Al2O3的表面处理及粒子尺寸对SBR导热橡胶性能的影响

以丁苯橡胶为基质，微米氧化铝与纳米氧化铝为导热填料，制备了填充型导热橡胶，研究了微米氧化铝填充量，偶联剂表面处理对导热橡胶导热性能的影响。比较了纳米氧化铝和微米氧化铝填充的导热橡胶的导热性能及物理机械性能。并将2种粒子以不同配比加入了苯橡胶基质中，对其影响进行了探讨。结果表明，随着微米氧化铝填充份数的增加，丁苯橡胶的导热系数增大，但共加工性能和物理机械性能下降；用硅烷偶联剂KH-570，KH-550，A-151和钛酸酯偶联剂TM-S105表面处理后的微米氧化铝对导热橡胶的导热性能有一定影响，但并不显著，在相同填充量下，纳米氧化铝填充的导热橡胶比微米氧化铝填充的导热橡胶具有更好的导热性能及物理机械性能；在合适的比例下，纳米氧化铝与微米氧化铝混合填充的导热橡胶其导热效果优于单纯使用微米粒子填充的橡胶。     

Mica as a filler for ABS/polycarbonate blends

Mica was incorporated in ABS/PC:65/35 blends prepared on a Haake Torque Rheometer System 9000 with Rheomix 600 mixer. To improve the polymer/filler interaction, a treatment using silane on mica surface was performed. Studies were conducted concerning mechanical properties (flexural and impact strength), thermal properties (DSC and Vicat softening temperature), rheology, and flame retardancy. The composition with 30 phr of mica gives the best properties and efficiency in reducing the rate of burning, then becoming an alternative material to be explored and possibly meet the new requirements sought by these market blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1361–1365, 1999     

Model filled rubber. VI: Dynamic property dependence on filler particle size of rubber compounds during curing

The effect of particle size on curing kinetics and dynamic properties was examined with model filled rubber compounds containing monodisperse size crosslinked polystyrene (PS) particles synthesized from emulsifier‐free emulsion polymerization. In the process of curing, the magnitude of the dynamic moduli increased and the gelation time (GP) decreased as PS particle diameter decreased from 1.25 to 0.315 μm. GP was 5.5 hours for the pure matrix, 13 minutes for the composite containing 0.315 μ.m particles, 1.4 hours for 0.688 μm particles and more than 2 hours for 1.25 μm particles. We propose that in PS particle filled systems, the ability to form clusters was due to interparticle dispersive interactions which increase with decreasing particle size. The particle clusters function as physical crosslinks, so that the overall crosslink density was significantly enhanced. Rheologically, the dynamic moduli and gelation rate were increased with decreasing particle diameter.     

激光粒度仪测量PVC树脂粒径的影响因素

通过激光粒度仪仪器参数设置和不同样品加入量的对比试验,确定了测量PVC树脂粒径分布的Mastersizer 3000型激光粒度仪最佳仪器参数:搅拌速度2 700 r/min、超声时间60 s、遮光度7.0％～9.0％.     

Diluent filler particle size effect for thermal stability of epoxy type resin

Epoxy resin is used as a material for electrical and electronics molding in various forms but its thermal conductivity must be controlled with various additives on account of its lower conductivity than metal or ceramics. Silicon dioxide (SiO₂) and silica were selected as the reinforcement and diluent filler for epoxy resins, respectively. The optimum amount of reinforcement filler, SiO₂, was 50 wt%. The thermal properties and thermal stability were observed according to silica ratio and particle size. An epoxy modified with a polyamide type hardener showed superior thermal conductivity to that modified with a cyclo-aliphatic amine type hardener. The thermal conductivity increased with increasing silica ratio and particle size. The thermal stability evaluation based on the particle size of silica was in the order of 14/18 mesh (1.00–1.16 mm) > 8/10 mesh (1.65–2.36 mm) > 28/35 mesh (0.42–0.59 mm). The optimum silica size of the diluent filler was 14/18 mesh (1.00–1.16 mm). An epoxy type resin transformer with excellent thermal properties and thermal stability could be designed when the mixing weight of epoxy resin was equal to that of the hardener.     

