聚丙烯结构形态对性能的影响

用红外光谱、动态粘弹谱、透射电镜、X光衍射仪、DSC、偏光显微镜和机械力学性能测试仪等手段对均聚、嵌段共聚、无规共聚PP进行了结构、形态与性能关系的研究。结果表明,嵌段共聚物中乙烯在红外谱图中显示两个特征峰,而无规共聚物中乙烯只出现—个特征峰。研究还证明,PP嵌段共聚物是PP、PE、EPR多元组分的共混物。PE包含在EPR中以球形无规地分散在PP基体中。EPR的含量是提高PP共聚物冲击性能的决定因素。无规共聚物形态接近均相体系,其冲击强度小于嵌段共聚物而大于均聚物。     

PP/UHMWPE共混物力学性能的研究

采用不同结构的聚丙烯(PP)分别与不同流动性能的超高摩尔质量聚乙烯(UHMWPE)进行共混，对共混物的力学性能进行了研究。发现PP和UHMWPE类型的适当匹配对共混物性能的提高非常重要。流动性较好的UHMWPE对熔体质量流动速率较小的嵌段共聚型PP(PPB)增韧增强效果突出，常温缺口冲击强度可达74．2kJ／m^2，断裂伸长率大于700％；同时共混物的强度和刚性也有一定程度的提高。在PPB／UHMWPE二元共混物中加入适当线性低密度聚乙烯(LLDPE)，能够起到“减粘”和“增容”作用，有利于共混物性能，尤其是抗冲性能的进一步提高。     

PPH/PPR/PPB共混体系力学性能的研究

研究了均聚聚丙烯(PPH)、无规共聚聚丙烯(PPR)、嵌段共聚聚丙烯(PPB)3种聚丙烯(PP)共混体季的力学性能，探讨了各组分对材料性能的影响。结果表明：PPH能使材料具有较高的刚性，PPB则能提高材料的韧性，PPH／PPR／PPB体系的冲击强度随PPB用量的增加而增加。     

高抗冲聚丙烯结构对冲击性能的影响

利用聚丙烯中试装置制备性能不同的抗冲共聚聚丙烯,考察了抗冲共聚聚丙烯结构、分子量及分子量分布、橡胶相与均聚相的相容性、橡胶相分散状态对产品冲击性能的影响。结果表明:增大橡胶相特性粘数,增加橡胶相中大分子含量,提高橡胶相和均聚相的相容性,橡胶相以相近的尺寸均匀分散在均聚相中都有利于产品冲击强度的提高。     

聚丙烯／PE-g-MAH／纳米SiO2复合材料性能研究

以PE-g-MAH(马来酸酐接枝聚乙烯)作为聚丙烯(PP)/纳米二氧化硅(SiO2)共混物的增容剂,通过不同的加工工艺制备了聚丙烯/PE-g-MAH/纳米SiO2复合材料,考察了不同处理方法及用量的纳米SiO2对PP基体的影响。结果表明:经表面处理,用量为4％的纳米SiO2和3％PE-g-MAH协同作用对PP的改性效果最好,冲击强度提高30％,弯曲强度提高10％,而改性PP的拉伸强度与未改性PP保持一致,且对嵌段共聚聚丙烯(PP-B)的改性效果优于无规共聚聚丙烯(PP-R)。同时,PP/PE-g-MAH/纳米SiO2复合材料的耐热性得到明显提高,较PP基体提高22℃,增幅为20％。     

SEP/蒙脱土混杂材料对PP/PS共混物性能的影响

研究了苯乙烯一乙烯／丙烯二嵌段的共取物（SEP）及其与改性蒙脱土的混杂材料对PP／PS共混物的形态、冲击强度和拉伸强度的影响。结果表明，对于PP／PS共混物，SEP／CJ1－MONT混杂材料对PP／PS共混物的增韧增强效果比SEP更强。     

