聚氨酯多元醇的应用和发展

对PIPA多元醇(聚氨酯多元醇)的合成原理,合成方法,影响其性能的关键因素进行了综述与讨论,指出制备PIPA多元醇存在的问题,并展望了其发展趋势。     

PIPA多元醇制备软质PU泡沫

将自制的PIPA多元醇用于发泡,对其进行各种性能测试,结果发现:用PIPA多元醇制备的泡沫,对泡沫的密度、回弹率、压陷硬度等性能都有不同程度的影响;在同样配方条件下,相对于不含PIPA多元醇的试样泡沫,有着更好的力学性能;高固含量PIPA多元醇泡沫相对于POP多元醇泡沫,具有更好的压陷硬度、回弹率、拉伸强度、伸长率以及撕裂强度等机械性能。     

高氨基甲酸酯含量PIPA多元醇的制备及应用

通过大量实验寻找出合适的特殊分散剂,通过添加此分散剂,可制备出高聚氨酯含量的多元醇PIPA,并用此多元醇制备聚氨酯泡沫,泡沫性能良好。     

聚合物改性聚醚多元醇及其阻燃性能

对几种聚合物改性多元醇如POP、PIPA、PHD的合成原理,制备方法和工艺条件,以及影响其性能的关键因素进行了综述,并重点讨论阻燃聚醚多元醇的改性,并展望了其发展趋势。     

基于蜜胺/PIPA多元醇的聚氨酯软泡性能的研究

以自制的蜜胺/PIPA多元醇为原料制备了软质聚氨酯泡沫塑料,研究了蜜胺/PIPA多元醇的用量对泡沫发泡成型、力学和阻燃性能的影响。结果表明:当使用蜜胺/PIPA多元醇代替普通聚醚多元醇发泡,其用量在20%～40%时,泡沫的压缩强度,65%/25%压陷比、落球回弹率和75%永久变形等性能有明显的提高;而泡沫的拉伸强度、断裂伸长率和撕裂强度则有不同程度的下降。当蜜胺/PIPA多元醇的用量为40%时所得到的泡沫综合性能最好,且与空白泡沫相比,其阻燃性能也有极大的提高,可达到离火10s内自熄。在此基础上,添加一种磷系阻燃剂起到N-P协同阻燃作用,产物氧指数显著提高。     

PIPA多元醇制备硬质聚氨酯泡沫

合成了聚氨酯改性聚醚多元醇（PIPA多元醇）,采用傅里叶变换红外光谱法、凝胶渗透色谱法等方法对其进行表征,发现聚醚多元醇A（TMN-450）/三乙醇胺/甲苯二异氰酸酯为110/10/9（质量比,下同）时,所合成的PIPA多元醇固含量为15 %左右,黏度约为3 400 mPaos,其作为发泡原料性能较好。采用此多元醇制备硬质聚氨酯泡沫塑料,考察泡沫稳定剂对体系发泡时间、泡沫塑料的泡孔结构、压缩强度、弯曲强度、冲击强度等力学性能的影响,发现加入1.0份泡沫稳定剂的样品泡孔平均直径约为0.5 mm,孔径分布窄,约40 s起泡,与未改性多元醇制备的泡沫塑料相比,冲击强度提高了23 %,压缩强度和弯曲强度略有上升,同时提高了泡沫塑料的强度和韧性。     

聚醚多元醇的研究现状与进展

对聚醚多元醇(PIPA)的合成原理,合成方法,影响其性能的关键因素进行了综述与讨论,并与其他2种填充聚醚多元醇做了比较。     

聚氨酯改性聚醚多元醇对硬质聚氨酯泡沫性能的影响

将聚氨酯改性聚醚多元醇（PIPA多元醇）与低羟值多元醇共混制备全水发泡硬质聚氨酯泡沫塑料,研究了扩链剂、交联剂、低羟值多元醇用量、异氰酸酯指数对材料压缩强度、弯曲强度、冲击强度等力学性能和动态流变性能的影响。结果表明：加入1,4-丁二醇和三羟甲基丙烷各1.0份,TMN-3050多元醇15份,异氰酸酯指数为1.15份的发泡材料的力学性能较好,兼具良好的强度和韧性。     