Effects of polymer molecular weight and filler particle size on flow behavior of wood polymer composites

The influence of polymer matrix molecular weight and filler particle size on rheological properties and extrudate distortions of metallocene polyethylene (mPE)/wood flour (WF) composites has been investigated by rotational and capillary rheometers. It was found that at low shear rates smaller filler particles provide higher shear viscosity than the larger sized filler. At high shear rates and WF loadings above 30 wt%, the effect of particle size on the melt flow properties becomes negligible. The relative increase of the storage modulus with decreasing particle size is more pronounced in the case of low molecular weight polymer matrix than that in higher molecular weight polyethylene based composites. The wood filled polyethylenes exhibit extrudate surface defects, which are complex function of the shear rate, polymer matrix molecular weight, and filler particle size. Increasing the shear rate results in pressure oscillations and spurt‐flow. It was also observed that the evolution of the extrudate surface tearing is strongly dependent on the pressure during a single pressure oscillation cycle in the spurt flow regime. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Influence of emulsifiers on particle size and particle size distribution of PVC latex synthesized by miniemulsion polymerization

We synthesized poly(vinyl chloride) (PVC) latexes via miniemulsion polymerization using a mixture of cetyl alcohol (CA) and sodium lauryl sulfate (SLS). A vinyl chloride miniemulsion is easily prepared by conventional mechanical stirring. Experimental design methods were applied to investigate the effects of composition and polymerization conditions on average particle size (APS) and particle size distribution (PSD) of the latexes produced. The APS of the latexes produced ranged from 0.4–0.7 μm. When the APS of the latex produced was above 0.7 μm, the resulting latex was highly unstable. The emulsifier ratio (CA/SLS) was the most prominent factor influencing APS and PSD.     

Effects of chicken eggshell filler size on the processing,mechanical and thermal properties of PVC matrix composite

The effects of filler particle size of poly(vinyl chloride)/chicken eggshell powder (PVC/ESP) composites on the processing, tensile properties, morphology and thermal degradation were investigated. The mixing of composites was done using Rheomix internal mixer. The processing torque of PVC/ESP composite at a particle of 0.2 μm exhibits lower processing torque compared to that at a particle size of 7 μm due to the dispersive resistance from larger ESP filler particles. Good interfacial adhesion exists between the filler and matrix in composites prepared via a filler particle size of 0.2 μm, which has improved the tensile strength and modulus of PVC/ESP composite compared to a filler particle size of 7 μm as justified from FESEM images on the tensile fracture surface of the composites. Thermogravimetric analysis results show that the filler particle size of 0.2 μm composite exhibits higher thermal stability compared to the filler particle size of 7 μm composite.     

Effect of calcium carbonate particle size on PVC foam

Calcium carbonate is the predominant filler used in polyvinyl chloride compounding. Selection of fillers, as in the case with other compounding ingredients, involves consideration of available types and their effects on processing, product properties, and economics. In this article the effect of the particle size of CaCO₃ on the properties of PVC foam is investigated. The study analyzes the correlation between fusion time, extrusion torque, and foam density as well as foam cell structure with the filler particle size. J. VINYL. ADDIT. TECHNOL. 12:55–57, 2006. © 2006 Society of Plastics Engineers.     

