PVC-U硬制品混料工艺及混料效果分析

介绍了PVC-U硬制品干混料的作用与原理及混料工艺对混料效果的影响.干混料的制备效果受热混、冷混温度,混料锅投料量,冷混锅冷却速度和干混料静置时间的影响;从白度、表观密度、热稳定时间、流动性等8个方面分析了如何监控干混料的质量.     

混料工艺对PVC型材性能的影响

介绍了混料原理和热混、冷混过程,测试了不同热混温度下干混料的表观密度、白度、热稳定性、干流性,采用转矩流变仪测试了干混料的流变性能,采用实验室挤出机制取试样,测试了其色差、拉伸强度、断裂伸长率、简支梁冲击强度、拉伸冲击强度、抗热老化性能等。结果表明：在试验配方下,最佳热混温度为110～115℃。     

制备工艺对Al2O3陶瓷的组织和冲蚀性能影响

论文采用二种工艺制备了Al2O3陶瓷材料，在相同条件下对所制备的陶瓷材料进行了冲蚀磨损实验；通过对冲蚀磨损前后材料的形貌和断口的扫描电镜观察，详细讨论、分析了实验结果。结果表明：采用搅拌磨混料和冷等静压处理工艺制备的试样具有优良的冲蚀磨损性能；与干混料干压成型制备的试样相比，冲蚀磨损率可以降低约50％；而且发现磨粒的形貌对材料的冲蚀磨损性能有一定的影响。     

PVC干混料粉体流动性的影响因素

介绍了与粉体流动性有关的理论,分析了PVC树脂、CPE、碳酸钙和冷混工艺对PVC干混料粉体流动性的影响,结果表明:①乙烯法PVC树脂的粉体流动性一般优于电石法PVC树脂,且波动较小;②某些厂家的冲击改性剂CPE可改善PVC干混料的粉体流动性,并且随着CPE用量的增加,PVC干混料的粉体流动性增加;③不同生产厂家的PVC/CPE体系对PVC干混料粉体流动性的影响规律不同,应不断摸索,找出最佳组合;④随着碳酸钙用量的增加,PVC干混料的粉体流动性降低,特别是在料斗上的表现更为突出;⑤充分冷却后的PVC干混料粉体流动性较好。     

PVC干混料的塑化特征及新型加工助剂JZ-W的作用

系统研究了聚氯乙烯(PVC)干混料在HAKEE转矩流变仪中的塑化过程,并从能量损耗的角度探讨了不同投料量、转速以及温度对PVC干混料的塑化特征的影响。结果表明,不同投料量、转速、温度下,PVC干混料的扭矩-时间曲线形态基本一致;但随投料量和转速增加,塑化时间缩短,能耗增加;外加温度的增加可使塑化时间和机械能耗同时减小。2 phr新型加工助剂JZ-W的引入,使干混料的塑化时间缩短约20%,而能耗仅增加6%。     

ACR类冲击改性剂的加工性能研究

简单介绍了用冲击ACR改性的PVC干混料的流变、挤出和加工热稳定性能。实验结果表明:与使用CPE改性的PVC干混料相比,使用冲击ACR改性的PVC干混料具有塑化时间短、塑化扭矩大、塑化温度高的特点。     

ACR类冲击改性剂的加工性能研究

简单介绍了用冲击ACR改性的PVC干混料的流变、挤出和加工热稳定性能。实验结果表明：与使用CPE改性的PVC干混料相比，使用冲击ACR改性的PVC干混料具有塑化时间短、塑化扭矩大、塑化温度高的特点。     

CPE在PVC型材中的应用

研究了CPE对PVC干混料流动性能和加工性能的影响,以及对PVC型材力学性能的影响。结果表明:①不同厂家CPE的流动性能各不相同,而其对PVC干混料流动性能的影响也各不相同,没有明显的规律;②CPE可以缩短PVC干混料的塑化时间,促进塑化;③加入CPE后,PVC型材的冲击性能提高,焊角强度下降。     

流变仪对PVC干混料流变性能的评价

介绍了流变仪对PVC干混料流变性能的评价以及其影响因素,认为通过流变曲线可评价PVC干混料的加工性能,以指导生产。     

用电能耗参数研究PVC干混料的塑化过程

通过转矩流变仪软件的能量积分功能可得到PVC干混料的电能耗参数,考察了原料生产厂家、碳酸钙用量、转矩流变仪设定参数、热混温度对电能耗的影响,指出电能耗可用于表征PVC干混料的加工性能,用来指导PVC型材生产。     

Poly(vinylidene fluoride-co-hexafluorpropylene)/polyaniline conductive blends: Effect of the mixing procedure on the electrical properties and electromagnetic interference shielding effectiveness