多嵌段共聚聚酰胺弹性体的制备及性能研究

以己内酰胺及十二内酰胺为主体,添加一定量的聚醚型预聚体进行阴离子无规共聚,获得系列多嵌段共聚聚酰胺弹性体;通过FTIR对其分子结构进行了表征,使用DSC、TG、DMTA研究了其热性能;并研究了多嵌段共聚聚酰胺弹性体材料力学性能与聚醚型预聚体用量及分子结构的关系。结果表明:随着聚醚型预聚体用量的提高,共聚物结晶度降低,高低温缺口冲击强度和断裂伸长率大幅增加,拉伸强度有所降低,材料表现出典型的弹性体性能特征。     

蓄电池用共混改性PP的研制

以均聚PP为主要原料,共聚PP、HDPE、SBS为改性剂,用挤出共混法研制蓄电池用共混改性PP塑料。通过对原材料的选择和配方试验,确定了共混物的基本配方:均聚PP100份,共聚PP10～15份,HDPE5～10份,SBS 3～5份,抗氧剂和紫外线吸收剂0.4～0.6份,其它2～3份,所得多元共混物的冲击强度比纯PP提高7～9倍,其他性能无明显下降,完全满足了使用要求。     

HYBRAR与α成核剂对PP性能的影响

将高性能热塑性弹性体苯乙烯、乙烯支化异戊二烯三嵌段共聚物（HYBRAR）及α成核剂与PP进行共混,并参照各测试标准制备试样。对共混物的力学性能及热稳定性进行了表征。研究结果表明,HYBRAR的加入使共混物的冲击强度和断裂伸长率显著提高,而拉伸强度降低,α成核剂的加入使得PP及PP／HYBRAR共混物的冲击强度和拉伸强度升高;α成核剂提高了共混物的热稳定性,而HYBRAR降低其热稳定性。     

无规共聚PP与嵌段共聚PP共混的研究

用IR、DSC、SEM和力学性能测试方法研究了一种无规共聚PP（PP-R）和一种嵌段共聚PP（PP-B）及其共混物的结构与性能。结果表明,PP-R和PP-B都能结晶,但PP-B结晶较慢、结晶度较低;PP-R不含而PP-B含有呈球粒状分散的乙丙橡胶（EPR）相和乙烯嵌段（PE）相;随共混物中PP-B含量增加,常温和低温冲击韧性显著提高,力学强度在略有下降后能持平或回升,这些性能变化是上述PP-R、PP-B结构特点的一种综合效应。     

Mechanical properties and morphology of crosslinked PP/PE blends and PP/PE/propylene–ethylene copolymer blends

Blending is an effective method for improving polymer properties. However, the problem of phase separation often occurs due to incompatibility of homopolymers, which deteriorates the physical properties of polyblends. In this study, isotactic polypropylene was blended with low-density polyethylene. Crosslinking agent and copolymers of propylene and ethylene (either random copolymer or block copolymer) were added to improve the interfacial adhesion of PP/LDPE blends. The tensile strength, heat deflection temperature, and impact strength of these modified PP/PE blends were investigated. The microstructures of polyblends have been studied to interpret the mechanical behavior through dynamic viscoelasticity, wide-angle X-ray diffraction, differential scanning calorimetry, picnometry, and scanning electron microscopy. The properties of crosslinked PP/PE blends were determined by the content of crosslinking agent and processing method. For the material blended by roll, a 2% concentration of peroxide corresponded to a maximum tensile strength and minimum impact strength. However, the mechanical strength of those products blended by extrusion monotonously decreased with increasing peroxide content because of serious degradation. The interfacial adhesion of PP/PE blends could be enhanced by adding random or block copolymer of propylene and ethylene, and the impact strength as well as ductility were greatly improved. Experimental data showed that the impact strength of PP/LDPE/random copolymer ternary blend could reach as high as 33.3 kg · cm/cm; however, its rigidity and tensile strength were inferior to those of PP/LDPE/block copolymer blend.     

