Experimental verification on UCST phase diagrams and miscibility in binary blends of isotactic, syndiotactic, and atactic polypropylenes

Issues in blends of polymers of the same chemical repeat unit but with different tacticities were addressed by investigating on the phase behavior and interaction strength of binary blends of three polypropylenes of different tacticities, i.e., isotactic polypropylene (iPP), syndiotactic polypropylene (sPP), and atactic polypropylene (aPP) using polarized optical microscopy (POM) and differential scanning calorimetry (DSC). Although blends of polypropylenes have been widely studied in the past, there are still on-going debates on true phase behavior (miscibility vs. upper critical solution temperature (UCST) or immiscibility). Except for several earlier theoretical predictions based on the Flory-Huggins mean field theories, UCST behavior had not been experimentally proven for blends of sPP/iPP or aPP/sPP, owing to interference from PP crystallinity. In addition, interaction strength of the blends of different tactic polypropylenes is yet to be established. Using the method of equilibrium melting points, the Flory-Huggins interaction parameter of the aPP/iPP blend was shown to possess a significantly negative value (χ₁₂ = −0.21), which proves that the blend is indeed miscible in the melted amorphous as well as semicrystalline states as previously reported in the literature. However, the interaction parameters for the sPP/iPP and aPP/sPP blends were found to be nearly zero (χ₁₂ = −0.02 and −0.0071, respectively, at T = 150-180 °C), indicating that the interactions in two blends are weak and that the corresponding phase behavior for them borders on immiscibility at ambient temperature. This study also utilized novel approaches in constructing UCST phase diagrams by separating the amorphous phase domains from the crystalline spherulites, yielding data plausible for experimentally determining the UCST in iPP/sPP blend vs. aPP/sPP blend.     

高熔体强度聚丙烯的制备

高熔体强度聚丙烯是聚丙烯改性研究的重要产品之一。产品具有较高的熔体强度和优异的物理机械性能,拓宽了聚丙烯的应用范围。本文综述了国内外高熔体强度聚丙烯的制备方法,包括射线辐射法、直接聚合法、反应挤出法、共混改性及交联技术。     

国产三乙基铝在间歇式聚丙烯装置上的应用

介绍了国产助催化剂三乙基铝在金陵石化有限责任公司塑料厂100kt/a间歇式聚丙烯装置上的试用情况，并与进口三乙基铝的使用情况进行了对比。     

PP-HBP改性PP／PVO的流变行为

研究了聚丙烯接枝超支化聚（酰胺酯）（PPHBP）／PP／聚氯乙烯（PVC）共混体系的流变行为。讨论了PP-HBP用煮对PP／PVC共混体系流变行为的影响。结果表明，当PP／PVC共混体系中加入PPHBP不大于5份时，PP／PVC／PPHBP共混体系的表观粘度大于PP／PVc共混体系的；当加入PP—HBP大于5份时，PP／PVC／PP-HBP共混体系的表观粘度小于PP／PVC共混体系的；随着温度升高，PP／PVC和PP／PVC／PP—HBP共混体系表观粘度减小。     

PTT／PP／PP-g-MAH共混材料的形态与性能研究

研究了马来酸酐接枝聚丙烯(PP-g-MAH)对聚对苯二甲酸丙二酯(PTT)/聚丙烯(PP)共混体系的形态结构和性能的影响。结果表明,PP在PTT连续相中分散均匀,粒子尺寸随着增容剂含量的增加而细化,分散相与连续相之间有较好的黏结作用,PP-g-MAH改善了PP与PTT的相容性。共混物熔体为假塑性流体,其假塑性随PP-g-MAH含量的增加而升高,熔体表观黏度从1．31 Pa·s降低到1．19 Pa·s,黏流活化能从64．5 kJ/mol降低到36．7 kJ/mol。共混物中PTT和PP可分别结晶,但结晶行为相互影响,PP-g-MAH促进了PTT在高温结晶。共混物的冲击强度随着PP-g-MAH含量的增加从14．2 kJ/m~2提高到33．5 kJ/m~2,拉伸强度在PP-g-MAH含量为5％～10％(质量分数,下同)时最大。共混物的热稳定性随着PP-g-MAH含量的增加而逐渐降低。     

丙纶可染性技术进展

综述了丙纶的本体着色、未改性染色及改性后染色技术的各自进展情况。色母粒法、共混改性法和氯化表面改性法仍然具有较大优势,丙纶未改性染色及专用染料、共混改性丙纶染色技术将有更好的发展前景。有14篇参考文献。     

