共查询到20条相似文献,搜索用时 31 毫秒
1.
Extensively studied thermal degradation of polyvinyl chloride (PVC) occurs with formation of free hydrogen chloride and conjugated
double bonds absorbing light in visible region. Thermogravimetric monitoring of PVC blends degradation kinetics by the loss
of HCl is often complicated by evaporation and degradation of plasticizers and additives. Spectroscopic PVC degradation kinetics
monitoring by absorbance of forming conjugated polyenes is specific and should not be affected by plasticizers loss. The kinetics
of isothermal degradation monitored by thermal gravimetric analysis in real time was compared with batch data obtained by
UV/Visible absorption spectroscopy. Effects of plasticizer on kinetics of polyene formation were examined. Thermal degradation
of PVC films plasticized with di-(2-ethylhexyl) phthalate (DEHP) and 1,2,4-benzenedicarboxylic acid, tri-(3-ethylhexyl) ester
(TOTM) was monitored by conjugated double bonds light absorption at 350 nm at 160, 180, and 200 °C. Plasticizer-free PVC powder
degradation kinetics and that of plasticized films were also obtained thermogravimetrically at temperatures ranging from 160
to 220 °C. Plasticizer-free PVC powder degradation and spectroscopically monitored degradation of plasticized PVC films occurred
with the same apparent activation energy of ≈150 kJ mol−1. No difference in degradation kinetics of films plasticized with DEHP and TOTM was detected. 相似文献
2.
Minkyu Hwang Hoichang Yang Sanghyun Park Dae Ho Lee Kilwon Cho 《Journal of Polymer Science.Polymer Physics》2008,46(3):263-271
We investigated the effects of solvent type (mono‐ester vs. di‐ester solvent) and aging on the structural development in the poly(vinyl chloride)/butyl benzoate (PVC/BB) and PVC/dibutyl phthalate(DBP) gels, as well as on their viscoelastic and mechanical behaviors. It was found that aged PVC/DBP gels held at RT for 7 days exhibit an improvement of about 100% in storage modulus (G′) compared to fresh gels, with a sudden drop in G′ around 50 °C, whereas the storage moduli of the PVC/BB gels decrease monotonically with temperature, irrespective of the postaging time. These different behaviors of the PVC/BB and PVC/DBP gels arise mainly because of the difference in the network structure produced by the formation of the polymer‐solvent complex between the C?O groups of the solvent and the polarized hydrogen moieties of PVC, as was confirmed with small angle X‐ray scattering and uniaxial tensile experiments. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 263–271, 2008 相似文献
3.
In order to develop an efficient and sustainable plasticizer, the waste cooking oil and malic acid were used as the main raw materials in this study to synthesize a bio-based plasticizer (acetylated-fatty acid methyl ester-malic acid ester, AC-FAME-MAE) by environment-friendly methods, and the structure was characterized by FTIR and 1H NMR. The properties of the poly (vinyl chloride) (PVC) with AC-FAME-MAE were tested and compared with those of the PVC plasticized with DOP (di-2-ethylhexyl phthalate) and EFAME (epoxy fatty acid methyl ester), respectively. The results of tensile test, TGA and leaching test showed that the mechanical properties, thermal stability and overall solvent resistance of PVC films with AC-FAME-MAE were significantly better than those of PVC films plasticized by DOP or EFAME. From the results of DMA, the plasticized efficiency of AC-FAME-MAE was as good as DOP. The application of AC-FAME-MAE has higher safety in the food industry based on the results of food simulation fluids experiment. 相似文献
4.
《International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry》1986,27(3):175-183
Different solid solutions of PVC in dibutyl phthalate, tritolyl phosphate, diallyl phthalate, and mixture of diallyl phthalate and dibutyl phthalate were subjected to gamma radiation. The chemical, physical and physicomechanical properties of the irradiated samples were investigated. With respect to PVC plasticates in dibutyl phthalate, it was found that the crosslinking reaction is the predominant reaction at doses higher than 0.2 MGy. Furthermore, as the dibutyl phthalate content increases, the degree of crosslinking increases. When PVC was blended with tritolyl phosphate, the extent of change in the samples was reduced. Diallyl phthalate promotes the crosslinking reaction in PVC. It was found that the concentration of diallyl phthalate has no considerable effect on the extent of crosslinking in the range under investigation. PVC plasticates as mixtures of diallyl phthalate and dibutyl phthalate show the same crosslinking percentage as the samples containing diallyl phthalate only (on the same weight basis). This shows that the internal viscosity of PVC has no effect on the conversion of diallyl phthalate. 相似文献
5.
