用拟二元方法研究iPP-DBP-DOP三元体系的热致相分离热力学

采用拟二元方法研究等规聚丙烯（iPP）‐邻苯二甲酸二丁酯（DBP）‐邻苯二甲酸二辛酯（DOP）三元聚合物溶液的热致相分离热力学,得出了拟二元相图的数学关联方法.采用光学显微镜法测定浊点温度, 采用差式扫描量热法（DSC）测定熔点、动态结晶温度.利用浊点测定数据回归聚合物-共溶剂的交互作用参数 χ的表达式,χ是共溶剂配比和温度的函数,以此为基础计算的拟二元相图与实验数据吻合较好.发现共溶剂中DBP份数增加,相分离类型由单纯固液分相形式转变为液液分相、固液分相依次发生形式,共溶剂配比能调控拟二元相图结构.研究表明,只需测定一个较低冷却速率下几种共溶剂配比的拟二元溶液的浊点温度、分别测定几个冷却速率下iPP–DOP二元溶液的动态结晶温度即可掌握该三元溶液热致相分离热力学的全部信息.其可用来指导制膜过程,并能准确预测形成的膜结构形貌.     

热致相分离法iPP中空纤维微空膜结构与性能--稀释剂的作用

Isotactic polypropylene （iPP） hollow fiber microporous membranes were prepared using thermally induced phase separation （TIPS） method. Di-n-butyl phthalate （DBP）, dioctyl phthalate （DOP）, and the mixed solvent were used as diluents. The effect of α （DOP mass fraction in diluent） on the morphology and performance of the hollow fiber was investigated. With increasing α, the morphology of the resulting hollow fiber changes from typical cellular structure to mixed structure, and then to typical particulate structure. As a result, the permeability of the hollow fiber increases sharply, and the mechanical properties of the hollow fiber decrease obviously. It is suggested that the morphology and performances of iPP hollow fiber microporous membrane can be controlled via adjusting the compatibility between iPP and diluent.     

Effect of diluents on the crystallization behavior of poly(4‐methyl‐1‐pentene) and membrane morphology via thermally induced phase separation

The effect of diluents on polymer crystallization and membrane morphology via thermally induced phase separation(TIPS) were studied by changing the composition of the mixed‐diluents systematically, in the system of poly(4‐methyl‐1‐pentene) (TPX)/dibutyl‐phthalate (DBP)/di‐n‐octyl‐phthalate (D‐n‐OP) with TPX concentration of 30 wt %. The TPX crystallization was observed with differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD). The membranes were characterized with scanning electron microscopy (SEM), porosity, and pore size measurement. As the content of D‐n‐OP increased in mixed‐diluents, the solubility with TPX increased, inducing the phase separation changing from liquid–liquid phase separation into solid–liquid phase separation, which changed the membrane morphology and structure. When the ratios of DBP to D‐n‐OP were 10 : 0, 7 : 3; 5 : 5, and 3 : 7, membranes were formed with cellular structure and well connected pores, while the ratio was 0 : 10, discernable spherulities were found with not well‐formed pore structure. The effect of composition of the mixed‐diluents on membrane morphology was more remarkable in TPX/dioctyl‐sebacate (DOS)/dimethyl‐phthalate (DMP) system, since good cellular structure was formed when the ratios of DOS to DMP were 10 : 0, 7 : 3, while spherulites were observed when 5 : 5. Dual endotherm peaks behavior on DSC melting curves emerged for all the samples in this study, which was attributed to the special polymer crystallization behavior, primary crystallization, and secondary crystallization occurred when quenching the samples. As the content of D‐n‐OP increased, the secondary crystallization enhanced which induced the first endotherm peak on DSC melting curves moving to a lower temperature and the broadening of the overall melting peak, as well as the increasing of the overall crystallinity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Role of multi-wall carbon nanotube network in composites to crystallization of isotactic polypropylene matrix