我国聚丙烯市场研究

阐述了我国聚丙烯市场的供应、消费状况及其市场结构变化，分析了聚丙烯市场的价格变化规律，综合论述了我国聚丙烯工业在加入WTO所面临的机遇与挑战，提出了我国聚丙烯工业的发展建议。     

木粉填充改性聚丙烯复合材料的研究

本实验利用木粉对聚丙烯(PP)进行改性研究，结果表明，加入木粉后，复合材料的弯曲强度、拉伸强度、断裂伸长率、硬度和维卡软化温度均有所提高，加工流动性能和冲击强度有所下降。     

Calcium dicarboxylates nucleation of β‐polypropylene

Seven dicarboxylates of calcium were synthesized. The effect of dicarboxylate on the formation of β‐form polypropylene was investigated by X‐ray diffraction. Calcium pimelate, calcium suberate, calcium phthalate, and calcium terephthalate have been found to be an effective β‐nucleator. The K_x values of the isotatic propylene samples with 0.5 wt % of the nucleators above are 0.95, 0.96, 0.93, and 0.62, respectively. Calcium succinate, calcium adipate, and calcium sebacate behave invalidly on the nucleating of the β‐phase. We conducted an investigation on the affect of particle shape, crystal form, and crystallinity upon the level of the β‐form. The X‐ray diffraction of the effective nucleators reveals a common character that their first reflection locate at the d‐spacing between 10 to 13 Å, indicating structural similarity of the nucleators with β‐polypropylene. The nucleation mechanism is explained by the cooperative effect of the nonpolar and polar part of nucleating agents in the crystallization of polypropylene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 633–638, 2002     

Competing effect between filled glass bead and induced β crystal on the tensile properties of polypropylene/glass bead blends

The blends of the polypropylene (PP‐1) with various glass bead contents were prepared via melt blending. Differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD) results indicated that the β crystal existed in PP‐1 and increased with increasing glass bead content up to 6 wt %. It was generally known that the stiffness of a polymer increased with introducing rigid particles, and the stiffness of the β crystal was less than that of the α crystal. This competing effect thus leads to the tensile modulus of PP‐1/glass bead blend decreasing with increasing glass bead content up to 6 wt %; thereafter, it increased with increasing glass bead content. For the purpose of comparison, the polypropylene (PP‐2) without the β crystal was employed to blend with glass bead. The tensile tests showed that the modulus of the PP‐2/glass bead blend increased continuously with increasing glass bead content. This result further supported that the tensile modulus behavior of PP‐1/glass bead blends resulted from the competing between the filled glass bead and the induced β crystal. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1729–1733, 2005     

Polypropylene/metallocene ethylene‐octene copolymer blends with a bimodal particle size distribution: Mechanical properties and their controlling factors

Blends of polypropylene homopolymer (PP) and metallocene produced ethylene‐octene copolymer (EOR) with a bimodal particle size distribution were investigated. The aim of the work was to study the influences of EOR characteristics and its concentration on the tensile and impact properties of the blends. The matrix ligament thickness between rubber particles was measured and compared to those predicted using the theoretical models. The relationships between blend morphology and impact property were reported. It was found that the content of comonomer and molecular weight of the EOR as well as its concentration in the blends were the major factors controlling the tensile and impact properties of the blends. These factors became ineffective to impact property when the ligament thickness of the matrix was larger than the critical value (T ～0.3–0.4 μm). To achieve blends of high impact strength, the ligament thickness between rubber particles should be smaller than the critical value, and for a certain ligament thickness, EOR with high octene content and high molecular weight was preferred. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2412–2418, 2002     

Compatibilizing effects for semicrystalline polymer-infiltrated amorphous polymer matrix: Mechanical (toughness), thermal,and morphological behavior of compatibilized polypropylene/polycarbonate blends

