Some Effects of Corona Discharge Treatment of Biaxially-Oriented Polypropylene Film

The effects of the unit corona-treatment energy on the contact angle of various liquids, on the surface free energy, on the extent of oxidation of a surface layer, and on the adhesion of acrylic adhesive were studied using a biaxially-oriented polypropylene (BOPP) film. The surface free energy was determined with the van Oss-Chaudhury-Good (VCG) approach as well as with the wettability method. The extent of oxidation of the surface layer of the corona-treated BOPP film was evaluated with X-ray photoelectron spectroscopy. The adhesion strength of joints between the BOPP film and the acrylic adhesive was measured using the 180°-peel test.

In the range of the unit corona-treatment energy up to 1.2 kJ/m², a rapid increase in the surface free energy with the treatment energy is observed. In the range above that value, the surface free energy rises relatively slowly. The extent of oxidation of the surface layer and the adhesion strength of joints between the BOPP film and the acrylic adhesive are approximately in direct proportion to the unit energy of the corona treatment. A five-fold growth of the adhesion strength of the studied joints within the examined range of the treatment energy was found.     

电晕处理对聚丙烯薄膜表面特征的影响研究

分析了电晕表面处理技术对聚丙烯(PP)薄膜表面特征及印刷适应性的影响。借助SEM、AFM和FT-IR等方法分析了电晕处理对聚丙烯薄膜表面化学分子结构及物理特征的影响。在综合分析实验结果的基础上,找出了提高聚丙烯薄膜印刷适应性能的方法。     

Corona Discharge Treatment of Polyolefins

The effects of corona discharge treatment on polyethylene and polypropylene homopolymers have been studied. X-ray photoelectron spectroscopy was used to determine surface compositions which were related to surface free energy estimates from contact angle measurements. Changes in composition and surface free energy were measured as a function of treatment level. The work of adhesion was seen to increase with oxygen incorporation. The increase was not linear and this is attributed to an increase in the degree of sub-surface to near-surface oxidation at intense treatment levels. Aging of samples followed by XPS and contact angle measurement showed that surface wettability is reduced whereas a slight increase in surface oxygen was found. This phenomenon was attributed to the reorientation/migration of functional groups. Morphological examination by scanning electron microscopy indicated no surface roughening at any power level.     

非离子型复合抗静电剂在聚丙烯薄膜中的应用

采用非离子型抗复合抗静电剂通过共混复合的方法制备出具有抗静电性能的聚丙烯,考察了抗静电剂的添加量、放置时间、环境湿度对抗静电聚丙烯的表面电阻率的影响。     

用接触角法测量聚合物共混体系的表面性能

利用接触角的方法研究了聚合物HDPF、PET及其共混物HDPE／PET的表面自由能、极化度以及与不同液体一水和甘油间界面张力的大小。     

Characteristics of pigment-filled polymer coatings on paperboard

Adding plate-like pigments such as talc or kaolin clay to a styrene-butadiene (SB) dispersion before coating paperboard on a pilot scale resulted in a coated material with improved water vapour barrier properties. Addition of paraffin wax further significantly reduced the water vapour permeability. A limited study was also performed using poly(vinyl alcohol) (PVA) as the matrix material and a similar result was obtained. In addition to the barrier properties, the surface characteristics (gloss, roughness, surface energy and chemical composition) and the printability of the coated substrate were evaluated. In general, it was found that the properties of the coated material were improved if the surface of the base substrate was smoothened prior to coating by a suitable surface treatment such as hot calendering or precoating. Such a treatment gave a more homogeneous coating film on the substrate. A comparison of the experimental results with the prediction of models for the effect of impermeable particles on the vapour permeability indicated that the pigments were not optimally dispersed (or oriented) in the coating layer. There is thus room for improvement. In a further series of experiments, nanoclays were incorporated into the coating layers. Exfoliation of the silicate layers was indicated in laboratory coating experiments using SB, but not on the pilot-scale coated materials. Thus no significant effects on the barrier properties were observed for such coated specimens. With PVA as the matrix polymer and low contents of the nanoclay, a marked decrease in the water vapour permeability took place, indicating a more pronounced exfoliation.     

双向拉伸聚丙烯烟膜热封性能的研究

研究了不同的聚丙烯共聚物、热封层厚度、薄膜总厚度、添加剂以及电晕处理工艺对双向拉伸聚丙烯薄膜（BOPP）烟膜热性能的影响，根据讨论结果，了BOPP烟膜热封性能的控制方法以及相关的注意事项。     

常压等离子体表面亲水化改性聚丙烯薄膜

采用常压等离子体表面处理聚丙烯薄膜,通过接触角考察氩气、氧气及处理时间、放电电压对聚丙烯表面亲水性的影响.同时比较不同条件下处理的聚丙烯薄膜接触角憎水性恢复现象.研究发现:聚丙烯薄膜表面经常压等离子体处理后,接触角显著下降,氧气较氩气条件下更低;随放电电压增高,处理时间延长,接触角呈下降趋势,最终稳定于一极小值;在氧气氛围中处理时间的延长有利于减轻接触角恢复程度,从而可获得较高的、稳定的亲水性聚丙烯薄膜.结果表明:常压等离子体是聚合物表面亲水化改性的简单有效的处理技术.     

