高剪切应力下不同弹性体对ABS材料力学性能影响

采用材料在熔融挤出共混过程中提高双螺杆挤出机螺杆转速的方法,研究了较高螺杆转速条件下双螺杆挤出机的高剪切应力、不同弹性体(SEBS、POE、EVA、NBR)等对ABS材料力学性能的影响.结果表明:双螺杆挤出机的高剪切应力可促进弹性体颗粒的分散和界面结合力的增强,引起共混材料力学性能的改善;NBR、EVA等弹性体有利于ABS材料韧性的提高,POE、EVA等弹性体有利于ABS材料加工流动性的改善.在220℃的挤出温度下,当螺杆转速由240 r/min提高至1200 r/min时,其中ABS/NBR(质量比90/10)共混材料的缺口冲击强度由22.1 kJ/m2提高至28.8 kJ/m2,提高了30%,比纯ABS树脂提高一倍.     

螺杆转速对ABS/EVA力学性能影响

采用在材料熔融挤出共混过程中提高双螺杆挤出机螺杆转速的方法,研究了较高螺杆转速条件下双螺杆挤出机的机械剪切应力对丙烯腈-丁二烯-苯乙烯共聚物/乙烯-乙酸乙烯共聚物(ABS/EVA)共混材料力学性能的影响。结果表明,双螺杆挤出机的高剪切应力可促进EVA颗粒的分散和界面结合力的增强。在220℃的挤出温度下,当螺杆转速由120 r/min提高至1 200 r/min时,ABS/EVA共混材料的缺口冲击强度由14.3 kJ/m2提高至16.6 kJ/m2。     

高剪切应力对ABS/NBR共混物力学性能的影响

研究了较高螺杆转速条件下双螺杆挤出机的机械剪切应力和挤出温度对丙烯腈-丁二烯-苯乙烯共聚物/丁腈橡胶（ABS/NBR）共混物力学性能的影响。结果表明,双螺杆挤出机的高剪切应力可促进NBR颗粒的分散,提高界面结合力,提高共混物的力学性能。在220 ℃的挤出温度下,当螺杆转速由240 r/min提高至1200 r/min时,ABS/NBR（90/10）共混物的缺口冲击强度由22.1 kJ/m2提高至28.8 kJ/m2,,提高了30 %。双螺杆挤出机的熔融挤出温度对ABS/NBR共混物力学性能的影响存在最佳值。     

高剪切应力对PP/PS/EPDM材料力学性能的影响

采用在材料熔融挤出共混过程中提高双螺杆挤出机螺杆转速的方法,研究了较高螺杆转速条件下双螺杆挤出机的机械剪切应力对聚丙烯(PP)/聚苯乙烯(PS)/三元乙丙橡胶(EPDM)共混材料力学性能的影响。结果表明:双螺杆挤出机的高剪切应力可促进PS颗粒的分散和界面结合力的增强,促使共混材料力学性能的改善。EPDM对PP/PS共混材料具有增容增韧作用,在220℃的挤出温度下,当螺杆转速由240 r/min提高至1 200 r/min时,其PP/PS/EPDM(质量比81/9/10)共混材料的缺口冲击强度最高达22.0 kJ/m2,。     

超细CaCO3对ABS材料力学性能的影响

采用双螺杆挤出机熔融挤出共混的方法,在较高螺杆转速条件下研究了CaCO3表面处理剂品种、CaCO3颗粒直径及其含量等因素对ABS／弹性体/CaCO,共混材料力学性能和加工流动性能的影响。结果表明,在CaC03颗粒直径1．08—1．96μm、C型表面处理剂、螺杆转速480r／min、220℃的共混条件下,可制得综合力学性能较好的ABS／高胶粉（GP）／CaCO3（质量比62．9：17．1：20）和ABS／EVA／CaCO3（质量比74．6：20．4：5）共混材料。     

挤出共混中的高剪切应力对PP-HDPE-滑石粉共混材料力学性能的影响

采用提高双螺杆挤出机螺杆转速的方法,研究了双螺杆挤出机的高剪切应力作用对聚丙烯(PP)、PP-滑石粉和PP-高密度聚乙烯(HDPE)-滑石粉共混材料力学性能的影响.结果表明:双螺杆挤出机的高螺杆转速、高剪切应力作用,可促进材料中滑石粉颗粒的均匀分散、促进HDPE均匀分散于PP基体的乙丙共聚物的相态之中,可引起PP或HDPE的断链反应、引起HDPE大分子自由基与PP基体中的EPR相以及与滑石粉表面偶联助剂之间的结合反应,引起共混材料缺口冲击强度的显著增大;少量极性烯类单体的加入和较低的挤出反应温度条件(180℃)有利于形成的大分子自由基与极性烯类单体的接枝、嵌段反应、界面间的偶联结合反应及其原位增粘作用,并引起PP-HDPE-滑石粉共混材料缺口冲击强度的进一步增大.     