Polycarbonates (PCs) have been extensively blended with polyolefins such as polypropylene (PP) due to pecuniary advantages. Although the toughness of a pristine PC matrix has been examined, limited works have investigated the toughness of heterogeneous PC/PP blend systems, focusing merely on PC-dispersed PP matrices. In this study, the mechanical/thermal properties of PP-dispersed PC matrix (PC-rich phase) were examined by using potential compatibilizers: poly(maleic anhydride-alt-α-olefin) (OM), ethylene-co-acrylic acid (EA), and cyclic olefin copolymer. The incorporation of 0.5–5.0 phr of compatibilizers (OM and EA) into PC substantially enhanced the toughness of PC/PP15 blends according to four different testing methods. The highest toughness was obtained with 0.5 phr of OM and EA. The compatibilized blends displayed enhanced various thermal properties such as glass transition temperatures, heat deflection temperature, and degradation point, due to the compatibilizing effect. Moreover, 0.5 phr of compatibilizers (OM and EA) were determined as the most effective concentration in terms of toughness and most properties, without compromising strengths and moduli. The morphology of PP-dispersed PC matrix (crystalline polymer-infiltrated amorphous polymer matrix) differed from that of PC-dispersed PP matrix. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47684.     

PP/PVC/PP-HBP共混体系研究

研究了聚丙烯接枝超支化聚(酰胺-酯)(PP-HBP)对聚丙烯／聚氯乙烯(PP／PVC)共混体系力学性能的影响。结果表明，在PP／PVC(质量比为70／30)共混体系中加入5份PP-HBP时，共混物拉伸强度和冲击强度均出现最大值。扫描电子显微镜（SEM)研究结果证明，PP-HBP增强了PP／PVC的界面粘结作用，减小了共混体系的相分离程度。     

The effect of heat sealing temperature on the properties of OPP/CPP heat seal. I. Mechanical properties

The effect of heat sealing temperature on the mechanical properties and morphology of OPP/CPP laminate films was investigated. The laminated films were placed in an impulse type heat sealing machine with both CPP sides facing each other. The temperatures investigated ranged from 100 to 250°C. T‐peel and tensile tests in combination with SEM were used to characterize the heat seals. A minimum seal initiation temperature of 120°C was identified for OPP/CPP laminate heat sealing. Peel strength increased sharply from zero at 110°C to maximum at 120°C, after which a gradual decrease was observed. Tensile strength initially increased until 120°C, after which it gradually decreased until 170°C and assumed a constant value beyond that. The initial rise has been associated to cold crystallization, while the reduction between 120°C and 170°C was due to relaxation in molecular orientation. Beyond 170°C, all the orientation in the laminate has been lost so orientation effects are nullified. Morphological studies with SEM revealed that seals were partially formed at lower temperatures, while the laminates were totally fused together at high temperatures, with intermediate temperatures showing properties that lie in between. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 753–760, 2005     

Study on processing of ultrahigh molecular weight polyethylene/polypropylene blends

The processing of ultrahigh molecular weight polyethylene (UHMWPE) by the addition of polypropylene (PP) and high‐density polyethylene (HDPE) was investigated. The results show that the addition of PP improves the processability of UHMWPE more effectively than does the addition of HDPE. UHMWPE/PP blends can be effectively processed with a twin‐roller and general single‐screw extruder. In the extrusion of UHMWPE/PP blends, PP is enriched at the surface of the blend adjacent to the barrel wall, thus increasing the frictional force on the wall; the conveyance of the solid down to the channel can then be carried out. The melt pool against the active flight flank exerts a considerable pressure on the UHMWPE powder in the passive flight flank, which overcomes the hard compaction of UHMWPE. The PP penetrates into the gaps between the particles, acting as a heat‐transfer agent and adhesive, thus enhancing the heat‐transfer ability in the material. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 977–985, 2004     

Pineapple leaf fiber reinforced thermoplastic composites: Effects of fiber length and fiber content on their characteristics

Pineapple leaf fiber (PALF) was used as a reinforcement in polyolefins. Polypropylene (PP) and low‐density polyethylene (LDPE) composites with different fiber lengths (long and short fibers) and fiber contents (0–25%) were prepared and characterized. The results showed that the tensile strength of the composites increased when the PALF contents were increased. It was observed that the composites containing long fiber PALF were stronger than the short fiber composites as determined by greater tensile strength. An SEM study on the tensile fractured surface confirmed the homogeneous dispersion of the long fibers in the polymer matrixes better than dispersion of the short fibers. The unidirectional arrangement of the long fibers provided good interfacial bonding between the PALF and polymer which was a crucial factor in achieving high strength composites. Reduction in crystallinity of the composites, as evident from XRD and DSC studies suggested that the reinforcing effect of PALF played an important role in enhancing their mechanical strength. From the rule of mixtures, the stress efficiency factors of the composite strength could be calculated. The stress efficiency factors of LDPE were greater than those of PP. This would possibly explain why the high modulus fiber (PALF) had better load transfers to the ductile matrix of LDPE than the brittle matrix of PP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of nano‐silica filler on the rheological and morphological properties of polypropylene/liquid‐crystalline polymer blends

