印刷质量与油墨触变性的关系

油墨触变性对印刷产品质量有较大的影响.所谓触变性是指油墨在外力和外界环境因素的作用与影响下,使它变稀或变稠,改变流动性的一种现象.对印刷工艺来说,要使产品印刷质量稳定,要求油墨应保持适度而又稳定的流动性,但是,由于油墨本身固有因素和印刷条件等原因,印刷过程中油墨不可避免会出现"触变"现象,影响了产品质量的稳定.所以,正确认识油墨的触变性,从工艺技术上采取一些措施,减少油墨印刷中触变的程度,才能较好地保证产品的印刷质量.     

磁流变液触变性评价指标研究

实验研究了可用于磁流变液触变性的评价指标。研究表明,基于表观粘度与剪切速率曲线得到的触变破解指数,测试简便且重复性好,可作为磁流变液触变性能的评价指标。触变环的测试数据具有良好的稳定性,含有丰富的材料性能信息,也可作为磁流变液触变性的评价指标,且较低的剪切速率以及较低的持续时间,易于得到较为显著的触变环。     

预聚物对UV胶印油墨乳化率影响的研究

UV胶印油墨的乳化率对油墨的印刷适性具有重要的影响,在UV胶印油墨的各个组分中,预聚物对于油墨乳化率的影响较大.为了改变油墨中预聚物的组成配制UV胶印油墨,探讨了不同预聚物配制的UV胶印油墨的乳化性能.研究结果表明:环氧类丙烯酸酯的含量是影响UV胶印油墨乳化性能的重要因素.     

填料对UV胶印油墨性能的影响

设计了UV胶印油墨的配方,选用了4种填料分别配制油墨样品,测试了油墨样品的黏度、固化时间、细度及耐摩擦性等主要特性。研究表明:不同种类的填料及其用量对油墨性能的影响不同,所选的4种填料中,选用硫酸钡加填可显著提高油墨层的耐摩擦性;使用二氧化钛加填配制的油墨样品,填料用量为5%(质量分数)时,油墨的细度小,黏度适中,固化时间短,耐摩擦性较高。     

UV印刷油墨在包装胶印中的应用分析

分析了使用普通胶印油墨印刷存在的主要问题,指出普通胶印油墨已不适应现代化印刷工业;介绍了使用UV油墨印刷的主要特点及其对胶印工序的要求;列出了在胶印中推广UV油墨印刷存在的主要问题,提供了一些解决办法.     

胶印联机冷烫胶黏剂的性能要求分析

目的获得胶印联机冷烫用胶黏剂的性能和冷烫印质量的关系,提出胶印联机冷烫用胶黏剂的性能要求。方法选用一种商用胶印联机冷烫胶黏剂,测试黏度、粘弹性、触变性、乳化率、粘性、干燥速率和固含量,分析其与冷烫印质量的关系。结果冷烫胶黏剂的初粘性要高并维持稳定,且具有较快的干燥速率。印刷适性如黏度、粘弹性、触变性、乳化率和普通胶印油墨要求相近,在保证印刷适性、粘性和合适的干燥速率的前提下,固含量越高越好。结论研究结果可为胶印联机冷烫胶黏剂的改进和胶印冷烫质量的提高提供参考。     

物质的触变性及触变材料的开发

触变性是分散体系流变学中一种特殊的现象,是指在搅动或其它机械力作用下,这些体系的粘度或切力随时间发生变化的一种流变现象。研究开发触变性材料,使其在"紧急"外力作用下,通过材料在结构性能上的短时"响应"变化,在紧急制动、减缓冲击、缓降逃生、防弹衣、泥浆固井等需要"瞬变响应"的工程场合加以应用,具有十分重要的意义。对自然界和工程中的触变性物质进行了综合分析,从正触变及负触变两方面介绍了触变材料的研究现状,分析了触变材料的应用领域和应用前景。     

半固态加工中的触变强度及其影响因素研究

结合半固态金属具有触变性的特点,提出触变强度是触变点对应的应力,阐述了触变强度的研究意义,并结合高固相率下半固态金属等温压缩真应力-应变曲线研究了外变量包括坯料的加热温度、应变速率、保温时间和内变量包括固相体积分数、晶粒尺寸、晶粒的球形度、结构参数、半固态材料的固相屈服强度、半固态材料的初始表观粘度等对触变强度的影响。     

可注射磷酸钙骨水泥的流变性能研究

采用高级流变扩展系统研究了添加剂种类及其含量对可注射磷酸钙骨水泥(ICPC)流变特性的影响。采用稳态流动实验表征浆体的静态粘度,用触变环面积、应力降低率和屈服应力表征ICPC浆体的触变性,并进行动态频率扫描和动态时间扫描实验动态监测ICPC的粘、弹、塑性变化规律以及水化反应过程流变参数的依时性。结果表明:添加剂并不改变ICPC的粘弹性。水溶性高分子化合物的加入提高了ICPC的粘度和触变性,利于整个体系的稳定;添加剂不同程度上提高了ICPC剪切后的网络结构恢复能力和稳定性,尤其以黄原胶和几丁糖最为明显。在此基础上,评估了加入黄原胶后ICPC形成凝胶的时间,约为2 563～2 600 s。此外,随着黄原胶含量的增加,ICPC触变环面积增加,但形成的网络结构在高剪切状态下并不稳定。     