蓖麻油聚醚多元醇在聚氨酯软泡中的应用

利用双金属催化剂(DMC)制备了相对分子质量在2000～5600之间的聚氨酯(PU)软泡用蓖麻油聚醚多元醇,并通过发泡实验与常用软泡聚醚多元醇H-330进行了性能比较。结果表明,相对分子质量2000的蓖麻油聚醚多元醇制备的泡沫拉伸强度、伸长率和压陷硬度等均优于H-330聚醚,表明蓖麻油聚醚多元醇完全可以取代普通聚醚多元醇用于普通软泡生产。     

溴化蓖麻油多元醇合成及其制备的阻燃聚氨酯硬泡性能

采用可再生的醇解蓖麻油多元醇为原料,与液溴进行加成反应制备溴化蓖麻油多元醇,通过红外光谱证实发生了溴化反应,并测定了产物粘度、羟值、酸值.通过发泡实验和氧指数、烟密度、水平燃烧等测试手段,考察了溴化蓖麻油基聚氨酯硬泡发泡参数和阻燃性质,并与工业级阻燃荆雅保RB-79制备的聚氨酯硬泡进行比较.结果表明,由溴化蓖麻油多元醇...     

pH responsive PAIAm-g-PIPA microspheres: Preparation and drug release

Poly(N-isopropylacrylamide) (PIPA) was synthesized by radical polymerization with 2,2′-azobisisobutyronitrile (AIBN) as an initiator and 3-mercaptopropionic acid (MPA) as a chain-transfer reagent in methanol (MeOH) at 70°C for 7 h. The resultant PIPA was grafted to polyallylamine hydrochloride (PAIAm · HCI) by amide formation under the influence of water-soluble carbodiimide 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). The graft polymer was made into microspheres (MS) by chemical crosslinking. The pH-responsive drug release of the graft polymer microspheres was examined by releasing phenobarbital natrium (PN), which was carried on the microspheres by physical adsorption. A dynamic dialysis technique was used in the drug-release experiment and the drug-release-rate constants reflecting the drug release characteristic of polymer microspheres were obtained by constituting a mathematical model. The results indicated that the homopolymer PAIAm microspheres and the copolymer PAIAm-g-PIPA microspheres are both pH responsive to release PN and that in the neutral pH condition the release rate is the slowest. © 1995 John Wiley & Sons, Inc.     

DIFFUSION MODELS OF PAPAYA AND MANGO GLACe' DRYING

The objective of this research was to develop diffusion models for papaya and mango glace' drying. Effective diffusion coefficients of papaya and mango glace' were evaluated by regression analysis of the experimental data to drying kinetic equation. Models 1 and 2 were developed by assuming that effective diffusion coefficients were constant and varied proportionally with the moisture ratio. Model 3, which the Arrhenius factor was a second-degree polynomial function of moisture content, was developed by assuming that the value of effective diffusion coefficient was constant over a short time interval. Model 4, which was similar to Model 3, was developed by considering the effect of volume shrinkage during drying. Four diffusion models were compared and it was found that the predicted values of moisture contents calculated by using Models 1 and 2 were close to experimental values during the early period of drying. Models 3 and 4 were able to have better predictions particularly towards the final period of drying. However, Model 4 was complicated. Therefore, Model 3 was recommended for calculating drying curves of papaya and mango glace' drying.     

N-Acetyl Glucosamine Obtained from Chitin by Chitin Degrading Factors in Chitinbacter tainanesis

A novel chitin-degrading aerobe, Chitinibacter tainanensis, was isolated from a soil sample from southern Taiwan, and was proved to produce N-acetyl glucosamine (NAG). Chitin degrading factors (CDFs) were proposed to be the critical factors to degrade chitin in this work. When C. tainanensis was incubated with chitin, CDFs were induced and chitin was converted to NAG. CDFs were found to be located on the surface of C. tainanensis. N-Acetylglucosaminidase (NAGase) and endochitinase activities were found in the debris, and the activity of NAGase was much higher than that of endochitinase. The optimum pH of the enzymatic activity was about 7.0, while that of NAG production by the debris was 5.3. These results suggested that some factors in the debris, in addition to NAGase and endochitinase, were crucial for chitin degradation.