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1.
The thermal radical curing of four diallylic monomers were studied and was found to be very similar. Dynamic DSC of diallyl orthophthalate (DAOP) showed a strong correlation between the cure rate and the half life temperature of the initiator employed. The extent of allylic cure was found by DSC to be very dependent on the reactivity of the initiator due to a dead-end effect, and to rise towards a plateau value with increasing initiator levels. DAOP was blended with poly(vinyl chloride) (PVC) in various weight ratios by both solution and melt compounding. The compatibility between DAOP and PVC was analysed by measuring the glass transition temperatures of mixtures with dynamic mechanical thermal analysis which showed that DAOP monomer and PVC were fully miscible regardless of the composition. The cure rate of the DAOP/PVC blends was found by dynamic DSC and isothermal NIR to increase with higher levels of PVC due to a gel effect accentuated by grafting to the PVC, while the final extent of cure decreased because of topological constraints.  相似文献   

2.
Diallyl orthophthalate (DAOP) is investigated as a reactive plasticizer to aid the processing of PVC by reducing the melt's viscosity and thus minimizing the processing temperature so that decomposition of PVC can be effectively avoided during time-consuming processing operations such as rotational moulding. A range of PVC/DAOP blends have been prepared with dicumyl peroxide (DCP) or cumyl hydroperoxide (CHP) as radical initiators, and their chemorheology, properties and morphology have investigated by dynamic rheometry, DMTA, SEM and solvent resistance. DCP was found to be a better initiator than CHP for polymerization of DAOP in blends with PVC because the former's high decomposition temperature matches well with the processing temperature of the PVC/DAOP blends. DMTA indicates that the Tg of the cured PVC/DAOP blends are very close to that of PVC and have a higher storage modulus at the rubbery region. SEM images show that phase separation occurs during cure of the blend and that solid poly(DAOP) nano-particles are embedded in the PVC continuous phase when the PVC content is more than 30 wt%. This cure and phase separation of DAOP from the PVC matrix can successfully recover the PVC's thermal-resistance properties.  相似文献   

3.
Postconsumer water bottle poly(ethylene terephthalate) (PET) flakes were depolymerized with ethylene glycol (EG) by the glycolysis reaction in the presence of zinc acetate as the catalyst. In the depolymerization reactions, different weight ratios of PET/EG were used. In order to obtain polyesters used as PVC plasticizers, these glycolysis products containing hydroxyl end groups were reacted with an adipic acid (AA)–containing diacid group at equivalent amounts. In order to obtain PVC plastisols, PVC was dispersed into a plasticizers' mixture composed of di-isooctyl phthalate (DOP) and polyester products by using a high-speed mixer (PVC/plasticizers, 65/35 w/w). For the preparation of plasticizer mixture polyester products were used at a weight ratio of 20%, 40%, 60% of DOP. Plasticized PVC sheets were prepared from plastisols and their glass transition temperatures (Tg), migration, and mechanical properties were determined. The results show that the polyester products obtained from glycolysis products of waste PET can be used as secondary plasticizers, with DOP for PVC.  相似文献   

4.
A novel plasticizer based on cardanol, hydrogenated cardanol glycidyl ether acetic ester containing phosphaphenanthrene group (HCGEP), was prepared and incorporated into poly(vinyl chloride) (PVC) for the first time. The molecular structure was characterized with Fourier transform infrared and 1H NMR spectroscopies. The thermal degradation behavior and flame retardant performance of PVC films with HCGEP as secondary or main plasticizer were investigated using thermogravimetric analysis, combustion tests, limiting oxygen index tests and morphological analysis of residues. Furthermore, the mechanical properties of PVC films were examined based on the results of tensile testing. The results were compared to those of the petroleum‐based plasticizer dioctyl phthalate. With the substitution of dioctyl phthalate with HCGEP, PVC films exhibited high thermal stability and better flame retardant performance. The tensile test results showed that the addition of HCGEP could endow PVC resin with well‐balanced properties of flexibility, strength and hardness. © 2017 Society of Chemical Industry  相似文献   

