单螺杆挤出机中PS/PMMA共混物形态演变的研究

通过组合包括剪切和混沌混炼元件在内的螺杆结构,利用自制的在线取样装置,研究了质量比为70:30的聚苯乙烯(PS)/聚甲基丙烯酸甲酯(PMMA)共混物在单螺杆挤出机沿程的形态演变.结果表明,沿螺杆输送方向,液滴分散相尺寸不断变小,层状分散相长厚比不断增大,在螺杆末端分散相形态以层状为主.     

PC／PS共混物流变行为的研究

本文考察了聚碳酸酯／聚苯乙烯（ＰＣ／ＰＳ）共混物的流变行为与力学性能。研究发现：ＰＳ的加入，可使共混体系的粘流活化能降低，改善了ＰＣ加工时对温度的依赖性。ＤＳＣ分析证实随着ＰＳ含量的增加，体系玻璃化温度逐渐下降，说明ＰＣ与ＰＳ是部分相容的。当ＰＳ用量在１０％以内时，共混物的拉伸强度和缺口冲击强度均高于纯ＰＣ的力学性能，而且随着ＰＳ含量的变化，两者均出现峰值，取得了既增韧又增强的双重效果。共混体系的表观粘度ηａ随剪切速率增大而下降，且高剪切速率下ηａ下降更快；ＰＳ含量增加，流动曲线向下移动，表观粘度下降，意味着流动性增加，减小了体系的流动阻力     

PMMA/SMA共混体系流变行为与温度依赖性的研究

研究了甲基丙烯酸甲酯/苯乙烯马来酸酐共聚物(PMMA/SMA)体系的流变行为,探讨了SMA中马来酸酐(MA)含量对于共混体系时温叠加和温度依赖性的影响。结果表明,MA含量为12%(质量分数,下同)的PMMA/SMA12体系符合时温叠加原理,在低温下松弛时间与组分的关系存在正偏差,随温度上升浓度涨落加剧而有负偏差的情况出现;MA含量为28%的PMMA/SMA28体系时温叠加原理由于动力学不对称性而失效,在低温区域松弛时间与组分符合对数线性关系,高温区域则出现正偏差;与PMMA/SMA12相比,PMMA/SMA28具有更强的温度依赖性。     

聚苯乙烯共混聚丙烯树脂的熔融流变行为

文章研究了聚苯乙烯（ＰＳ）与聚丙烯（ＰＰ）共混物的熔融流变行为。采用索氏抽提法研究表明ＰＳ与ＰＰ产生了接技反应，ＰＳ用量在０～２０ｗｔ％范围内，１０ｗｔ％共混物接技量为最大，同时在ＰＰ中分散的ＰＳ粒径最小。随着ＰＳ含量的增加，减少了熔融粘度，组成－熔融粘度曲线在ＰＳ为１０ｗｔ％时略有所弯曲，通过接技反应，增大了ＰＰ粒子的范畴。     

NR/PMMA互穿网络共混物性能的研究

以NR和甲基丙烯酸甲酯（MMA）为主要原材料（NR／MMA用量比为60／40）制备NR／聚甲基丙烯酸甲酯（PMMA）互穿网络共混物，研究其物理性能，并与NR／PMMA动态硫化共混物进行对比。结果表明，共混体系中MMA发生聚合反应生成了PMMA，且与NR形成了一定的互穿结构；随着硫化剂DCP和交联剂DVB用量的增大，NR／PMMA互穿网络共混物的50％定伸应力、拉断强度和撕裂强度提高，拉断伸长率降低；NR／PMMA互穿网络共混物的拉伸性能优于NR／PMMA动态硫化共混物。     

PS/改性纳米CaCO3的共混挤出制备

通过共混挤出方法制备聚苯乙烯(PS)／改性纳米CaCO3复合材料,分析测试其冲击强度和弯曲性能及维卡软化温度,并表征了纳米CaC,3子在PS中的分散状态。当w(nano-CaCO3)为2．5％-5．0％时,复合材料的冲击强度和弯曲强度均显著提高,对热性能影响较小,维卡软化温度仍维持在98℃左右。透射电子显微镜观测表明,纳米CaCO3粒子在复合材料中仍呈纳米分散状态。     