滑石粉粒径及含量对PVC/滑石粉复合体系动态流变行为的影响

考察了滑石粉粒径及含量对PVC/滑石粉复合体系动态流变行为的影响。结果表明:随着滑石粉的粒径减小、含量增加,PVC/滑石粉复合体系的黏度和模量增加,损耗因子减小,van Gurp-Palmen曲线向高复合模量方向移动。     

PVC树脂粒径分布的测定及其塑化性能关系的探讨

介绍了用分析测试方法测定PVC树脂的粒径分布,利用此方法对不同厂家的PVC树脂进行了测试,并根据数据结果分析探讨了粒径分布与塑化性能的关系。确定了粒径分布此项质量指标原重要性,在PVC生产中可据此对聚合工艺配方进行调整,以满足不同用户需求。     

填充料粒度对石墨电极焙烧效果的影响研究

通过对填充料粒度的影响所造成的石墨电极理化参数的变化进行统计归纳,认为通过合理调节填充料粒度配比,能够有效改善石墨电极焙烧品的理化参数,提高焙烧品尤其是接头产品的合格率。     

Rheological characterization of room temperature vulcanized silicone sealant: Effect of filler particle size

The rheological properties of silicone sealant filled with different calcium carbonate (CaCO₃) particles varying in size were investigated. It is found that as particle size decreases, the dynamic storage modulus (G′) and shear viscosity (η) increase; whereas, the width of linear viscoelastic region decreases. At low shear rate, a modulus plateau appears and the shear thinning behavior becomes apparent. The reasons for these can be ascribed to the enhanced particle–particle interaction and formation of filler network structure. Moreover, results dealing with the buildup of network structure monitored by kinetic recovery experiments reveal that both the rate of recovery and magnitude of rheological parameters increase with decreasing particle size. This phenomenon is consistent with the data collected from creep and recovery measurements, indicating an enhanced elasticity and network structure. Furthermore, transmission electron microscopy (TEM) observation and mechanical properties tests for cured sealant samples were also carried out to provide an evidence for the discussion further. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Mechanical properties of talc-filled polypropylene. Influence of filler content,filler particle size and quality of dispersion

Mechanical properties of polypropylene-talc composites are measured as a function of talc concentration up to 40 wt.-%, Young's modulus of filled polypropylene shows linear increase with talc concentration up to double the value of unfilled polymer. Yield stress and Charpy notch toughness decrease with increasing talc content below matrix level at the highest filler content. Composite ultimate tensile elongation and tensile impact strength decrease sharply beginning at the lowest filler concentration. The influence of the talc particle size on the mechanical properties, especially composite toughness, mentioned above, is investigated. Four type of talc were used. Notch toughness decreases according to a linear dependence with mean size of talc particles. Evaluating impact strength possible content of agglomerates of filler and other additions is necessary to be included: tensile impact strength gives slow linear dependence with increasing content of filler particles and/or agglomerates above about 10 μm. The influence of talc particle size on the toughness of filled polypropylene becomes strong if the rubber particles are present.     

激光衍射散射式测粒技术在聚氯乙烯糊树脂粒径分析中的应用

介绍了激光衍射散射式测粒技术在聚氯乙烯糊树脂(PPVC)粒径分析中的应用情况,讨论了实验条件的优化。结果表明:激光衍射散射式测粒技术的可测粒径范围广、测量过程快速、测量结果准确,能准确地测量具有双峰分布的样品,是测量和表征PVC乳液颗粒粒径及粒度分布的理想方法。     

Rheological properties of PDMS filled with CaCo3: The effect of filler particle size and concentration

The effects of filler particle size and concentration on the rheological properties of hydroxyl terminated polydimethylsiloxane (HO‐PDMS) filled with calcium carbonate (CaCO₃) were investigated by an advanced rheometric expansion system (ARES). The Casson model was used to describe the relationship between shear stress and shear rate for steady‐state measurement. Micron‐CaCO₃ could not afford the CaCO₃/HO‐PDMS suspensions obvious shear thinning behavior and a yield stress high enough, whereas nano‐CaCO₃ could provide the suspensions with remarkable shear thinning behavior and high yield stress. Incorporation of nano‐CaCO₃ into HO‐PDMS resulted in the transformation of HO‐PDMS from a mainly viscous material to a mainly elastic material. With increasing nano‐CaCO₃ content, shear thinning behavior of nano‐CaCO₃/HO‐PDMS suspensions became more obvious. Remarkable yield stress was observed in nano‐CaCO₃/HO‐PDMS suspensions with high filler content, and increased with increasing nano‐CaCO₃ content. The degree of thixotropy was quantitatively determined using a thixotropic loop method. It was found that nano‐CaCO₃ favored more the buildup of filler network structure in the suspensions than micron‐CaCO₃ at the same weight fraction. Furthermore, increasing nano‐CaCO₃ content accelerated the establishment of filler network structure in the nano‐CaCO₃/HO‐PDMS suspensions. An overshoot phenomenon was observed in the nano‐CaCO₃/HO‐PDMS suspensions at high shear rates. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3395–3401, 2006     