Two laboratory-based linear horizontal agitation methods for determining a range of phthalate esters from soft polyvinyl chloride (PVC) toys are presented in compliance with EU legislation. Both of these methods were validated through interlaboratory trials using a PVC reference disc and four soft PVC toy/childcare articles intended or likely to be mouthed. Two of these commercial samples contained diisononyl phthalate (DINP), one diisodecyl phthalate (DIDP) and one bis(2-ethylhexyl) phthalate (DEHP). Acceptable repeatability (r, within-laboratory) and reproducibility (R, between-laboratory) data were demonstrated for both the analytical detection technique (GC-MS) (r = 9.8% and R = 8.1%) and agitation/extraction procedure (r=21.9% and R = 35.3% at 37 degrees C; r = 22.7% and R = 31.1% at 65 degrees C) for DINP. This was achieved through the participation of six laboratories. The remaining three phthalates from the EU Scientific Committee for Toxicity, Ecotoxicity and the Environment (CSTEE) list--dibutyl phthalate (DBP), benzyl butyl phthalate (BBP) and di-n-octyl phthalate (DnOP)--were not tested due to the unavailability of suitable materials. 相似文献
6.
The synthesis and photorelease properties of a new phototrigger for alcohols are described. Compared to ester 4 caged by the reported [7-(diethylamino)coumarin-4-yl]methoxycarbonyl (DEACM) phototrigger, the caged ester 3 shows an efficient single-photon photolysis efficiency upon irradiation of long wavelength light (λ = 475 nm) and a stronger two-photon photolysis sensitivity with 800 nm laser light. Its promising properties and the efficient photorelease of adenosine make it very useful as a caging group for biological applications. 相似文献
7.
Laura J. Waters S. A. Leharne J. C. Mitchell J. P. Hanrahan 《Journal of Thermal Analysis and Calorimetry》2007,90(1):283-288
Micelle/water partition coefficients for three dialkyl phthalate esters — dimethyl phthalate ester (DMP), diethyl phthalate
ester (DEP) and dipropyl phthalate ester (DPP) were obtained by micellar liquid chromatography (MLC). Experiments were conducted
over a temperature range which led to calculation of a Gibbs free energy, enthalpy and entropy of transfer for the phthalate
esters. In addition, small angle neutron scattering (SANS) experiments were conducted with no substantial change observed
in micelle size before and after phthalate ester incorporation.
Overall, a novel method for obtaining thermodynamic information, based on partitioning data, has been developed for dialkyl
phthalate esters using micellar liquid chromatography. 相似文献
8.
9.
Radiation crosslinking of PVC in the presence of triallyl cyanurate as a sensitizer, dioctyl phthalate as a plasticizer and lead and tin stabilizers was examined. Standard methods of testing PVC materials were used. Direct relations between crosslinking extent, elongation, and Vicat softening temperature changes were found. Lead stabilizers proved to be more efficient than tin stabilizers. The influence of radiation dcse on immediate and long-term changes of PVC was investigated. 相似文献
10.
K. Saido T. Kuroki S. Motohashi T. Ikemura M. Kirisawa 《European Polymer Journal》1984,20(11):1061-1065
2,4-Diphenylbutyl-2,4-diphenylbutyrate (DPBDPB) and 2,4,6-triphenylhexyl-2,4,6-triphenylhexoate (TPHTPH), plasticizers for poly(vinyl chloride), were synthesized from the products of thermal decomposition of waste polystyrene. Their heat stabilities were studied by thermogravimetric analysis and differential thermal analysis, and compared with those of typical plasticizers for PVC such as dibutyl phthalate (DBP), dihexyl phthalate (DHP) and bis(2-ethylhexyl) phthalate (DOP). DPBDPB and TPHTPH showed much higher heat resistance than DOP. PVC was plasticized with a mixed system consisting of DOP as the primary plasticizer and DPBDPB as the secondary. It became clear that DPBDPB is an excellent heat-resistant plasticizer which does not affect the compatibility of PVC with DOP. 相似文献
11.
