COPU/PBMA,COPU/PST和COPU/PMMA交联共聚物,在动态力学性能上是半相容体系,而COPU/PMA和COPU/PBA交联共聚物是互容体系。     

负载蛋白质的胶原/聚两性电解质IPN角膜替代物

以碳二亚胺/N-羟基琥珀酰亚胺(EDC/NHS)和聚乙二醇二丙烯酸酯(PEGDA)为交联剂分别对猪皮去端肽Ⅰ型胶原和3-(甲基丙烯酰胺)丙基-二甲基(3-磺丙)胺(MPDSAH)进行交联, 制备了具有互穿聚合物网络(IPN)结构的角膜替代物. 胶原基IPN角膜替代物的折光指数和白光透过率与天然人角膜相似. IPN水凝胶具有优于纯胶原凝胶的力学性能, 同时PMPDSAH网络的引入明显提高了IPN凝胶在胶原酶中的稳定性. 体外细胞培养实验结果表明, IPN角膜替代物支持人角膜上皮细胞生长. 通过冷冻干燥-溶胀后包覆技术可将牛血清白蛋白(BSA)和神经生长因子(NGF)装载到角膜替代物中, 负载药物的冻干凝胶可干态保存, 避免了湿态下蛋白质等活性因子的失活和漏泄; 再吸水恢复原状的特性可使角膜替代物完好地移植病灶部位, NGF具有良好的缓释效果. 此负载NGF的复合角膜替代物有望促进角膜组织和神经的再生.     

脂肪族聚碳酸酯型聚氨酯/聚甲基丙烯酸甲酯互穿网络聚合物的研究

用同步法合成了聚碳酸亚丙酯聚氨酶／聚甲基丙烯酸甲醇互穿网络聚合物（PPCPU／PMMA，IPN），调节IPN中两组分配比制备出多种高聚物共混物。用DSC、TEM对IPN的研究结果表明．PPCPU／PMMA之IPN的两组分是互不相容的。同时对各种组成比的IPN材料进行力学性能测试，并用SEM对断面进行了观察，发现IPN的密度大于相应体系体积加和值。     

丁腈羟聚氨酯/聚环氧树脂互穿网络高聚物的研究

本文用同步法合成了丁腈羟聚氨酯/聚环氧树脂(PU/PE)体系的互穿网络高聚物(IPN),研究了各种因素对其形态和玻璃化转变行为的影响,并用扭辫及扭摆(TPA)在-100℃-+150℃温度区间内,测试全部试样的动态力学谱。结果表明,PU/PE是不相容体系,在电镜片上呈现细胞状结构(400-800Å)。由于两组份网络互穿,发生“强迫互容”,使T_g内移,通过调整组份比和加不同扩链剂等能提高阻尼值,加宽T_g转变区。     

聚氨酯聚二甲基硅氧烷半IPN透气性研究

近年来,互穿聚合物网络(IPN)的开发受到了广泛的关注。以聚氨酯为一组分,聚丙烯腈、聚酯及环氧树脂等为另一组分的IPN体系的研究已有报道,而聚氨酯与有机硅的IPN体系的研究报道很少。在本文中,我们对聚氨酯(PU)与聚二甲基硅氧烷(PDMS)半IPN的透气性与结构的关系进行了研究。     

聚[丙烯酸甲酯-甲基丙烯酸2-(二甲氨基)乙酯]/环氧树脂IPN力学性能的研究

用同步法合成聚[丙烯酸甲酯-甲基丙烯酸2-(二甲氨基)乙酯]/环氧树脂(P(MA-DMA)/EP)互穿聚合物网络(IPN),对其力学性能进行了研究,结果表明,该体系IPN由于两网络间接枝导致相客性比较好,动态力学谱仅出现一个转变温度,当P(MA-DMA)/EP=20/80时,力学性能显示正协同效应,对环氧树脂的增韧效果最佳,不同组成比的IPNT_g实-T_g计与(d_实-d_计)差值成正比。     

聚苯乙烯/聚丙烯酸丁酯乳胶互穿聚合物网络的动态力学性能研究

<正> 互穿聚合物网络(IPN)是一种新型聚合物共混物.自Sperling在1969年合成聚丙烯酸乙酯/聚苯乙烯异步IPN(Sequential IPN)后,该领域进展很快.乳胶IPN(latex IPN)是用改进的乳液聚合法合成的一种微观互穿IPN.在前文中,我们报道了聚苯乙烯/聚丙烯酸丁酯(PS/PBA)乳胶IPN的合成,本文研究一些因素对PS/PBA乳胶IPN动态力学性能的影响.     