高剪切应力诱导引发乙丙橡胶与马来酸酐官能化反应的研究

采用在熔融挤出过程中提高双螺杆挤出机螺杆转速的高剪切应力诱导引发方法和采用添加引发剂与提高螺杆转速的应力诱导复合引发方法,研究了乙丙橡胶(EPR)与马来酸酐(MAH)的官能化反应;采用化学分析、熔体流动速率测定、FT IR、SEM观测和材料力学性能测试等方法考察了官能化产物(EPR-g-MAH)性能及其对PA66/EPR-g-MAH共混材料力学性能的影响。结果表明:双螺杆挤出机的螺杆转速和官能化反应温度对产物的接枝(嵌段)率和熔体流动速率具有重要影响;与热引发方法相比较,270℃条件下螺杆转速由80 r/m in提高至800 r/m in时,产物的接枝(嵌段)率由0.26%提高至0.47%;与引发剂引发方法相比较,产物熔体流动速率由每10 m in约0.07 g提高至1.80 g,抑制或避免了官能化过程中的交联副反应;所得产物的接枝(嵌段)率和熔体流动速率易于控制,对于PA66的增韧作用,存在最佳接枝(嵌段)率(约0.66%)和最佳熔体流动速率(每10 m in约2.0 g)。     

mLLDPE及mLLDPE/LDPE共混物挤出加工性能的研究

使用双螺杆挤出机、单螺杆挤出机研究了mLLDPE及mLLDPE/LDPE共混物挤出表面、螺杆扭矩与喂料速度、螺杆转速之间的关系 ,并讨论了有机硅对mLLDPE/LDPE共混物挤出性能的影响     

高剪切应力引发HDPE/EPDM的官能化反应

在熔融挤出过程中采用提高双螺杆挤出机螺杆转速的应力诱导引发和添加引发剂/提高螺杆转速的复合引发方法,研究了高密度聚乙烯(HDPE)和三元乙丙橡胶(EPDM)共混物(质量比为70∶30)与马来酸酐(MAH)的官能化反应.结果表明:双螺杆挤出机的高螺杆转速所产生的高剪切应力作用直接诱导了HDPE/EPDM大分子链的断链反应...     

ABS增韧废PET饮料瓶片的性能与形态研究

采用熔融挤出的方法研究了丙烯腈-丁二烯-苯乙烯共聚物(ABS)增韧废聚对苯二甲酸乙二醇酯(r-PET)饮料瓶片的力学性能和微观形态变化。结果表明,使用缩聚型反应挤出机对r-PET/ABS的混合效果优于使用双螺杆挤出机的,反应挤出机最佳螺筒温度为:245,260,255,255,240℃,最佳螺杆转速为80r/min;ABS质量分数为30%以下时,ABS以球状均匀地分散在r-PET连续相中;r-PET/ABS质量比为80/20的力学性能最佳,与r-PET相比,拉伸强度提高10 MPa,无缺口冲击强度提高6倍多,缺口冲击强度提高近l倍。     

HDPE functionalization via high shear stress‐induced initiation and its effects on HDPE/GF composite

The functionalization reaction of high density polyethylene (HDPE) with maleic anhydride (MAH) or with MAH and γ‐methacryloxy‐propyltrimethoxysilane (MAS) performed in melt state through a high shear stress‐induced initiation by increasing the screw rotation speed of twin‐screw extruder and through a compounded initiation by adding some initiator and increasing the screw rotation speed was investigated in this article. The results show that by increasing the screw rotation speed during melt‐extruding process, the scission of HDPE chain bonds can be caused to form macroradicals, the functionalization reaction of HDPE with MAH or with MAH, and MAS can be realized. The percentage of grafting and the melt flow rate of the functionalized products depend on the screw rotation speed and reaction temperature. The crosslinking reaction during melt extrusion can be suppressed by increasing the screw rotation speed and the reaction of HDPE with MAH can also be promoted by adding a second grafting monomer MAS. The high shear stress‐induced reaction products have a higher reactivity with the coupling agents coated on the surface of glass fibers and can obviously increase the mechanical properties of HDPE/GF composite. The SEM experimental results indicate that an oriented crystal transition layer exists between the interface of glass fiber and the matrix, the interfacial bonding strength is the determining factor of the formation of the oriented crystal layer. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

挤出反应温度与剪切应力对动态硫化PP/EPDM性能的影响

采用动态硫化的方法,在双螺杆挤出机中制备了聚丙烯(PP)/三元乙丙橡胶(EPDM)热塑性弹性体,研究了挤出反应温度与螺杆转速提供的剪切应力对动态硫化PP/EPDM热塑性弹性体性能的影响。结果表明,适当提高挤出反应温度或螺杆转速可提高PP/EPDM热塑性弹性体的拉伸强度、拉断伸长率和凝胶含量,当挤出反应温度为200℃、螺杆转速为600 r/min时,热塑性弹性体的综合拉伸性能最好,拉伸强度为19.87 MPa,拉断伸长率为527.3%,凝胶含量为54.69%。高螺杆转速提供的高剪切应力可在一定程度上提高PP/EPDM热塑性弹性体的熔融温度。     

Functionalization of ethylene–propylene–diene monomer rubber with maleic anhydride in the melt state through high‐shear stress‐induced initiation

