聚丙烯／氯化聚乙烯共混物的形态结构

用透射电子显微镜方法研究了聚丙烯（ｉＰＰ）和氯化聚乙烯（ＣＰＥ）共混物溶液浇铸膜的形态结构．共混物中ＣＰＥ含量≤７０％时不妨碍ｉＰＰ球晶两种结构（交叉结构和条状结构）区域的生成．在ＣＰＥ含量≥８０％时，分散相ｉＰＰ形成近乎直角（８０°）交叉的稀疏的片晶网络．在共混物的全组成范围内，ＣＰＥ结晶在ｉＰＰ片晶上附生生长，二者结晶Ｃ轴的交角为５０°     

高密度聚乙烯／低密度聚乙烯／乙烯－醋酸乙烯共聚物共混体系的结晶行为

通过ＤＳＣ和ＷＡＸＤ研究了高密度聚乙烯／低密度聚乙烯／乙烯－醋酸乙烯共聚物（ＨＤＰＥ／ＬＤＰＥ／ＥＶＡ）三元共混体系的热行为和结晶性能。发现当ＨＤＰＥ含量小于４０％时，ＥＶＡ对ＬＤＰＥ起稀释剂作用，促进ＨＤＰＥ、ＬＤＰＥ的晶相分离，使ＨＤＰＥ、ＬＤＰＥ单独结晶．当ＨＤＰＥ含量高于４０％时，ＬＤＰＥ片晶进入ＨＤＰＥ晶相。形成与ＬＤＰＥ在片晶水平上的共晶。     

高密度聚乙烯／低密度聚乙烯／乙烯—醋酸乙烯共聚物共混体系的结晶行为

通过ＤＳＣ和ＷＡＸＤ研究了高密度聚乙烯／低密度聚乙烯／乙烯－醋酸乙烯共聚物（ＨＤＰＥ／ＬＤＰＥ／ＥＶＡ）三元共混体系的热行为和结晶性能，发现当ＨＤＰＥ含量小于４０％时，ＥＶＡ对ＬＤＰＥ起稀释剂作用，促进ＨＤＰＥ、ＬＤＰＥ的晶相分离，使ＨＤＰＥ、ＬＤＰＥ单独结晶，当ＨＤＰＥ含量高于４０％时，ＬＤＰＥ片晶入进ＨＤＰＥ晶相，形成与ＬＤＰＥ在片晶水平上的共晶。     

接枝共聚物氯化聚乙烯－苯乙烯对聚苯乙烯的共混改性

用氯化聚乙烯接枝苯乙烯共聚物（ＣＰＥ－ｇ－Ｓｔ）和氯比聚乙烯（ＣＰＥ）对聚苯乙烯（ＰＳ）进行共混改性．当ＣＰＥ含量为２５％时，用ＣＰＥ－ｇ－Ｓｔ改性的共混物的冲击强度为１８．５ｋＪ·ｍ￣（－２），是用ＣＰＥ改性的共混物冲击强度的２．１倍；其拉伸强度不低于３４ＭＰａ．     

接枝共聚物氯化聚乙烯—苯乙烯对聚苯乙烯的共混改性

用氯化聚乙烯接枝苯乙烯共聚物（ＣＰＥ－ｇ－Ｓｔ）和氯化聚乙烯（ＣＰＥ）对聚苯乙烯（ＰＳ）进行共混改性。当ＣＰＥ含量为２５％时，用ＣＰＥ－ｇＳｔ改性的共混物的冲击强度为１８．５ｋＪ．ｍ＾－＾２，是用ＣＰＥ改性的共混物冲击强度的２．１倍；其拉伸强度不低于３４ＭＰａ。     

聚环氧乙烷/聚乙基■唑啉共混体系结晶行为及相容性的研究

用偏光显微镜（ＰＬＭ）、ＤＳＣ、ＩＲ和ＷＡＸＤ等测试方法对聚环氧乙烷（ＰＥＯ）／聚乙基唑啉（ＰＥＯｘ）共混体系结晶行为及相容性进行了研究．结果表明，ＰＥＯ含量在３０％以上的共混体系中，几乎完全被球晶充满，非晶态ＰＥＯｘ作为微区分散在大球晶之间或之中；含量为２０％的共混体系照片上呈树枝状晶；含量低于１０％时则看不到结晶出现，体系形成单一的非晶相．对任何组成的共混物，均只出现单一的玻璃化转变温度（Ｔｇ），而且符合Ｆｏｘ方程揭示的规律；随ＰＥＯｘ组分含量的增加，共混体系的结晶度减小，熔点下降，并利用平衡熔点方程计算出ＰＥＯ与ＰＥＯｘ的相互作用能密度．非晶ＰＥＯ与ＰＥＯｘ热力学相容，其相容性是由于这两种分子间存在着特殊相互作用．ＰＥＯｘ的加入不会改变ＰＥＯ的晶胞参数．     