5.
Rheology can supply valuable and practical information regarding the properties of fresh concrete, how to reach an optimization of the product and how to attain it by the use of rheograph. Otherwise, the optimization is largely based on feeling. The rheograph reveals in a systematical way the effects of diverse changes on the rheological behavior of the cement based suspension and thus is a convenient and essential tool to compare different concrete types and examine the behavior relative to changed quantities of constituents. Effects of many admixtures as well as the basic constituents of fresh concrete have been revealed in rheographs. In principle the effect of two or more constituents can be added in a rheograph to estimate the combined effect, which constitutes a so-called vectorized-rheograph approach.Different applications and types of concrete like slipform, underwater, and high strength, are described by workability boxes. New rheograph with boxes for various types of self compacting concrete is proposed.  相似文献   

6.
刘容德  王晶  李静  桂俊杰  谢侃 《聚氯乙烯》2010,38(10):19-23
研究了高分子耐寒改性剂对PVC电缆料耐低温性能的影响以及抗氧剂体系、稳定剂体系对PVC电缆料耐老化性的影响,最终确定的最佳汽车用环保PVC电缆料配方为PVC,100份;增塑剂A/DOS,50份;稳定剂A,6~8份;CPE,10份;耐磨改性剂A,10份;高岭土,10份;润滑剂,适量;1010,0.8份;抗氧剂A,0.8份;耐寒改性剂B,15份。  相似文献   

7.
杨忠久  胡建荣 《聚氯乙烯》2010,38(9):23-24,27
详细论述了PVC型材挤出生产过程中形成亮带、暗带、收缩痕的机制、原因与处理方法。  相似文献   

8.
A polyester (PE) based on the glycolyzed products of PET was prepared and added in different concentrations to a series of SBR/PVC blends. The addition of the polyester showed that all properties of SBR/PVC blends were improved by incorporation of PE. Highest mechanical strength values were obtained at a polyester concentration of 7.5 phr. Thermal analysis as well as dynamic mechanical properties of SBR/PVC blends after the addition of 7.5 and 10 phr polyester indicated one single glass transition temperature. The dielectric losses (?") were analyzed in the frequency domains in the two terms of Fröhlich related to the Maxwell Wagner effect and the orientation of the aggregates caused by the movement of the main chain. The permittivity (?') values were found to increase by increasing the polyester content. This increase was followed by a decrease in the ?" up to a 7.5 phr polyester content after which no pronounced change was noticed.  相似文献   

9.
Plasticized poly(vinyl chloride) (PVC) is one of the most useful polymeric materials on an industrial scale because of its processability, wide range of obtainable properties, and low cost. PVC plastisols are used in the production of flexible PVC foams. Phthalates are the most used plasticizers for PVC, and in a previous article (part I of this series), we discussed the influence of phthalate ester type plasticizers on the foaming process and on the quality of the foams obtained from the corresponding plastisols. Because the use of phthalate plasticizers has been questioned because of possible health implications, the objective of this work was to undertake a similar study with 11 commercial alternative plasticizers to phthalates. The evolution of the dynamic and extensional viscosity and the interactions and thermal transitions undergone by the plastisols during the heating process were studied. Foams were obtained by rotational molding and were characterized by the determination of their thermomechanical properties, density, and cell size distribution. Correlations were obtained between the molecular weight and structure of the plasticizer and the behavior of the corresponding plastisols. After the characterization of the final foamed product, we concluded that foams of relatively good quality could be prepared with alternative plasticizers for replacing phthalates. Several plasticizers {Mesamoll (alkylsulfonic phenyl ester), Eastman 168 [bis(2‐ethylhexyl)‐1,4‐benzenedicarboxylate], Hexamoll [di(isononyl) cyclohexane‐1,2‐dicarboxylate], Citroflex A4 acetyl tributyl citrate (ATBC), and Plastomoll (dihexyl adipate)} were found to be interesting alternatives in the production of soft PVC foams because they provided very good quality foams with properties similar to, or even better than, those obtained with phthalate plasticizers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

10.
11.
Char, char-supported catalysts and ilmenite were investigated for the steam reforming of biomass tar derived from the pyrolysis of mallee wood in situ. Special attention was given to the reforming of aromatic ring systems in tar. The results indicated that the char-supported iron/nickel catalysts exhibited much higher activity for the reforming of tar than the char itself. Ilmenite and the char-supported iron catalyst contained similar active phase but showed different tar reforming activities. Kinetic compensation effects demonstrated that the reaction pathways on the char-supported catalysts were similar but were different from those on ilmenite. The proprieties of support could play important roles for the activities of the catalysts and the reaction pathways on the catalysts. Char would not only disperse the catalysts but also interact with the catalysts to enhance their activity for the steam reforming of tar.  相似文献   