花生壳粉表面性能及木塑复合材料界面性能的研究

通过动态法研究了浸润粉层的液体质量的平方随时间的变化规律,测定了不同探测液对花生壳的接触角。采用平衡接触角仪测定了探测液对改性聚乙烯的接触角,进而根据Focks理论推导出花生壳和改性聚乙烯的表面自由能及其极性分量和非极性分量,并计算出花生壳粉/聚乙烯复合材料的界面张力和黏附功。结果表明:相容剂Bondyram 5108的加入,使聚乙烯的极性分量和非极性分量都不同程度地增加,改善了花生壳粉在聚乙烯基体中的分散性,降低了复合材料的界面张力,增大了黏附功。     

Physico-Chemical Criteria for Maximum Adhesion. Part II: A New Comprehensive Thermodynamic Analysis

In this paper, two parameters defined as the relative work of adhesion [W_A/γ_L] and the relative interfacial energy [γ_SL/γ_L] have been examined for their assumed usefulness in correlating the thermodynamic properties of the components of the system substrate/ adhesive with its practical performance (strength). It is shown that the minimum value of [γ_SL/γ_L] relevant to conditions for the maximum adhesion becomes zero only for those systems (relatively rare) for which interaction factor Φ₀ is equal to 1.0.

Several transition points were identified for boundary conditions acquired at θ = 0° and θ = 90° which can be used to predict the properties and performance of an adhesive joint. These transition points are: a_MIN—energy modulus of the system (E. M. S.), relevant to the minimum interfacial energy; a_S—E. M. S. where self-spreading of adhesive occurs; a_CRIT—E. M. S. relevant to conditions under which the thermodynamic work of adhesion becomes negative and the system exhibits a tendency for self-delaminating or has “zero-strength”; a_CF—E. M. S. beyond which the geometry of the interface at any interfacial void or boundary of the joint may be regarded as a crack tip.

It is shown that only in those systems for which Φ₀ = 1.0 can a minimum contact angle of 0° indicate a condition for the maximum strength. If Φ₀ is known, the optimum contact angle can be estimated and hence the optimum surface energy of the substrate (adjusted by surface treatment, etc.) for the maximum adhesion.     

氧等离子体对聚丙烯粉体的表面处理研究

用氧等离子体对聚丙烯（PP）粉体进行表面处理,采用水接触角（WCA）、红外光谱（IR）对处理前后PP粉体的水接触角、表面组分的变化进行了分析。实验结果表明,随着等离子体处理时间延长,水接触角减小。IR分析表明,在氧等离子体处理中,PP粉体表面有含氧极性官能团生成,导致粉体表面水接触角减小。     

Morphology and Properties of Modified Polypropylene for Extruded Film Applications

Abstract

Change in crystallization morphology of polypropylene (PP) on blending with high density polyethylene (HDPE), and on incorporation of cross-linking agent, trimethyl propane triacrylate (TMPTA), and nucleating agent, aluminium dibenzoate (DBS), was studied using differential scanning calorimetry (DSC), polarizing light microscopy (PLM), and small angle light scattering (SALS). In all, three blend systems: PP-HDPE, PP-HDPE-TMPTA, and PP-HDPE-DBS were developed. Analysis of crystallization exotherm, PLM, and SALS studies indicate that DBS is an effective nucleating agent for PPHDPE system and results in appreciable reduction in spherulite size and increase in percent crystallinity, while on cross-linking there is reduction in both percentage crystallinity and spherulite size. Improvement in overall mechanical properties is observed in all the systems studied. As it is desirable to work with PP having a high degree of crystallinity, low spherulite size and low melt flow index (MFI) for oriented film applications, PP-HDPE-DBS system with a low MFI grade HDPE is found to be most suitable.     

The role of the surface free energy in the selection of a suitable excipient in the course of a wet-granulation method

Pellets containing metronidazole were produced in a centrifugal granulator, with hydroxypropylcellulose (Klucel LF®) as binding agent, and corn starch, microcrystalline cellulose (Vivapur 101®) and lactose as excipients. The wettability of the pharmaceutical powders was assessed by means of contact angle measurements, and the dispersive and polar surface energies were determined. The spreading coefficients, the work of adhesion and the work of cohesion were calculated and correlated with the pellet properties (friability, bulk and tapped density, and porosity). The aim was to investigate the role of the surface free energy of one- and two-component powder compositions in pellet production. The interactions between the particles were found to be connected with the measured pellet parameters. It was concluded that, in the course of the growth of the pellets, the particle sizes of the pharmaceutical powders and the interactions between them are important. If the work of cohesion of the binder is lower than the work of cohesion of the substrate and the work of adhesion, then the optimal amount of the binding agent is that which coats the particles uniformly in minimal quantity and in continuous layer.     

