Relationship between Viscoelastic and Peeling Properties of Model Adhesives. Part 1. Cohesive Fracture

The viscoelastic and peeling properties of polybutadiene/tackifying resin compatible blends have been studied in detail. Viscoelastic properties have been described through the variations of the complex shear modulus, G*(ω), as a function of frequency, ω and peeling properties through the variations of peeling force (F) as a function of peeling rate (V).

After showing the objective character of the peeling curves obtained, the variations of the peeling force and peeling geometry have been studied as a function of volume fraction of the tackifying resin.

In this first paper, the analysis is focused on the first domain of the peeling curves, i.e. the cohesive fracture region. In this region, the peeling properties have been related to the viscoelastic properties in the terminal region of relaxation. It is shown that the longest relaxation time, τ_o, is a reducing parameter of the peeling curves, so a peeling master curve-which is independent of temperature, resin volume fraction and polymer molecular weight-may be defined. Furthermore, the variations of the test geometry as a function of peeling rate have been investigated: the variations of the radius of curvature of the aluminium foil have been analyzed with respect to the viscoelastic behavior of the adhesive, which in fact governs the test geometry.

A detailed analysis of all these features leads to a model which allows one to calculate the peeling curves in the cohesive domain from the adhesive formulation.     

Relationship between Viscoelastic and Peeling Properties of Model Adhesives. Part 1. Cohesive Fracture

The viscoelastic and peeling properties of polybutadiene/tackifying resin compatible blends have been studied in detail. Viscoelastic properties have been described through the variations of the complex shear modulus, G*(ω), as a function of frequency, ω and peeling properties through the variations of peeling force (F) as a function of peeling rate (V).

After showing the objective character of the peeling curves obtained, the variations of the peeling force and peeling geometry have been studied as a function of volume fraction of the tackifying resin.

In this first paper, the analysis is focused on the first domain of the peeling curves, i.e. the cohesive fracture region. In this region, the peeling properties have been related to the viscoelastic properties in the terminal region of relaxation. It is shown that the longest relaxation time, τ_o, is a reducing parameter of the peeling curves, so a peeling master curve-which is independent of temperature, resin volume fraction and polymer molecular weight-may be defined. Furthermore, the variations of the test geometry as a function of peeling rate have been investigated: the variations of the radius of curvature of the aluminium foil have been analyzed with respect to the viscoelastic behavior of the adhesive, which in fact governs the test geometry.

A detailed analysis of all these features leads to a model which allows one to calculate the peeling curves in the cohesive domain from the adhesive formulation.     

Peeling of Acrylic Pressure Sensitive Adhesives: Cross-Linked versus Uncross-Linked Adhesives

In this paper we analyze the adhesive properties of two kinds of adhesives, determined by a 90[ddot] peeling test on a Pyrex^TM substrate. Simultaneously, we observe the mechanisms of flow at the peeling front. An uncross-linked acrylic pressure-sensitive adhesive is used, whereas the second one, of the same class, is slightly cross-linked. The mechanisms of peeling are compared with the ones of our previous study (Benyahia et al [8]) and are found to be identical in the case of uncross-linked adhesives. On the other hand, we find new regimes of flow when the adhesive is cross-linked.

To investigate these differences further, we determine the rheometrical properties of the adhesives in dynamic shear tests and in uniaxial elongational experiments. Furthermore, surfaces are characterized.

A discussion of the peeling curves is finally presented, showing the combined effects of the rheological properties and the surface ones. Conditions for predicting the type of regimes and transitions are also investigated.     

超快固化高性能太阳能电池用EVA封装膜的研制

以33%VA(醋酸乙烯)含量的EVA(乙烯-醋酸乙烯共聚物)为聚合物基体,采用熔融共混法制成改性EVA母粒;然后采用流延成膜法制得C1(不含改性EVA胶粒的胶膜)和C2(含改性EVA胶粒的胶膜)。通过对比试验法探讨了不同EVA胶膜的交联度、剥离强度和耐老化性能。结果表明:C2的层压时间短、剥离强度高、耐老化性能较好,其各项性能与美国EVA胶膜接近,达到超快固化高性能EVA胶膜的使用要求,完全符合太阳能电池的封装条件。     

Relationship Between Viscoelastic and Peeling Properties of Model Adhesives. Part 2. The Interfacial Fracture Domains

The viscoelastic and peeling properties of polybutadiene/tackifying resin compatible blends have been studied in detail. Viscoelastic properties have been described through the variations of the complex shear modulus, G*(w), as a function of frequency, W, and peeling properties through the variations of peeling force (F) as a function of peeling rate (V).

The first paper of this series presented the cohesive fracture domain and the present paper explores the interfacial fracture domain: (i) rubbery interfacial (interfacial 1); (ii) stick-slip; (iii) glassy interfacial (interfacial 2). After a general survey of the properties in the three domains we present a quantitative relationship between the peeling and linear viscoelastic properties as a function of the adhesive formulation, discussing the use of time-temperature equivalence for adhesive properties. The third part of the paper presents the trumpet model of de Gennes describing the crack shape and propagation: starting from a mechanical analysis of the peeling test, it is shown how one may calculate the variations of the peeling force as a function of peeling rate in the various interfacial fracture domains: this model defines a single interfacial fracture criterion which coexists with the cohesive fracture criterion defined earlier, whatever the fracture location.

