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以纤维素材料为基质的降解塑料的研究进展 总被引:5,自引:0,他引:5
本文详述了以天然高分子纤维素材料为基质的降解塑料的发展。纤维素材料由于其来源丰富,有良好的反应性,优异的生物降解性,无毒性等,因而可用来制备降解塑料.其开发和应用是解决目前世界范围内的“白色污染”的一条理想途径. 相似文献
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Radical copolymerization reaction of vinyl acetate (VA) and methyl acrylate (MA) was performed in a solution of benzene‐d6 using benzoyl peroxide (BPO) as the initiator at 60°C. Kinetic studies of this copolymerization reaction were investigated by on‐line 1H‐NMR spectroscopy. Individual monomer conversions vs. reaction time, which was followed by this technique, were used to calculate the overall monomer conversion, as well as the monomer mixture and the copolymer compositions as a function of time. Monomer reactivity ratios were calculated by various linear and nonlinear terminal models and also by simplified penultimate model with r 2(VA)=0 at low and medium/high conversions. Overall rate coefficient of copolymerization was calculated from the overall monomer conversion vs. time data and k p . k t ?0.5 was then estimated. It was observed that k p . k t ?0.5 increases with increasing the mole fraction of MA in the initial feed, indicating the increase in the polymerization rate with increasing MA concentration in the initial monomer mixture. The effect of mole fraction of MA in the initial monomer mixture on the drifts in the monomer mixture and copolymer compositions with reaction progress was also evaluated experimentally and theoretically. 相似文献
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Polymerisation of vinyl acetate in microemulsions with methanol 总被引:1,自引:0,他引:1
D. Donescu L. Fusulan C. Petcu A.-G. Boborodea D.-S. Vasilescu 《Colloid and polymer science》2000,278(10):927-935
The homogeneity domains for the system vinyl acetate – methanol – monomaleate of nonylphenol ethoxylated with 25 mol ethylene
oxide as an aqueous solution (MEMNPEO25) (33%) have been studied; it has been shown that, due to the shorter chain of methanol,
these domains are more reduced than in the case of ethanol. The changes in refractive indexes and electrical conductivities
have shown the formation of microemulsions with different structures (water-in-oil, bicontinuous or oil-in-water). Ammonium
persulphate is soluble only in oil-in-water or in bicontinuous microemulsions. The initial polymerisation rates as well as
the decomposition rates for the initiator are apparently affected when the microemulsion structure is modified. The polymerisation
rate of vinyl acetate is higher in the presence of methanol than in the presence of ethanol for similar compositions; this
fact may be attributed to a higher degree of ionisation of the initiator in the presence of methanol. Also, in polymerisations
initiated by benzoyl peroxide, the conversions are influenced by the microstructure; thus, the maximum corresponds to water-in-oil
microemulsions. By measuring the amount of unreacted MEMNPEO25 (gel permeation chromatography) we were able to show that the
copolymer formed consisted of vinyl acetate and reactive surfactant.
Received: 9 March 1999/Accepted: 13 March 2000 相似文献
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Novel oligomeric intumescent flame retardants, poly(amino phosphonate ester)s (PAPEs), containing both phosphorous and nitrogen, were synthesized by reacting diethyl phosphite with two different polyschiff bases obtained from the reaction of diamines with dialdehyde. The target PAPEs (designated as PAPE‐d and PAPE‐e, respectively) were characterized by 1H NMR, 31P NMR, Fourier Transform infrared spectroscopy, elemental analysis, gel permeation chromatography and thermogravimetric analysis (TGA) techniques. Thermal stability and flammability of ethylene‐vinyl acetate copolymer (EVA)/PAPE blends with various PAPE content were investigated by TGA, limited oxygen index (LOI), vertical burning test (UL‐94) and microscale combustion colorimeter (MCC). The results indicate that PAPEs effectively improve the flame retardancy of EVA. The EVA/30%PAPE‐e blend has a LOI value of 28, and its peak heat release rate (PHRR) value in MCC measurement is reduced by 36%. At the same time, the EVA/PAPE blends also have high yield of residual char, indicating that PAPEs are effective charring agents. Scanning electron microscopy observations of the residues of the EVA/PAPE blends show the existence of compact char layer on the surface of the residues, which is responsible for the improvement of the flame retardancy of EVA. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献