共查询到19条相似文献,搜索用时 109 毫秒
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二氧化碳共聚物为基聚氨酯的生物降解性研究 总被引:5,自引:0,他引:5
以CO2为起始物合成生物降解型聚合物,既能利用丰富的CO2资源,减轻温室效应;又能减轻聚合物垃圾造成的污染。聚碳酸亚乙酯(PEC)经动物体内实验和土埋实验,证明具有良好的生物降解性[1,2]。由PEC合成的聚氨酯可获得有良好力学性能的材料,但是否具有... 相似文献
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生物降解性聚己内酯-聚醚嵌段共聚物的合成及表征 总被引:8,自引:2,他引:8
A new biodegradable Poly (e-caprolactone)-Poly (ethylene glycol) block copolymer (PCL-b-PEG) has been synthesized by co-polycondensation reaction of e-caprolactone (e-CL) and poly (ethylene glycol) (PEG) in the presence of Ti(OBu)4 catalyst. The composition,hy-drophilicity and crystallinity of the copolymer can be controlled by changing the feeding dose of reaction system. The degradation rate of the PCL-b-PEG copolymer is improved by introducing the PEG segment, and the more the PEG content in the copolymers,the faster the degradation rate of the copolymer. 相似文献
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合成了一系列苯乙烯.马来酸酐共聚物(SMA)。并对共聚物的结构进行了表征。用土埋法和CO2释放法研究了共聚物的生物降解性。探讨了分子量、组成、环境等因素对生物降解性的影响,发现共聚物的分子量降低。降解率增大;共聚物中马来酸酐含量提高。降解率增大;适宜的环境有利于生物降解。 相似文献
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淀粉-醋酸乙酯-甲基丙烯酸甲酯接枝共聚物的合成及生物降解研究 总被引:15,自引:0,他引:15
用硝酸铈铵为引发剂,合成了淀粉 醋酸乙烯酯 甲基丙烯酸甲酯接枝共聚物,用质子核磁共振谱研究了接枝支链的化学组成,用X 射线粉末衍射研究了接枝共聚物的结晶结构变化,分别用实验室酶分解法和室外土壤掩埋法测定了接枝共聚物的生物降解性能,结果说明,仅接枝共聚物中的淀粉部分能被微生物降解,接枝支链部分不能被降解. 相似文献
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可生物降解聚酯酰胺共聚物的合成与表征 总被引:8,自引:0,他引:8
以两种合成的酰胺二元醇和癸二酸为原料合成了可生物降解的聚酯酰胺共聚物,研究了该癸半晶性聚合物的合成、结晶及其生物降解性,并应用IR,^1H NMR,SEM及DSC进行了表征。 相似文献
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Gianluca Ciardelli Alfonsina Rechichi Piero Cerrai Mario Tricoli Niccoletta Barbani Paolo Giusti 《Macromolecular Symposia》2004,218(1):261-272
Degradable segmented poly(ether-ester-urethanes) of variable segment chemistry and content were synthesized and characterized. Polycaprolactone diol, a series of poly(ether-ester) block copolymers, and a diisocyanate giving non toxic degradation products were used to form the prepolymer. Cyclohexane dimethanol and a L–phenylalanine–based diester (Phe diester) were used as chain extenders. The influence of α-chimotrypsin on the degradation was investigated by exposing the polymers to buffer and enzyme solutions for 12 days. The SEM, SEC, and gravimetric results showed that a significant erosion of the Phe diester containing polymer compared with the control polyurethane occurred in the presence of the enzyme but not in a normal buffer solution. 相似文献
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超支化聚氨酯的合成及应用 总被引:1,自引:0,他引:1
超支化聚合物因其独特的结构和性能逐渐成为聚合物领域的研究热点之一,各种合成超支化聚合物的方法相继被报道。但对于超支化聚氨酯(HBPU)这一类聚合物,由于其官能团的特殊性,很难用传统的方法制得。本文总结了近十几年来制备HBPU的两类主要方法:一种为单单体法(SMM),包括光气法、叠氮化合物法、AA′ B′B2法、高选择性化学反应等;另一种为双单体法(DMM),包括扩链法,低聚物A2 B3法。另外简要介绍了HBPU在固体电解质、相变材料、油墨以及纳米粒子制备等领域的应用。 相似文献
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Abstract CoMFA (comparative molecular field analysis) has been used to correlate the biodegradability of several classes of compounds. The technique uses an atomic probe to detect the steric and electrostatic fields around a molecule. Good cross-validated correlations were obtained for some series (alcohols, carboxylic acids and linear alkyl benzene sulphonates). Correlations were weaker for esters and benzene sulphonates, and were non-existent for phenols. These results may reflect the unreliability of biodegradation data, but may also be a result of molecular misalignment in the CoMFA procedure. CoMFA appears to be a potentially very useful method for the prediction of biodegradability. 相似文献
