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The effect of pan-milling on the rheological properties of high density polyethylene (HDPE) was studied. Aninnovative milling apparatus, viz. an inlaid pan-mill, was used. Melt indexer, capillary rheometer, Haake Rheocord 90 single-screw extruder and Brabender rheometer were used to evaluate the rheologieal properties of HDPE. HDPE with higher initialmolecular weight and larger particle size was easier to degrade under pan-milling stress, as indicated by the melt index.Pressure oscillation in capillary flow occurred at significantly higher shear stress and shear rate for milled HDPE than forunmilled HDPE. The apparent shear viscosity of HDPE decreased with increasing times of milling. After milling, the flowactivation energy decreased and thus the sensitivity of viscosity to temperature was reduced. Die pressure and torque duringsingle screw extrusion were reduced significantly after milling. Plasticizing time as measured in a Brabander mixer decreasedmarkedly with increasing milling times. 相似文献
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Mechanochemical pretreatment of hardwood cellulose was conducted by our self-designed pan-mill equipment which has an unique
and smart structure and can exert strong shear forces and pressure on materials in between and break them down. The structure
transformations, including particle size, powder morphology, molecular structure, crystalline structure during milling were
investigated by Laser Diffraction Particle Size Analyzer, SEM, FT-IR and WAXD, respectively. Compared with standard method
of ball-milling, the pan-mill shows a much higher efficiency in mechanochemical pretreatment of hardwood cellulose. The average
particle size reduced to 21 μm and the specific surface area increased to 0.8 m2/g after 40 milling cycles. Mechanical milling also led to collapse of hydrogen bonds and reduction of crystallinity. The
crystallinity index of cellulose powder decreased from its original 65 to 22, after milling for 40 cycles. Thermal analysis
and solubility testing illustrated that pan-milled cellulose has lower thermal stability and higher solubility in aqueous
alkali. 相似文献
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磨盘碾磨制备PP/石墨复合粉末的研究 总被引:2,自引:0,他引:2
通过磨盘碾磨制备了PP 石墨复合粉末 ,用粒度分析、SEM和XRD表征了复合粉末的形貌特征、结构与性能 .结果表明 ,磨盘碾磨实现了PP与石墨的粉碎、分散和混合 ,经过 2 5遍碾磨 ,石墨与PP已互相嵌入 ,均匀分散 ;PP 石墨复合粉末具有不规则薄片状形貌特征 ;XRD表明 ,磨盘碾磨使PP和石墨的结晶度降低 ,晶面间距增大 ,晶粒尺寸减小 .PP 石墨复合粉末与聚丙烯共混复合可制备出具有良好抗静电性能的复合材料 . 相似文献
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磨盘形力化学反应器及其在高分子材料制备中的应用 总被引:13,自引:0,他引:13
介绍了自行设计制造的可用于聚合物及填料的粉碎、混合及力化学反应的磨盘形力化学反应器的特点,研究了聚丙烯、聚乙烯、聚氯乙烯、聚苯乙烯及二氧化钛等在磨盘碾磨过程中结构性能的变化,讨论了磨盘形力化学反应器在高分子材料制备中的应用前景. 相似文献
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Hua Huang Polymer Research Institute Sichuan University Chengdu China School of chemistry Chemical Technology Shanghai Jiao Tong University Shanghai China 《高分子科学》2000,(4):363-367
A detailed study was performed on the crystal structures of pan-milled high-density polyethylene (HDPE) usingdifferential scanning calorimetry (DSC) and X-ray diffraction. The crystallinity of HDPE first decreased slightly, followed bya gradual increase with increasing milling times. Monoclinic crystals appeared after 4 cycles of milling. With increasingtimes of milling, the proportion of monoclinic crystals increased significantly while the proportion of orthorhombic crystalsdecreased gradually. With increasing times of milling, the crystallite size of orthorhombic form decreased greatly, while thesize of monoclinic crystallites kept almost constant during milling. 相似文献
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