Poly(vinyl
chloride) (PVC), plasticized by di(2-ethylhexyl) phthalate (DEHP), medium
molecular mass polyesterurethane (PU) or by both plasticizers, was thermally
degraded under dynamic thermogravimetric conditions and the kinetics of decomposition
was studied by isoconversional methods and by non-linear regression. It has
been found that the initial decomposition temperature is higher for PVC plasticized
with PU, as compared with PVC plasticized with di(2-ethylhexyl) phthalate
(DEHP) or plasticized with PU/DEHP, and thermal degradation shows features
of a multi-step complex process. Application of polymeric plasticizer leads
to the increase and a 'smoothing' effect in the course of energy
of activation and pre-exponential factor at the initial stage of decomposition
indicating thus the hindered migration of medium molecular mass compound from
PVC matrix (in comparison with PVC containing monomeric DEHP) due to steric
hindrances as well as due to specific interactions between C=O and Cl groups
along the macrochains. Kinetic model function of the decomposition process
of PVC/DEHP and PVC/DEHP/PU blends was found to be a two-stage autocatalyzed
reaction of nth
order; autocatalytic effect is associated most likely with the role of HCl
formed during PVC decomposition. For PVC/PU blend best fit was found by non-linear
regression for a two-stage scheme in which first stage was Prout-Tompkins
model and the second was autocatalytical model of nth
order - the first one involves particle disintegration, which was promoted
by product generation at branching PVC 'pseudo-crystals' nuclei,
thus exposing more surface on which decomposition reaction proceeds. 相似文献
12.
Chad M. Higa Andy T. Tek Rudy J. Wojtecki Rebecca Braslau 《Journal of polymer science. Part A, Polymer chemistry》2018,56(21):2397-2411
Branched and linear nonmigratory internal plasticizers attached to PVC by a pendant triazole linkage were synthesized and investigated. Copper-free azide-alkyne thermal cycloaddition was employed to covalently bind triazole-based phthalate mimics to PVC. To systematically investigate the effect of plasticizer structure on glass transition temperature, several architectural motifs were explored. Free volume theory was considered when designing many of these internal plasticizers: hexyl-tethers were utilized to generate additional space between the triazole-phthalate mimic and the polymer backbone. Miscibility of these triazole-plasticizers in PVC is important: variation of the ester moieties on the triazole possessing alkyl and/or poly(ethylene oxide) chains produced a wide range of glass transition temperatures (Tg): from anti-plasticizing 96 °C, to highly efficient plasticized materials exhibiting Tg values as low as −42 °C. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2397–2411 相似文献
13.
Thorsten Rothenbacher Wolfgang Schwack 《Rapid communications in mass spectrometry : RCM》2009,23(17):2829-2835
In the European Community, selected phthalic acid esters (PAE) are restricted in their use for the manufacture of toys and childcare articles to a content of 0.1% by weight. As PAE are mainly used as plasticisers for poly(vinyl chloride) (PVC), a rapid screening method for PVC samples with direct analysis in real time ionisation and single‐quadrupole mass spectrometry (DART‐MS) was developed. Using the ions for the protonated molecules, a limit of detection (LOD) of 0.05% was obtained for benzyl butyl phthalate, bis(2‐ethylhexyl) phthalate and diisononyl phthalate, while for dibutyl phthalate, di‐n‐octyl phthalate and diisodecyl phthalate the LOD was 0.1%. Validation of identification by the presence of ammonium adducts and characteristic fragment ions was possible to a content of ≥1% for all PAE, except for benzyl butyl phthalate (≥5%). Based on the fragment ions, bis(2‐ethylhexyl) phthalate could clearly be distinguished from di‐n‐octyl phthalate, if the concentrations were ≥5% and ≥1% at measured DART helium temperatures of 130 and 310°C, respectively. The complete analysis of one sample only took about 8 min. At the generally used gas temperature of 130°C, most toy and childcare samples did not sustain damage if their shape fitted into the DART source. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
14.
Positron lifetime measurements in polyvinyl chloride (PVC), plasticized with the aid of dibutyl phthalate and tricresyl phosphate have been made. The plasticizers, the first range plasticizers, are an organic and an inorganic ester, respectively. The influence of the different concentration of the plasticizer in the PVC on positron lifetimes in the polymer have been investigated. A conventional fast-slow coincidence lifetime spectrometer with plastic scintillators has been used for the lifetime measurements. All the measurements have been performed in air, at room temperature. Mean free volumes radii have been calculated from the lifetime data. 相似文献
15.
Positron lifetimes measurements in pure polyvinyl chloride (PVC) and in the plasticized PVC have been performed. Dioctyl phthalate has been used as a plasticizer. Samples have been prepared of the PVC with eight different plasticizer concentrations (from 0 to 35% of the plasticizer in the PVC). All of the measurements have been performed in air at room temperature. A conventional fast-slow coincidence lifetime spectrometer has been used for the measurements. Mean free volumes radii have been calculated from the lifetime data. It has been found that the mean free volumes radii are in the investigated region of plasticizer concentrations a linear function of the concentration of the dioctyl phthalate in the PVC. © 1996 John Wiley & Sons, Inc. 相似文献
16.
