共查询到20条相似文献,搜索用时 31 毫秒
1.
Thangamani Rajkumar Chinnaswamy Thangavel Vijayakumar Palanichamy Sivasamy Bojja Sreedhar Charles A. Wilkie 《Journal of Thermal Analysis and Calorimetry》2010,100(2):651-660
Imparting thermal stability to polymethyl methacrylate (PMMA) without affecting its optical clarity is attempted by incorporating
HET acid based oligoesters. Pure PMMA and PMMA containing five and 20 wt% of four different oligoesters are separately prepared
using bulk polymerization. The thermal properties of the materials studied using DSC, TG, TG–FTIR and Pyr–GC–MS are presented.
The main volatile degradation products identified are CO, HCl, CO2, H2O, hexachlorocyclopentadiene, hexachloroendomethylene tetrahydrophthalic acid/anhydride and methyl methacrylate. A detailed
mechanism for the influence of the degradation products of HET acid based oligoesters on the thermal degradation of PMMA is
also presented. 相似文献
2.
P. Poomalai 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(4-5):695-702
Poly(methyl methacrylate) (PMMA) and thermoplastic polyurethane (TPU) blends in different compositions viz., 95/05, 90/10, 85/15 and 80/20 (by wt/wt% of PMMA/TPU) have been prepared by melt mixing using a twin screw extruder. The thermal stability of these blends has been characterized by thermogravimetric (TG) analysis. All the blends are stable up to 381°C and complete degradation occurs at 488°C. A slight improvement in thermal stability was noticed with an increase in TPU content in the blends. Surface morphology of the blends has been studied by an optical microscope. Optical microphotographs revealed two‐phase morphology for all the blends. 相似文献
3.
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
4.
Sung‐Young Park Hee‐Young Park Hwa‐Soo Lee Sang‐Wook Park Chang‐Sik Ha Dae‐Won Park 《Journal of polymer science. Part A, Polymer chemistry》2001,39(9):1472-1480
This study was related to the investigation of the chemical fixation of carbon dioxide to a copolymer bearing epoxide and the application of the cyclic carbonate group containing copolymer‐to‐polymer blends. In the synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] [poly(DOMA‐co‐EA)] from poly(glycidyl methacrylate‐co‐ethyl acrylate) [poly(GMA‐co‐EA)] and CO2, quaternary ammonium salts showed good catalytic activity. The films of poly(DOMA‐co‐EA) with poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) blends were cast from N,N′‐dimethylformamide solution. The miscibility of the blends of poly(DOMA‐co‐EA) with PMMA or PVC have been investigated both by DSC and visual inspection of the blends. The optical clarity test and DSC analysis showed that poly(DOMA‐co‐EA) containing blends were miscible over the whole composition range. The miscibility behaviors were discussed in terms of Fourier transform infrared spectra and interaction parameters based on the binary interaction model. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1472–1480, 2001 相似文献
5.
Nancy Alvarado Luz Alegría Claudia Sandoval Galder Kortaberría Angel Leiva Ligia Gargallo 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):864-872
The synthesis of a poly(diethylaminoethyl methacrylamide) (BP), based on a lineal methacrylamide with diethylaminoethyl branches was carried out. Thermal behavior was studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Relatively high thermal stability is found. Blends with poly(methylmethacrylate) (PMMA), poly(acrylic acid) (PAA) and poly(monomethyl itaconate) (PMMI) were prepared. Their thermal properties in blends were studied together with miscibility, in order to improve thermal properties of vinylic polymer blends. An increase of thermal stability was found for certain blend compositions. By FTIR analysis, higher band displacements were found for low BP compositions. AFM and molecular simulation analysis were carried out in order to elucidate the structural origin leading to thermal stability and miscibility increases. Hydrophobic interactions among methyl end groups of BP and methylene groups of vinylic polymers should be the responsible of miscibility and thermal stability increases. 相似文献
6.
C. K. Radhakrishnan A. Sujith G. Unnikrishnan 《Journal of Thermal Analysis and Calorimetry》2007,90(1):191-199
The thermal behaviour of styrene butadiene rubber (SBR)/poly (ethylene-co-vinyl acetate) (EVA) blends was studied by using
thermogravimetry (TG) and differential scanning calorimetry (DSC). The effects of blend ratio, cross-linking systems and compatibilization
on the thermal stability and phase transition of the blends were analyzed. It was found that the mass loss of the blends at
any temperature was lower than that of the components, highlighting the advantage of blending SBR and EVA. The addition of
compatibilizer was also found to improve the thermal stability. DSC studies indicated the thermodynamic immiscibility of SBR/EVA
system even in the presence of the compatibilizer. This is evident from the presence of two different glass transition temperatures,
corresponding to SBR and EVA phases in both compatibilized and uncompatibilized blends. 相似文献
7.
