超高速BOPP薄膜专用料的研制和开发

研究了超高速双向拉伸聚丙烯薄膜(BOPP)专用料的分子结构,即分子质量和分子质量分布、熔融与结晶行为,优化了生产工艺和添加剂体系。结果表明,所研制的专用料分子质量分布宽,达7.0,并增加了超高分子质量部分,熔点和结晶度略低,分别为163.37℃、40.33%,链段规整性稍差,具有良好的抗热、氧降解能力,在450 m/m in的超高速拉伸速度下能长期连续稳定生产。     

Surface structure and adhesive properties of biaxially oriented polypropylene film grafted with poly(acrylic amide) using corona discharge

Corona discharge was explored as a means of forming chemically active sites on the surface of biaxially oriented polypropylene (BOPP) film. The active species formed in air was used to induce graft copolymerization of acrylic amide (AAM) in aqueous solution. The surface structure, hydrophilicity and adhesion of the grafted BOPP film were characterized by the extent of grafting, electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), peel strength and contact angle measurements. Surface graft‐copolymerization of AAM onto BOPP film by corona discharge in air can be carried out with high efficiency. With increasing copolymerization time, the degree of grafting of AAM onto BOPP increases. The degree of grafting achieved a relatively high value of 2.13 wt% for the conditions of 1 min corona discharge and a copolymerization reaction time of 2.5 hr in 20% AAM aqueous solution at 70°C. After corona discharge grafting, the contact angle of water on the BOPP film decreased and the peel strength increased compared with those for ungrafted BOPP film. The hydrophilicity and adhesion of BOPP were improved by surface graft copolymerization with AAM induced by corona discharge.     

氟弹性体类加工助剂改性双向拉伸薄膜用PP

采用氟弹性体加工助剂母粒(简称母粒)对聚丙烯(PP)进行改性,考察了双向拉伸薄膜用PP(BOPP)的光学性能、力学性能和加工性能。结果表明:母粒对PP结晶度有一定影响,可提高结晶速率,且助剂质量分数为0.06%时对PP结晶度的影响最大;母粒会降低BOPP薄膜雾度,与只在BOPP薄膜的芯层加入母粒相比,在芯层和表层同时加入母粒,更易降低BOPP薄膜雾度;仅在BOPP薄膜芯层加入母粒,薄膜的光泽度更好;薄膜纵向的力学性能有所下降,但都能满足标准要求,母粒还能降低PP熔体表观黏度及剪切应力,改善加工性能。     

Effect of low-pressure O2 and Ar plasma treatments on the wettability and morphology of biaxial-oriented polypropylene (BOPP) film

Low-pressure plasma treatments in an rf discharge of O₂ and Ar were employed to introduce polar functional groups onto the biaxial-oriented polypropylene (BOPP) surfaces to enhance the wettability and activation. The effects of plasma treatment on the morphology and wettability of the BOPP films were characterized using static contact angle measurements, attenuated total reflection (ATR)–FTIR spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM).     

Effect of copolymerized ethylene unit on the crystallization behavior of poly(propylene-co-ethylene)s

The crystallization behavior of two kinds of commercial poly(propylene-co-ethylene)s (PPE1, PPE2) with similar average molecular weight and molecular weight distribution, isotacticity and copolymerized ethylene unit content and their fractions was investigated by differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and polarized optical microscopy (POM) techniques. The results indicate that the PPE1 isothermally crystallized films possess thicker and less cross-hatched lamellar structure than those of the PPE2. As for the fractionated samples, the thin films of low temperature (≤90 °C) fractions (PPE1-80, PPE2-80) of both PPE1 and PPE2 exhibit similar crystallization behavior, while for the high temperature (≥95 °C) fractions (PPE1-108, PPE2-108), the crystalline morphology has marked differences. Compared with PPE2-108, the PPE1-108 isothermally crystallized thin films possess thicker lamellae and less cross-hatched lamellar structure, while for the fibrous crystal number, the former is less than that of the latter. The main reason to create the crystallization behavior differences between the two PPEs and their fractions is due to the effect of molecular chain structure, i.e. the different distribution of copolymerized ethylene unit in polypropylene chains.     