聚对苯二甲酸乙二酯／热致液晶聚合物共混体系中液晶组分的诱导结晶效应

用差示扫描量热法对聚对苯二甲酸乙二酯（ＰＥＴ）／热致液晶高分子（ＬＣＰ）共混体系的等温和非等温结晶行为进行了研究．结果表明，由于液晶组分的加入，共混体系中ＰＥＴ的结晶速率和结晶度均得到提高．说明ＬＣＰ具有ＰＥＴ结晶成核剂的作用．在较低的ＬＣＰ组分含量下（～２ｗｔ％），这一效果最为明显，说明ＬＣＰ是以很小的微区或某些ＬＣＰ分子链介晶微束的形式对ＰＥＴ的结晶起成核剂的作用．     

引入离子基团改善聚苯乙烯和热致液晶聚合物的相容性 Ⅰ热性能和形态

ＤＳＣ和ＳＥＭ研究结果表明聚苯乙烯（ＰＳ）与一种热致液晶聚合物（ＬＣＰ）（ＰＨＢ／ＰＥＴ（６０／４０）共聚酯）完全不相容．共混体系具有与组分无关的Ｔｇ，并且表现出明显的两相结构．将ＰＳ进行化学改性（引入磺酸基团）制备成磺化聚苯乙烯（ＳＰＳ），随中和盐离子的变化有：酸式、Ｌｉ、Ｎａ、Ｚｎ和Ｍｎ盐五种形式．用ＤＳＣ和ＳＥＭ对ＬＣＰ与ＳＰＳ共混物的热性能和形态进行了分析和表征．共混体系有一个与组成相关，且明显低于纯ＳＰＳ的Ｔｇ．这表明了ＰＳ与ＬＣＰ的相容性因为磺酸基团的引入而得到了改善．同时用Ｆｏｘ方程计算了ＬＣＰ的Ｔｇ．当ＳＰＳ含量较低时（不大于５０％）在各个共混体系中，所估算的ＬＣＰ的Ｔｇ相互吻合．表明共混体系满足Ｆｏｘ方程的前提条件，即ＬＣＰ与ＳＰＳ形成相容体系．当ＳＰＳ含量较低时（２５％），ＬＣＰ／ＳＰＳ的共混物为较均一体系，断面光滑；而ＳＰＳ含量较高时，在脆断面可以观察到纳米级的颗粒．电子能谱分析证明了这些颗粒是ＳＰＳ负离子的聚集体．     

LLDPE／EAA共混体系结晶行为及相容性

通过ＤＭＡ、ＤＳＣ、偏光显微镜（ＰＬＭ）、ＷＡＸＤ及力学性能测试等方法，对线性低密度聚乙烯（ＬＬＤＰＥ）／乙烯－丙烯酸共聚物（ＥＡＡ）共混体系的研究表明，ＬＬＤＰＥ与ＥＡＡ的非晶相可部分相容，结晶相不能形成共晶；共混物结晶时，两组分相互影响，ＬＬＤＰＥ的结晶速度高于ＥＡＡ，两者结晶没有进入对方晶胞中．还发现ＬＬＤＰＥ与ＥＡＡ力学性能上相容．低含量ＥＡＡ共混体系显示出较佳的力学性能．     

聚β－羟基丁酸酯／聚醋酸乙烯酯共混体系的相容性与结晶行为

研究了制样过程对聚β－羟基丁酸酯（ＰＨＢ）／聚醋酸乙烯酯（ＰＶＡｃ）共混体系的相容性和结晶行为的影响，ＤＳＣ、ＳＡＸＳ、ＰＯＭ等实验结果表明，ＰＨＢ／ＰＶＡｃ共混物经溶液成膜后处于分相的状态，ＰＶＡｃ对ＰＨＢ的结晶能力影响不大，而经熔融处理后，ＰＨＢ／ＰＶＡｃ共混物则处于相容的均相状态，随ＰＶＡｃ在共混物中含量的增加，ＰＨＢ的冷结晶温度升高，球晶增长速率下降，织态结构变得不规整。当ＰＶＡｃ的含量高于８０％时，ＰＨＢ失去结晶能力。     