Impact strength and melt viscosity of bisphenol-a polycarbonate and styrene-maleic-anhydride copolymer blends

Mixtures of 90, 80, and 70 percent by weight bisphenol-A-polycarbonate (PC) and 10, 20, and 30 percent by weight styrene maleic anhydride (SMA) copolymer were melt-blended in a single screw extruder. Differential scanning calorimetry (DCS) and scanning electron microscopy (SEM) were used to determine the miscibility of the blends. The viscosity, as a function of shear rate and temperature, was measured by an Instron capillary viscometer. The notched impact strength as a function of temperature was measured by an Izod impact tester. The results of DSC showed two glass transition temperatures which merged slightly towards each other, indicating marginal miscibility of these blends. There was a decrease in viscosity as the fraction of SMA copolymer was increased. The most significant decrease occurred with the initial addition of SMA copolymer. The viscosity also decreased with increases in temperature. The impact strength of the blends was also dependent on SMA copolymer content. The blends showed six to ten times lower impact strengths at room temperature than the 100 percent polycarbonate. SEM analysis helped to determine the reason why the impact strength was lower for the blends. High magnification showed the presence of SMA copolymer inclusions dispersed throughout the PC matrix. These inclusions, which increased in size as SMA copolymer content was increased, acted as defects in the system.     

固体超强酸催化PLA-PEG嵌段共聚物的合成

采用开环聚合法,固体超强酸SO42-/ZrO2-CeO2为催化剂,催化丙交酯和聚乙二醇合成PLA-PEG嵌段共聚物,研究了聚乙二醇(PEG)分子量、反应时间、温度、催化剂用量等条件对共聚物的影响,并通过红外光谱、Hammett指示剂法及NH3-TPD等方法对固体超强酸的酸性质进行了表征。结果表明,当焙烧温度为650℃时,得到的固体超强酸SO24-/ZrO2-CeO2酸强度与酸量最大,用该催化剂催化合成PLA-PEG嵌段共聚物,当PEG分子量为6 000,反应时间9 h、反应温度170℃,催化剂用量为丙交酯质量分数的1.0%时,得到PLA-PEG共聚物的特性粘数最大,为1.693 g/dL。     

Viscosity behavior of acrylonitrile–ammonium itaconate copolymer solutions in dimethyl sulfoxide

The viscosity behavior of dimethyl sulfoxide (DMSO) solutions of acrylonitrile–ammonium itaconate copolymer is discussed. The intrinsic viscosity was determined by an Ubbelohde viscometer. It is shown that an increase in the viscosity of acrylonitrile–ammonium itaconate copolymer solutions with time is considerably reduced by mechanical mixing. The viscosity of copolymer solutions with dimethyl formamide as an additive decreases monotonically. The viscosity of copolymer solutions decreases with the addition of H₂O, and as the content of H₂O in DMSO goes beyond 3 wt %, the viscosity shows a trend toward increase. The intrinsic viscosity decreases quickly with the addition of NaCl. As the concentration of NaCl goes beyond 0.015 mol/L, the viscosity increases solwly. The viscosity of copolymer solutions containing sodium ethoxide and sodium hydroxide appears to increase after an initial drop. The viscosity of copolymer solutions upon the addition of diethylamine increases continuously with time and changes in viscosity become less prominent after a period of a few hours. The effects of bases on the tacticity of highly isotactic copolymers follow the order of base strength. Diethylamine is more effective for moderating the stabilization exotherm of highly isotactic copolymers compared to sodium ethoxide and sodium hydroxide. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2622–2626, 2004     

Studies on impact modification and fractography of solution cast blends of PVC and NR/PU block copolymers