Interactions in the system isotactic polypropylene–calcite

Interaction in the system isotactic polypropylene–calcite was investigated using X-ray diffraction and transmission electron microscopy. Calcite acts as a weak nucleation agent for polypropylene crystallization and its activity could be increased or decreased by a suitable surface treatment. Investigation of the morphology on the polypropylene–calcite interface using calcite single crystals disclosed the tendency of polypropylene for epitaxial crystallization along preferred substrate crystallographic directions. This tendency was analogous to polymer crystallization on other ionic crystals.     

Exfoliation and dispersion enhancement in polypropylene nanocomposites by in‐situ melt phase ultrasonication

A novel process using ultrasonics to enhance the exfoliation and dispersion of clay platelets in polypropylene‐based nanocomposites has been proposed and investigated. The materials studied were isotactic polypropylene of various molecular weights reinforced with organophilic montmorillonite clay (nanoclay) at 4–6 wt% loadings. X‐ray diffraction (XRD) and rheological measurements, on a model system of nanoclay in mineral oil, were first used to determine ultrasonic energy requirements. The effectiveness of the proposed ultrasonic processing technique on polypropylene nanocomposites was evaluated by XRD and transmission electron microscopy (TEM). The effects of added maleic anhydride–grafted polypropylene compatibilizer, polypropylene molecular weight, and pretreatment of the nanoclays on the nanocomposite exfoliation were also investigated. Results indicate that ultrasonic processing of polymer nanocomposites in the melt state is an effective method for improving exfoliation and dispersion of nanoclays. Issues regarding molecular weight degradation, optimization, mechanical properties, and continuous processing are beyond the scope of the present study and are currently being investigated in our laboratory. Polym. Eng. Sci. 44:1773–1782, 2004. © 2004 Society of Plastics Engineers.     

A new kinetic model for interdiffusion at semicrystalline polymer interfaces

A kinetic model has been developed to describe the behavior of semicrystalline polymer interfaces. In these systems, the competition between interdiffusion and crystallization drives the overall transport. The crystallization rate is based on the Avrami equation, in which the Avrami exponent and the crystallization rate constant as a function of temperature and blend composition are determined by in situ optical microscopy and differential scanning calorimetry. The mutual diffusion coefficient is obtained by using the fast mode theory. The predicted density profiles as a function of position are used to extract the interfacial widths, which are affected by molecular weight, equilibrium degree of crystallinity, and temperature. At low temperatures, the crystallization rate is fast, and the crystals present near the interface hinder the interdiffusion, causing the interfacial width to be small. At high temperatures, the crystallization is much slower, and interdiffusion dominates crystallization. The model predictions are compared with interfacial behavior observed by transmission electron microscopy and small angle X-ray scattering in a system composed of polyethylene and isotactic polypropylene and the agreement with the experiments is satisfactory.     

Influence of incorporation of ZnO nanoparticles and biaxial orientation on mechanical and oxygen barrier properties of polypropylene films for food packaging applications

In this work, the effect of zinc oxide (ZnO) concentration and shape on processing and properties of new biaxially oriented polypropylene (BOPP)‐ZnO nanocomposites was studied. The use of spherical nanoparticles and nanorods was expected to differently influence the properties of the final material. Films of isotactic polypropylene prepared with different ZnO incorporation were biaxially oriented under conditions of temperature and strain rate that were similar to those encountered in a commercial film process. Scanning electron microscopy analysis was performed to visualize the dispersion degree of the ZnO nanoparticles in the polymer matrix and to observe the surface and the orientation of the elongated nanoparticles. Furthermore, the prepared ZnO‐BOPP nanocomposites were evaluated for both mechanical and oxygen barrier property enhancement. A good combination of mechanical and oxygen barrier properties was obtained for the ZnO‐BOPP films. This result makes the ZnO‐BOPP nanocomposite a proper material for applications such as food packaging. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

BOPP烟用包装膜专用树脂结构性能研究

对气相法聚丙烯生产的双向拉伸聚丙烯(BOPP)烟用包装膜专用树脂F 1002进行了结构性能研究。研究结果表明，烟用包装膜专用树脂具有特征性分子量及其分布，即既含有较高的分子量组分，又含有适量低分子量组分，从而保证其在双向拉伸成型工艺中具有较高的熔体强度及熔体流动稳定性，使得制品厚度均匀性优异。同时，适宜的等规指数(96．5％～97．5％)及其等规序列分布特性，使采用均聚型烟用包装膜专用树脂加工成型的BOPP薄膜具有挺度高，满足烟用包装膜的特性要求。     

