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1.
Direct insertion probe pyrolysis mass spectrometry (DIP-MS) analyses of poly(methyl methacrylate) (PMMA), poly(vinyl acetate) (PVAc) and binary PMMA/PVAc guests, coalesced from their inclusion compounds (ICs) formed with host γ-cyclodextrin (γ-CD) through removal of the γ-CD host, have been performed. A slight increase in the thermal stabilities of the coalesced polymers were recorded both by TGA and DIP-MS compared to the corresponding as-received polymers. The DIP-MS observations pointed out that the thermal stability and degradation products of these polymers are affected once they are included inside the IC channels created by the stacked host γ-CDs. DIP-MS observations suggested that the degradation mechanisms for PMMA and PVAc chains in their coalesced blend were significantly altered from those observed in their as-received and solution blended samples. This was attributed to the presence of specific molecular interactions between the intimately mixed PMMA and PVAc chains in their coalesced blend. 相似文献
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Direct insertion probe pyrolysis mass spectrometry (DIP-MS) analyses of polycarbonate/poly(methyl methacrylate)/poly(vinyl acetate), (PC/PMMA/PVAc), ternary blends have been performed. The PC/PMMA/PVAc ternary blends were obtained by coalescing from their common γ-cyclodextrin-inclusion compounds (CD-ICs), through the removal of the γ-CD host (coalesced blend), and by a co-precipitation method (physical blend). The coalesced ternary blend showed different thermal behaviors compared to the co-precipitated physical blend. The stability of PC chains decreased due to the reactions of CH3COOH formed by deacetylation of PVAc above 300 °C, for both coalesced and physical blends. This process was more effective for the physical blend most likely due to the enhanced diffusion of CH3COOH into the amorphous PC domains, where it can further react producing low molecular weight PC fragments bearing methyl carbonate chain ends. The decrease in thermal stability of PC chains was less significant for the coalesced ternary blend indicating that the diffusion of CH3COOH was either somewhat limited or competed with intermolecular reactions between PMMA and PC and between PMMA and PVAc, which were detected and were associated with their close proximity in the intimately mixed coalesced PC/PMMA/PVAc ternary blend. 相似文献
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聚甲基丙烯酸甲酯与聚醋酸乙烯酯共混的红外光谱研究 总被引:2,自引:0,他引:2
用红外光谱(FTIR)研究了聚甲基丙烯酸甲酯(PMMA)与聚醋酸乙烯酯(PVAc)共混体系相容性,在160℃以上共混体系发生相分离;分相体系与非分相体系的FTIR谱明显不同;共混体系的FTIR谱不能从两统组分红外光谱简单加和得到;结果表明大分子构象发生了变化,PMMA/PVAc体系相容可能是大分子构象熵变所致。 相似文献
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聚乙二醇-b-聚乳酸的合成及其电纺形成超细纤维研究 总被引:2,自引:2,他引:0
为了提高聚乳酸的亲水性,以辛酸亚锡为催化剂、聚乙二醇单甲醚(mPEG)为大分子引发剂进行丙交酯(LLA)开环聚合,合成聚乙二醇-b-聚乳酸两嵌段共聚物(PELA).以红外光谱1、H核磁共振谱、接触角测试、差热扫描量热分析等方法对PELA的结构及性能进行表征.结果表明,通过调控mPEG与LLA的投料比可以控制PELA的相对分子质量,而随着mPEG组分含量或链长增加,共聚物亲水性增强,但其Tg、Tcc、Tm有所降低.由普通电纺制备PELA超细纤维,并分别由乳液电纺和同轴电纺得到以水溶性聚氧化乙烯(PEO)为芯、PELA为壳的芯/壳结构复合超细纤维(E-PEO/PELA和C-PEO/PELA).扫描电镜和透射电镜结果表明,PELA、E-PEO/PELA和C-PEO/PELA超细纤维形貌良好.随着PELA中mPEG含量的增加,电纺PELA纤维膜的吸水率增强,而由乳液电纺和同轴电纺制备的PEO/PELA芯/壳结构超细纤维膜,亲水性均好于PELA超细纤维膜. 相似文献
