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以偶氮二甲酰胺(AC)为发泡剂,采用单螺杆挤出机制备了发泡三元乙丙橡胶(EPDM)/聚丙烯(PP)热塑性硫化胶(TPV),探讨了挤出温度、机头温度及螺杆转速对发泡TPV性能及形态结构的影响。结果表明,在保证EPDM/PPTPV充分塑化熔融及顺利挤出的前提下,较低的挤出温度和机头温度有利于制备密度低、泡孔尺寸小且分布均匀、表面光洁度高的发泡TPV,最佳的挤出温度和机头温度分别为185,170℃;随着螺杆转速的提高,发泡TPV的密度和拉伸性能均先降低后增高;泡孔平均直径基本不变,泡孔面密度先增大后减小,泡孔尺寸分布先变窄后变宽,最佳的螺杆转速为65r/min。 相似文献
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北京化工大学和吉林石化公司研究院采用螺杆挤压脱水膨胀干燥一步法干燥稀土异戊橡胶,考察了机头温度、机筒温度、机头压力和螺杆转速对产品质量和生产能力的影响。确定了最佳工艺参数:螺杆转速为80~90r·min-1,机头温度为150℃,机筒温度为160℃,机头压力为14~16MPa。在最佳工艺条件下,装置运行和工艺参数控制平稳,干燥后稀土异戊橡胶挥发分含量小于1.0%,门尼黏度降幅小于10%,能够满足产品应用的要求。 相似文献
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从聚丙烯挤出发泡的加工设备包括挤出机的类型、发泡机头的设计、发泡剂的注入和计量控制以及聚丙烯挤出发泡的成型工艺包括螺杆转速、压力降和压力降速率、成核剂的分散、发泡机头的温度等系统介绍了聚丙烯挤出发泡中的一些关键技术。目前的研究表明:采用双螺杆挤出机进行挤出发泡时需要考虑发泡剂逃逸和压力的升高与稳定;可以通过改变机头的形状和尺寸获得不同的压力降和压力降速率,从而控制挤出发泡的成核速率。提高螺杆转速、增加压力降和压力降速率有利于优质发泡材料的获得;优选适宜的发泡机头温度可以抑制气体逃逸,提高发泡倍率,获得更低密度的聚丙烯发泡材料。 相似文献
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采用双螺杆挤出成型的方法生产稻壳粉/PVC门条线,研究了机头温度、螺杆转速对挤出难易程度、门条线密度及其力学性能的影响,并优化了工艺参数。结果表明:机头温度175℃,螺杆转速10 r/min,主机功率8 kW时,门条线综合质量最佳。此时门条线的吸水率、低温长收缩率、低温宽收缩率分别为0.42%,0.15%和0.22%。 相似文献
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以水为增塑剂兼物理发泡剂,氢氧化铝(ATH)为无机阻燃剂兼异相成核剂,通过热塑挤出方法制备了无机阻燃聚乙烯醇/氢氧化铝(PVAL/ATH)复合泡沫材料,采用扫描电子显微镜(SEM)等研究了水和ATH含量、口模温度、螺杆转速、交联剂对复合泡沫材料泡孔结构的影响。结果表明,适当的口模温度和螺杆转速是实现体系中水的可控、连续、稳定发泡的关键因素,适量添加的阻燃剂能够起到良好异相成核剂的作用,在最佳工艺条件下,当PVAL/ATH/水为100/80/30,口模温度为125℃,螺杆转速为30 r/min时,制备得到综合性能优异的无机阻燃PVAL/ATH泡沫材料,泡沫材料的表观密度为0.32 g/cm3,膨胀倍率为10.0,泡孔密度约为1.6×105个/cm3。此外,引入硼酸作为交联剂,有效提高了熔体强度并改善了泡孔结构,交联后泡沫材料的拉伸强度和断裂伸长率分别提高到6.3 MPa和59.2%。 相似文献
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Poly(ethylene terephthalate)/polypropylene (PET/PP) blends of different compositions were extruded through a 2‐mm capillary die using a corotating twin‐screw extruder. The extrudates were cryogenically fractured and examined using scanning electron microscopy. The viscosity ratio of the constituent polymers alone was found to be unsuitable for explaining the polymer blend morphology. At a PET concentration of 20%, the extrudate consists of three regions. The skin layer, which is about 10 μm thick, has a lower concentration of the dispersed PET phase than the overall concentration. The intermediate region, which is about 400 μm thick, has profuse PET fibers and some small PET particles. The central region, which is approximately 800 μm in diameter, mainly contains PET particles that are generally bigger. A low barrel temperature, low die temperature, and fast cooling rate helped to retain the fibers near the extrudate skin. Meanwhile, the variation of the barrel temperature, die temperature, and cooling media did not produce a significant affect on the PET particle size distribution in the central region of the extrudate. A high screw speed and a high postextrusion drawing speed were very effective in producing fibers in the extrudates through elongation of particles. At a PET concentration of 30%, coalescence of the PET phase was prevalent, leading to the formation of PET platelets near the extrudate skin and irregular PET networks in the central region of the extrudate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1743–1752, 2003 相似文献
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Poly(ethylene terephthalate)/polypropylene (PET/PP) blends of different compositions were extruded through a 2‐mm capillary die using a corotating twin‐screw extruder. The extrudates were cryogenically fractured and examined using scanning electron microscopy. The viscosity ratio of the constituent polymers alone was found not suitable for explaining the polymer blend morphology. At a PET concentration of 20%, the extrudate consists of three regions: The skin layer, about 10 μm thick, has a lower concentration of the dispersed PET phase than that of the overall concentration. The intermediate region, about 400 μm thick, has profuse PET fibers and some small PET particles. The central region, approximately 800 μm in diameter, contains mainly PET particles that are generally bigger. A low barrel temperature, low die temperature, and fast cooling rate helped to retain the fibers near the extrudate skin. Meanwhile, variation of the barrel temperature, die temperature, and cooling media did not affect the PET particle‐size distribution significantly in the central region of the extrudate. A high screw speed and a high postextrusion drawing speed were very effective in producing fibers in the extrudates through elongation of the particles. At a PET concentration of 30%, coalescence of the PET phase was prevalent, leading to the formation of PET platelets near the extrudate skin and irregular PET networks in the central region of the extrudate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3100–3109, 2003 相似文献
