Effect of high‐energy ball milling on the structure and mechanical properties of ultra‐high molecular weight polyethylene

The structure and properties of ultrahigh‐molecular‐weight polyethylene (UHMWPE) powder after severe deformation processing in a planetary ball mill were studied by means of scanning electron microscopy, differential scanning calorimetry, and X‐ray analysis. We found that the severe deformation processing of UHMWPE changed the morphology of the powder and caused amorphization and partial changes in the structure of the crystalline phase. Monolithic samples were obtained from the pretreated polymer with a hot‐pressing method in a wide range of temperatures. The effect of preliminary deformation processing on the mechanical properties of UHMWPE was studied. It was revealed that during monolitization in its melting temperature range, the mechanical properties of the powder increased, whereas the percentage elongation decreased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2971–2977, 2013     

Recycling von marinen Sekundärrohstoffen

As a waste product, oyster shells pose a major environmental pollution problem and the reuse of the material is becoming increasingly important. Since the comminution process in the recycling of secondary raw materials defines the properties of the material, oyster shells were grinded using a planetary ball mill and an impact mill and the fractions obtained were analyzed in terms of size and shape and compared with each other. A comminuted material from the impact mill was used for a series of wetting experiments, which helped to demonstrate the surface free energy of the material.     

行星搅拌球磨机超细粉碎机理分析

描述了行星搅拌球磨机的工作原理,针对物料在其中被粉碎时复杂的运动轨迹和受力方式,通过对超细粉碎过程的颗粒粉碎速度、颗粒碰撞速度的数学分析以及从流体力学角度对湿法粉碎机理的分析,综合分析了利用行星搅拌球磨机制备超细粉的机理。     

LDPE composite films incorporating ceramic powder emitting far‐infrared radiation for advanced food‐packaging applications

A ceramic powder that emits far‐infrared radiation (FIR) was incorporated into low‐density polyethylene (LDPE) via melt‐compounding and subsequent melt‐extrusion processes. To investigate the feasibility of as‐prepared LDPE/FIR composite films for use in packaging applications, the composite films were characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, FIR emissivity and emissive power, antimicrobial activity assays, and storage tests. The physical properties and antimicrobial activities of the composite films were found to strongly correlate with the changes in the chemical and morphological structures that originate from different contents of FIR ceramic powder. A higher content of FIR ceramic powder in the LDPE/FIR composite film provided increased FIR emissivity and emission power of the composite and resulted in good antimicrobial activity. Storage tests also showed that incorporation of FIR ceramic powder into LDPE film was an effective method for maintaining the freshness of lettuce. Furthermore, the incorporation of FIR ceramic powder into LDPE films induced higher thermal stability and crystallinity and enhanced their barrier properties, which suggest these LDPE/FIR composite films are potential candidates for advanced packaging materials for the food and medical industries. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43102.     

机械力化学法制备单相莫来石的机理研究

以高岭土和氢氧化铝为原料,采用机械力化学法制备出了单相莫来石。用热重-差示扫描分析研究了混合粉体经高能球磨后的结构变化,并讨论了单相莫来石的形成机理。结果表明：高能球磨破坏了混合物的晶体结构;随着粉磨的进行,混合物的比表面积会增加,无序程度也会增加,键能会减小,从而导致了内部贮能的增加,反应活化能的减小,并可得到均匀混合物。粉磨30h混合物制成的烧结体的热膨胀系数要比未粉磨的低约20％。     

Study of the morphology and granulometry of polyethylene–clay nanocomposite powders

Medium‐density polyethylene (MDPE) matrix nanocomposites reinforced with different clay contents were produced by using a planetary ball mill. The morphology of all the milled samples, including pure polyethylene and the polyethylene–clay nanocomposites, was examined by scanning electron microscopy. To investigate the effects of milling time and clay content on the particle size of polyethylene powder, sieve analysis was used. The results showed that during milling, the regular shape of pure polyethylene powder converts into flake shapes and the average particle size of the powder increases upon increasing the milling time because the welding mechanism is predominant. Also, the presence of the clay can increase the maximum‐particle size, and increasing the clay content can decrease the milling time required to reach the same maximum particle size. J. VINYL ADDIT. TECHNOL., 2010. © 2009 Society of Plastics Engineers     

油性铝银浆的制备工艺及改进对策

本文阐述了制备油性铝银浆3个工艺过程。首先,简单介绍了球磨工艺过程中行星式球磨机的球磨机理及微球铝粉片状化过程,并讨论了用球磨机在球磨铝粉过程中的几个影响因素;其次,是分离工艺过程中筛分和过滤待改进的工艺条件;第三,探讨了捏合过程对整个产品体系稳定性的影响;最后,简易配制涂料,采用相关仪器对产品质量进行评价,并提出三方面的改进要求。     