Annealing induced microstructure and fracture resistance changes in isotactic polypropylene/ethylene‐octene copolymer blends with and without β‐phase nucleating agent

Previous work showed that annealing induced the great improvement of fracture resistance of β‐iPP, relating to the decreased number of chain segments in the amorphous region. To further prove the rationality of this observation, in this work, the ethylene‐octene copolymer (POE) toughened isotactic polypropylene (iPP) blends with or without β‐phase nucleating agent (β‐NA) were adopted and the changes of microstructure and fracture resistance during the annealing process were further investigated comparatively. The results showed that, whether for the α‐phase crystalline structure (non‐nucleated) or for the β‐phase crystalline structure (β‐NA nucleated) in iPP matrix, annealing can induce the dramatic improvement of fracture resistance at a certain annealing temperature (120–140 °C for β‐NA nucleated blends whereas 120–150 °C for non‐nucleated blends). Especially, non‐nucleated blends exhibit more apparent variations in fracture resistance compared with β‐NA nucleated blends during the annealing process. The phase morphology of elastomer, supermolecular structure of matrix, the crystalline structure including the degree of crystallinity and the relative content of β‐phase, and the relaxation of chain segments were investigated to explore the toughening mechanism of the samples after being annealed. It was proposed that, even if the content of elastomer is very few, the excellent fracture resistance can be easily achieved through adjusting the numbers of chain segments in the amorphous phase by annealing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Toughening of a propylene‐b‐(ethylene‐co‐propylene) copolymer by a plastomer

Several blends, covering the entire range of compositions, of a metallocenic ethylene‐1‐octene copolymer (CEO) with a multiphasic block copolymer, propylene‐b‐(ethylene‐co‐propylene) (CPE) [composed of semicrystalline isotactic polypropylene (iPP) and amorphous ethylene‐co‐propylene segments], have been prepared and analyzed by differential scanning calorimetry, X‐ray diffraction, optical microscopy, stress‐strain and microhardness measurements, and dynamic mechanical thermal analysis. The results show that for high CEO contents, the crystallization of the iPP component is inhibited and slowed down in such a way that it crystallizes at much lower temperatures, simultaneously with the crystallization of the CEO crystals. The mechanical results suggest very clearly the toughening effect of CEO as its content increases in the blends, although it is accompanied by a decrease in stiffness. The analysis of the viscoelastic relaxations displays, first, the glass transition of the amorphous blocks of CPE appearing at around 223 K, which is responsible for the initial toughening of the plain CPE copolymer in relation to iPP homopolymer. Moreover, the additional toughening due to the addition of CEO in the blends is explained by the presence of the β relaxation of CEO that appears at about 223 K. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1869–1880, 2002     

Energetic potential and kinetic behavior of peats

The miscibility of blends of isotactic polypropylene and propylene-1-hexene (PH) copolymers with 11 and 21 mol% of 1-hexene (PH11 and PH21, respectively) has been studied theoretically and using DSC, DMA, and AFM techniques. Using experimental PVT data, the solubility parameter approach leads to a critical difference in 1-hexene content for melt miscibility of 17 mass% (~11 mol%) at 200 °C and 0.1 MPa. The theoretical window for miscibility is in close agreement with thermal properties of the blends. The glass transition (T _g) of miscible blends (iPP/PH11 and PH11/PH21) decreases proportionally to the content of PH having the lowest T _g, while immiscible blends (iPP/PH21) display invariable T _g with blend composition. The same trend was extracted from the analysis of the β-relaxation by dynamic mechanical analysis. Room temperature AFM images of blends quenched from 200 °C into liquid nitrogen confirm phase segregation of iPP/PH21 in domains of 1–5 microns, while the AFM images of iPP/PH11 and PH11/PH21 lack any obvious signature of phase separation prior to crystallization.     