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The crystallization process of poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA)and PEO/poly(vinyl acetate) (PVAc) blends has been characterized by Fourier Transform Infrared(FTIR) spectra in conjunction with Differential Scanning Calorimeter (DSC) measurements. Thecrystallinity of PEO varies consistently with PEO content in PEO/PVAc blends and the PEO/PMMAblends containing 50 wt% or less PMMA. For the PEO/PMMA blends containing 60 wt% ormore PMMA, the crystallinity of PEO decreases more than PEO content but develops with crystal-lization time. These results can be explained in terms of difference between the crystallization tem-perature (T_c) and glass transition temperature (T_g) of the blends as a function of content of amorphouscomponent. 相似文献
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IR spectral shifts of carbonyl vibrational absorption for ethyl acetate, which acts analogically as the structural unit of poly(methyl methacrylate), in cyclohexane, chloroform, chlorinated paraffins, poly(vinyl chloride) and chlorinated poly(vinyl chloride) were measured. The results suggest that there are specific interactions between the carbonyl groups and the chlorinated hydrocarbons which could be responsible for the apparent compatibility of poly(vinyl chloride)—poly(methyl methacrylate) and chlorinated poly(vinyl chloride)—poly(methyl methacrylate) blends. Additionally, the effects of the preparation mode of blend films on phase separation and observed compatibility are discussed. 相似文献
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To assess the compatibility of blends of synthetic poly(propylene carbonate) (PPC), with a natural bacterial poly(3-hydroxybutyrate) (PHB), a simple casting procedure of blend was used. poly(3-hydroxybutyrate)/poly(propylene carbonate) blends are found to be incompatible according to DSC and DMA analysis. In order to improve the compatibility and mechanical properties of PHB/PPC blends, poly(vinyl acetate) (PVAc) was added as a compatibilizer. The effects of PVAc on the thermal behavior, morphology, and mechanical properties of 70PHB/30PPC blend were investigated. The results show that the melting point and the crystallization temperature of PHB in blends decrease with the increase of PVAc content in blends, the loss factor changes from two separate peaks of 70PHB/30PPC blend to one peak of 70PHB/30PPC/12PVAc blend. It is also found that adding PVAc into 70PHB/30PPC blend can decrease the size of dispersed phase from morphology analysis. The result of tensile properties shows that PVAc can increase the tensile strength and Young’s modulus of 70PHB/30PPC blend, and both the elongation at break and the tensile toughness increase significantly with PVAc added into 70PHB/30PPC. 相似文献
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Tamer Uyar Cristian C. Rusa Xingwu Wang Mariana Rusa Jale Hacaloglu Alan E. Tonelli 《Journal of Polymer Science.Polymer Physics》2005,43(18):2578-2593