The composites (iPP/CNTs) made of isotactic polypropylene (iPP) and multi-wall carbon nanotubes (CNTs) were prepared by solution blending. To improve compatibility between CNTs and iPP and to enhance dispersion of CNTs in iPP matrix, CNTs were chemically modified by grafting alkyl chains. The chemically modified CNTs had about 6 wt% grafted alkyl chains. Rheological measurements indicated that CNTs caused gelation in iPP/CNTs due to CNT network formation and the critical gelation CNT concentration was about 7.4 wt%, which was considered to be high due to the low CNT aspect ratio in this study. Crystallization behaviors of iPP/CNTs were studied by using optical microscopy (OM) and differential scanning calorimetry (DSC). Radial growth rates of spherulites during isothermal crystallization of iPP/CNTs with CNT concentrations less than 2.0 wt% measured by using OM showed decreasing trends with increasing CNT concentration. Avrami analysis of the exothermic heat flow curves during isothermal crystallization of iPP/CNTs measured by DSC indicated that crystallization rates were accelerated when CNT concentrations were lower than the critical gelation concentration, because CNTs mainly functioned as nucleating agents for crystallization, while crystallization rates did not change obviously when CNT concentrations were higher than the critical gelation concentration, because CNT network could form and mainly functioned to provide restriction to mobility and diffusion of iPP chains to crystal growth fronts.     

Effect of diluents on membrane formation via thermally induced phase separation

The effect of diluents on isotactic polypropylene (iPP) membrane formation via thermally induced phase separation was investigated. The diluents were methyl salicylate (MS), diphenyl ether (DPE), and diphenylmethane (DPM). The cloud-point curve was shifted to a lower temperature in the order iPP–MS, iPP–DPE, and iPP–DPM, whereas the crystallization temperature was not influenced so much by diluent type. Droplet-growth processes were investigated under two conditions: quenching the polymer solution at the desired temperature and cooling at a constant rate. Although droplet sizes were in the order iPP–MS, iPP–DPE, and iPP–DPM in both cases, the difference was more pronounced with the constant cooling rate condition. Scanning electron microscopy indicated that interconnected structures were obtained when the polymer solution was quenched in ice water. The effect of the diluents on these structures was observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 169–177, 2001     

Controllable fabrication and properties of polypropylene nanofibers

Thermoplastic nanofibers in yarn form were prepared by melt extrusion of immiscible blends of cellulose acetate butyrate (CAB) and thermoplastic polymers and subsequent removal of the CAB matrix. Isotactic polypropylene (iPP) nanofiber, with diameters ranging from 75 to 375 nm, were made by using CAB/iPP blends, with a ratio of 97.5–2.5, and a hot‐drawn ratio of 25 in a twin‐screw extruder. Dispersion of iPP in CAB and shear and elongational deformation are major factors to result in nanosized fibers. The spheres and nanofibers with different diameters of iPP dispersed phases in the CAB matrix can be well controlled by changing the flow field and the blend ratio. Differential scanning calorimeter and wide angle X‐ray diffraction results showed that the nanofibers had lower crystallinity and crystallite thickness compared with bulk iPP. The atomic force microscopy images presented the well‐defined nanofiber morphology and the excellent manipulability of single iPP nanofiber separated from a bundle of iPP nanofibers. POLYM. ENG. SCI., 47:1865–1872, 2007. © 2007 Society of Plastics Engineers     

Study on morphology evolution and fractal character of the miscible blend between isotactic polypropylene and copolymer of ethylene and propylene

The compatibility of isotactic polypropylene (iPP) with a block copolymer of ethylene and propylene (mEP) was evaluated by glass transition temperature measurements and Han curves. The morphology of the dispersed phase in alloys of iPP with mEP was observed by scanning electron microscopy (SEM). The average diameters, dp, of the dispersed phase in iPP/mEP alloys were calculated from SEM images. The results indicated that dp depends on the composition and mixing condition of the alloys. The distribution of dp was studied using graph-estimation methods and found to be log-normal in character. The calculated standard deviation, σ, characterizes the dispersed phase particle distribution width, and depends on the composition and mixing conditions of the blends. The fractal behavior of the phase morphology shown by SEM images of the alloys was studied, and the fractal dimensions were calculated by the changing coarse-graining level and measure relations methods. The self-similarity of the systems is discussed. The fractal dimensions depend on the composition and mixing conditions of the alloys.     

高生物基含量光固化涂料的制备及其性能研究

环氧化大豆油丙烯酸酯(AESO)已大规模用于UV固化涂料中,但目前同时获得高生物基含量以及优异机械性能的大豆油基光固化涂料依然是一个很大的挑战。文中设计并合成了异山梨醇甲基丙烯酸酯(ISDMA)作为光固化活性稀释剂。使用流变仪研究了ISDMA对AESO稀释性的影响。将ISDMA与AESO混合制备了一系列生物基UV固化涂料,并对这些涂料的热机械性能、力学性能和涂层基本性能进行了评估。结果表明:ISDMA对AESO表现出良好稀释性的同时,可以有效地提高固化涂层的玻璃化转变温度(T_g)、储能模量和硬度。     