COPU／PMMA AB交联聚合物的性能

AB交联聚合物(ABCP)是由聚合物A链与化学组成不同的聚合物B链交联构成。它的网络结构不同于IPN。IPN是由两个独立的网络构成,而在ABCP中仅存在一个聚合物网络。目前人们对它远不及对IPN了解得多。 本文选用蓖麻油为原料,与甲基丙烯酸甲酯共聚,合成了一种ABCP。研究了它的力学性能,转变与松弛,相容性及形态结构与组成及交联密度的关系。     

蓖麻油聚氨酯/甲基丙烯酸甲酯交联共聚物的合成与表征

<正> AB交联共聚物(ABCP)和互穿网络聚合物(IPN)都属交联网状聚合物,只是前者形成一个网络,后者构成两个独立网络(图1),因此两者的性能有明显差别,特别是相容性。目前对ABCP的研究主要是聚酯,聚醚体系,本工作选用便宜的蓖麻油聚氨酯(COPU)和MMA为原料,合成ABCP,得到具有阻尼性能的材料。     

Copolymerization of Polymethyl Methacrylate Macromers with n-Butyl Acrylate and Mechanical Properties of the Graft Copolymers

The copolymerization of polymethyl methacrylate (PMMA) macromer with butyl acrylate in benzene was studied. the PMMA macromer was obtained by radical polymerization in the presence of thioglycollic acid as a chain transfer agent, followed by termination with glycidyl methacrylate. the copolymerization rate and effects of various copolymerization conditions, such as molecular weight of macromer, charging ratio of macromer to monomer, amount of initiator, kind of solvent, concentration, and copolymerization temperature, on grafting efficiency and molecular weight of copolymer were investigated. the copolymers were purified by fractional precipitation. the purified copolymers with uniform PMMA grafts were characterized by GPC, IR, UV, and DSC. Structural parameters of the copolymers were determined by VPO and membrane osmometry. Average grafting number per chain decreases with an increase of conversion. Measurement of mechanical properties of the copolymers shows that both molecular weight and the content of the macromer affect mechanical properties of the copolymer, and within a certain range they behave like a thermoplastic elastomer.     

环氧树脂/聚丙烯酸酯型网间交联互穿网络聚合物的研究(Ⅰ)——形态和动态力学行为

互穿网络聚合物(IPN)中两个网络相互贯穿、缠结,增大了组分间的相容性,使玻璃化转变温度(T_g)内移,表现出相当宽的温度(频率)范围,引起人们广泛注意。但由于普通的IPN体系两个T_g间往往有一个凹谷,不是一种理想的吸震材科,Scarito及其同事采用网络间交联的方法提高了凹谷的高度。本工作以甲基丙烯酸乙二醇脂为网     

Understanding the Miscibility and Morphology of Poly(methyl methacrylate) and Styrenic Copolymer Blends of Tunable Domain Sizes

In the present study, we have investigated the miscibility, morphology and mechanical behavior of poly(methyl methacrylate) (PMMA) blends with a series of poly(styrene-co-maleic anhydride) (SMA) copolymers containing varying amounts of maleic anhydride (MA) content (from 8 to 26%). The experimental findings have been substantiated by the modeling studies to gain fundamental understanding of the observed phenomena with respect to the miscibility of the PMMA and SMA blends of a given MA content. The morphological differences, molecular weights, domain sizes and mechanical behavior of the blends at a given ratio of PMMA and copolymers have been investigated and a correlation has been made between the morphological understanding to the molecular weights and mechanical properties. The results indicate that the PMMA/SMA blends are miscible only at a certain MA content providing transparent PMMA/SMA blends without affecting any of the enabling properties of PMMA that are of commercial interest through a facile melt mixing process. The surface hardness and % recovery (nano-indentation) of these blends were evaluated as well to gain fundamental understanding of the surface characteristics and mechanicals of the blends.     