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Maike Unverferth Oliver Kreye Alexander Prohammer Michael A. R. Meier 《Macromolecular rapid communications》2013,34(19):1569-1574
1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene (TBD)‐catalyzed polycondensation reactions of fatty acid derived dimethyl dicarbamates and diols are introduced as a versatile, non‐isocyanate route to renewable polyurethanes. The key step for the synthesis of dimethyl carbamate monomers from plant‐oil‐derived dicarboxylic acids is based on a sustainable base‐catalyzed Lossen rearrangement. The formed polyurethanes with molecular weights up to 25 kDa are characterized by SEC, DSC, and NMR analysis.
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L. Fambri A. Pegoretti J. Kolarik C. Gavazza A. Penati 《Journal of Thermal Analysis and Calorimetry》1998,52(3):789-797
Different polyester urethanes and polyether urethanes were exposed to hydrolytic degradation at 70°C for up to 16 weeks. The
dried samples were subsequently analysed in thermooxidation tests in the range 250-300°C by measuring the lifetime relating
to 5% mass loss. The experimental results showed that polyether urethanes have lower thermal stabilities than those of polyester
urethanes; the activation energies determined from the Arrhenius plot are around 65 and 80 kJ mol-1, respectively. The activation energies of polyether urethanes did not change significantly as hydrolysis proceeded. In contrast,
the polyester urethanes exhibited a progressive decrease in activation energy, which fell (after 16 weeks of hydrolysis) to
the values characterizing polyether urethanes. The entropic parameter of the Arrhenius equation was also evaluated and related
to the chemical composition of the as-received and hydrolysed polymers.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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BaoHuaLIU LiBanCHEN MinZHANG AiFangYU 《中国化学快报》2003,14(7):752-754
CO2-copolymer based polyurethane foams were synthesized and characterized in this paper. The foams were found to have higher strength and lower heat of combustion than the conventional polyether polyurethane foams. They may find wide applications in many fields. 相似文献
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Summary: Novel polyurethane elastomers (PUs) were synthesized with ethylene glycol (EG) as a chain extender. The macrodiol was poly(ethylene adipate) (PEA), MW = 2000 ± 50. Two isocyanates were employed: 4,4′-methylene bis(phenyl isocyanate) (MDI) and 4,4′-dibenzyl diisocyanate (DBDI). The conformational mobility of DBDI causes an unusually wide range of mechanical, physical and chemical properties, associated with the possibility of pronounced phase separation into a domain – matrix morphology, and with a higher tendency to crystallization and self-association by hydrogen bonding. Materials were characterized by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), dynamic mechanical analyses (DMA), and mechanical measurements. Results were discussed in terms of the effect of PUs crystallinity. In the case where the chain extender–diisocyanate couple was EG-DBDI, the hard segments were observed to crystallize. The DBDI based PUs displayed higher flow stress in the hard phase caused by stronger phase segregation. 相似文献