Yuancheng Qin Yutie Bi Hongbo Ren Fanghua Zhu Prof. Dr. Meiming Luo Lin Zhang 《中国化学》2010,28(12):2527-2532
Poly(methyl methacrylate) (PMMA) nanocomposites containing (methacryloxy)propyl polyhedral oligomeric silsesquioxane (methacryl‐POSS) were prepared by bulk‐polymerization process. The structures of the products were characterized by FTIR, solid‐state NMR, TEM, XRD, DSC, TGA, XPS and UV‐Vis spectra. The hybrid materials were found to be largely homogeneous. DSC and TGA results indicate that the thermal properties of PMMA nanocomposites are significantly improved. The glass transition temperature (Tg) and thermal decomposition temperature (Tdec) of the nanocomposites increased by 58 and 110°C, respectively. The bulk hybrid material maintains excellent optical transparency in visible region. 相似文献
8.
Hongyao Xu Benhong Yang Jiafeng Wang Shanyi Guang Cun Li 《Journal of polymer science. Part A, Polymer chemistry》2007,45(22):5308-5317
The soluble poly(methyl methacrylate‐co‐octavinyl‐polyhedral oligomeric silsesquioxane) (PMMA–POSS) hybrid nanocomposites with improved Tg and high thermal stability were synthesized by common free radical polymerization and characterized using FTIR, high‐resolution 1H NMR, 29Si NMR, GPC, DSC, and TGA. The POSS contents in the nanocomposites were determined based on FTIR spectrum, revealing that it can be effectively adjusted by varying the feed ratio of POSS in the hybrid composites. On the basis of the 1H NMR analysis, the number of the reacted vinyl groups on each POSS molecules was determined to be about 6–8. The DSC and TGA measurements indicated that the hybrid nanocomposites had higher Tg and better thermal properties than the pure PMMA homopolymer. The Tg increase mechanism was investigated using FTIR, displaying that the dipole–dipole interaction between PMMA and POSS also plays very important role to the Tg improvement besides the molecular motion hindrance from the hybrid structure. The thermal stability enhances with increase of POSS content, which is mainly attributed to the incorporation of nanoscale inorganic POSS uniformly dispersed at molecular level. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5308–5317, 2007 相似文献
9.
Thermal properties of compatibilized and filled natural rubber/acrylonitrile butadiene rubber blends
The thermal behaviour of natural rubber/acrylonitrile butadiene rubber (NR/NBR) was studied using thermogravimetry (TG) and differential scanning calorimetry (DSC) in terms of blend ratio, crosslinking systems, fillers and compatibilizer (neoprene) were analyzed. The presence of NBR markedly increases the thermal stability of their blends and it lies in between NR and NBR. DSC studies revealed the thermodynamic immiscibility of the NR/NBR blends by the presence of two distinct glass transition temperatures and the immiscibility was prominent even in the presence of a compatibilizer. 相似文献
10.
The nano poly(phenylsilsesquioxane) spheres (nano-PPSQ) were prepared by the sol?Cgel method and incorporated into poly(methyl methacrylate) (PMMA) by in situ bulk polymerization of methyl methacrylate. The structure of nano-PPSQ was confirmed by transmission electron microscope and thermogravimetry analysis (TG). The interaction between nano-PPSQ and PMMA was investigated by Fourier transform infrared spectra (FT-IR). The influence of nano-PPSQ on the thermal stability of PMMA was investigated by TG and differential scanning calorimetry (DSC) measurements. The results indicated that nano-PPSQ enhanced the thermal stability and the temperatures of glass transition (T g) of nanocomposites. The effect of the heating rate in dynamic measurements (5?C30?°C?min?1) on kinetic parameters such as activation energy by TG both in nitrogen and air was investigated. The Kissinger method was used to determine the apparent activation energy for the degradation of pure PMMA and nanocomposites. The kinetic results showed that the apparent activation energy for degradation of nanocomposites was higher than that of pure PMMA under air. 相似文献
11.