12.
A newly designed extruder reactor for grafting vinyl monomers onto polyolefins was studied experimentally and theoretically. The process was made up of a self‐wiping co‐rotating twin screw extruder with a separated reaction zone and two vent zones. The reactive extrusion was performed using a linear low density polyethylene, vinyltrimethoxysilane and di‐t‐butylperoxide under different operation conditions. For the purpose of process analysis, we built a computer simulation based on the reaction kinetics and rheological models studied in the preceding paper. The flow field in the extruder was calculated by the flow analysis network (FAN) method with non‐isothermal non‐Newtonian flow conditions. The iterative procedure was organized to predict local pressure, filling factor, cumulative residence time and temperature along the extruder. Furthermore, we succeeded in representing the profiles of reaction conversion and shear viscosity. Calculated results showed good agreements with the experimental data.  相似文献   

13.
The plasticizing and thermostabilizing effect of poly(ethylene glycol)–polyhedral oligomeric silsesquioxane (PEG‐POSS) on poly(vinyl chloride) (PVC) is discussed thoroughly in this work. As PEG‐POSS content increases, PVC becomes more flexible and the decomposition temperature of PVC increases slightly. Meanwhile, the temperature of maximum HCl emission is elevated from 265.3 °C in neat PVC to 285.7 °C in PVC nanocomposites, with the peak intensity of HCl emission decreased by 30.8%, and a new lower intensity of HCl emission peak appearing at much higher temperature (around 370 °C), which is in accordance with the maximum degradation temperature of PEG‐POSS. Thereby, a possible dehydrochlorination mechanism is suggested according to the fact that the electron donor effect of ether groups would stabilize the C? Cl bonds by means of more electron cloud stacked in those bonds, which agrees with Fourier transform infrared and X‐ray photoelectron spectroscopy experiments in terms of hydrogen bonds. © 2016 Society of Chemical Industry  相似文献   

14.
50 : 50 natural rubber (NR) and ethylene–propylene–diene monomer rubber (EPDM) blends were prepared with different contents of cashew nut shell liquid (CNSL), a natural product obtained from the shells of the cashew nut, as a plasticizer. For comparison, a commercial paraffin oil plasticizer was also used. The effect of plasticizer content on the cure characteristics, processability, and mechanical properties such as tensile strength, elongation at break, and Young's modulus before and after ageing was investigated. Scanning electron microscopy (SEM) was used to observe the blend morphology. The results indicated that the CNSL plasticizer resulted in lower Mooney viscosity and lower cure time of the 50 : 50 NR/EPDM blends. The incorporation of CNSL into 50 : 50 NR/EPDM blends improved tensile strength and elongation at break but decreased Young's modulus. On addition of CNSL the resistance of the blends to heat and weathering ageing improved. Scanning electron micrographs revealed that the morphology of the blend plasticized with CNSL is finer and more homogeneous compared with the blend plasticized with paraffin oil. Overall results indicate that CNSL can be used as a cheaper plasticizer to replace paraffin oil in NR/EPDM blends with improved processability and mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

15.
A series of hyperbranched poly(?‐caprolactone) (HPCLs, denoted as DX) with different molecular weights were synthesized by the copolymerization of GPCL (PCL initiated by glycidol) and succinic anhydride. The chemical structure of DX was characterized by 1H‐NMR gel permeation chromatography and inherent viscosity, and DX was used as the plasticizer for poly(vinyl chloride) (PVC) compared to traditional plasticizer di‐(ethylhexyl) phthalate (DEHP). The thermal properties, morphology, mechanical properties, and migration stabilities of PVC films were explored with differential scanning calorimetry, thermogravimetric analysis, scanning electron microscope, tensile, and migration tests. PVC/D1 exhibited the best plasticization efficiency up to 107%, with enhanced tensile strength (18.5 MPa) and ultimate elongation (416%) compared to PVC/DEHP (11.5 MPa and 375%, respectively). PVC/D1 exhibited remarkably high plasticization efficiency as compared to PVC/DEHP at a plasticizer concentration of PVC below 40 wt %. Moreover, the migration test for PVC/DX films exhibited minimal plasticizers migration even at very harsh conditions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46542.  相似文献   