A procedure for the formation of intimate blends of three binary polymer systems polycarbonate (PC)/poly(methyl methacrylate) (PMMA), PC/poly(vinyl acetate) (PVAc) and PMMA/PVAc is described. PC/PMMA, PC/PVAc, and PMMA/PVAc pairs were included in γ‐cyclodextrin (γ‐CD) channels and were then simultaneously coalesced from their common γ‐CD inclusion compounds (ICs) to obtain intimately mixed blends. The formation of ICs between polymer pairs and γ‐CD were confirmed by wide‐angle X‐ray diffraction (WAXD), fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). It was observed [solution 1H nuclear magnetic resonance (NMR)] that the ratios of polymers in coalesced PC/PMMA and PC/PVAc binary blends are significantly different than the starting ratios, and PC was found to be preferentially included in γ‐CD channels when compared with PMMA or PVAc. Physical mixtures of polymer pairs were also prepared by coprecipitation and solution casting methods for comparison. DSC, solid‐state 1H NMR, thermogravimetric analysis (TGA), and direct insertion probe pyrolysis mass spectrometry (DIP‐MS) data indicated that the PC/PMMA, PC/PVAc, and PMMA/PVAc binary polymer blends were homogeneously mixed when they were coalesced from their ICs. A single, common glass transition temperature (Tg) recorded by DSC heating scans strongly suggested the presence of a homogeneous amorphous phase in the coalesced binary polymer blends, which is retained after thermal cycling to 270 °C. The physical mixture samples showed two distinct Tgs and 1H T1ρ values for the polymer components, which indicated phase‐separated blends with domain sizes above 5 nm, while the coalesced blends exhibited uniform 1H spin‐lattice relaxation values, indicating intimate blending in the coalesced samples. The TGA results of coalesced and physical binary blends of PC/PMMA and PC/PVAc reveal that in the presence of PC, the thermal stability of both PMMA and PVAc increases. Yet, the presence of PMMA and PVAc decreases the thermal stability of PC itself. DIP‐MS observations suggested that the degradation mechanisms of the polymers changed in the coalesced blends, which was attributed to the presence of molecular interactions between the well‐mixed polymer components in the coalesced samples. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2578–2593, 2005 相似文献
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聚酰胺-胺的合成与表征 总被引:1,自引:0,他引:1
<正> 1970年以来,Ferruti等发表了一系列文章关于聚酰胺-胺(PAA)的研究。PAA是一类由伯胺或双仲胺和双丙烯酰胺通过氢移位聚合生成的新聚合物: 相似文献
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研究比较线型聚酯胺和超支化聚酯胺作为添加剂用于静电纺丝时,对低浓度聚甲基丙烯酸甲酯溶液可纺性的改善效果及其机理.结果表明,只需加入1wt%的添加剂,无论是线型的还是超支化聚酯胺均能够提高低浓度聚甲基丙烯酸甲酯溶液的可纺性,得到无"串珠"结构的均匀纤维,其直径比不加添加剂而在高浓度纺丝时得到的均匀纤维细很多.通过溶液性能的测试,发现提高可纺性的原因均是由于溶液电导率的提高.超支化聚酯胺因其多枝的结构而含有较多的极性端基,致使本身电导率较高,因而对可纺性的改善效果好于线型聚酯胺. 相似文献
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The ultrasonic degradation of poly(ethylene oxide) and poly(vinyl acetate) in benzene solution, and grafting reaction of poly(vinyl acetate) with poly(ethylene oxide) were studied. It is found that the chain-scission reactions follow the course suggested by D. W. Ovenall. The structure of the copolymer was identified by IR, NMR and DTA, showing that the copolymer prepared is a graft copolymer mainly. The copolymer formed by irradiating 1% PEO/PVAc solution (PEO/PVAc:1/1 by weight) for a period of 10 rain at 18.2 kHZ, with 2.0 A input current on reversed main circuit, amounts to 10.5%. 相似文献