PS/PETG共混物的流变性能和发泡行为研究

采用密炼机制备了聚苯乙烯(PS)和聚对苯二甲酸乙二醇酯1,4环己二甲醇酯(PETG)共混物;以超临界二氧化碳(CO2)为物理发泡剂,采用釜压法制备了PS和PS/PETG共混物发泡试样。通过旋转流变仪、扫描电子显微镜对PS和PS/PETG共混物的流变性能和泡沫的泡孔形态进行了表征。结果表明,加入PETG没有对PS的流变性能产生明显的影响,但对PS泡沫的泡孔形态影响显著,加入10 %的PETG时,其平均泡孔直径由纯PS的2268 μm降至758 μm,泡孔密度由345×108个/cm3提高到447×109个/cm3,泡孔尺寸分布明显变窄,说明PETG在PS中起到明显的气泡成核作用。     

PC／PS／PC—g—PS共混物的流变性能

研究了在聚碳酸酯/聚苯乙烯(PC/PS=70/30,质量比)共混物中加入5％～15％(质量百分数)聚碳酸酯-聚苯乙烯接枝共聚物(PC-g-PS)后对此共混物流变性质的影响。结果表明:PC中加入PS或PS/PC-g-PS)流动性得到改善,各种组成的共混物其表观粘度(η_a)皆随剪切速率和温度的增加而降低,当PC/PS中加入5％PC-g-PS后,其η_a有明显的增加,进一步加入PA-g-PS对η_a的影响减小。     

PS/PMMA共混物中超声波传播特性研究

利用自行设计的装置,采用改变入射角的方法将超声波纵波和横波导入不相容的聚苯乙烯/聚甲基丙烯酸甲酯(PS/PMMA)共混物体系中。研究了两种波的声速和声衰减随共混体系共混比变化的情况,并结合扫描电子显微镜(SEM)检测得到的相畴尺寸进行了分析。结果表明:共混物中的相畴尺寸与其散射衰减之间存在对应关系;由于横波波长更为接近共混体系中的相畴尺寸,横波的散射衰减明显大于纵波。     

聚合物共混体系流变行为的研究进展

介绍了聚合物共混体系的研究现状以及研究聚合物共混体系的流变行为的必要性,并讨论了影响聚合物共混体系的流变行为的各种因素。     

ABS/SAN/中粘度PMMA三元共混物的性能研究

制备不同配比的丙烯腈－丁二烯－苯乙烯（ABS）／苯乙烯－丙烯腈（SAN）／中粘度聚甲基丙烯酸甲酯（PMMA）合金，分别测试其缺口冲击强度、拉伸强度、热变形温度、熔体流动指数等，结果表明：ABS／SAN可以引发中粘度PMMA产生大量的银纹，从而大幅度提高共混物的冲击强度；引入中粘度PMMA可以提高ABS／SAN的耐热性能；添加中粘度PMMA，合金的流动性能呈现下降的趋势。     

Iniferter法合成星型PI/PMMA/PS嵌段共聚物

采用Iniferter法,以自合成的1,3,5-(N,N-二甲基二硫代氨基甲酸)-2,4,6-均苯三甲基苄酯为引发剂,分别合成了星型二嵌段共聚物聚异戊二烯/聚甲基丙烯酸甲酯(PI/PMMA)、聚异戊二烯/聚苯乙烯(PI/PS)和星型三嵌段共聚物聚异戊二烯/聚甲基丙烯酸甲酯/聚苯乙烯(PI/PMMA/PS)。利用IR和1HNMR对各嵌段共聚物的结构和组成进行了表征。     

Rheological study of copovidone and solid dispersion blend used for hot melt extrusion

The focus of this work is to generate rheological parameters using AR 2000EX rheometer for PVP VA64 and Compound A – PVP VA64 blend at different temperatures, which can then be subsequently used to identify hot melt extrusion process conditions. Addition of Compound A to the neat PVP VA64 shows a drop in storage modulus and loss modulus as compared to the neat PVP VA64. It appears that Compound A is acting as a plasticizer by increasing the separation of the polymer chains and thus results in reduction of viscosity of Compound A blends compared to polymer only samples. For both systems, based on low standard error of fit, Cross model was chosen as the best fit for the rheological data and temperature dependency of viscosity was assessed by Williams–Landel–Ferry (WLF) model. This approach can be applied to screen formulations with new chemical entities (NCEs) and generate rheological information with various extruding polymers at fixed/variable drug loading in polymer matrix to determine suitability for hot melt extrusion process and appropriate temperature for conducting hot melt extrusion. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43278.     