16.
Part I of this study covered the matrix and pocessibility studies to establish the feasibility of a non-CVD process for manufacturing high performance C-C composites. Part II of this study covers the overview of Carbonization and Graphitizations investigations that ultimately led to a satisfactory product in processing times that were more than an order of magnitude shorter than those of typical CVD processes.  相似文献   

17.
In the accompanying paper, Part I, the advantages of the rapid thermal response (RTR) molding process were investigated for thin-wall-mold filling by employing coupled analysis of flow and heat transfer. Besides the complete filling of the cavity, frozen-in molecular orientation is another major quality issue in thin wall molding. The frozen-in orientation causes residual stress and birefringence, and potential part distortion. The present work focuses on the prediction and visualization of birefringence in RTR-molded parts. To calculate birefringence, flow-induced residual stress is computed first and the stress-optical law is then applied. The simulation results show that the amount of molecular orientation, residual stress, and birefringence level considerably decrease in the RTR-molding process. The effect of the mold temperature on the level of birefringence was also studied and predicted birefringence patterns were compared with experimental results for a thin-walled rectangular strip. Both predicted and experimental patterns of birefringence are in agreement on the observation that the birefringence level diminishes significantly when the mold temperature is raised to above the glass transition temperature.  相似文献   

18.
The Buss‐Kneader has proven to be a suitable reactor for the polymerization of acrylates. In this second part, the polymerization of methyl methacrylate and the ter‐polymerization of methyl methacrylate (MMA), hydroxyethyl methacrylate and n‐butylmethacrylate is carried out in a pilot Buss‐Kneader. The reactor had to be pressurized up to about 10 bars to avoid evaporation of MMA. Instabilities in output rate and temperature profiles were observed as a result of fluctuating die pressures. Because of good mixing there may be no diffusion limitation for radicals. As a result, even at high conversions, no gel effect was observed.  相似文献   

19.
In this study, a new ion-selective electrode for Ba2+ is described, illustrating 3-deoxy-d-erythro-hexos-2-ulose bis (thiosemicarbazone) (DHUT) in a poly(vinylchloride) (PVC) membrane with benzyl acetate (BA) as a plasticizer and sodium tetraphenyl borate (NaTPB) as an anionic additive. This sensor presented very good selectivity and sensitivity towards the Ba2+ ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The electrode revealed a great improvement in the selectivity coefficients for the Ba2+ ions in comparison with the formerly reported Ba2+ sensors. The proposed electrode exhibited a significantly enhanced response towards the Ba2+ ions across the concentration range of 1.0 × 10− 6-1.0 × 10− 2 M for the pH variation from 2.6 to 11 with a lower detection limit of 5.6 × 10− 7 M. Moreover, the sensors displayed the Nernstian slope of 29.6 ± 0.5 mV per decade, having a fast response time within 15 s over the entire concentration range. It could also be used for at least 2 months with no potential divergence. As a result, the developed sensor was successfully applied to the direct barium ion determination in solutions, rock samples and as an indicator electrode in the Ba2+ ion potentiometric titration with EDTA.  相似文献   

20.
Multifunctional carboxylic acids, such as 1,2,3,4‐butanetetracarboxylic acid (BTCA), were used to bond a hydroxy‐functional organophosphorus oligomer (FR) to cotton fabric in the presence of a catalyst, such as sodium hypophosphite (NaH2PO2). Previously, it was found that the cotton fabric treated with FR and BTCA showed a high level of phosphorus retention after one home laundering cycle. However, the flame retardant properties quickly deteriorated as the number of home laundering cycles was increased. In this research, it was found that the free carboxylic acid groups bound to the cotton fabric form an insoluble calcium salt during home laundering, thus diminishing the flame retardant properties of the treated cotton fabric. It was also found that the free carboxylic acid groups on the treated cotton fabric were esterified by triethanolamine (TEA), and that the formation of calcium salt on the fabric was suppressed by the esterification of the free carboxylic acid groups by TEA. The cotton fabric treated with BTCA and the hydroxy‐functional organophosphorus oligomer significantly improved its flame retardance when a new catalyst system consisting of hypophosphorous acid (H3PO2) and TEA was used in the system. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

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