UV固化技术发展历程及未来趋势

由于UV油墨及涂料生产效率高,性能优良,近年来,UV固化技术在印刷业的应用呈上升趋势。UVN化技术不仅在传统工艺中得到应用,在新技术中也得到了应用,如UV喷墨印刷、混合油墨印刷。毫无疑问,UV固化技术的应用今后仍会继续增长。UV固化技术既包括UV油墨,也包括UV涂料,在胶印纸张印刷、胶印印铁、胶印上光、柔性版印刷、丝网印刷、大幅面喷墨印刷、凹版印刷等领域均有应用。     

Preparation and characterization of injectable calcium phosphate cement paste modified by polyethylene glycol-6000

An ICPC with high structure recoverability and paste stability was successfully developed directly incorporating PEG-6000 into the liquid phase of CPC. The rheological behavior of ICPC was investigated with rheometric scientific ARES902-30004 controlled strain rheometer. Novel approaches of flow rate, shear thinning index (SI), shear stress slowdown (Δτ) and thixotropy loop area have been applied to assess the injectability and structure recoverability of the ICPC paste. The addition of PEG-6000 to ICPC resulted in a thixotrophic structure with shortened setting time, slightly increased viscosity, larger thixotropic hysteresis loop area and lower Δτ, with the improvement largely dependent on the PEG-6000 content. With acceptable injectability and shortened setting time, ICPC (1%) showed the lowest Δτ and the highest SI, endowing the paste good structure recoverability and paste stability. The ICPC (1%) was bioactive and facilitated cell attachment and proliferation. The optimized ICPC (1%) paste with a relatively good structure stability and paste stability may serve as a good candidate for tooth root-canal fillings and percutaneous vertebroplasty in microinvasive surgery.     

Time-Dependent and Flow Properties of Foams

Foams have been prepared from water added with a surfactant and a polymer. A controlled stress rheometer was used to study the changes of their rheological properties during ageing by the mean of different rheological tests: shear viscosity measurements, creep compliance tests at a constant low shear stress and dynamic experiments have been performed. It has been observed that apparent viscosity decreases with ageing. A thixotropic behaviour was also found, loading and unloading curves present an hysteresis. Then, the choice of the stress ascent time is of primary importance to study the time-dependent properties of the foam. The viscosity was found to decrease with the stress ascent time while the thixotropic area decreases. Creep flow and harmonic tests have shown important viscoelastic properties of the foams.The second part of this work is concerned with the study of the flow properties of the foams. Pressure drops were measured during flow in capillary tubes in laminar regime. Pronounced wall slip effects were found. While the Mooney method for slip correction is not applicable, the Oldroyd–Jastrzebski method leads to satisfactory results. The Metzner and Reed correlation method was found to be applicable in the case of the corrected data.     

The preparation of prolonged action formulations in the form of semi solid matrix into hard gelatin capsules of oxprenolol II. Thixocap Method

In this study, it was aimed to obtain prolonged release preparations in the form o f semisolid matrices (SSM) o f Oxprenolol as a model drug into mixtures possessing thixotropic property by filling in the hard gelatin capsules.

The results of this study showed that the formulation, prepared with liquid paraffin and Cutina HR, gave kinetic values close to that of the polymeric matrix preparation of Oxprenolol HCl used for comparison. However, in the thixotropic formulations, prepared with Isopropyl Myristate and Isopropyl Palmitate by adding Arerosil 200, the drug release was slow, there fore the release in expected period of time and level can be ensured by.adding different. proportions of hydrophilic substances forming channels in the mass without damaging thixotropic structure.     

The rheology of a partially solid alloy

The effect of various thermomechanical treatments on the structure and rheological behaviour of Sn-15% Pb alloy in its solidifcation range was investigated using a concentric cylinder viscometer. The apparatus was designed to permit wide ranges of cooling rates up to 25° C min^–1 and shear rates up to 750 sec^–1. Initially, the alloy was continuously sheared as it cooled from above the liquidus to a desired volume fraction solid. In one series of experiments, shear was stopped and the alloy quenched. In a second series, the alloy was held isothermally and subjected to various mechanical treatments. The size and morphology of primary solid particles during continuous cooling is influenced by shear and cooling rates and volume fraction of solid — faster cooling results in finer structures while increased rate of shear reduces the amount of entrapped liquid in individual particles. The viscosity of the slurry, at a given volume fraction solid, decreases with decreasing cooling rate and increasing shear rate. Exercising the full range of shear and cooling rates possible in the viscometer, the apparent viscosity of a 0.55 volume fraction solid slurry varied from 3 to 80P. The structure and viscosity of isothermally held slurries follow the same trends as slowly cooled slurries. However, their viscosity at a given volume fraction solid is consistently lower than that of continuously cooled slurries. The slurries are thixotropic and show a hysteresis loop phenomenon similar to other well known thixotropic systems. Measured areas of hysteresis loops increase with increasing volume fraction solid, initial viscosity and time at rest. The potential applications to improve existing or develop new metal-forming processes are being investigated in a variety of alloys with different solidifcation ranges and temperatures.     

