结晶条件对超高分子量聚乙烯熔融再结晶行为的影响

应用常压差示扫描量热(DSC)仪和高压DSC仪研究了熔融温度、熔融时间、冷却速率以及压力对不同分子量的超高分子量聚乙烯(PE–UHMW)熔融再结晶行为的影响。常压DSC的研究表明,随着熔融温度、熔融时间以及冷却速率的增加,PE–UHMW的结晶峰值温度(Tc)逐渐下降。在相同的熔融温度和熔融时间下,PE–UHMW的Tc随分子量的增加而逐渐增加,但在所研究的冷却速率范围内(2.5～40℃／min),在相同的冷却速率下,Tc随分子量的增加变化不大。高压DSC的研究结果表明,结晶过程中增加压力导致PE–UHMW的Tc有所下降,并且结晶峰半峰宽变大。     

尼龙6改性超高分子量聚乙烯

采用挤出成型工艺制备了尼龙6(PA6)改性超高分子量聚乙烯(PE–UHMW)共混材料。研究了PA6含量对PE–UHMW/PA6共混材料热性能及力学性能的影响。研究表明,PA6质量分数为30%时维卡软化温度达到145.9℃,较纯PE-UHMW提高了14℃,邵氏硬度达到69,较纯PE-UHMW提高了15%;共混材料的缺口冲击强度随PA6质量分数的增加而降低,在PA6含量不变的条件下,添加适量的增容剂能够改善共混材料的缺口冲击强度。同时结合DSC测试共混材料中PE–UHMW的结晶度与对共混材料的微观形貌扫描观察,进行了PE–UHMW与PA6的作用机理分析。     

制动装置用碳纤维复合材料耐磨性能表征及影响研究

以环氧树脂和碳纤维为原料,采用模压成型工艺制备了汽车防抱制动装置用碳纤维复合材料,研究了模压压力、加压温度、固化温度和固化时间对碳纤维复合材料摩擦磨损性能的影响,并分析了其摩擦磨损机理。结果表明,当模压压力为10 MPa、加压温度为110℃、固化温度为140℃、固化时间为30 min时,汽车防抱制动装置用碳纤维复合材料的摩擦系数较小,到达磨合期较短,具有良好的耐磨性能,为适宜的模压成型工艺。可以通过调整模压成型工艺参数,制备出耐磨性能良好的汽车防抱制动装置用碳纤维复合材料。     

PE-UHMW分子量及其分布表征技术进展

针对常规分子量表征手段很难用于超高分子量聚乙烯(PE–UHMW)的分子量测试现状,综述了PE–UHMW分子量分布及其大小测试方法。PE–UHMW分子量分布可以通过以下方式实现:利用不同温度时溶解性不同实现分离,利用凝胶色谱柱实现分离,利用运动速度与分子量之间的关系实现分离。PE–UHMW分子量测试目前主要有黏度法、凝胶色谱连用技术、流变仪法等,其中黏度法在实际生产中得到了广泛应用,但这种方法重复性差,其可靠性和准确性还不稳定。     

超临界CO_2微孔发泡PE–LLD/PE–UHMW共混物

研究了线型低密度聚乙烯(PE–LLD)/超高分子量聚乙烯(PE–UHMW)共混物的超临界CO2微孔发泡行为,探讨了PE–UHMW含量、发泡温度和饱和压力对泡孔形貌的影响。采用差示扫描量热仪和旋转流变仪对PE–LLD及其共混物的热性质和流变性质进行了测试和表征,并通过扫描电子显微镜表征和分析了发泡样品的泡孔形貌。结果表明,少量PE–UHMW的加入可以显著降低PE–LLD发泡样品的孔径,增加孔密度。随着发泡温度的升高,PE–LLD样品的泡孔结构会发生塌陷现象,而加入少量PE–UHMW可以提高基体的黏度,起到支撑孔壁防止塌陷的作用,并最终得到均匀的开孔结构。另一方面,当温度一定时,饱和压力升高可以降低孔径并且得到开孔形貌的泡孔结构。     

超高分子量聚乙烯熔体流动性改性研究进展

介绍了超高分子量聚乙烯(PE–UHMW)的性能及成型方法,针对PE–UHMW熔体流动性差的缺点,综述了近年来PE–UHMW熔体流动改性所取得的新进展,分析了改性的原理,并指出了今后的发展方向。     