Rheological behavior and flow instability in capillary extrusion of ultrahigh-molecular-weight polyethylene/high-density polyethylene/nano-SiO2 blends

Rheological behaviors of ultrahigh-molecular-weight polyethylene (PE)/high-density PE/SiO₂ blends are investigated using parallel-plate rheometer and capillary rheometer. The molecular chain conformational change mechanism is used to explain flow instabilities during extrusion. The viewpoints are proposed: (1) critical shear rate depends on the relative strength of irreversible viscous loss and reversible elastic orientation for molecular chains in transverse velocity gradient field inside the die and (2) critical shear stress depends on the extent of molecular chain conformational change inside the die, and the ease of conformational recovery after leaving the die. Modified nano-SiO₂ particles are detected a certain interfacial adhesion in PE matrix. The interfacial interaction limits viscous flow inside the die and conformational recovery after leaving the die, thus causing not only the flow instabilities to occur prematurely on shear rate and delaying sharkskin on shear stress, but also an alternate “sharkskin-melt fracture” appearance after global extrusion fracture. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47713.     

Effects of ultrasonic oscillation on processing behaviors of PS,EPDM, and PS/EPDM blend

In this study, the extrusion processing behaviors of polystyrene (PS), ethylene–propylene–diene terpolymer (EPDM), and their blend (PS/EPDM, 80/20) were studied by using a special ultrasonic oscillation extrusion system developed in our laboratory. The die pressure and volume flow rate were measured at different ultrasonic intensities and screw rotation speeds. The dependences on ultrasonic intensity of die pressure, volume flow rate, and apparent viscosity of polymers, as well as die swell at the same screw rotation speed were investigated. The effects of screw rotation speed on the processing behaviors of polymers and their blend at the same ultrasonic intensity were also studied. The experimental results showed that in the presence of ultrasonic irradiation, the processibilities of polymers and their blend were improved. Their possible mechanism is discussed in this article. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1856–1863, 2006     

聚碳酸酯—聚苯乙烯的反应性挤出共混研究（Ⅱ）

用ＤＳＣ进一步研究了ＰＣ／ＰＳ共混物的相容性。考察了在ＰＣ／ＰＳ混合过程中加入ＲＰＳ对机械力学性能的影响,结果表明：ＲＰＳ显示良好的增容作用,使反应性挤出共混物的拉伸强度,弯曲强度和冲击强度都高于相应的非反应性共混物。     

PPESK／PS共混物流变性能的研究

以溶液共沉淀的方法制备了含二氮杂萘联本结构的聚芳醚砜酮（PPESK）。聚苯乙烯（PS）共混物，用毛细管流变仪测定了共混物的流为性能。结果表明，在本实验条件下，PPESK／PS共混物熔体属假塑性非牛顿汉体，其熔体粘度随PS含量的增加、温度的升高、剪切速率的增大而下降。PS的加入有利于改善PPESK的熔融加工流动性。     

PAN/PMMA共混制备纳米碳纤维的结构与性能

以N,N-二甲基甲酰胺(DMF)为溶剂,以聚丙烯腈(PAN)为碳前驱体,聚甲基丙烯酸甲酯(PMMA)为热裂解聚合物,制备PAN/PMMA溶液共混体系,经湿法纺丝及碳化工艺制备了纳米碳纤维(CNFs);讨论了影响CNFs形态、尺寸的主要因素,通过傅里叶变换红外光谱、X射线衍射、拉曼光谱和电导率测试等对CNFs进行了表征。结果表明:相对分子质量为8.0×10~4的PAN与PMMA以质量比30/70进行共混纺丝和碳化,可以得到CNFs;增加原丝的拉伸倍数有利于减小CNFs的直径,当拉伸倍数提高到6时,CNFs直径为50～150nm;碳化温度为800℃时,CNFs出现石墨相结构;提高碳化温度有利于CNFs石墨化结构的形成与电导率的提高。     

PP/EVA/COPET共混物流变性能的研究

采用CFT-500型毛细管流变仪研究了聚丙烯/乙烯-醋酸乙烯酯/碱溶性聚酯(PP/EVA/COPET)共混物的流变性能。结果表明:PP/EVA/COPET共混物出现剪切变稀现象,非牛顿指数小于1,熔体为假塑性流体;熔体表观粘度随EVA含量的增加呈现先减小后增大趋势,并随温度的上升而下降;EVA质量分数为15%的共混物的表观粘度最低,粘流活化能最小。