Segmented polyurethanes based on toluene diisocyanate (TDI) with three different chain extender diols, viz., propylene glycol (PG), 1,4-butanediol (1,4-BDO), and 1,3-butanediol (1,3-BDO) were synthesized by a two-step, solution polymerization method. These different NR-b-PU block copolymers were incorporated into PVC at various compositions by the solution blending method. These blend systems were subjected to FTIR analysis, DSC, tensile testing, tensile impact measurements, and tensile impact fracture studies by SEM. It was observed that systems showed modification in tensile impact properties. Optimum impact properties were shown at concentrations 6–8% of the block copolymer. At higher compositions there is deterioration in impact properties. High impact properties showed by these blends are attributed to the optimum level of compatibility achieved between the blend components. Tensile impact fracture studies revealed that failure pattern for these blend system transitioned from brittle to ductile fracture. Blends up to 10 wt% of block copolymer showed partially compatible heterogeneous nature exhibiting domain morphology. Blends with higher block copolymer content showed deterioration in tensile strength, modulus, yield strength, and tensile impact strength due to higher particle size of the agglomerated rubber soft segments of the block copolymer.     

两嵌段SI对SiS及其热熔压敏胶性能的影咱

研究了两嵌段SI对SIS及其热熔压敏胶性能的影响。结果表明,SI含量增加,SIS的拉伸强度降低,熔体流动速率（MFR）增大,其热熔压敏胶初粘性增大、持粘性减小,180°剥离强度先增大后减小,熔融黏度和软化点降低。两嵌段SI分子质量增加,SIS的MFR降低,其热熔压敏胶的熔融黏度和软化点增大。两嵌段SI嵌段比增加,SIS的硬度增大、MFR降低,其热熔压敏胶的初粘性减小,熔融黏度和软化点增大。     

Graft polymerization of some vinyl monomers onto acrylic rubber. II. Mechanical properties of graft polymers

Some mechanical properties of styrene and acrylonitrile copolymers grafted onto acrylic rubber are investigated. The impact strength of graft polymers depended upon the nature and the concentration of the catalyst, the composition and the intrinsic viscosity of the rubber, and the acrylonitrile content in the rigid matrix. The most desirable result was obtained when benzoyl peroxide as the catalyst, n-butyl acrylate–acrylonitrile copolymer of 7–10% acrylonitrile content, and about 0–5% acrylonitrile in the rigid matrix were used. Dynamic mechanical tests show the increase in efficiency of rubber modification by the grafted chains. The better weathering resistance of these graft polymers, as compared with commercial ABS plastics, was confirmed.     

PA6／POE／EAA共混体系的相态与性能的研究

采用乙烯－1－辛烯共聚物弹性体（POE）为增韧剂、乙烯－甲基丙烯酸共聚物（EAA）作为增溶剂制备了以尼龙6（PA6）为基体的PA6／POE／EAA共混合金。详细研究了弹性体用量与共混体系的亚微观相态、力学性能和流变性能的关系。结果表明随着弹性体含量的增加，共混体系的分散相粒子尺寸大小没有明显变化，共混体系的冲击强度增加，拉伸强度和弯曲弹性模量降低。弹性体的增加使体系的熔体粘度降低，改善了体系的加工性能，但当POE增加到20％时，随着POE的增加，粘度不再下降。     

Melt Viscosities and Mechanical Properties of PC/SAN Blends

Abstract

Melt viscosities and mechanical properties of polycarbonate (PC), styrene-acrylonitrile copolymer (SAN), and their blends were studied. PC and SAN were melt blended at different compositions using a single screw extruder. Melt viscosities were measured with a capillary rheometer. The melt viscosity test showed that increasing the PC content increases the viscosity of the blends, and melt viscosities of blends are intermediate between the values of PC and SAN. Standard mechanical property tests were performed on injection molded ASTM test specimens. Tensile strength and modulus increase but elongation at break decreases when the SAN content increases. Notched Izod impact strength decreases rapidly with the addition of SAN into PC. Unnotched impact strength is higher than notched impact strength and is less sensitive to the addition of SAN.