超高分子量聚乙烯力学性能与可纺性研究

以分子量在350万～450万的6种牌号的超高分子量聚乙烯(PE–UHMW)纤维级原料为例,研究了原料微观物理性能与可纺性和力学性能的关系。结果表明,PE–UHMW的分子量分布是影响材料可纺性的关键因素,分子量分布窄而均匀的冻胶丝能被均匀地超级拉伸,平均粒径细和粒径分布宽度窄的粉末也有利于纺丝;PE–UHMW的冲击强度与材料的结晶度、微晶尺寸、缠结点密度等多因素有关,结晶度越高韧性越差,在一定范围内微晶越小材料的冲击性能越好,缠结点密度大能提高冲击强度。     

热拉伸过程中PE–UHMW/PE–HD共混纤维的晶体结构演变

将超高分子量聚乙烯(PE–UHMW)与高密度聚乙烯(PE–HD)按照质量比为6︰4进行共混熔融纺丝,并对初生丝进行高倍热拉伸制得PE–UHMW/PE–HD共混纤维。利用广角X射线衍射、差示扫描量热、声速取向试验等方法研究了PE–UHMW/PE–HD共混纤维在热拉伸过程中的晶体结构演变过程。研究显示,随着热拉伸过程的进行,纤维的分子链沿纤维的轴向取向度逐渐增加,熔融峰温度逐渐升高,结晶度逐渐增加;沿径向的晶粒尺寸逐渐减小,而沿轴向的晶粒尺寸逐渐增加,即形成了更细长的晶粒;晶体的取向度逐渐增加。当拉伸倍数由1增大至6时,上述现象变化显著,当拉伸倍数由9增至15时,上述现象变化缓慢。与PE–HD共混后的纤维结晶度、晶体取向度和分子链取向度更高,晶粒更加细长。     

多孔PE–UHMW材料的制备及其摩擦性能的研究

采用模板–滤取法制备多孔超高分子量聚乙烯(PE–UHMW)材料,探究其存储油液和输出油液的能力及摩擦学性能。结果表明,孔隙率越大,多孔PE–UHMW的储油能力和出油能力越强。在干摩擦条件下,孔隙率越大,多孔PE–UHMW的摩擦系数越大。在贫油润滑条件下,孔隙率较高的多孔试样U30,U40,U50的摩擦系数低于普通PE–UHMW。多孔试样U40在贫油润滑条件下的摩擦系数只有干摩擦时的30.3%。因此,孔隙的存在能够提高PE–UHMW存储油液和输出油液的能力,并且能够改善贫油润滑条件下的摩擦性能。     

PE–UHMW粉坯压制

在室温下制备了超高分子量聚乙烯(PE–UHMW)粉坯,考察了压制压力和时间对PE–UHMW粉坯密度和尺寸的影响。结果表明,PE–UHMW粉坯密度随压制压力增大呈现非线性变化,压力较低时,粉坯密度随压力提高快速增大,压力达到40 MPa后,粉坯密度增加缓慢;压制压力越高,粉坯密度达到该压力下极限值的时间越短,压制压力为40 MPa时,压制12 min后粉坯密度便趋于不变;粉坯出模后轴向弹性膨胀随压制压力的提高呈现先增大后减小的趋势,径向弹性膨胀不明显,其值最大仅为1.19%。     

乙烯酮(双乙烯酮)下游产品废水的治理技术

乙烯酮(双乙烯酮)是十分重要的化工中间体,其下游产品较多。江苏某化工厂开发生产乙烯酮(双乙烯酮)下游产品三十多个,年生产规模三万多吨,是国内以乙烯酮(双乙烯酮)为中间体生产精细化学品的综合骨干企业。针对乙烯酮(双乙烯酮)下游产品废水特点,该厂结合企业实际,开展了产品优化,结构调整,清洁生产,资源循环利用,节水降耗等工作,从源头削减了污染物的生产。同时投资二千多万元新建预处理装置三套,6000m3/d废水生化处理装置一套,使全厂乙烯酮(双乙烯酮)下游产品的废水得到了有效的治理。     

几种乙炔加压设备性能的比较

阐述并比较了几种加压设备在乙炔加压清净过程中的性能和特点。     

三种煤样燃烧热的测定

本文通过三个厂家提供的三种煤样燃烧热的测定,由测定结果综合得出3号煤样燃烧最完全、燃烧热也最大,是三个煤样中最好的一种。     

Semi-empirical equation of state of metals. Equation of state of aluminum

A semi-empirical equation of state for metals is described. Its capabilities are demonstrated by the example of the equation of state for aluminum. New experimental data are presented on the location of the isentrope of aluminum for unloading from the state at p = 229.71 GPa on the shock adiabat to an aerogel (SiO₂) of density 0.08 g/cm³. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 2, pp. 61–75, March–April, 2008.     