活性稀释剂对环氧豆油丙烯酸酯光固化体系的影响

用环氧豆油与丙烯酸反应制备出环氧豆油丙烯酸酯预聚物,研究了活性稀释剂的组成、配比对紫外光固化速率、固化膜性能及施工性能的影响,并利用红外光谱对涂料光固化前后的结构进行了表征。结果表明:活性稀释剂的加入量以30%为宜,当其配比为10%苯乙烯,20%三羟甲基丙烷三丙烯酸酯时,光固化速率较快,固化膜无色透明,表面光滑平整,其硬度达到3H,且具有较好的柔韧性和附着力。     

Interplay between crystallization behaviors and extensional deformation of isotactic polypropylene and its blend with poly(ethylene-co-octene)

Comparison investigation of the interaction between crystallization behaviors and extensional deformation of both isotactic polypropylene (iPP) and its blend with poly(ethylene-co-octene) (iPP/PEOc) was carried out in this study. The samples of iPP and the iPP/PEOc (80/20, wt.%) blend were prepared by changing the cooling rate during nonisothermal crystallization. Tensile testing showed that with the decrease of cooling rate, the progressive destruction of ductility of the two samples was resulted from the more perfect crystallites formed in the cooling process. The influence of cooling rate on the tensile properties is more prominent for pure iPP than for the iPP/PEOc blend. The crystalline structure was proven to be partially destroyed under the extensional deformation, and such crystalline structure destruction was in close association with the deformation of the specimens. The oriented noncrystalline molecular chains could easily be reorganized into more perfect crystals in postheating runs. The original crystalline structure has been found, to some extent, to determine the extensional deformation and the final crystallization behavior.     

The influence of HOCP oligomer on the crystallization and morphology of iPP/HDPE blends

Summary Ternary mixtures of isotactic polypropylene (iPP), high density polyethylene (HDPE) and hydrogenated oligo(cyclopentadiene) (HOCP) commercial products were prepared by melt mixing. The crystallization behaviour of iPP/HDPE and (iPP/HDPE)/HOCP systems were compared. It was shown that the ternary system separated in two binary systems. The presence of HOCP modified the morphology of iPP and HDPE phases. The polyolefins nucleation and crystal growth rates decreased due to the diluent effect of the oligomer. HDPE showed higher compatibility with HOCP than iPP.     

Isothermal crystallization kinetics and morphology development of isotactic polypropylene blends with atactic polypropylene

The crystallization kinetics and morphology development of pure isotactic polypropylene (iPP) homopolymer and iPP blended with atactic polypropylene (aPP) at different aPP contents and the isothermal crystallization temperatures were studied with differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized optical microscopy. The spherulitic morphologies of pure iPP and larger amounts of aPP for iPP blends showed the negative spherulite, whereas that of smaller amounts of aPP for the iPP blends showed a combination of positive and negative spherulites. This indicated that the morphology transition of the spherulite may have been due to changes the crystal forms of iPP in the iPP blends during crystallization. Therefore, with smaller amounts of aPP, the spherulitic density and overall crystallinity of the iPP blends increased with increasing aPP and presented a lower degree of perfection of the γ form coexisting with the α form of iPP during crystallization. However, with larger amounts of aPP, the spherulitic density and overall crystallinity of the iPP blends decreased and reduced the γ‐form crystals with increasing aPP. These results indicate that the aPP molecules hindered the nucleation rate and promoted the molecular motion and growth rate of iPP with smaller amounts of aPP and hindered both the nucleation rate and growth rate of iPP with larger amounts of aPP during isothermal crystallization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1093–1104, 2007     

Morphological features and melting behavior of nanocomposites based on isotactic polypropylene and multiwalled carbon nanotubes

Nanocomposites based on low molar mass isotactic polypropylene (iPP) and a low concentrations (1–2 wt %) of multiwalled carbon nanotubes (MWCNTs) were studied using thermal analysis, optical and electronic microscopy, and X‐ray diffraction/scattering techniques. It was first determined that MWCNT decrease induction time and act as nucleating agents of the iPP crystals during nonisothermal crystallization. One of the consequences of the nucleation effect was that the original spherulitic morphology of iPP was transformed into a fibrillar‐like. The corresponding long period of the original well‐defined lamellar structure slightly increased suggesting the formation of thicker crystals in samples containing MWCNT. The nature of the α‐iPP crystalline structure was not affected by MWCNT. After nonisothermal crystallization, two melting endotherms were present during thermal scanning of the iPP/MWCNT nanocomposites their proportion changing with the heating rate. After resolving the total DSC signal in its components using MDSC, the overall evolution of such behavior could be explained in terms of the melting/recrystallization mechanism. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Origin of various lamellar orientations in high-density polyethylene/isotactic polypropylene blends achieved via dynamic packing injection molding: bulk crystallization vs. epitaxy