Morphology and crystallization behavior of the PP/PET nanocomposites

Nanocomposites containing polypropylene (PP), PET, and montmorillonite were prepared in a twin‐screw extruder. X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, polarized optical microscopy, and differential scanning calorimetry were used to characterize the samples. Intercalated and exfoliated morphology were observed in the nanocomposites. The PET domains usually presented spherical shapes and they were the start point to PP crystallization. The average diameter and number of PET domains was evaluated. The influence of addition of PP‐MA as compatibilizer on PP/PET was investigated. The interconnected morphology was observed in the nanocomposite containing PP‐MA. The clay located predominantly in the interphase and in the PET phase. The crystallization process was monitored and the PET crystallization rate was slower in the nanocomposites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of biaxially oriented polypropylene film with high molecular orientation in the machine direction by sequential biaxial stretching

Novel approach of applying the ternary polymer blend of long‐chain branched polypropylene (LCB‐PP), conventional polypropylene (PP), and hydrogenated polydicyclopentadiene (hDCPD) has been employed to tensilize biaxially oriented polypropylene (BOPP) film in the machine direction (MD) by successive sequential biaxial stretching method. It is found that the addition of LCB‐PP improves the MD stretchability of the BOPP film of PP/hDCPD blend. Depending on the content of LCB‐PP, LCB‐PP/PP/hDCPD ternary blend could be biaxially stretched up to the MD stretching ratio (MDX) of 12 without film breakage whereas that of PP (conventional BOPP film) resulted in the MDX up to 6. This excellent MD stretchability enabled to tensilize the BOPP film in the MD, where Young's modulus in the MD could be increased up to 4.9 GPa, twice higher than that of conventional BOPP film. The orientation of total molecular chains and that of crystalline molecular chains were evaluated by in‐plane distribution of refractive indices and wide‐angle X‐ray diffraction, respectively. The results are discussed from the viewpoint of deformation behavior during stretching process. Moreover, the resultant film had a dimensional stability substantially equivalent to that of conventional one, in spite of the higher stretching ratio, and an improved moisture barrier property. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Study of polypropylene/montmorillonite nanocomposites prepared by solid‐state shear compounding (S3C) using pan‐mill equipment: the morphology of montmorillonite and thermal properties of the nanocomposites

In this paper, polypropylene (PP)/organophilic montmorillonite (OMMT) nanocomposites were successfully prepared without any compatibilizers by solid‐state shear compounding (S³C) using pan‐mill equipment. X‐ray diffraction (XRD) patterns show that the OMMT characteristic (001) peak at 2θ equal to 4.59 degrees disappeared for the milled OMMT and corresponding composites. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) photographs show that the thickness of pan‐milled OMMT decreased from ca 100–200 nm to ca 30–50 nm, and OMMT was partly exfoliated in the PP matrix because the pan‐type mill can exert fairly strong squeezing force in the normal direction and shearing force in both radial and tangential directions on milled materials. PP/OMMT nanocomposites at low OMMT loading have higher melting point, crystallization temperature, thermal degradation temperature and heat distortion temperature than those of neat PP. Moreover, addition of OMMT accelerates crystallization of PP significantly. S³C is a novel approach to prepare polymer/layered silicate nanocomposites with high performances at low filler loading. Copyright © 2004 Society of Chemical Industry     

洗衣机用抗冲聚丙烯的结构与性能研究

使用核磁共振(13C NMR)、凝胶渗透色谱(GPC)、偏光显微镜、扫描电镜等手段表征了两种聚丙烯洗衣机专用料的结构与组成,并与产品性能进行关联,以研究影响抗冲聚丙烯性能的因素。结果表明,抗冲聚丙烯中橡胶相的含量、组成、相态结构、分子量及分子量分布,抗冲聚丙烯的结晶度和结晶温度等都对其性能有重要影响。     

A new method for achieving nanoscale reinforcement of biaxially oriented polypropylene film