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PPEKK/PEI共混物的相容性及拉伸性能 总被引:3,自引:0,他引:3
作为相容体系 ,聚芳醚酮与聚醚酰亚胺 (PEI)共混物体系的研究受到了研究者的重视[1~ 4] .由于现在已商品化的聚芳醚酮基本上都是半结晶型聚合物 ,所以有有关无定型聚芳醚酮与聚醚酰亚胺共混物的研究鲜见报道 .含二氮杂萘酮结构聚芳醚酮酮 (PPEKK)是一种新型耐高温聚合物 ,相比于已经商品化的各种聚芳醚酮 ,PPEKK除具有优异的综合性能外 ,它最大的特点表现在以下两方面 ,PPEKK耐热性突出 ,玻璃化转变温度 (Tg)为 2 4 5℃左右 ,远高于各种商品化的聚芳醚酮 ;PPEKK为无定型聚合物 ,易溶于多种有机极性溶剂 ,大大的扩… 相似文献
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Thermal and photochemical stability of poly(methyl methacrylate) and its blends with poly(vinyl acetate) 总被引:1,自引:0,他引:1
An investigation of the thermal stability of poly(methyl methacrylate) (PMMA) blends with poly(vinyl acetate) (PVAc) revealed that PVAc acts as a stabilizer as concerns thermal and photochemical degradation when the processes take place in air. The temperatures of decomposition of these blends are higher than that of pure PMMA. The efficiency of photodegradation and photooxidation in the blends is lower than that of pure PMMA. 相似文献
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Hung‐Ling Liu Shu‐Hsien Li Eamor M. Woo 《Journal of Polymer Science.Polymer Physics》2006,44(8):1147-1160
This study investigated and discovered a new miscible ternary blend system comprising three amorphous polymers: poly(vinyl acetate) (PVAc), poly(vinyl p‐phenol) (PVPh), and poly(methyl methacrylate) (PMMA) using thermal analysis and optical and scanning electron microscopies. The ternary compositions are largely miscible except for a small region of borderline ternary miscibility near the side, where the binary blends of PVAc/PMMA are originally of a borderline miscibility with broad Tg. In addition to the discovering miscibility in a new ternary blend, another objective of this study was to investigate whether the introduction of a third polymer component (PVPh) with hydrogen bonding capacity might disrupt or enhance the metastable miscibility between PVAc and PMMA. The PVPh component does not seem to exert any “bridging effect” to bring the mixture of PVAc and PMMA to a better state of miscibility; neither does the Δχ effect seem to disrupt the borderline miscible PVAc/PMMA blend into a phase‐separated system by introducing PVPh. Apparently, the ternary is able to remain in as a miscible state as the binary systems owing to the fact that PVPh is capable of maintaining roughly equal H‐bonding interactions with either PVAc or PMMA in the ternary mixtures to maintain balanced interactions among the ternary mixtures. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1147–1160, 2006 相似文献
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以辛酸亚锡为催化剂,季戊四醇(PTOL)为引发剂,引发对二氧环己酮(PDO)单体开环聚合,合成了以PTOL为核的四臂聚对二氧环己酮(4s-PPDO).通过直接将4s-PPDO预聚物和聚乙二醇(PEG)于熔点以上、惰性气体保护下与偶联剂甲苯二异氰酸酯(TDI)交联共聚得到聚对二氧环己酮/聚乙二醇(PPDO-b-PEG)两亲性共网络聚合物(PPDO-PEG APCNs).研究了两亲性聚合物共网络结构、配比组成、溶剂种类等对聚合物溶胀率的影响,结果表明APCNs在不同类型的溶剂中表现出不同的溶胀行为,可以通过调节偶联剂的用量及PPDO/PEG的投料比来满足不同的实际需求.通过示差扫描量热分析(DSC)详细研究APCNs的结晶性能,证实交联反应降低APCNs的结晶度和结晶尺寸. 相似文献
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聚氧化乙烯和聚醋酸乙烯酯在超声波辐照下接枝反应的研究 总被引:1,自引:0,他引:1
本文分别研究了聚氧化乙烯(PEO)和聚醋酸乙烯酯(PVAc) 在苯溶液中的超声波辐照降解,PEO与PVAc在苯溶液中的超声波辐照共聚反应。实验证明,降解反应可用Ovenall方程描述。用IR、NMR和DTA分析了在超声波辐照作用下PEO与PVAc在苯溶液中生成的共聚物的结构,证明所得产物主要为接枝共聚物,将浓度为1%的(PEO-PVAc)苯溶液在频率为18.2kHz、逆变器主迥路输入电流为2.0安的超声波强度下,辐照10分钟,共聚物的产率为10.54%,接枝点密度为33.3%,平均接枝链长为17。 相似文献