Crystallization behavior of isotactic propylene‐1‐hexene random copolymer revealed by time‐resolved SAXS/WAXD techniques

The crystallization behavior of isotactic propylene‐1‐hexene (PH) random copolymer having 5.7% mole fraction of hexene content was investigated using simultaneous time‐resolved small‐angle X‐ray scattering (SAXS) and wide‐angle X‐ray diffraction (WAXD) techniques. For this copolymer, the hexene component cannot be incorporated into the unit cell structure of isotactic polypropylene (iPP). Only α‐phase crystal form of iPP was observed when samples were melt crystallized at temperatures of 40 °C, 60 °C, 80 °C, and 100 °C. Comprehensive analysis of SAXS and WAXD profiles indicated that the crystalline morphology is correlated with crystallization temperature. At high temperatures (e.g., 100 °C) the dominant morphology is the lamellar structure; while at low temperatures (e.g., 40 °C) only highly disordered small crystal blocks can be formed. These morphologies are kinetically controlled. Under a small degree of supercooling (the corresponding iPP crystallization rate is slow), a segmental segregation between iPP and hexene components probably takes place, leading to the formation of iPP lamellar crystals with a higher degree of order. In contrast, under a large degree of supercooling (the corresponding iPP crystallization rate is fast), defective small crystal blocks are favored due to the large thermodynamic driving force and low chain mobility. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 26–32, 2010     

Epitaxial crystallization and oriented structure of linear low‐density polyethylene/isotactic polypropylene blends obtained via dynamic packing injection molding

In this work, as a part of a long‐term project aimed at controlling of crystal structure and phase morphology for a injection molded product, we investigated the oriented structure and possible epitaxial growth of polyolefin blend (low‐density polyethylene (LLDPE)/isotatic polypropylene (iPP)), achieved by dynamic packing injection molding, which introduced strong oscillatory shear on the gradually‐cooled melt during the packing process. The crystalline and oriented structures of the prepared blends with different compositions were estimated in detail through 2D X‐ray diffraction, calorimetry, and optical microscopy. As iPP was the dominant phase (its content was more than 50 wt%), our results indicated that it could be highly oriented in the blends. In such case, it was interesting to find that LLDPE epitaxially crystallized on the oriented iPP through a crystallographic matching between (100)_LLDPE and (010)_iPP, resulting in an inclination of LLDPE chains, about 50° to the iPP chain axis. On the other hand, as iPP was the minor phase, iPP was less oriented and no epitaxial growth between iPP and LLDPE was observed; even LLDPE remained oriented. The composition‐dependent epitaxial growth of LLDPE on oriented iPP could be understood as due to: (1) the effect of crystallization sequence, it was found that iPP always crystallized before LLDPE for all compositions; (2) the dependence of oriented iPP structure on the blend composition; (3) the “mutual nucleation” between LLDPE and iPP due to their partial miscibility. Copyright © 2009 John Wiley & Sons, Ltd.     

PE-CPE blends and their graphene oxide nanocomposites with reduced low temperature brittleness

The low-temperature flexibility of polyethylene (PE)–chlorinated polyethylene (CPE) blends and their composites with a small amount of graphene oxide filler was studied. Quantitative height variation in the AFM images, rheological as well as fracture analyses were employed to gain insights into the generation of flexibility in the matrix phase. The semi-crystalline CPE (CPE25) polymer did not induce viscoelastic behavior at temperatures lower than the glass transition temperature of PE, whereas the amorphous CPE (CPE35) had completely different behavior. The samples with CPE35 could not be sufficiently hardened even at ?180 °C and remained too soft for cryosectioning. Therefore, compression, which results in a 30–60 % reduction in length along the cutting direction with no change in the dimension perpendicular to it, was very prominent for both thin section and block face of the sample. The composites had even higher degree of compression due to additional effect of weak filler matrix interactions and as a consequence, the topographical variations led to filler pull out during sectioning. It was also confirmed using the rheological analysis that composites (and blends with 10 % CPE35 content) had phase immiscibility as CPE phase was suspected to concentrate near the graphene oxide phase leading to generation of chlorine-rich phases. The addition of graphene oxide did not lead to reduced flexibility and the composites also retained the modulus similar to pure polymer. The mechanical fracture of the samples also confirmed the flexibility of the CPE containing blends and composites as these samples were still flexible at ?195 °C.     