The functionalization reactions of ethylene–propylene–diene monomer rubber (EPDM) with maleic anhydride (MAH) in melt state through high‐shear‐stress‐induced initiation by an increase in the screw rotation speed of the twin‐screw extruder and through compounded initiation by the addition of some initiator and an increase in the screw rotation speed were investigated. The results show that, with increasing screw rotation speed and reaction temperature, the percentage grafting and melt flow rate of the functionalized products (EPDM‐g‐MAH) were noticeably increased, and the viscosity‐average molecular weight decreased, which implied that the grafting reaction consisted of the chain scission and grafting reaction of the produced macroradicals with MAH. In the presence of a certain peroxide initiator, the crosslinking reaction during melt extrusion was suppressed by an increase in the screw rotation speed. The percentage grafting of EPDM‐g‐MAH amounted to 1.1%, its melt flow rate was between 0.3 and 4.0 g/10 min, and its gel content was less than 1.0%, depending on the screw rotation speed and reaction temperature. Impact testing and scanning electron microscopy showed that the functionalized product prepared through the high shear stress‐induced initiation had a higher blocking activity with the amide terminated of PA66 than that prepared through the peroxide initiation or through the compound initiation, and the impact strength of the PA66/EPDM blends, improved by the high‐shear‐stress‐induced product was noticeably higher than those of the peroxide‐initiated product or the compound‐initiated one. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

ABS／纳米CaCO3复合材料流变性能的研究

采用双螺杆挤出机，通过熔融共混工艺制备了丙烯腈-丁二烯-苯乙烯共聚物／纳米碳酸钙（ABS／nano-CaCO3）复合材料，利用转矩流变仪研究了其流变行为，探讨了nano-CaCO3用量、剪切速率和温度对复合材料黏度的影响。实验数据显示：ABS／nano-CaCO3熔体为假塑性流体，非牛顿指数n〈1；适量加入nano-CaCO3使复合体系熔体的n值增加，“柱塞流动”现象降低；在低剪切速率下，ABS／nano-CaCO3复合体系的熔体黏度较纯ABS熔体低；在高剪切速率下,复合体系的熔体黏度较纯ABS熔体高。     

Morphological evolution of polypropylene/polystyrene blends in a twin‐screw extruder

The effects of the blend composition and rotation speed on the morphological evolution of polypropylene (PP)/polystyrene (PS) blends were investigated in a twin‐screw extruder. When PS was the major component, the rate of melt and the rate of dispersion played final roles in the morphological development of the polymer melts. However, when PP was the major component, the rate of dispersion and the rate of coalescence played key roles. A high tendency to coalesce occurred at a high rotation speed and/or a high content of the dispersed phase. When the PP/PS blend composition was close to 1, a cocontinuous morphology was observed to transmute into a coarse one with increasing rotation speed. Attempts were made to correlate the morphology and mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical,thermal and morphological properties of environmentally degradable ABS and poly(vinyl alcohol) blends

Blends of acrylonitrile–butadiene–styrene (ABS) with 5, 10, 15, and 20 wt % of poly(vinyl alcohol) (PV) were prepared by extruding in a corotating twin screw extruder. The ABS material was blended with PVA with the objective to enhance the degradability of ABS. The extrudate strands were cut into pellets and injection molded to make test specimens. These ABS/PVA blend specimens were tested for physicomechanical properties like tensile strength, elongation, modulus of elasticity, abrasion resistance, density, and water absorption, These blends were further characterized by melt flow Index, differential scanning calorimetry, thermogravimetry analysis, and scanning electron microscopy. The morphological analysis reveals the existence of PVA domains in the ABS matrix. Differential scanning calorimetry thermograms indicates the chemical interaction between ABS and PVA domains. The prepared blends show enhanced environmental and thermal degradation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of screw rotation speed on the properties of polystyrene/organoclay nanocomposites prepared by a twin‐screw extruder

We discuss the effect of screw rotation speed on the mechanical and rheological properties and clay dispersion state of polystyrene (PS)/organoclay (clay) nanocomposites prepared by melt compounding with a counterrotating‐type twin‐screw extruder. Poly(styrene‐co‐vinyloxazolin) (OPS) was used as an additional material. The Young's modulus of the PS/OPS/clay nanocomposites showed the maximum value at a screw rotation speed of 70 rpm in this study. This implied the existence of an optimized screw rotation speed for the melt compounding of the polymer/clay nanocomposites. For PS/clay systems without the addition of OPS, the peak intensity from clay increased and the distance between clay platelets in the nanocomposites decreased with the screw rotation speed. On the other hand, inverse results were obtained for PS/OPS/clay systems. According to the transmission electron microscopy photographs, the PS/OPS/clay nanocomposite at 70 and 100 rpm had fully exfoliated clay platelets. The dynamic rheological properties of the PS/clay nanocomposites were almost the same as those of neat PS. On the other hand, the storage and loss moduli of the PS/OPS/clay nanocomposites at the same frequency were larger than those of the PS/clay system. On the whole, the bonding between clay platelets and PS was important for increasing the viscosity and elasticity in the melts of the PS/clay system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1165–1173, 2006