Effect of particle size of magnesium silicate filler on physical properties of paper

Fillers are essential component of printing papers to increase the opacity, brightness, and to improve formation and printing properties. As a very little work has been reported so far on magnesium silicate (talc), the study was conducted with the filler of different particle size for papermaking. The sheets were made in the laboratory with refined mixed hardwood chemical pulp with five grades of talc, ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC) fillers with 15–24% ash level. Apparent density along with tensile, burst, tear index, Z‐direction tensile strength (ZDTS) and bending stiffness index were evaluated for talc filled sheets, and compared with GCC and PCC. Physical strength properties of talc filled sheets were decreased at a faster rate on increasing filler loading in paper and decreasing the particle size of the filler. With same type of filler its particle size determines the physical properties of paper. The postulate was not found to be valid for all the three varieties of fillers viz., talc, PCC and GCC. Shape and geometry of the PCC and GCC fillers determine the individual property. © 2012 Canadian Society for Chemical Engineering     

Zinc compounds as flame retardants and smoke suppressants for rigid PVC

Abstract

The effect of the concentration of zinc hydroxy-stannate and zinc borate on the fire performance of rigid PVC formulations has been investigated. Fire testing was carried out using cone calorimetry as well as the limiting oxygen index (LOI) test. In addition, further testing was done to check that incorporation of the fire retardant additives did not have any detrimental effects on other properties of the formulated PVC, such as heat stability, colour or impact strength. The results demonstrated that zinc hydroxy-stannate is an excellent fire retardant and smoke suppressant at additions levels of 3 parts per hundred parts of PVC. Zinc borate did not have the excellent fire retardant properties of zinc hydroxy-stannate, but was found to be an efficient and cost-effective smoke suppressant, although the presence of free zinc oxide in the sample affected the thermal stability of the formulation.     

Effects of particle size of calcium and calcium compounds on catalytic graphitization of phenolic resin carbon

Phenolic resin containing finely dispersed Ca(SCN)₂ was cured, then heat treated in the range 500–2600°C in order to examine the catalytic graphitization action. The results are compared with those obtained with bulky Ca, Ca compounds and Ca vapor reported previously. Regardless of the kind or particle size of the Ca source, CaC₂ is formed as an intermediate in the catalytic graphitization process; and the carbide particle size is roughly proportional to that of the Ca source. The catalytic action is affected by the carbide catalyst particle size as follows: Bulky catalyst forms graphitic carbon; finely dispersed catalyst forms specific turbostratic carbon; and hyperfine catalyst, resulting from Ca vapor, accelerates the gradual graphitization of the entire carbon.     

Emulsion polymerization of vinyl chloride: A new method for particle size analysis of latexes of PVC and applications

A new particle size analysis of latexes has been developed using a disc centrifuge allowing a very fast zonal sedimentation of particles followed by an automatic optical device. This method, which involves 5-10 minutes, permits the routine control of fabrication for emulsions of PVC. Linked to a computer, it permits accurate determinations of particle sizes in terms of weight, surface or number averages. The complete operation for one latex requires less than 15 minutes. This technique has been used to follow the growth of particles in seeding operations, i.e., monosized seed latex and the competitive growth of 2 populations of seed particles. Some results have also been obtained by comparing accurate particle size analyses of latexes with rheological properties of plastisols obtained from these latexes.