茂金属线型低密度聚乙烯的加工性能

采用齐聚-共聚复合催化剂合成出了相对分子质量分布指数大于4的原位共聚线型低密度茂金属聚乙烯(mLLDPE)。流变实验结果表明,mLLDPE具有切敏性和非温敏性。改性实验结果表明,向100质量份mLLDPE中加入5质量份氟母粒,或10质量份LDPE,或2质量份氟母粒和5质量份LDPE,可使mLLDPE的加工流动性能获得改善,聚合物的机械性能不会发生明显降低,可用常规加工设备加工。加工成型实验结果表明,使用65型管材挤出机和TDL-12L中空成型机,以氟母粒-LDPE复合改性mLLDPE为原料,可生产出内、外表面均光滑的32管材和10L中空容器,挤出过程稳定。     

浅色补强填充剂LEE白滑粉在合成橡胶中的应用

介绍了新型浅色补强填充剂ＬＥＥ白滑粉的组成、物化性质、加工特性、硫化胶性能及应用前景。     

Sheet molding compound characterization using spiral flow

Sheet molding compound (SMC) is a fiber‐reinforced polymeric composite. It is often used in automotive, marine, and industrial applications over other materials because of its high strength to density ratio, resistance to corrosion, and low cost. There is a demand in the SMC industry to be able to characterize SMC processability. This is particularly true for heavy truck body panels, one of the fastest growing applications of SMC. Because of their large size and high strength requirement, the molding forces have a major influence in the molding cycle. Also because of the long flow paths involved, the ability of the paste to carry glass needs to be properly characterized when developing new SMC materials. In this article, we demonstrate the benefits of using spiral flow as a processability tester. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

HDPE管材专用树脂的流变性能

应用动态流变仪、毛细管流变仪和转矩流变仪,对新型双峰高密度聚乙烯(HDPE)管材专用树脂 6380 M进行流变性能测试分析,并与国内外相同压力等级的HDPE管材专用树脂进行比较。结果表明,6380 M的各种流变性能与进口管材专用树脂相当,而与单峰HDPE管材专用树脂相比具有弹性模量低、零切黏度低、拉伸黏度低的流变特性,从而对其加工性能产生影响。6380 M流动性好,其临界剪切速率高,但熔体强度不及单峰HDPE。     

不同原料生产的CPE对PVC改性的影响

选取三种不同PE原料,采用相同的氯化工艺及配方生产CPE,通过对经CPE改性后的PVC流变性能测试和型材加工应用实验,研究了不同原料生产的CPE对PVC改性的影响。     

稀土BR／SBR共混胶的性能

研究了４种共混比的ＬｎＢＲ／ＳＢＲ共混生胶、混炼胶及硫化胶的性能，并与ＮｉＢＲ／ＳＢＲ共混胶进行了对比。结果表明，共混生胶的ＭＬ均低于ＬｎＢＲ及ＳＢＲ；当ＬｎＢＲ／ＳＢＲ共混混炼胶的ＭＬ、剪切应力、出口膨胀及硫化速度均低于ＮｉＢＲ／ＳＢＲ共混胶，挤出物外观优于后者；共混硫化胶的拉伸强度、热空气老化、拉伸疲劳、湿滑、耐磨等性能均明显优于后者，生热和透气率高于后者。     

CPE和ACR对PVC-U型材加工性能的影响

从抗冲改性机理、微观形态、加工性能、冲击性能及老化性能等方面对PVC-U冲击改性剂氯化聚乙烯(CPE)和丙烯酸酯类(ACR)进行比较,客观地分析了各自性能的优劣。     

Flexibilized Copolyimide Adhesives

Two copolyimides, LARC-STPI and STPI-LARC-2, with flexible backbones were prepared and characterized as adhesives. The processability and adhesive properties were compared to those of a commercially available form of LARC-TPI.

Lap shear specimens were fabricated using adhesive tape prepared from each of the three polymers. Lap shear tests were performed at room temperature, 177°C, and 204°C before and after exposure to water-boil and to thermal aging at 204°C for up to 1000 hours.

The three adhesive systems possess exceptional lap shear strengths at room temperature and elevated temperatures both before and after thermal exposure. LARC-STPI, because of its high glass transition temperature provided high lap shear strengths up to 260°C. After water-boil, LARC-TPI exhibited the highest lap shear strengths at room temperature and 177°C, whereas the LARC-STPI retained a higher percentage of its original strength when tested at 204°C [68% versus 50% (STPI-LARC-2) and 40% (LARC-TPI)].

These flexible thermoplastic copolyimides show considerable potential as adhesives based on this study and because of the ease of preparation with low cost, commercially available materials.     

Studies on blends of natural rubber and ethylene propylene diene rubber modified with phosphorylated cardanol prepolymer: Processability,physico‐mechanical properties,and morphology

The melt processability and physico‐mechanical properties of blends of natural rubber (NR) and ethylene propylene diene rubber (EPDM) containing different dosages (0–10 phr) of phosphorylated cardanol prepolymer (PCP) were studied in unfilled and china‐clay‐filled mixes. The plasticizing effect of PCP in the blends was evidenced by progressive reduction in power consumption of the mixing and activation energy for melt flow with an increase in the dosage of PCP. The PCP‐modified blend vulcanizates showed higher tensile properties and tear strength despite a decrease in the chemical crosslink density (CLD) index. This is presumably due to the formation of a crosslinked network structure of PCP with the rubbers and improved dispersion of the filler particles in the rubber matrix, as evidenced by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Thermogravimetric analysis showed an increase in thermal stability of the blend vulcanizate in presence of 5 phr of PCP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5123–5130, 2006     

Recycling of ethylene propylene diene monomer (EPDM) waste. III. Processability of EPDM rubber compound containing ground EPDM vulcanizates

The rheological behavior of ethylene propylene diene monomer (EPDM) compounds containing ground EPDM waste (W‐EPDM) of known composition was studied by using a Monsanto processability tester in a temperature range of 90–110°C and a shear rate range of 306.7–1533.24 s^?1. It is found that the shear viscosity decreases slightly with increasing W‐EPDM loading because of wall slip that results from the migration of lubricants from the W‐EPDM. The addition of W‐EPDM to raw EPDM results in a decreased die swell at all temperatures and shear rates. SEM photomicrographs of the EPDM extrudate surface show improved surface smoothness and reduced extrudate distortion when EPDM is blended with W‐EPDM. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2204–2215, 2003