水泥水化热测定方法综述

水泥水化热是中、低热水泥和核电工程用水泥的一项关键的技术指标。全球范围内测定水泥水化热的方法有溶解法、直接法/半绝热法、等温传导量热法三种。本文总结了中、美、欧相关方法标准,对其测试原理、仪器设备、试验过程等方面进行了比对,并对其在领域的应用做了简单的概括。     

小议汽车涂装工艺设计对涂装成本的影响

论述了涂装工艺设计对涂装设备投资、涂装生产成本的影响。     

Calorimetric and Computational Study of Enthalpy of Formation of Diperoxide of Cyclohexanone

A thermochemical rather simple experimental technique is applied to determine the enthalpy of formation of Diperoxide of ciclohexanone. The study is complemented with suitable theoretical calculations at the semiempirical and ab initio levels. A particular satisfactory agreement between both ways is found for the ab initio calculation at the 6–311G basis This set level. Some possible extensions of the present procedure are pointed out.     

Measurement of the gradient of viscosity with composition of mixtures of non-ideal gases

A perturbation viscometer is a differential capillary viscometer that measures the logarithmic viscosity gradient of the viscosity-composition curve for gas mixtures. Measurements are made at different gas mixture compositions. Integration of the logarithmic viscosity gradients measured over the full composition range gives the mixture viscosity relative to the viscosity of one of the pure components of the gas mixture. This method is attractive because, for measurements of equal precision, integration of the gradients is potentially an order of magnitude more precise than measurement of the viscosities directly. It can also work at high and low temperatures and perhaps high pressures.The perturbation viscometer has been used to make measurements on ideal gas mixtures at ambient and elevated temperatures. The situation is more complicated when the gas mixtures are non-ideal. Extra effects due to density differences, molar volume change on mixing and differential thermal expansion may be measured in addition to the desired viscosity change producing systematic errors in the results. Thus, a more sophisticated apparatus is required. The standard perturbation viscometer has been modified to separate out the extra effects to permit measurement of the true change in viscosity. In addition, the theoretical operation of the modified apparatus has been revised to account for the design changes to permit calculation of the viscosity-composition profiles from the results.The apparatus has been tested using helium-HFC-125 mixtures and two new viscosity-composition profiles are presented for these mixtures at 23 and . Internal consistency tests have been used to confirm that the data produced are of high quality with an estimated uncertainty in the viscosity ratio data at of 0.9% and at of 1.5%.     

塔设备改造选型的分析

就当前扩产增容中塔设备设计和改造时板式塔和填料塔的选型问题加以分析。在评述目前国内常用的几种塔板和新型填料之后，着重介绍一种新型塔板（导向梯形浮阀塔板）和一种新型填料（波环填料——乾隆帕克）。     

Effect of degree of deacetylation of chitin on the properties of chitin crystallites

In the present article, chitin from crab shell was systematically deacetylated using a NaOH treatment with control of the reaction time. The degree of deacetylation, monitored using solid-state NMR, revealed that the reaction was pseudo-first order. Based on this, swollen and NaOH-saturated particles are proposed as the reaction system. The weight loss of the partially saponified and neutralized samples after HCl hydrolysis increased linearly with the degree of deacetylation. The crystallinity of the samples was found to increase after acid hydrolysis. According to conductimetric titration, the surface charge density of the crystallites, after acid hydrolysis, was found to increase with base treatment time. The effect of surface charge on the formation of a chiral nematic phase, due to the rodlike nature of the crystallites, was explored. These results show that because the contribution of charged particles to the ionic strength was significant the double layer compression was affected, especially since the surface charge density was close to the Manning limit. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:373–380, 1997