Optimized experimental design for natural clinoptilolite zeolite ball milling to produce nano powders

Nano powder of natural clinoptilolite zeolite was mechanically prepared by using a planetary ball mill. Statistical experimental design was applied to optimize wet and dry milling of clinoptilolite zeolite. To determine appropriate milling conditions with respect to the final product crystallinity, particle size and distribution, different milling parameters such as dry and wet milling durations, rotational speed, balls to powder ratio and water to powder ratio (for the wet milling) were investigated. Laser beam scattering technique, scanning electron microscopy and X-ray diffraction analyses were carried out to characterize samples. Results showed that larger than 1 mm particle size of clinoptilolite powder may mechanically be reduced into the size range of less than 100 nm to 30 μm by means of planetary ball milling.     

The effect of ball milling time and rotational speed on ultra high molecular weight polyethylene reinforced with multiwalled carbon nanotubes

Ultra high molecular weight polyethylene (UHMWPE) composites reinforced with multiwalled carbon nanotubes (MWCNT) were produced using planetary ball milling. The aim was to develop a more wear resistant composite with improved mechanical properties to be used in stress bearing joints. The effect of manufacturing parameters such as the effect of ball milling time and rotational speed on the final composite was analyzed by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), particle size distribution, and contact angle measurements. Ball milling as a mixing technique for UHMWPE based composites is not a new approach but yet, the effect of time, rotational speed, loading of milling jar, and type of ball mill has not been reported properly for UHMWPE. Composites with 0.5 and 1.0 wt% UHMWPE/MWCNTs were manufactured with different rotational speed and mixing times. The results indicate that rotational speed rather than mixing time is important for dispersing MWCNTs using planetary ball milling. Tensile test showed a slight decrease for the MWCNT concentration of 1 wt% suggesting that this amount is the threshold for a satisfactory distribution of the fillers in the matrix. POLYM. COMPOS. 37:1128–1136, 2016. © 2014 Society of Plastics Engineers     

Scale-up method of planetary ball mill

The objective of this paper is to investigate the scale-up method of the planetary ball mill by the computational simulation based on Discrete Element Method. Firstly, the dry grinding of a gibbsite powder by using four different scales of planetary mill was developed to compare the grinding rate with the specific impact energy of balls calculated from computational simulation. The grinding rate is well correlated with the specific impact energy in all mills; and its relationship is expressed by a linear correlation. It points out that the specific impact energy is very useful for estimation of the grinding rate and optimization for the operational conditions. Secondly, the scale-up method for the planetary mill was established by evaluating the impact energy. The impact energy is proportional to the cube of the diameter of the pot, the depth of the pot and the revolution radius of the disk, respectively. When the planetary mill is scaled-up in geometrical similarity, the impact energy of the balls is proportional to 4.87 power of the scale-up ratio.     

Effects of different milling conditions on the properties of lanthanum hexaboride nanoparticles and their sintered bodies

In this study, the preparation and consolidation of nanocrystalline LaB₆ powders originating from powder blends of La₂O₃, B₂O₃ and Mg were reported. A consecutive route of mechanochemical synthesis (MCS) and purification was utilized for the achievement of nano-sized LaB₆ powders. As-synthesized powders were leached out from intermediate reaction products or impurities. Then, a sequential step of cold pressing (uniaxial pressure at 800 MPa) and pressureless sintering (at 1700 °C for 5 h under Ar gas flow) were utilized for the consolidation of the purified LaB₆ powders. The type of mill (vibratory and planetary high-energy ball mills) was employed as a MCS parameter to reveal its effect on the physical, microstructural and mechanical properties of the LaB₆ powders, and their bulk structures. Compositional, physical and microstructural properties of the products after powder processing were determined via X-ray diffractometer (XRD), particle size analyzer (PSA), differential scanning calorimeter (DSC), stereomicroscope (SM), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectrometer (EDS) coupled with both SEM and TEM, and vibrating sample magnetometer (VSM). The bulk properties of the LaB₆ consolidated from nanocrystalline powders with a minimum 99.99% purity, and ∼62 nm (for vibratory ball mill) or ∼74 nm (for planetary ball mill) average particle size were compared according to various properties. LaB₆ powders were synthesized in planetary mill at an approximately six times longer duration than that of in vibratory mill. According to the results, density, surface area and mean particle size values of the vibratory ball-milled samples (containing paramagnetic powders) are better than those of planetary ball-milled (containing diamagnetic powders) ones. However, mechanical properties such as hardness, surface roughness, wear rate, friction coefficient, and also electrical conductivity were improved in the planetary ball-milled LaB₆ bulks.     