A fumed hydrophilic nano‐silica‐filled polypropylene (PP) composite was blended with a liquid‐crystalline polymer (LCP; Rodrun LC5000). The preblended polymer blend was extruded through a capillary die; this was followed by a series of rheological and morphological characterizations. The viscosity of the PP matrix increased with the addition of the hydrophilic nano‐silica. At shear rates between 50 and 200 s^?1, the composite displays marked shear‐thinning characteristics. However, the incorporation of LC5000 in the PP composite eliminated the shear‐thinning characteristic, which suggests that LC5000 destroyed the agglomerated nano‐silica network in the PP matrix. Although the viscosity ratio of LCP/PP was reduced after the addition of nano‐silica fillers, the LCP phases existed as droplets and ellipsoids. The nano‐silicas were concentrated in the LC5000 phase, which hindered the formation of LCP fibers when processed at high shear deformation. We carried out surface modification of the hydrophilic nano‐silica to investigate the effect of modified nano‐silica (M‐silica) on the morphology of the PP/LC5000 blend system. Ethanol was successfully grafted onto the nano‐silica surface with a controlled grafting ratio. The viscosity was reduced for PP filled with ethanol‐M‐silica when compared to the system filled with untreated hydrophilic nano‐silica. The LC5000 in the (PP/M‐silica)/LC5000 blend existed mainly in the form of fibrils. At high shear rates (e.g., 3000 s^?1), the LC5000 fibril network was formed at the skin region of the extrudates. The exclusion of nano‐silica in the LC5000 phase and the increased viscosity of the matrix were responsible for the morphological changes of the LCP phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1484–1492, 2003     

Melting,nonisothermal crystallization behavior and morphology of polypropylene/random ethylene—propylene copolymer blends

The melting, nonisothermal crystallization behavior and morphology of blends of polypropylene (PP) with random ethylene–propylene copolymer (PP‐R) were studied by differential scanning calorimetry, polarized optical microscopy, scanning electron microscopy, and X‐ray diffraction. The results showed that PP and PP‐R were very miscible and cocrystallizable. Modified Avrami analysis was used to analyze the nonisothermal crystallization kinetics of the blends. The values of the Avrami exponent indicated that the crystallization nucleation of the blends was heterogeneous, the growth of the spherulites was tridimensional, and the crystallization mechanism of PP was not affected by PP‐R. The crystallization activation energy was estimated using the Kissinger method. An interesting result was obtained with the modified Avrami analysis and the Kissinger method, whose conclusions were in good agreement. The addition of a minor PP‐R phase favored an increase in the overall crystallization rate of PP. Maximum enhancing effect wass found to occur with a PP‐R content of 20 wt %. The relationship between the composition and the morphology of the blends is discussed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 670–678, 2006     

聚丙烯/蒙脱土纳米复合材料的制备与性能研究

以马来酸酐接枝低分子量聚丙烯为相容剂,采用双螺杆挤出机熔融挤出法,制备插层型聚丙烯/有机钠基蒙脱土、聚丙烯/酸化有机化钠基蒙脱土、聚丙烯/钠基蒙脱土3种纳米复合材料,发现有机钠基蒙脱土、酸化有机化钠基蒙脱土和钠基蒙脱土对PP力学性能和燃烧性能均有一定程度的提高。经X射线衍射(XRD)和扫描电子显微镜(SEM)观察,发现有机钠基蒙脱土片层间距增幅最大,复合材料的燃烧性能也有很大提高。     

接枝共聚改性氯化聚丙烯乳液的研究

以丙烯酸酯单体作为接枝共聚单体,合成了无芳烃低VOC的CPP(氯化聚丙烯)乳液。以接枝率和耐水性作为衡量指标,采用单因素试验法优选出制备CPP乳液的最佳工艺条件。结果表明:当反应温度为95℃、反应时间为3.5 h、w(总引发剂)=1.0%(其中10%引发剂在滴加单体以前加入,并且间隔时间为10 min)、w(丙烯酸酯单体)=30%和w(丙烯酸)=5%时,相应CPP乳液的综合性能相对较好,并且其对聚丙烯(PP)基材的附着力相对最好。