The effect of compatibilizers on the crystallisation, melting and polymorphic composition of β-nucleated isotactic polypropylene and polyamide 6 blends

Non-compatibilized and compatibilized blends of isotactic polypropylene (iPP) and polyamide 6 (iPP/PA6) as well as their β-nucleated versions were prepared using maleic anhydride functionalized iPP (MAPP) with different anhydride contents as compatibilizer. Ca-suberate, a highly efficient and selective β-nucleating agent was added to the blends in order to promote the formation of the β-modification of iPP. The melting and crystallisation characteristics, as well as the polymorphic composition of the blends were studied by differential scanning calorimetry (DSC). The supermolecular and phase structure of the blends were studied by polarised light microscopy (PLM). iPP and PA6 form blends with heterogeneous phase structure; the PA6 component is dispersed in the iPP matrix in the concentration range studied. The compatibilizer promotes the dispersion of PA6 resulting in smaller particles than without MAPP. In the non-compatibilized β-nucleated blends, an iPP matrix consisting mainly of the α-modification was formed already at low PA6 content. On the contrary, predominantly β-iPP matrix developed in the presence of MAPP compatibilizers. The formation of α-iPP matrix in the absence of compatibilizer is related to the selective encapsulation of the nucleating agent in the polar PA6 phase. The influence of the blending technique on the polymorphic composition of the matrix supports the hypothesis of selective encapsulation. Compatibilizers, besides their traditional benefits assist the distribution of the β-nucleating agent between both phases of the blends and promote the formation of a matrix rich in β-iPP. In the presence of β-nucleating agent MAPP with low anhydride content and blends of iPP containing maleated polypropylene crystallise predominantly in the β-form.     

聚丙烯/高密度聚乙烯高取向共混物的附生结晶

<正> 最近,聚合物之间的附生结晶引起人们的极大兴趣和关注。附生结晶是一种结晶物质在另一种结晶物质上的取向生长,二者之间有特殊的作用。这种附生作用对结晶聚合物共混体系的形态结构和性能有极为重要的影响。本工作以电子显微镜方法研究熔体拉伸直接导致等规聚丙烯(iPP)和高密度聚乙烯(HDPE)共混物附生结晶。     

Insight into understanding the evolution of the epitaxy crystallization in isotactic polypropylene and polyethylene blends

In this article, epitaxial structures have been successfully obtained in the isotactic polypropylene (iPP)/polyethylene (PE) blends by an accessible injection molding methods. By studying a series of iPP/PE blends, the evolution of the epitaxial growth of PE lamellae on the oriented iPP lamellae has been detailedly discussed via wide‐angle X‐ray diffraction, small‐angle X‐ray scattering, scanning electron microscopy and differential scanning calorimetry. Unexpectedly, the exactly epitaxial angles between peculiarly arranged PE lamellae and oriented PP lamellae are all larger than the classical epitaxy theory value of 50°, and it even increases gradually with increasing PP content. It is inferred that the special crystallization of PE is the consequence of joint construction of the oriented PP crystals and the continuous intense shear field provided by pressure vibration injection molding. The epitaxial structures play a positive role in the interfacial connection between two components; thus, the mechanical properties of the blends are improved. This work provides an insight understanding on the formation mechanism of the epitaxy crystallization under shear field. Copyright © 2017 John Wiley & Sons, Ltd.     

The β‐crystalline form of isotactic polypropylene in blends of isotactic polypropylene and polyamide‐6/clay nanocomposites

Blends of isotactic polypropylene and polyamide‐6/clay nanocomposites (iPP/NPA6) were prepared with an internal batch mixer. A high content of the β‐crystalline form of isotactic polypropylene (β‐iPP) was observed in the injection‐molded samples of the iPP/NPA6 blends, whereas the content of β‐iPP in the iPP/PA6 blends and the iPP/clay composite was low and similar to that of neat iPP. Quiescent melt crystallization was studied by means of wide‐angle X‐ray diffraction, differential scanning calorimetry, and polarized optical microscopy. We found that the significant β‐iPP is not formed during quiescent melt crystallization regardless of whether the sample used was the iPP/NPA6 blend or an NPA6 fiber/iPP composite. Further characterization of the injection‐molded iPP/NPA6 revealed a shear‐induced skin–core distribution of β‐iPP and the formation of β‐iPP in the iPP/NPA6 blends is related to the shear flow field during cavity‐filling. In the presence of clay, the deformation ability of the NPA6 domain is decreased, as evidenced by rheological and morphological studies. It is reasonable that the enhanced relative shear, caused by low deformability of the NPA6 domain in the iPP matrix, is responsible for β‐iPP formation in the iPP/NPA6 blends. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3428–3438, 2004