Structural,thermal, micromechanical and electrical study of polyimide composite thin films incorporating indium tin oxide

Studies of composite films incorporating inorganic materials are of immense importance for current technological applications. Polyimide (PI) composite thin films incorporating indium tin oxide (ITO) at various weight ratios were processed using an in situ generation approach. The resultant product was imidized up to 350 °C to test the ability of the material to endure high temperatures without affecting the host matrix. The morphological behaviour of the PI/ITO composite films was investigated using Fourier transform infrared, scanning electron microscopy and atomic force microscopy characterization techniques. The degrees of crystallinity and ITO particle size within the PI matrix were studied using X‐ray diffraction. The thermal, structural and electrical properties were analysed using thermogravimetric analysis, differential scanning calorimetry, UV‐visible spectroscopy and the four‐probe technique. The micromechanical properties of the composites were evaluated in terms of tensile strength, tensile modulus and elongation. An overall improvement in the properties of the composite films was observed in comparison to those of pure PI. The synergistic improvement in the composite films is associated with the interaction mechanism between ITO and PI, where ITO becomes dispersed and interacts within the PI matrix. This leads to a decrease in available free‐space volume and increases the surface enrichment providing reinforcement to the matrix. Copyright © 2010 Society of Chemical Industry     

中国超细粉碎和精细分级技术现状及发展

综述了中国超细粉碎与精细分级技术与设备的现状、近5年的进展 .20世纪90年代中期以来,中国超细粉碎和分级技术取得了显著进步,现已具备了研制和生产气流粉碎机、高速机械冲击式超细粉碎机、搅拌球磨机、振动球磨机、塔式搅拌磨、行星球磨机、高压射流磨、旋风自磨机等各类超细粉碎及涡轮式气流分级机和离心式水力分级机等设备的能力,并在流态化床式气流粉碎机、飓风自磨机、搅拌球磨机和砂磨机、行星球磨机、高压水射流磨机以及精细分级原理和分级设备等方面取得了一些进展,具有自主知识产权的新技术、新设备显著增多.指出中国目前在超细粉碎和精细分级领域仍然存在大型设备不足、工艺控制技术落后、磨耗和单位产品能耗偏高、特殊粒形超细粉体的生产工艺和设备落后等问题.最后对21世纪初中国超细粉碎和分级技术的主要发展趋势进行了展望.     

球磨法制备超细镍粉及其表征

为了获得在自然条件下稳定存在的超细镍粉,通过控制行星式高能球磨机的转速、研磨时间、磨球数、运转时间、暂停间隔、转动方向等参数对镍粉进行了研磨实验,并对不同参数下的研磨结果进行了测试表征。结果表明,在转速260 r/min、研磨时间19 h、运行时间3 min、暂停时间30 s、磨球数为10个、原料5 g且晴朗天气下实验,可以制备出亚微米级超细镍粉,并在空气中稳定存在。     

Effects of mechanical properties of polymer on ceramic-polymer composite thick films fabricated by aerosol deposition

ABSTRACT: Two types of ceramic-polymer composite thick films were deposited on Cu substrates by an aerosol deposition process, and their properties were investigated to fabricate optimized ceramic-based polymer composite thick films for application onto integrated substrates with the advantage of plasticity. When polymers with different mechanical properties, such as polyimide (PI) and poly(methyl methacrylate) (PMMA), are used as starting powders together with α-Al2O3 powder, two types of composite films are formed with different characteristics - surface morphologies, deposition rates, and crystallite size of α-Al2O3. Through the results of micro-Vickers hardness testing, it was confirmed that the mechanical properties of the polymer itself are associated with the performances of the ceramic-polymer composite films. To support and explain these results, the microstructures of the two types of polymer powders were observed after planetary milling and an additional modeling test was carried out. As a result, we could conclude that the PMMA powder is distorted by the impact of the Al2O3 powder, so that the resulting Al2O3-PMMA composite film had a very small amount of PMMA and a low deposition rate. In contrast, when using PI powder, the Al2O3-PI composite film had a high deposition rate due to the cracking of PI particles. Consequently, it was revealed that the mechanical properties of polymers have a considerable effect on the properties of the resulting ceramic-polymer composite thick films.     

Mechanical properties of poly lactic acid composite films reinforced with wet milled jute nanofibers

In the present study, waste jute fibers generated in textile industries, were wet pulverized to the scale of nanofibers of 50 nm diameter using high energy planetary ball milling for 3 h. The presence of water during wet pulverization found to reduce the rising temperature of mill, which prevented sticking of nanofibers on the mill wall and resulted in unimodal size distribution. In the subsequent stage, 1, 5, and 10 wt% of jute nanofibers were incorporated in poly(lactic acid) (PLA) matrix to prepare nanocomposite films by solvent casting. The reinforcement of nanofibers was investigated from the improvements in mechanical properties based on tensile tests, dynamic mechanical analysis, and differential scanning calorimetry. The maximum improvement was observed in case of 5 wt% nanocomposite film where initial modulus and tensile strength increased by 217.30% and 170.59%, respectively as compared to neat PLA film. These improvements are attributed to the increased interaction between nanofibers and matrix as well as to the increased crystallinity of PLA in composites. The improvements in load bearing capacity of nanocomposite films were significant at 60°C than 35°C, which showed ability of jute nanofibers to improve the softening temperature of PLA matrix. In the end, experimental results of Young's modulus were compared with predicted modulus of mechanical models. A good level of agreement was observed up to 5 wt% loading of jute nanofibers. POLYM. COMPOS., 34:2133–2141, 2013. © 2013 Society of Plastics Engineers     