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张玲;张云灿;傅伟宁 《中国塑料》2010,24(11):49-53
采用提高双螺杆挤出机螺杆转速的应力诱导引发方法和添加引发剂与提高螺杆转速的复合引发方法,研究了高剪切应力作用下马来酸酐(MAH)与低密度聚乙烯 (PE-LD)的官能化反应,并且考察了官能化产物PE-LD-g-MAH对铝萡/PET薄膜(Al/PET)热熔胶的T型黏合接头剥离强度的影响。结果表明,高剪切应力作用可直接引起大分子链的断链,形成大分子自由基,引发PE-LD的接枝反应;通过改变螺杆转速可有效抑制交联副反应,制得具有较高接枝率、较好熔体流动速率和较低凝胶含量的官能化产物,当螺杆转速为800 r/min时,产物的接枝率为0.71 %,熔体流动速率为0.87 g/10 min,凝胶含量0.40 %;高剪切应力诱导引发法所得官能化产物可明显提高Al/PET热熔胶T型黏合接头的剥离强度,当反应温度为310 ℃,螺杆转速为600 r/min,三元乙丙橡胶(EPDM)含量为80 %(质量分数,下同)时,可使Al/PET的T型黏合接头的剥离强度达3.87 N/mm。 相似文献
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用单螺杆挤出装置,以CO2为发泡剂,对聚丙烯(PP)/CaCO3复合材料进行挤出发泡;采用正交法设计实验,利用Design-Expert统计软件对实验数据进行统计处理,观察制品纵截面上泡体的形态变化,从而得到加工工艺参数对泡体形态的影响规律,回归拟合得到泡孔平均直径、面密度、形变程度和倾向角的预测模型,并进行实验验证;最后用回归模型求解出较合适的加工参数范围。结果表明,转速为46~52 r/min、机头温度为170 ℃、熔体温度为180~189 ℃、CaCO3含量为6.67 %~7.9 %时,可得到较好的PP/CaCO3发泡制品。 相似文献
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Clémence Nikitine Elisabeth Rodier Martial Sauceau Jean‐Jacques Letourneau Jacques Fages 《应用聚合物科学杂志》2010,115(2):981-990
A study on the extrusion of Eudragit E100 was carried out using supercritical carbon dioxide (scCO2) as plasticizer and foaming agent. ScCO2 modifies the rheological properties of the material in the barrel of the extruder and acts as a blowing agent during the relaxation when flowing through the die. For experiments, a single‐screw extruder was modified to be able to inject scCO2 within the extruded material. The aim is to determine a correlation between operating conditions and foam structure. The effect of three parameters was studied: the temperature in the die and in the metering zone, the screw speed, and the volumetric flow rate of CO2. An increase in temperature enhances the expansion rate and the average pore diameter and appears to be the most significant parameter. The effect of CO2 concentration is significant at small concentrations only: the higher the CO2 concentration, the lower the pore density and the higher both the pore diameter and the expansion rate. The effect of the screw speed is tricky because a variation of this speed involves a decrease of CO2 weight ratio. This study shows that the structure of the extrudates does not evolve with a coupling of screw speed increase and a subsequent CO2 weight ratio decrease. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
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高速铁路用热塑性聚酯弹性体发泡材料挤出成型研究 总被引:2,自引:0,他引:2
采用挤出成型工艺制备热塑性聚酯弹性体(TPEE)发泡材料。研究了发泡剂的用量,成核剂的种类和用量,交联剂对TPEE挤出发泡材料性能的影响。采用万能力学测试机和扫描电子显微镜分别测试和观察了TPEE发泡材料的力学性能和泡孔结构,并测试了TPEE发泡材料的表观密度。结果表明:TPEE发泡材料的性能与发泡剂用量之间的关系并不是简单的线性关系;恰当的成核剂种类和用量能够为发泡体系提供大量的成核点,进而利于均匀泡孔的生成;加入过氧化二异丙苯(DCP)可提高发泡材料的力学性能,但降低了发泡率和均匀性;合理的加工参数对得到优质的TPEE发泡材料极为重要。综合考虑,当发泡体系中偶氮二甲酰胺(AC)为0.8份,苯甲酸钠为1.6份,采用压缩比为3:1的销钉式单螺杆挤出机,转速为70r/min,挤出温度为205℃,并且不加入DCP的工艺条件下制得的TPEE发泡材料的泡孔结构更为规整,整体性能更为理想。 相似文献
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H. A. Jongbloed R. K. S. Mulder L. P. B. M. Janssen 《Polymer Engineering and Science》1995,35(7):587-597
The copolymerization of n-butylmethacrylate with 2-hydroxypropylmethacrylate was studied in a closely intermeshing counterrotating twin-screw extruder. The average molecular weight of the product can be increased by increasing the screw rotation rate or the die resistance or by decreasing the throughput or the barrel temperature. The conversion can be improved by decreasing the throughput, increasing the die resistance, and (within limits) increasing the barrel temperature, as well as through post-initiation. Compared with various classical polymerization processes, this situation requires that particular attention be paid to the occurrence of a gel effect, the existence of a thermodynamic ceiling temperature, and the reactivity ratio of the monomers used. 相似文献