Dual-phase polymer electrolyte with enhanced phase compatibility based on Poly(MMA-g-PVC)/PMMA 总被引:1,自引:0,他引:1
A new plasticized dual-phase polymer electrolyte (DPE) with enhanced phase compatibility based on Poly(MMA-g-PVC)/PMMA blends has been studied. For the DPE, PMMA is selectively impregnated with the lithium salt solution forming an ion-conducting network, while Poly(MMA-g-PVC) produces good mechanical strength. Their chemical characters, thermal behavior, morphology, ionic conductivity and interfacial compatibility with lithium metal electrode were characterized by using of infrared spectroscopy (IR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), optical microscopic images, alternating current impedance (AC impedance) and linear sweep voltammetry (LSV), respectively. The ionic conductivity of DPE increases with the ratio of PMMA/Poly(MMA-g-PVC) (by weight), and the absorbed liquid electrolyte in the polymer blends plays the first important way in this behavior. Room-temperature ionic conductivity of the order of 10−3 S cm−1 has been achieved for DPE, in addition, the DPE also shows good compatibility with Li electrodes and sufficient electrochemical stability for safe operation in Li batteries. 相似文献
12.
The thermal and structural properties of binary blends of Nylon-6 (N6) and a chemically related biopolymer, Bombyx mori silk fibroin (SF), are reported in this work. Homopolymers and blends, in composition ratios of N6/SF ranging from 95/05
to 70/30, were investigated by thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), Fourier transform
infrared (FTIR) spectroscopy and wide angle X-ray scattering (WAXS). Silk fibroin typically degrades at temperatures just
above 210°C, which occurs within the melting endotherm of N6. In TG studies, the measured mass remaining was slightly greater
than expected, indicating the blends had improved thermal stability. No beta sheet crystals of SF were detected by FTIR analysis
of the Amide I region.
Strong interaction between N6 and SF chains was observed, possibly as a result of formation of hydrogen bonds between N6 and
SF chains. DSC analysis showed that the addition of SF to N6 caused a decrease in the crystallization temperature, the melting
temperature of the lowest melting crystals and the crystallinity of N6. Furthermore, the α-crystallographic phase dominates
and the γ-crystallographic phase was not observed in N6/SF blends, in contrast to the homopolymer N6, which contains both
phases. We suggest that the addition of SF might result in changes of the chain extension of N6, which lead to the appearance
of α-rather than γ-phase crystals. 相似文献
13.
Diego Lomonaco Francisco Jonas Nogueira Maia Selma Elaine Mazzetto 《Journal of Thermal Analysis and Calorimetry》2013,111(1):619-626
In this study, the thermal-oxidative stability of poly(methyl methacrylate), PMMA, 1 % additivated with replenishable phenolic lipids is evaluated by thermogravimetric (TG/DTG) analyses and differential scanning calorimetry (DSC) analyses. Since technical cashew nutshell liquid (CNSL), a byproduct from the cashew industry, is composed basically of two phenolic lipids, cardanol and cardol, the utilization of this industrial waste and its main components as a new source of bioadditives for use as antioxidants is evaluated. The TG analyses revealed that addition of the phenolic constituent of CNSL increased the thermal stability of PMMA films considerably. The results obtained were also confirmed by DSC analyses. 相似文献
14.
A series of blends of poly(vinyl chloride) (PVC) and polyaniline (PANI) was prepared by solution casting and investigated
by methods of thermal analysis, namely thermogravimetric analysis (TG), coupled with Fourier transform infrared spectroscopy
(TG-FT/IR) and differential scanning calorimetry (DSC). It was found that the thermal stability of this polymer system depends
on the composition of blend; the main product of prevailing PVC decomposition process — hydrogen chloride — seems to play
specific role during degradation since it can react with PANI structures, characterized by different protonation degree.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
15.
A. V. Maldhure A. R. Chaudhari Jayant D. Ekhe 《Journal of Thermal Analysis and Calorimetry》2011,103(2):625-632
Microwave-assisted chemical modification of lignin was achieved through esterification using maleic anhydride. Modified lignin
(ML) was blended in different proportions up to 25 mass% with polypropylene (PP) using Brabender electronic Plasticorder at
190 °C. The structural and thermal properties of blends were investigated by thermogravometric analysis (TG), differential
scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). TG analysis showed
increased thermal stability of blends due to antioxidant property of ML, which opposed oxidative degradation of PP. DSC analysis
indicted slight depression in a glass transition temperature and melting temperature of blends due to partial miscible blend
behavior between PP and ML. All blends showed higher crystallization temperatures and continuously reducing percentage crystallinity
with increasing ML proportion in the blends. WAXD analysis indicated that PP crystallized in β polymeric form in addition
to α-form in the presence of ML. However, proportion of β-form did not show linear relation with increase in ML proportion,
thus ML acts as β nucleating agent in the PP matrix. SEM analysis showed good dispersion/miscibility in PP matrix indicating
modification in lignin is useful. 相似文献
16.