Preparation of polyimide/siloxane‐functionalized graphene oxide composite films with high mechanical properties and thermal stability via in situ polymerization

An effective approach to prepare polyimide/siloxane‐functionalized graphene oxide composite films is reported. The siloxane‐functionalized graphene oxide was obtained by treating graphene oxide (GO) with 1,3‐bis(3‐aminopropyl)‐1,1,3,3‐tetra‐methyldisiloxane (DSX) to obtain DSX‐GO nanosheets, which provided a starting platform for in situ fabrication of the composites by grafting polyimide (PI) chains at the reactive sites of functional DSX‐GO nanosheets. DSX‐GO bonded with the PI matrix through amide linkage to form PI‐DSX‐GO films, in which DSX‐GO exhibited excellent dispersibility and compatibility. It is demonstrated that the obvious reinforcing effect of GO to PI in mechanical properties and thermal stability for PI‐DSX‐GO is obtained. The tensile strength of a composite film containing 1.0 wt% DSX‐GO was 2.8 times greater than that of neat PI films, and Young's modulus was 6.3 times than that of neat PI films. Furthermore, the decomposition temperature of the composite for 5% weight loss was approximately 30 °C higher than that of neat PI films. © 2015 Society of Chemical Industry     

Properties of composite films comprising surface modified fine collagen particles dispersed in polyurethane matrix

Collagen-rich natural leather powders (PPd) with average particle size of 12 μm were modified and dispersed in a polyurethane (PU) matrix. Three kinds of surface modification techniques were employed; surface polyaddition of PU, copolymerization with acrylamide (AAm), and grinding of the PPd with PU powder in a planetary ball mill. Surface modification was confirmed mainly by FTIR signals from the modifier. The DTA exothermic peak shifted toward a higher temperature by 260 K when copolymerized with AAm. On the copolymerized sample, the IR peak due to C(DOUBLE BOND)O stretching appeared between those of the original AAm and PPd, indicating the mutual chemical interaction. The tensile yield stress and critical strain of the composite films increased by surface modification with PU, while the latter decreased for the film containing the PPd powders copolymerized with AAm. Judging from the micrographs of the expanded films, the increase in the adhesive strength between the powder surface and the matrix after modification by AAm was larger than those by PU. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1693–1700, 1997     

Synthesis and characterization of polyimide/hexagonal boron nitride composite

Polyimide (PI)/hexagonal boron nitride (h‐BN) composites were produced via the thermal imidization procedure from solution mixtures of a polyamicacid, which is prepared from 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride and 3,3′‐diaminodiphenyl sulfone (DADPS) in N‐methyl‐2‐pyrrolidone (NMP), and alkoxysilane functionalized h‐BN. The structure, thermostability, thermal behavior, and surface properties of the resulting materials were characterized by means of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM). The thermal characteristics of PI/h‐BN films were better than the pure PIs. The physical and mechanical properties of the films were evaluated by various techniques such as contact angle, chemical resistance, and tensile tests. The flame retardancy of the composite materials was also examined by the limiting oxygen index (LOI). The experiments showed that the LOI values of PIs increased from 32 to 43 for the materials containing hexagonal boron nitride. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Interfacial reaction and side effect of MgB2 superconducting material through low-rotation mechanical milling

Powder processing by ball milling is an effective approach for materials engineering. Although various methods for material processing are available, only high-energy shaker/vibratory or planetary mills have been intensively utilized to develop mechanical milling or alloying routes for structural control of MgB₂ superconducting materials. Herein, we have attempted structural modification by using a low-rotation shaker, which is categorized as a low-energy and economical mill in terms of industrial applications. The operation speed was kept constant at 40 rpm, which is much lower than typical conditions employed for planetary mills. Instead of adjusting the low rotational speed, the other processing parameters were controlled to enhance the energy transfer from the balls to powders. The applied milling conditions were ultimately found to cause severe plastic deformation of the raw powders. The shape and size changed drastically, depending on the processing time. The morphological variation of the processed powders as precursors for the MgB₂ materials influenced the void structure and the composition including amorphous phases. By considering these results, we also elucidated the mechanism underlying the structural changes upon ball milling and their effects on the transport critical current performance. The present approach for powder processing offers potential as an effective milling route for structural modification of superconducting materials.