Epitaxial growth of high-density polyethylene (HDPE) onto lamellae of isotactic polypropylene (iPP), with HDPE chains inclined about 50° to that of iPP, has been achieved for the first time in their blends via dynamic packing injection molding. Even more, the epitaxial growth was found to be dependent on composition of the blends. The sequence of crystallization is not the dominant factor, but the fact that iPP crystallizes before HDPE is prerequisite for epitaxial growth of PE. Various lamellar orientations with composition can be explained by the competition between bulk crystallization and epitaxy at interfaces (i.e. iPP lamellae). In 20PP (20 wt% iPP by weight in blends), HDPE can readily crystallize in the bulk as a result of shear, and no epitaxial growth of PE is observed. For 80PP, however, bulk crystallization of HDPE can be depressed due to lack of nuclei in its bulk, resulting from a much finer droplets dispersed in the iPP matrix, and then epitaxial growth prevails.     

Effect of chain disentanglement on melt crystallization behavior of isotactic polypropylene

Isotactic polypropylene (iPP) with “disentangled” chains was generated through crystallization of iPP from its mineral oil solution. TGA test assured complete removal of mineral oil from iPP precipitates. Time sweep rheological measurements showed the modulus build-up with time indicating the formation of “disentangled” chains in iPP after the sample disentanglement treatment. The “disentangled” chains could preserve for a certain time before completely re-entangled during melting. Crystallization kinetics of iPP with “disentangled” chains was studied by using polarized optical microscope. The growth rate of spherulites in “disentangled” iPP was faster than that in the entangled one.     

Einfluß der Hydrierung auf Haltbarkeit und ernährungsphysiologische Eigenschaften von Qualitätsrapsölen

Effect of Hydrogenation on Stability and Nutritional Properties of Low-Erucic Rapeseed Oils Low-erucic rapeseed oils, Lesira and Erglu, were converted to more stable edible oils by selective hydrogenation of the linolenic acid moieties while retaining most of the linoleic acid groups. Feeding Lesira oil, hydrogenated Lesira oil, soybean oil and hydrogenated soybean oil to rats did not result in any appreciable differences in growth rates, whereas feeding conventional rapeseed oil caused extensive depression of growth. Among all the groups of animals the group fed conventional rapeseed oil showed the highest weights of heart and liver. The fatty acid patterns of depot and organ lipids did not show any major difference between the groups fed hydrogenated fats and those fed the corresponding unhydrogenated oils. The fatty acid composition of the organ lipids did not reveal deficiency in essential fatty acids. In the groups fed Lesira oil and hydrogenated Lesira oil half of the animals investigated exhibited myocardial lesions of light degree, probably due to the relatively high residual level of long-chain monoenoic fatty acids, whereas in the groups fed soybean oil and hydrogenated soybean oil only one-eighth of the rats examined exhibited such effects. The occurrence and severity of these myocardial lesions are known to be much higher in rats fed conventional rapeseed oils.     

Isothermal crystallization behavior of isotactic polypropylene blended with small loading of polyhedral oligomeric silsesquioxane