Maurizio Penco Luciana Sartore Stefania Della Sciucca Luca Di Landro Alberto D'Amore 《Macromolecular Symposia》2007,247(1):252-259
In this work the effect of melt mixing condition and of a trans-esterification catalyst on miscibility of poly(methyl methacrylate) (PMMA)/polycarbonate of bisphenol A (PC) blends is studied. In particular, at high temperature chemical reactions between PMMA and PC phases can take place; these strongly change the compatibility in the blend and materials having single Tg can be obtained. FT-IR analyses, coupled with solvent extraction, suggest that a grafting reaction of PC on PMMA is involved. SEC and DSC data are consistent with spectroscopic results, and some decrement of the molar weight distribution (MWD) of PC phase is observed. On the other hand, the presence of a fraction of modified material having higher MWD of starting PMMA is also noticed. The single Tg characteristic of some materials has been confirmed by experimental data of structural relaxation performed by differential scanning calorimetry (DSC). These materials showed optical clarity and the morphological analysis performed by scanning electron microscopy (SEM) confirm the homogeneity of these materials. 相似文献
17.
D. W. Park J. Y. Moon H. J. Jang M. R. Kim J. K. Lee C. S. Ha 《Reaction Kinetics and Catalysis Letters》1998,65(2):219-226
In the present study, the synthesis of bis(cyclic carbonate) from carbon dioxide and bisphenol A (or bisphenol S)-diglycidyl
ether was investigated using quaternary ammonium salts as catalyst. Among the salts tested, the one having a larger alkyl
group and more nucleophilic counter anion exhibited a better catalytic activity. Poly(hydroxyurethane)s were prepared by the
polyaddition reaction of bis(cyclic carbonate) and diamine. The poly(hydroxyurethane) has shown higher thermal stability than
conventional polyurethane, and is expected as novel reactive polyurethane. The miscibility of blends containing poly(hydroxyurethena)
and poly(styrene-co-acrylonitrile)(SAN) has been also studied by the optical clarity method and DSC. 相似文献
18.
TG-FTIR study of the thermal degradation of polyoxymethylene (POM)/thermoplastic polyurethane (TPU) blends 总被引:1,自引:0,他引:1
A series of blends of polyoxymethylene (POM)/thermoplastic polyesterurethane (TPU) has been obtained by mechanical processing
using a double screw extruder. The thermal stability and the thermal degradation profiles of POM/TPU blends were investigated
by thermogravimetric analysis (TG) coupled on-line with Fourier transform infrared spectroscopy (FTIR). It was found that
incorporation of TPU into POM matrix resulted in increase of thermal stability of blends in comparison with pristine materials.
The thermal degradation of TPU in inert gas atmosphere proceeds in two steps while the thermal degradation of POM is basically
a one step process with a substage in a higher temperature range. The most abundant volatile products of the thermal degradation
were identified; the possibly routes of their formation have been presented.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
Naïma Belhaneche-Bensemra Belkacem Belaabed Abdelmalik Bedda 《Macromolecular Symposia》2002,180(1):203-216
The aim of this paper is to study the miscibility and the thermal degradation of PVC/PMMA blends. For that purpose, blends of variable compositions from 0 to 100 wt% were prepared with and without plasticizer. Their physico-chemical characterization was carried out by differential scanning calorimetric analysis (DSC) and Fourier transform infrared spectroscopy (FTIR). Their thermal degradation under nitrogen at 185°C was studied and the HCl evolved from PVC was measured by the pH method. Degraded samples were characterized, after purification, by FTIR and UV-visible spectroscopy. The DSC analysis showed polymer miscibility up to 60 wt% of PMMA. This miscibility is due to a specific interaction of hydrogen bonding type between carbonyl groups (C=O) of PMMA and hydrogen from (CHCl) groups of PVC as evidenced by FTIR analysis. On the other hand, it was found that PMMA exerted a stabilizing effect on the thermal degradation of PVC by reducing the zip dehydrochlorination and by leading to the formation of short polyenes. 相似文献
20.
S. Makhija E. M. Pearce T. K. Kwei 《Journal of polymer science. Part A, Polymer chemistry》1992,30(13):2693-2698
Thermal oxidation of poly(ethylene oxide) (PEO) and its blends with poly(methyl methacrylate) (PMMA) were studied using oxygen uptake measurements. The rates of oxidation and maximum oxygen uptake contents were reduced as the content of PMMA was increased in the blends. The results were indicative of a stabilizing effect by PMMA on the oxidation of PEO. The oxidation reaction at 140°C was stopped at various stages and PMMA was separated from PEO and its molecular weights were measured by gel permeation chromatography (GPC). The decrease in the number-average molecular weight of PMMA was larger as the content of PEO increased in the blends. The visual appearance of the films suggested that phase separation did not occur after thermal oxidation. The activation energy for the rates of oxidation in the blends was slightly increased compared to pure PEO. © 1992 John Wiley & Sons, Inc. 相似文献