Orientational birefringence of uniaxially compressed PMMA networks in the unswollen state

Swollen PMMA networks show significant deviations from the theory of rubber elasticity. The unusual mechanical, optical and swelling properties have been explained by the existence of associations, well known for PMMA solutions.Unswollen PMMA networks show stress optical properties which are very similar to the networks swollen in carbon tetrachloride which is known as a strong complexing solvent. This indicates that associations exist in the bulk material. Swelling in carbon tetrachloride does not change the content of associations, only the glass transition temperature is reduced.Increasing the amount of crosslinking agent proves that the stress optical coefficient depends on the crosslinking density. This is contrary to the theoretical predictions. An explanation given by the effect of short network chains is not satisfactory. However, the consideration of a crosslinking chain instead of a crosslinking point gives a sufficient explanation. An oriented crosslinking chain gives a positive contribution to the total optical anisotropy while a PMMA chain shows a change from negative values (hindered rotation) to positive values (free rotation).Part I in Colloid & Polym Sci 262:182 (1984)Deceased Sept. 4, 1984     

Effect of oil and cured agent content on the structure and properties of thermoplastic vulcanizates

The effect of oil and curing agent content on the mechanical behavior of thermoplastic vulcanizates, based on a polypropylene (PP) and ethylene‐propylene‐diene copolymer (EPDM), was investigated. Mechanical properties such as Young's modulus, stress at 100% elongation and ultimate stress were investigated as a function of blends' composition and phase morphology. Experimental studies show that the Young's modulus of the vulcanizates depends on both PP/EPDM ratio and oil content in the blends; both ultimate strength and stress at 100% elongation increase with curing agent content.     

TOUGHENING OF POLYCARBONATE WITH PBA-PMMA CORE-SHELL PARTICLES

The miscibility, mechanical properties, morphology and toughening mechanism of PC/PBA-PMMA blends were investigated. The dynamic mechanical results show that PC/PBA-PMMA blend has good miscibility and strong interfacial adhesion. The Izod impact strength of blend PC/PBA-PMMA with 4% (volume fraction) PBA-PMMA core-shell modifier is 16 times higher than that of pure PC. The core-shell volume fraction and thickness of the PMMA shell have effect on the toughness of PC/PBA-PMMA blends. As PMMA volume fraction increases, the toughness of PC/PBA-PMMA blend increases, and reaches a maximum value at 30% volume fraction of PMMA or so. The tensile properties of PC/PBA-PMMA blend with a minimum amount of PBA-PMMA modifier show that brittle-tough transition has no significant variance in comparison with that of pure PC. The scanning electron microscopic (SEM) observation indicates that the toughening mechanism of the blend with the pseudo-ductile matrix modified by small core-shell latex polymer particles is the synergetic effect of cavitation and shear yielding of the matrix.     

Poly(ethylene-co-vinyl alcohol) and poly(methyl methacrylate) blends: Phase behavior and morphology

In this work blends of poly(ethylene-co-vinyl alcohol) (EVOH) with different ethylene contents (27, 32, 38 and 44 mol%) and poly(methyl methacrylate) (PMMA) were prepared by mechanical mixing in the melted state. The miscibility and melting behavior as a function of blend composition and the ethylene content in EVOH copolymers were investigated by means of differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The morphology of the cryofractured surfaces was examined by scanning electron microscopy (SEM). DSC and DMTA data show that EVOH/PMMA blends are immiscible, independent of EVOH and blend composition. The SEM analysis in agreement with DMTA analysis indicates that the morphology of phases depends on the blend composition, with phase inversion occurring as the concentration of one or other polymer component increases. However, the copolymer composition apparently does not affect the domain size distribution for blends containing 20 wt% of EVOH or 20 wt% of PMMA. A better phase adhesion is observed mainly for blends with 50 wt% of each polymer component.     

Effect of molecular interactions on the miscibility and structure of polymer blends

The effect of polymer-polymer interactions on the miscibility and macroscopic properties of PVC/PMMA, PVC/PS and PMMA/PS blends were studied in the entire composition range. The miscibility of the components was characterized by the Flory-Huggins interaction parameter or by quantities related to it. Thermal analysis, light transmittance measurements, and scanning electron microscopy were carried out on the blends and their mechanical properties were characterized by tensile tests. Interactions were analyzed by infrared spectroscopy and contact angle measurements. All three polymer pairs form heterogeneous blends, but the strength of molecular interactions is different in them, the highest is in PVC/PMMA system resulting in partial miscibility of the components and beneficial mechanical properties. The structure of these blends depends strongly on composition. A phase inversion can be observed between 0.5 and 0.6 PMMA content accompanied with a significant change in structure and properties. The PVC/PS and the PMMA/PS pairs are immiscible, though the results indicate the partial solubility of the components. The analysis of the surface characteristics of the components and the comparison of quantities derived from them with miscibility as well as with the macroscopic properties of blends revealed that blend properties cannot be predicted in this way, since they are affected by several factors.