Poly(vinylidene fluoride-co-hexafluoropropylene)/polyaniline (PVDF-co-HFP/PAni) conductive blends were prepared by two methodologies involving the in situ polymerization in two different media and dry blending approach using ball milling. Dodecylbenzenesulfonic acid (DBSA) was used both as surfactant and as protonating agent in PAni synthesis. X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible (UV–Vis) spectroscopy, and thermogravimetric analysis were used for characterizing the blends. PAni and PVDF/PAni prepared by in situ polymerization in H₂O/toluene medium exhibited superior electrical conductivity, higher thermal stability and significantly higher electromagnetic interference shielding effectiveness (EMI SE) than those prepared in H₂O/dimethylformamide (DMF) medium. PVDF/PAni with high-PAni content (>40%) prepared by the dry blend approach presented higher conductivity and EMI SE than those prepared by in situ polymerization. The molding temperature exerted significant influence on the conductivity and EMI SE for the blend containing higher amount of PAni. The free-solvent dry blending approach using ball milling presented similar conductivity value but the higher EMI SE when compared with in situ polymerization, and is considered environmentally and technologically interesting.     

PC／ABS共混物的结构和性能

综合分析了有关PC/ABS共混物的文献,重点介绍了PC/ABS共混物的结构,力学性能和热性能,以及改进性能的途径。同时介绍了共混的可能性、共混方法和成型加工要点等。     

Improving transparency of stretched PET/MXD6 blends by modifying PET with isophthalate

Compatibilized blends of PET and MXD6 have good transparency because their refractive indices match closely. However, haziness is observed when the blends are stretched because stretching imparts greater refractive index anisotropy to PET than to MXD6. Analysis of the strain-dependent birefringence reveals that different molecular deformation models describe the intrinsic birefringence of PET and MXD6. This study focuses on reducing the intrinsic birefringence of PET by partially replacing terephthalate with isophthalate. Statistical copolymers are prepared by conventional copolymerization of the monomers. Alternatively, blocky copolymers are obtained by melt blending PET with poly(ethylene isophthalate) (PEI). A close refractive index match with stretched MXD6 is achieved with copolymers containing 15-20% isophthalate. Statistical copolymers in this composition range are not satisfactory for blending because they have low molecular weight and are difficult to stretch. However, blocky copolymers containing 15-20% isophthalate form blends that stretch readily. After biaxial stretching, transparency of blends with 10 wt% MXD6 approaches that of PET. Good transparency of the blends is validated with stretch-blown bottle walls. Oxygen transport measurements confirm that partial replacement of terephthalate with isophthalate does not affect the good gas barrier properties of biaxially stretched PET blends.     

Effects of blending time and catalyst on the properties of nylon 1010/acrylate rubber blends

Nylon 1010 and acrylate rubber (ACM) were prepared by melt blending. The effects of blending time and catalyst on the properties of the blends were studied. It was found that ester‐amide exchange reactions between the Nylon 1010 and ACM occurred during melt processing. Long blending time and Tetrabutyl titanate (Ti(OBu)₄) as a catalyst could promote the reactions, and grafted copolymer Nylon‐g‐ACM was in situ generated as a compatibilizer during processing procedure. The tensile strength of the blends increased from about 12.0–15.0 MPa when the blending time increased from 10 to 30 min. The presence of Ti(OBu)₄ led to the decrease in melt flow index (MFI), independent of the blending time (30 or 60 min). Glass transition temperature and heat of fusion of the blends increased after addition of the catalyst. Rheological behavior analysis provided evidence of formation of Nylon‐g‐ACM graft copolymer. Scanning electron microscopy (SEM) showed that the compatibility of the blends was improved by longer blending time and the addition of catalyst. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4587–4597, 2013     

A three-dimensional numerical study of the combustion of coal blends in blast furnace

The practice of blending coals for pulverized coal combustion is widely used in ironmaking blast furnace. It is desirable to characterize the combustion behaviour of coal blends and their component coals. A three-dimensional numerical model is described to simulate the flow and combustion of binary coal blends under simplified blast furnace conditions. The model is validated against the experimental results from a pilot-scale combustion test rig for a range of conditions, which features an inclined co-axial lance. The overall performance of coal blend and the individual behaviours of their component coals are analysed, with special reference to the influences of particle size and coal type. The synergistic effect of coal blending on overall burnout is examined. The results show that the interactions between component coals, in terms of particle temperature and volatile content, are responsible for the synergistic effect. Such synergistic effect can be optimized by adjusting the blending fraction. The model provides an effective tool for the design of coal blends.     

