热塑性聚氨酯弹性体熔融指数影响因素的探讨

研究了软段结构、硬段结构、合成工艺等因素对热塑性聚氨酯(TPU)弹性体熔融指数的影响。结果表明:随多元醇相对分子质量增大,熔融指数降低;相同硬度条件下,聚碳酸酯型TPU比聚己内酯型TPU熔融指数低,1,4–丁二醇扩链比对苯二酚二羟乙基醚(HQEE)扩链熔融指数低;随着异氰酸酯指数或硬段含量增加,TPU熔融指数逐渐降低;合成反应温度越高,熔融指数越低;两步法工艺比一步法工艺有更好的加工流动性。     

不同相对分子质量的尼龙6流变性能研究

用毛细管流变仪研究了尼龙 6试样相对分子质量对其流变性能的影响。结果表明 ,在实验范围内试样熔体为假塑性流体。随着相对分子质量的增加 ,非牛顿指数 (n)减小 ;熔体稠度 (K)增大 ;lgη～lg γ直线的斜率和截距均增大 ;粘流活化能降低。且试样的相对分子质量与表观粘度及熔融指数均有较好的对数线性关系。     

关于聚苯乙烯的摩尔质量分布与性能

对国内外聚苯乙烯瓣摩尔质量分布的渗透色谱法测定结果,结合有关性能进行了分析和讨论,表明了熔融指数不仅随重均摩尔质量的增高而变小,而且和摩尔质量分布有关。国内某些厂（批）的聚苯乙烯性脆问题与低聚物含量较多有关。     

聚合工艺对低不饱和度高相对分子质量聚醚性能的影响

采用双金属氰化络合物催化剂（DMC）合成了低不饱和度高相对分子质量聚醚（DL-4000D）,讨论了聚合温度、聚合压力、低聚物脱水时间等聚合工艺条件对DL-4000D及其制品性能的影响。结果表明,聚合温度在115~125℃、低聚物脱水时间在2 h左右,聚合压力小于100 kPa等工艺条件下,制备的聚醚不饱和度低,相对分子质量分布窄,由其制得的聚氨酯制品的综合性能好。     

复合助剂对易开口聚乙烯膜料性能的影响

以吉林石化公司线性低密度聚乙烯(LLDPE)DFDA 7042粉料为基料,分别加入不同量的A、B、C、D四种易开口聚乙烯复合助剂,经共混、挤出造粒、吹膜,考察了不同助剂及不同助剂用量对DFDA7042熔融指数、相对分子质量、相对分子质量分布和氧化诱导期的影响,考察了助剂对膜料开口性能、光学性能和力学性能的影响。同样条件下测试了国内市场常见的易开口聚乙烯薄膜专用料中沙天津石化222WT、SABIC 218W和兰州石化DFDA 7042H粒料的熔融指数、相对分子质量及其分布、氧化诱导期及膜料开口性、光学性能和力学性能,结果表明:通过对A、B、C、D助剂量调整,能够得到与中沙天津石化222WT、SABIC 218W和兰州石化DFDA 7042H同一水平的的易开口聚乙烯膜料产品。     

影响热塑性聚氨酯弹性体力学性能的因素

热塑性聚氨酯弹性体主要由含OH的低聚物多元醇、小分子扩链剂和异氰酸酯等原料聚合而成。本工作讨论了低聚物多元醇的相对分子质量、扩链剂的用量、异氰酸酯指数和后硫化时间对弹性体力学性能的影响，分析了柔性链段的组成、原材料中的水分含量等对弹性体性能的影响。     

引发剂用量对本体法丙烯酸酯橡胶结构及性能的影响

以丙烯酸乙酯、氯乙酸乙烯酯为原料,偶氮二异丁腈为引发剂,采用本体法合成了丙烯酸酯橡胶(ACM),考察了引发剂用量对其结构和性能的影响。结果表明,随着引发剂用量的增多,ACM相对分子质量下降,分子量分布变宽;生胶中低聚物含量增多;开炼机热处理可脱除生胶中的小分子物质和低聚物,提高硫化胶的拉伸强度、耐热老化性能,使压缩永久变形减小。     

聚苯乙烯装置末段反应器更换前后产品性能的对比分析

对聚苯乙烯装置末段反应器更换前后产品性能进行了对比分析;末段反应器更换后聚合转化率上升,产品的残留单体和低聚物的质量分数下降,产品的相对分子质量分布变宽,加工稳定性增加。     