Emanuela Calò Antonio Greco Alfonso Maffezzoli 《Polymer Degradation and Stability》2011,96(5):784-789
Soft PVC was obtained by using a new plasticizer, based on cardanol, a renewable resource characterized by chemical and physical properties very close to those of diethylhexyl phthalate (DEHP). Cardanol acetate (CA) was obtained by solvent free esterification of cardanol, and used as secondary plasticizer, by partial substitution of DEHP in soft PVC formulations. Ageing tests were performed in order to study the stability of properties of the soft PVC formulations related to plasticizer diffusion. Tensile properties and hardness changes were used to monitor the macroscopic effects of plasticizer diffusion. Soft PVC obtained by partial substitution of DEHP by CA showed a significant modification of mechanical properties related to a higher plasticizer evaporation during ageing tests. Migration tests confirmed that CA is characterized by a higher diffusivity in soft PVC compared to DEHP. 相似文献
17.
G. Adam 《Tetrahedron》1973,29(20):3177-3183
UV-irradiation (λ 300 nm) of 3-dehydro-gibberellin A3 methyl ester 1 in the crystalline state leads via [2+2] cycloaddition to two cyclobutane-type photodimers 2 and 6. Further irradiation of both compounds gives, with loss of carbon dioxide, the corresponding ring A aromatic dimers. Photolysis of 1 as a thin film causes intramolecular photodecarboxylation to give the monomeric phenolic ester 8. 相似文献
18.
π-Bonded silaacrylate was isolated in argon matrix at 10K by the photolysis (λ > 360 nm) of ethyl pentamethyldisilanyldiazoacetate. The silaacrylate immediately changed to (ethoxydimethylsilyl) (trimethylsilyl)-ketene at 10K by the brief irradiation with the light of shorter wavelength (λ > 240 nm). 相似文献
19.
The bio-based plasticizers have been extensively developed due to their high compatibility and low toxicity. In this study, the bio-based plasticizers of methyl 10-(2-methoxy-2-oxoethansulfonyl) octadecanoate (MDA) and ethyl 10-(2-ethoxy-2-oxoethanesulfonyl) octadecanoate (EDA) were synthesized from the oleic acid and thioglycolic acid and characterized by 1HNMR and FT-IR. The prepared materials were applied as plasticizers in Poly(vinyl chloride) (PVC) and their properties were compared with the commercial plasticizer, Bis(2-ethylhexyl) phthalate (DOP). The viscosities of prepared plastisols from novel designed plasticizers were lower than DOP. The results of mechanical properties showed that the synthesized plasticizers of MDA and EDA have the ability of plasticizing effects similar to DOP on PVC. Thermogravimetric analysis (TGA) indicated that both MDA and EDA have higher thermal stability than DOP. Two polar ester as well as polar sulfone groups in the chemical structure of MDA and EDA led to lower migration, volatility and exudation than DOP. 相似文献
20.
Michael M. O'Mara 《Journal of polymer science. Part A, Polymer chemistry》1970,8(7):1887-1899
A pyrolysis–gas chromatographic–mass spectrometric technique for analyzing the pyrolysis products from polymers in an inert atmosphere is described. Initial studies encompassing the pyrolysis of poly(vinyl chloride) homopolymer and a series of PVC plastisols (based on o-phthalate esters) have provided a complete qualitative and semi-quantitative analysis of the pyrolysis products from these materials. PVC resin yields a series of aliphatic and aromatic hydrocarbons when pyrolyzed at 600°C; the amount of aromatic products is greater than the amount of aliphatic products. Benzene is the major organic degradation product. A typical PVC plastisol [PVC/o-dioctyl phthalate (100/60)] yields, upon pyrolysis, products that are characteristic of both the PVC matrix and the phthalate plasticizer. The pyrolysis products from the plasticizer dilute those from the PVC portion of the plastisol and are, in turn, the major degradation products. There are no degradation products resulting from an interaction of the PVC with the plastisol. The pyrograms resulting from pyrolysis of the various plastisols of PVC can be used for purposes of “fingerprinting.” Identification of the major peaks in a typical plastisol pyrogram provides information leading to a precise identification of the plasticizer. The pyrolysis data from this study were related to a special case of flammability and toxicity. 相似文献