Effect of Holding Time on Thixotropic Fluidity of Semi-solid AZ91D Magnesium Alloy

To investigate the thixotropic fluidities, microstructures and mechanical properties of semi-solid AZ91D magnesium alloy during reheating, a self-made die set with channels of different sizes were used. The results show that critical forming forces and maximal forming forces could be obtained and related to the holding times in the semi-solid forming process. In the holding time of 0-2700 s, with increasing the holding time, maximal forming force decreased sharply and critical forming force decreased slowly. In the whole thixotropic flowing process, the filling-in was steady and the surface fineness was good. The forming force increased when the slurry changed the flowing direction or flowed from the big-diameter chamber to the small-diameter one. The tensile strength and elongation to failure of the sample after holding time for 2700 s, compared to as-cast sample, are increased by approximately 42.7% and 180%, respectively, and the fractured surfaces presented dimple-like pattern.     

纳米CaCO3对水泥-石灰石粉浆体流变作用

试验采用Rheolab QC型旋转黏度计测试了掺纳米CaCO₃的水泥-石灰石粉浆体的流变曲线,应用Herschel-Bulkley流变模型对其剪切应力-速度（τ-γ）曲线进行拟合,得到浆体的动态屈服应力、稠度系数和流变指数,并用触变环面积表征浆体的触变性。结果表明：随石灰石粉掺量的增加,水泥-石灰石粉浆体的动态屈服应力逐渐减小,稠度系数增大,触变性先增大后减小;纳米CaCO₃未改变水泥-石灰石粉浆体的流变类型都呈现出剪切稀化行为;随纳米CaCO₃掺量的增加,水泥-石灰石粉浆体动态屈服应力和稠度逐渐增大,触变性减小,纳米CaCO₃使水泥-石灰石粉浆体流变性能变差,但使其稳定性增强。     

聚苯胺复合电极的制备及电化学性能研究

以化学法合成导电聚苯胺，研究了氧化剂和掺杂剂以及反应温度和时间对聚苯胺的产率和电导率的影响。在确定的配方和工艺条件下，聚苯胺的合成产率为94％，电导率在5.6S/cm，将合成得到的聚苯胺掺杂导电粉体制备成高分子是合电极材料，在恒电流上进行充放电性能测试。结果表明，开路电位和放电电位较高，在以4mA/cm^2恒电流放电，终止电位为1．2V时，放电时间可持续16.5h，放电容量大。     

喷射环流反应器传质性能及应用研究

喷射环流反应器结合了喷射与环流的技术优势,具有传质效率高、水力停留时间短、容积负荷高、抗冲击负荷能力强等特点。对课题组自主研制开发的喷射环流生物反应器的传质性能试验结果表明,反应器中氧转移速率为传统曝气法氧转移速率的8～10倍。处理大庆东城区生活污水的试验结果表明,水力停留时间为0．5～1h,系统处理出水可达标排放。同时在好氧条件下,具有良好的脱氮除磷效果。     

Modeling plastic deformation effects in steel on hysteresis loops with the same maximum flux density

Plastic deformation affects the hysteretic magnetic properties of steels because it changes the dislocation density, which affects domain-wall movement and pinning, and also because it places the specimen under residual strain. An earlier paper proposed a model for computing hysteresis loops on the basis of the effect of grain size d and dislocation density /spl zeta//sub d/. In that paper, hysteresis loops were compared that all had the same maximum flux density B/sub max/. The result was that coercivity H/sub c/ exhibited a linear relationship with inverse grain size (1/d) and /spl zeta//sub d//sup 1/2/. The same was true of hysteresis loss W/sub H/. If one compared hysteresis loops all with the same H/sub max/, these linear dependences were only approximately found. Because the relationships are simpler for loops of constant B/sub max/, core loss experimenters compare loops that all have the same B/sub max/. In this paper, we modify the model to study the effect of plastic tensile deformation on hysteresis loops with the same B/sub max/. We found linear relationships between H/sub c/ and residual plastic strain /spl epsiv//sub r/ and between W/sub H/ and /spl epsiv//sub r/. With increasing residual tensile strain, H/sub c/ increases (whereas with increasing elastic tensile strain, H/sub c/ decreases). Also, with increasing residual tensile strain, the slope of the hysteresis loop decreases (whereas with increasing elastic tensile strain, the slope increases). We also consider the effect of compressive plastic deformation.