硅氧烷低聚物的合成及其在泡沫染色中的应用

为了通过泡沫染色和光固化改善棉织物的染色性能，合成了一种含有不饱和双键的硅氧烷低聚物，设计了合适的含有聚合型黄色蒽醌染料、硅氧烷低聚物、光引发剂2,4,6-三甲基苯甲酰基-二苯基氧化膦（TPO）、表面活性剂十二烷基硫酸钠（SDS）的泡沫体系对棉织物进行泡沫染色。采用1HNMR和GPC分析了硅氧烷低聚物的化学结构和相对分子质量分布，采用FTIR表征了硅氧烷低聚物和染色棉织物的化学结构，采用SEM观察染色棉织物的表面形态。探讨了硅氧烷低聚物用量、染料用量、SDS质量浓度、TPO用量对泡沫性能和染色性能的影响，分析了硅氧烷低聚物的固色机理。结果表明，染料质量浓度30 g/L、硅氧烷低聚物用量为染料质量的2倍、SDS质量浓度2.0 g/L、TPO用量为染料质量的5%、紫外光照时间5 min时，染色织物染色深度可达5.70，耐皂洗色牢度和干/湿摩擦色牢度均为4～5级，水接触角为110.1°，紫外防护系数>50。硅氧烷低聚物通过侧基上的不饱和双键发生自由基聚合和硅醇基偶合交联实现固色，并赋予织物良好的疏水性能和抗紫外线性能。     

一种生物基聚氨酯丙烯酸酯的制备及其在光固化3D打印中的应用

以生物基聚乳酸二元醇与脂肪族二异氰酸酯为原料,通过两步法制得生物基聚乳酸–聚氨酯丙烯酸酯(PLA–PUA)低聚物,探究二元醇相对分子质量、二异氰酸酯种类和封端剂种类对低聚物性能的影响;筛选不同的单体和光引发剂与PLA–PUA低聚物共混,添加颜料、填料等助剂优化配方,最终得到一种高硬度、高强度、适用于LCD3D打印的光固化树脂,以及一种兼具强度和韧性、适用于DLP3D打印的光固化树脂。     

DSC技术在PE100树脂分析中的应用

采用差示扫描量热法（DSC）研究了低聚物对高密度聚乙烯管材PE100热性能的影响,并且对比分析了5种国内外树脂的热行为。结果表明,通过改变树脂中低聚物配比的方法可以控制树脂的结晶行为。当等温结晶温度升高时,树脂的DSC热分级曲线的低温熔融峰面积和高温熔融峰面积的比例会发生变化。国外进口树脂的低温熔融峰面积相对较低。     

纳米二氧化硅对充油SEBS改性PP材料的性能影响

纳米二氧化硅（SiO2）经表面改性后,制备PP／Oil-SEBS／nano—SiO2共混体系材料。研究了不同的纳米SiO2含量下共混体系的DSC熔融峰和结晶峰,同时考察其的力学性能种流变性能。结果表明：随着SiO2含量的增大,熔融峰基本不变,结晶峰在纳米SiO2含量较大时略为增加,体系的拉伸强度、冲击强度先增大后减小．硬度则先减小后增大,熔体流动速率略有下降。     

茂金属聚乙烯蜡对PE共混体系流变行为的影响

用毛细管流变仪研究了茂金属聚乙烯蜡改性聚乙烯共混体系的流变行为，探讨了茂金属聚乙烯蜡用量对共混体系熔体流变行为、熔体黏度、非牛顿指数和流动活化能的影响。结果表明：茂金属聚乙烯蜡对LLDPE／LDPE流动黏度降低明显，增加用量可使黏度逐渐降低；而对MPE／LLDPE／LDPE共混体系流动行为的影响比较复杂，在低剪切应力下黏度随茂金属聚乙烯蜡用量增加而逐渐降低，而在高剪切应力下黏度先增后减；茂金属聚乙烯蜡与MPE／LLDPE／LPDPE的相容性好于LLDPE／LDPE共混体系。     

瓶级聚酯质量对流变及加工性能的影响研究

研究和分析了加工温度、特性黏数、摩尔质量及其分布、间苯二甲酸含量(IPA)、二甘醇(DEG)含量等因素对瓶级聚酯流变性及加工性能的影响。结果表明,在低剪切速率下,温度的升高使熔体的切力变稀现象逐渐减弱,当剪切速率达到8 000 s-1以上时,温度及剪切速率都几乎对熔体的表观黏度没有影响;摩尔质量越高,熔体黏度的切变速率依赖性越大,摩尔质量分布宽有利于成型加工条件的控制;在相同剪切速率下,熔体的剪切黏度随着IPA含量的增大而逐渐降低;DEG含量低的聚合物熔体在低剪切速率下出现非牛顿性流动的现象比DEG含量高的要明显得多。     

优化赫斯特工艺操作提升PE100级管材产品质量

介绍了中国石油吉林石化公司30万t/a高密度聚乙烯装置提升PE100级管材产品JHMGC100S质量情况。通过优化赫斯特低压淤浆法中催化剂制备和聚合等生产工艺,指出关键参数熔融指数、熔流比和密度的调整思路,使产品熔融指数稳定性、拉伸屈服应力、拉伸断裂标称应变、简支梁冲击强度等重要指标不断提升,逐步解决PE100级管材产品氧化诱导期不稳定、加工性能差、内壁有麻点、拉伸屈服强度不够和个别批次静液压实验通不过等诸多难题。     

Permanently electrostatic dissipative (ESD) property via polymer blending: Rheology and ESD property of blends of PETG/ESD polymer