功能表面材料与流体界面相互作用对垂直降液膜流动特性的影响

通过调节水温度、添加表面活性剂以及铝合金壁面表面改性处理来改变降膜流体与固体表面之间的表面自由能差值,运用JDC-2000型精密测微仪测定垂直降液膜的厚度,研究固体表面和液体间相互作用对流体垂直降膜流动特性的影响;考察了液膜雷诺数、流体温度、添加表面活性剂、固体表面材料物理化学性质等因素对垂直壁面降液膜流动特性的影响规律。实验结果表明:改变固体表面与降液膜流体的物理化学特性,即改变固液界面的相互作用能够改变流体的降膜流动特性。降液膜平均厚度随液固表面自由能差的增大而减小。     

Some curious observations of soap film contact lines

Contact lines between soap films and solid surfaces have been studied comparatively little. This is surprising, as a network of these contact lines constitutes the contact between an aqueous foam and an imperfectly wetted surface, and is critical for understanding foam slip on this type of surface. Data on the tension at a ‘creeping’ soap film contact line are presented. Surprisingly, given that viscous interactions were shown to be unimportant at these low velocities, this was substantially less than the sum of the ‘creeping’ tension for one wetting and one de-wetting contact line on the same surfaces. A possible explanation for this observation is presented, involving a free energy analysis of the deformed lamellae.     

热处理对BOPP薄膜性能的影响研究

介绍了热处理在BOPP薄膜生产中的作用,讨论了纵横向热处理对薄膜性能的影响。研究表明:纵向热处理对BOPP薄膜的结构和性能影响甚小;而横向热处理则影响很大;随着横向热处理温度的变化,BOPP薄膜的结构和性能将产生较大差异,其间存在一个最佳的温度值,需要根据工艺和设备进行优选。此外,热处理对BOPP薄膜的光学性能和收缩率产生显著影响,其中薄膜的雾度随热处理温度的上升而上升,光泽度随热处理温度的上升而下降; 收缩率随处理温度的上升而下降,尤其是横向收缩率的下降幅度最大。     

Physico-Chemical Criteria for Maximum Adhesion. Part I: Theoretical Concepts and Experimental Evidence

This paper presents an analysis of the literature with the aim of defining basic criteria and developing a general model to describe joint strength. Two particular cases of the relationship: cosθ = f(γ_L) have been identified as prerequisites for further analysis of interfacial phenomena and conditions governing their existence were discussed.

The fact has been pointed out, based on available experimental results, that for the most important case in practice where 0.6 ≤ cosθ ≤ 1.0, the relation cos θ = f(γ_L) can be treated as rectilinear. This finding will be utilized in the comprehensive development of criteria defining joint performance in Part II.

Variability of the interaction factor Φ for various systems has been investigated in relation to cos θ, for the identified particular cases of the relationship cos θ = f(γ_L) A special value of the interaction factor, ₀, was found. The importance of the rectilinear particular case of cos θ = f(γ_L) was shown, which involves constant factor Φ₀ instead of variable Φ.     

聚丙烯塑料（PP）涂装前的表面处理方法

介绍了PP的表面处理方法,着重对常用的有机溶剂法、氧化液法、火焰处理法、紫外线照射法等进行综述。     

电晕处理对聚乙烯薄膜热封性能的影响

聚乙烯薄膜经过电晕处理后,热封温度提高,热封强度降低。这可通过降低电晕处理强度,适当延长热封时间和添加一定比例的mLLDPE树脂,以减小电晕处理对聚乙烯薄膜热封性能的影响。     

Flame Treatment and Surface Characterisation of Rubber-Modified Polypropylene

The flame treatment of a rubber-modified polypropylene has been studied using XPS, contact angle measurement, SEM, vapour-phase derivatisation, and a composite butt adhesion test. Optimum air-to-gas ratio and the distance from the inner cone tip to the polymer surface were found to be ∼ 11:1 and ∼ 0.5 cm, respectively. The lack of correspondence between contact angle and surface oxygen concentration was proposed to be due to the reorientation/migration of surface functional groups that had been incorporated during flame treatment. SEM shows changes in surface topography induced by intense flame treatment. Trifluoroacetic anhydride (TFAA) was found to derivatise-OH groups selectively by using model polymers. About 30% of the incorporated oxygen on flame-treated polypropylene surfaces was found to be present as-OH. Under most flame conditions studied, the interfacial adhesion with an epoxy adhesive or a polyurethane paint was found in excess of the polymer's cohesive strength. The results obtained are compared with those from a propylene homopolymer and an ethylene/propylene copolymer.