Blends of novel L‐tyrosine‐based polyurethanes and polyphosphate for potential biomedical applications

Elastomeric biodegradable polyurethanes and polyphosphate have been developed using an L ‐ tyrosine‐based diphenolic monomer desaminotyrosine‐tyrosine hexyl ester (DTH). Soft segments, which are polycaproloctone diol (PCL) and polyethylene glycol (PEG) have been used for the synthesis of two biodegradable L ‐tyrosine polyurethanes (LTUs), which are PEG‐C‐DTH and PCL‐C‐DTH. An investigation of the physico‐chemical properties shows that these polymers have dramatically different properties. By blending LTUs with L ‐tyrosine polyphosphate (LTP), we hope to produce a family of materials with a wide range of thermal, morphological, surface, and degradative properties. Examination of the blends shows a smooth surface morphology with a partially phase‐separated structure. These findings are consistent with the results obtained from thermal analysis of the blends. Hydrophilic nature of PEG imparts the PEG‐based blends (PEG‐C‐DTH/LTP) with a significantly higher surface and bulk hydrophilicity compared with the PCL‐based blends (PCL‐C‐DTH/LTP). Finally, the blends demonstrate a rapid initial hydrolytic degradation in phosphate buffered saline (PBS) followed by a significantly slower, prolonged degradation. The observed trend may occur due to the rapid hydrolytic degradation rate of the polyphosphate polymer followed by the degradation of the polyurethane component. Thus, tuning the physical properties by blending LTUs with LTP may be useful for drug delivery device and soft tissue engineering scaffold applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Rheological Properties of Thermoplastic Polyvinyl Alcohol and Polypropylene Blend Melts in Capillary Extrusions

A single screw extruder with a static mixer was used to prepare molten blends of thermoplastic polyvinyl alcohol (TPVA) and polypropylene (PP). The effects of shear rate, blending ratio and temperature on rheological properties for the blends in capillary extrusions were investigated, and ends correction was also carried out. Rheological parameters such as non-Newtonian index and activation energy were also calculated and evaluated. It was found that the viscosities of the blends were lower than those of TPVA and PP; moreover, the non-Newtonian indices and the activation energies of the blend melts were higher than those of the homopolymers. In particular, the blend with 60 wt% TPVA had the highest non-Newtonian indices and activation energies among blend melts. These results indicate that TPVA and PP blends are negative deviation blends. Furthermore, at a blending ratio of 60 wt% of TPVA, the shear-sensitivity of the viscosity was the lowest and the temperature dependence of the viscosity was the highest. In addition, an increase in temperature led to an increase in non-Newtonian index, therefore the shear-rate dependence of the blend viscosities decreased with a rise in temperature. As the shear rate was increased, the variation of the viscosity over blending ratios decreased while the activation energy of the blends decreased. Thus the effects of temperature and blending proportion on flow behavior were diminished by increasing shear rate.     

In situ fiber composites based on metallocene polyethylene matrices

Binary blends of metallocene polyethylenes with polyethylenes and polypropylene were made in a co‐rotating twin‐screw extruder. A stretching process was carried out afterwards in the melt state at the extruder's exit to study the effect of the induced orientation on their thermal and tensile properties. Capillary rheometry was performed to the neat polymers to determine the viscosity ratios of the blend components as a function of the shear rate. SEM and Micro‐Raman analyses were done to study the morphology of the stretched and nonstretched blends. As expected, an increase in the modulus and tensile stress was obtained through blending. Additionally, the elastomeric behavior of the metallocene polyethylene (mPE) sample is observed in all blends and it was not lost through blending. Nevertheless, all blends without stretching exhibited a negative deviation of the linear additivity rule of blending. The stretching of the blends made with metallocene polyethylenes as matrices and other types of PEs as dispersed phase did not improve the tensile properties, although some differences in the dispersed phases were found by DSC, and microfibrils could be seen in the drawn mPE/HDPE blend. However, blending with PP produced an improvement in the modulus and tensile stress of the drawn samples in comparison to their undrawn counterpart. The tensile stresses of PP blends are more sensitive to the drawing process than the modulus, which can be attributed to the appearance of large fibril fractions during this process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

A Study on Grafting of Natural Rubber and Nitrile Rubber on Thermoplastic Low Density Polyethylene Using Maleic Anhydride and Acrylic Acid

ABSTRACT

LDPE/NR and LDPE/NBR blends were prepared by conventional mixing on two-roll mill. Modified blends were prepared by grafting (reactive blending). Grafting was carried out using acrylic acid and maleic anhydride. Compression-molded sheets were prepared out of the compounds and properties were evaluated. Mechanical properties like tensile strength, ultimate modulus, elongation at break, and hardness were determined. Effect of heat aging and effect of chemicals were estimated. The blends were characterized using FTIR spectrum. The electrical properties, abrasion resistance, solubility tests, and flammability tests for the compounds were also conducted. In all experiments results are found to be much higher for grafted compounds compared to ungrafted blends.     

A free volume study of miscible polyester blends

Four blend systems (miscible binary polyester blends) have been examined by positron annihilation lifetime spectroscopy (PALS). The ortho-Positronium pick off lifetime, τ₃, is related to the mean free volume cavity size in these miscible blends. The measured free volume cavity size for the blends is compared to the size predicted from linear additivity of the homopolymers. A negative deviation from linear additivity is observed for τ₃ in each of the blend systems, and this behaviour is interpreted as a contraction of the mean free volume cavity size due to the changes in molecular packing that occur on blending. The consequence of these free volume results for the mechanical properties of miscible polyester blends is discussed and tested for the polycarbonate/Kodar system. The glass transition data suggest weak specific interactions in the blends; however, the mechanical properties are significantly affected by blending.