Rheological and electrical properties were studied on blends of a PETG polyester (cyclohexanedimethanol-modified polyethylene terephthalate) and an inherently static dissipative high molecular weight polyether based copolymer, hereafter referred to as ESD polymer. Several important electrical properties and flow phenomena have been observed. First of all, the PETG blends could result in ESD protected material with excellent performance and a minimal effect on physical properties and melt processability. The rheological characterization reveals that the ESD polymer has a high melt viscosity even at a temperature more than 150 degrees above its melting temperature and that it exhibits pseudoplastic behavior. The PETG melt shows a near constant dynamic viscosity at a low frequency region. The viscosity of the ESD polymer and PETG melt exhibits a cross over at the temperature range from 200–220°C; the PETG melt is the lower viscosity component at low shear rate and the ESD polymer is the lower viscosity component at high shear rate. This appears to result in the existence of a small composition difference in the thickness direction of an injection-molded ESD polymer/PETG part, with a greater fraction of the ESD polymer component in the skin section. This, in turn, could enhance the surface conductivity of the skin region of an injection-molded part. © 1993 John Wiley & Sons, Inc.     

Experimental investigation of the influence of molecular weight distribution on the rheological properties of polypropylene melts

An experimental study of steady shear and elongational flow Theological properties of a series of polypropylene melts of varying molecular weight and distribution is reported. Broadening the molecular weight distribution increases the non-Newtonian character of the shear viscosity function and increases the principal normal stress differences at fixed shear stress. The behavior is compared to earlier rheological property-molecular weight studies. Correlations are developed for these properties in terms of molecular structure. Elongational flow studies indicate that for commercial and broader molecular weight distribution samples, ready failure by neck development occurs and the elongational viscosity appears to decrease with increasing elongation rate. For narrower molecular weight distribution samples, the elongational viscosity is an increasing function of elongation rate, The implication of these experimental results to viscoelastic fluid constitutive equations and polymer melt processing is developed.     

聚丙烯/膨胀石墨/碳纤维导热复合材料

研究了聚丙烯(PP)/膨胀石墨(EG)/碳纤维(CF)复合材料的导热、力学以及加工性能.研究发现:当膨胀石墨的质量含量达到20％时,热导率是纯聚丙烯的2倍,但熔体流动性能有所下降;添加1％的聚乙烯蜡可以明显改善体系的熔体流动性能;将膨胀石墨与5％的碳纤维杂化使用,热导率达0.91 W·m-1K-1,是纯聚丙烯的5倍,熔体指数达到1.72 g/10 min,同时该复合材料具有较好的力学性能.     

Interrelationship of strength and flow characteristics of polystyrene

This study investigated the interrelationship between strength and flow characteristics of general-purpose polystyrene (GPPS) used in injection molding applications. The ease of flow was chosen as a measure of processability and was evaluated using the melt flow rate and capillary rheometer techniques. Of the different strength tests that were examined, flexural and notched tensile strength tests were most effective in differentiating between commercial grades of high and low molecular weight GPPS. While characterizing strength of injection molded specimens, the degree of molecular orientation was taken into consideration. For unplasticized resins, increasing the weight average molecular weight by about 100,000 enhanced the flexural strength by 10%, but also increased the viscosity at low shear rates (10 to 100 s^?1). The increase in molecular weight had virtually no effect on viscosity at the highest shear rates (up to 10,000 s^?1). Plasticized resins displayed a 6% loss in flexural strength as well as a significant reduction in viscosity (throughout the shear rate range) as compared with the unplasticized resins. As expected, the improvement in strength achieved by increasing molecular weight leads to a simultaneous increase in the viscosity, i.e., a deterioration of processability. In addition, our study indicates that for samples without preferential molecular orientation, narrowing the molecular weight distribution significantly improves the balance of strength and melt flow rate properties.     

Effect of Morphology on the Biodegradation of Thermoplastic Starch in LDPE/TPS Blends

In this study, thermoplastic starch (TPS) was mixed with low density polyethylene with different melt flow indexes in a one-step extrusion process to produce LDPE/TPS blends varied from 32% to 62% by weight of TPS. The influence of starch content and LDPE viscosity on morphology, biodegradation and tensile properties of LDPE/TPS blends were evaluated. Starch continuity and biodegradability were studied by hydrolytic, enzymatic and bacterial degradation. The LDPE viscosity had a considerable effect on the morphology and the connectivity of the starch particles. Evaluation of hydrolytic extraction showed that blends having TPS content above 50 wt% possessed a full connectivity. Studies of biodegradation indicated that the bacterial attack on starch resulted in weight loss of TPS of 92%, 39% and 22%, for PE1/TPS having 62% and 32% TPS, and PE2/TPS (31% TPS), respectively. Comparatively, the weight loss was more significant at 100%, 66% and 31% by hydrolytic extraction. Differences between these two techniques were discussed in terms of the accessibility of starch domains to microorganisms. Tensile properties (ε_b and E) decreased with increasing exposure time to activated sludge. Changes in tensile properties were highly dependent on the biodegradation rate. PE1/TPS blends having 32% starch remained ductile after 45 days of exposure to bacterial attack.