The isothermal crystallization kinetics and morphology development of isotactic polypropylene (iPP) blended with small loading of nanostructure of polyhedral oligomeric silsesquioxane (POSS) were studied with differential scanning calorimetry (DSC), polarized optical microscopy (POM), and wide-angle X-ray diffraction (WAXD). The crystallization behaviors of iPP/POSS composites presented an unusual crystallization behavior during isothermal and nonisothermal crystallization conditions. The exothermic morphologies of isothermal and nonisothermal crystallization of iPP/POSS composites changed remarkably with increasing POSS. Moreover, the developments of spherulitic morphology for iPP/POSS composites showed that the major dispersed POSS molecules became nanocrystals first and then aggregated together forming thread- or network-like morphologies, respectively, depending on POSS content, which was observed. It implies that these major POSS nanocrystals' morphologies appeared as an effective nucleating agent and promoted the nucleation rate of iPP, whereas the minor dispersed POSS molecules that had slight miscibility between iPP retarded the nucleation and growth rates of iPP in the remaining bulk region. Therefore, the isothermal crystallization showed a single exothermic peak at pure iPP and POSS-1.0, whereas at POSS-2.0 and POSS-3.0, displayed the multi-exothermic peaks during isothermal crystallization. These faces indicated that POSS molecules were both influence on the transport of iPP chain in the melted state and on the free-energy of formation the critical nuclei of iPP assisted by the POSS structures were observed. Therefore, we postulated that the crystallization mechanisms of multi-exothermic peaks in isothermal crystallization may proceed to combine the “nucleating agent inducing nucleation of iPP event assisted by the POSS domains” that the nucleation of iPP does occur preferentially on the surfaces of the POSS “threads” or “networks” structures, and “nucleation and growth of iPP in the remaining bulk melted iPP region retarded by dispersed POSS molecules”. Therefore, effects of POSS content on the isothermal and nonisothermal crystallization behaviors of iPP/POSS composites due to the POSS molecules partially miscible with iPP, at very small loading of POSS molecules, promoted or retarded the rates of nucleation and growth of iPP depending on the POSS content and crystallization temperature were discussed.     

Properties of thin films of isotactic polypropylene blended with polyisobutylene and ethylene-propylene-diene terpolymer rubbers

An experimental study was carried out to investigate the kinetic, morphological and thermodynamic properties of thin films of isotactic polypropylene (iPP) blended with several elastomers such as ethylene-propylene-diene terpolymer (EPDM) and three samples of polyisobutylene (PIB) with different molecular masses. The addition of the rubber to iPP causes drastic modifications in the morphology, nucleation density, spherulite growth rate and thermal behaviour of iPP. Such modifications depend strongly on the chemical and molecular mass of the added elastomer and on the composition of the blend. All the elastomers studied seem to act as nucleating agents for the iPP spherulites. The addition of PIB to iPP results in a reduction of the spherulite growth rate G, whereas the addition of EPDM does not seem to have a great influence. For the iPP/PIB_HM iPP/PIB_MM and iPP/EPDM blends a depression of the equilibrium melting temperature T_m, with respect to that of pure iPP, is observed. This depression is increased for the blend containing 20% rubber. This effect is probably related to phenomena of partial miscibility in the melt and to the coexistence of processes such as molecular fractionation and preferential dissolution of the more defective molecules.     

Influence of the amount of salts of rosin acid on the nonisothermal crystallization,morphology, and properties of isotactic polypropylene

The nonisothermal crystallization of Isotactic polypropylene (iPP) containing different concentration of nucleating agent potassium dehydroabietate (DHAA‐K) or sodium dehydroabietate (DHAA‐Na) at the cooling rate of 10°C/min was investigated using differential scanning calorimetry (DSC) together with Jeziorny's method. It was found that the temperature at which the maximum rate of crystallization occurred shifted to a higher region by about 13.7–16.9°C, and the rate of crystallization became faster for iPP with DHAA‐K (PPK) or DHAA‐Na (PPNa) in comparison to the virgin iPP. Avrami exponent for virgin PP, PPK, and PPNa was about 3.1, 2.2, and 2.2, respectively, suggesting the change of the crystal growth mechanism of iPP with the addition of the nucleating agents. The morphology of iPP with and without nucleating agent examined by a cross polarized light microscope indicated that the size of spherulites marginally decreased, which then remained stable with the increase of the concentration of DHAA‐K or DHAA‐Na. The measurements of the optical and mechanical properties of iPP showed that the transparency, gloss, and flexural modulus increased with increasing nucleating agent before its optimal concentration. POLYM. ENG. SCI., 47:889–897, 2007. © 2007 Society of Plastics Engineers     

Effect of the addition of EPM copolymers on the properties of high density polyethylene/isotactic polypropylene blends: II. Morphology and mechanical properties of extruded samples

The influence of the addition of two ethylene-propylene random copolymers (EPM) with different composition on the mechanical properties, thermal behavior and overall morphology of high density polyethylene (HDPE)/isotactic polypropylene (iPP) blends, was investigated on extruded samples. The experimental data showed that the morphology of binary HDPE/iPP blends is drastically modified by these additives and that the ultimate mechanical properties of these mixtures are greatly improved. A reasonable explanation of these results can be ascribed to the fact that these copolymers can act as “compatibilizing agents” in the amorphous regions of the two semicrystalline homopolymers. The extent of such effects is dependent on the chemical structure and/or on the molecular mass of the added copolymer as well as on the HDPE/iPP blend compositions.