Nanolayers of poly(ethylene oxide) (PEO) produced by layer-multiplying coextrusion crystallize as single, high aspect ratio lamellae that resemble large single crystals. The confined crystallization habit imparts two orders of magnitude reduction in the gas permeability. We now demonstrate how the highly oriented lamellar nanolayers can be obtained with biaxial stretching. For this purpose, we chose biaxially oriented polypropylene (BOPP) film for modification and incorporated PEO nanolayers under conditions that mimicked the typical fabrication process. Sheet that contained a center core with 33 alternating layers of polypropylene (PP) and PEO was coextruded and subsequently biaxially oriented at 145 °C. Biaxial stretching reduced the PEO layer thickness from the spherulitic microscale to nanolayers of highly oriented PEO single lamellae. The nanolayers improved the oxygen barrier by an order of magnitude without sacrificing the high clarity and good tear resistance of BOPP film.     

Ce-MCM-22分子筛的合成与吸附性能

采用静态水热晶化法,以硅溶胶为硅源、六亚甲基亚胺(HMI)为模板剂,通过掺杂Ce合成了具有MWW层状结构的Ce-MCM-22分子筛.利用粉末X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等方法对其进行了表征,考察了各种因素对Ce-MCM-22分子筛吸附亚甲基蓝溶液的影响,结果表明当Ce-MCM-22分子筛的投加量为0.6 g/L,亚甲基蓝浓度为2.0 mg/L,pH值为7,震荡60 min时,吸附脱色效果较好.     

A cross-sectional preparation method for TEM and AFM investigations on layered poylmer interfaces

Summary The epitaxial crystallization of polyethylene (PE) on uniaxially oriented isotactic polypropylene (iPP) has been investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The cross-sectional morphology of the epitaxial interfaces of multi-layered samples prepared by a new preparation method has been observed with view direction parallel to the epitaxial interfaces. It is found that fairly oriented PE lamellae grow perpendicular to the iPP layers with nucleation initiation on the iPP surfaces.     

聚丙烯/改性膨润土复合材料的制备结构与性能

用十六烷基三甲基溴化铵嵌入到具有层状结构的膨润土片层中,经与聚丙烯熔共混制得ＰＰ／改性膨润土插层复合材料。通过透射电子显微镜,Ｘ射线衍射谱图和动态力学分析等手段,研究了复合材料的结构特征和结晶行为。结果表明,复合材料的缺口冲击强度得到大幅度的提高,而拉伸强度则基本保持不变。     

Through-thickness analysis of the skin layer thickness of multi-layered biaxially-oriented polypropylene films by micro-thermal analysis

A novel method is presented for the determination of the thickness of a polymer layer on a solid substrate by through-thickness local thermal analysis (LTA) measurements using a micro-thermal analyser (μTA). The feasibility of the method is illustrated for a poly(methyl methacrylate) film spin-cast on a silicon wafer. Subsequently the method is applied to determine the skin layer thickness of multi-layered biaxially-oriented polypropylene (BOPP) films. Although the melting temperatures of skin and core layer are only 15 °C different, it proved to be possible to determine the skin layer thickness. The film thickness obtained by μTA correlates well with the thickness observed by transmission electron microscopy (TEM) in a 0.1-1.6 μm range. The method is shown to be accurate, robust, and fast.     

Influence of high power ultrasound on physical–chemical properties of polypropylene films aimed for food packaging: barrier and contact angle features

Investigation was focused on the impact of high power ultrasound (HPUS), also called thermosonication, on the oxygen permeation properties (permeability, solubility and diffusion coefficients) of barrier films aimed for food packaging. For this purpose, biaxially oriented polypropylene (BOPP) coated with acrylic/polyvinylidene chloride (BOPPAcPVDC) and biaxially oriented coextruded polypropylene (BOPPcoex) were used. The physical–chemical profile of the samples was determined using goniometry. There is a significant impact only of extreme HPUS conditions (the longest time and the highest amplitude) on the permeability, solubility and diffusion coefficients of oxygen through the BOPP films. The highest influence on the oxygen permeability in both investigated BOPP samples involved an HPUS with an amplitude of 100% during a 6 min treatment. However, BOPP samples showed different sensitivities at lower HPUS treatments. © 2017 Society of Chemical Industry