We present as a conclusion a critical discussion of the relevance and physical meaning of such a criterion and present a new outlook for the modeling and improvement of adhesive formulations.     

Relationship Between Viscoelastic and Peeling Properties of Model Adhesives. Part 2. The Interfacial Fracture Domains

The viscoelastic and peeling properties of polybutadiene/tackifying resin compatible blends have been studied in detail. Viscoelastic properties have been described through the variations of the complex shear modulus, G*(w), as a function of frequency, W, and peeling properties through the variations of peeling force (F) as a function of peeling rate (V).

The first paper of this series presented the cohesive fracture domain and the present paper explores the interfacial fracture domain: (i) rubbery interfacial (interfacial 1); (ii) stick-slip; (iii) glassy interfacial (interfacial 2). After a general survey of the properties in the three domains we present a quantitative relationship between the peeling and linear viscoelastic properties as a function of the adhesive formulation, discussing the use of time-temperature equivalence for adhesive properties. The third part of the paper presents the trumpet model of de Gennes describing the crack shape and propagation: starting from a mechanical analysis of the peeling test, it is shown how one may calculate the variations of the peeling force as a function of peeling rate in the various interfacial fracture domains: this model defines a single interfacial fracture criterion which coexists with the cohesive fracture criterion defined earlier, whatever the fracture location.

We present as a conclusion a critical discussion of the relevance and physical meaning of such a criterion and present a new outlook for the modeling and improvement of adhesive formulations.     

Rheological study on the adhesion properties of the blends of ethylene vinyl acetate/terpene phenol adhesives

Measurements of the shear, tensile, peel, and creep strength of ethylene vinyl acetate (EVA)/CaCO₃/terpene phenol adhesive system at three different ratios [100/60/0 (EVA-O), 80/48/20 (EVA-20), and 60/36/40 (EVA-40) by weight, using wood and aluminum as adherends] were conducted. Over a wide range of temperatures and rates of deformation, adhesion shear, tensile, and peel strength results, as well as the creep response over a broad range of temperature and stresses, were found to yield a single master curve by means of the reduced-variable technique. It was observed that the peak of E′ representing Tg, shifted toward higher temperatures as the amount of terpene phenol in the blend was increased. The most obvious effect of increasing the tackifier resin was the shifting of the adhesion strength master curves to the direction of lower rates. The shift was associated with the rise in Tg as the blend ratio was increased. The influence of the tackifier resin in modifying the viscoelastic properties of the adhesive was further described in a comparison of the adhesion strength master curves with corresponding dynamic viscoelastic curves of the adhesive films. The master curves for the creep response of the adhesives showed that the stress-breaking time relationship shifts toward longer time for EVA-40 with high Tg. Thus, it was found that the strength of adhesion is due mainly to dynamic effects in the adhesive of a viscous nature in the same way to the cohesive strength of the viscoelastic materials. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 409–418, 1998     

Effect of Peel Load on Stringiness Phenomena and Peel Speed of Pressure-Sensitive Adhesive Tape

The factors governing interfacial separation in lightly cross-linked polymer adhesives at low pulling rates as demonstrated by their stringiness phenomenon are investigated.

Cohesive failure and adhesive/substrate interfacial separation of uncross-linked polymer adhesives have been adequately explained. However, in lightly cross-linked polymer adhesives, where cohesive failure cannot occur because there is no viscous flow, there are two regions of interfacial separation at low rate and this phemonenon cannot be readily explained by present viscoelastic theories.

Investigation of the stringiness phenomenon of peeling pressure-sensitive adhesive tapes at constant loads shows that two peeling speeds exist for any peeling load up to the vicinity of 200 g/25 mm. Also it is clear that stringiness structure differs greatly at each peeling speed. The stringiness phenomenon of each of these two regions is analyzed using Miyagi's observation apparatus. These two measurements are then reversed and a comparison shows that the two peeling speeds correspond to each steady peeling region.

This field of investigation, when added to the present viscoelastic property studies, should lead to a new peeling adhesive theory which, in turn, may lead to the development of new high peel force pressure-sensitive adhesives.     

臭氧氧化处理法对聚丙烯表面涂装性的改良 Ⅲ.聚丙烯表面含氧官能团相对生成量和涂膜剥离强度的关系

研究了用臭氧氧化法对聚丙烯表面进行涂装性改良时,丙烯均聚物、乙烯—丙烯嵌段共聚物及无规共聚物表面上含氧官能团相对生成量和涂膜剥离强度之间的关系。结果表明,当各种聚丙烯表面上以FT-IR中1710cm~(-1)和973cm~(-1)峰的吸光度比(log(I_0/I)_(1710)/log(I_0/I)_(973))所表示的COOH基的相对生成量在0.6附近时,可反应性涂料的涂膜剥离强度均出现最大值。这是因为在涂膜剥离过程中存在着接着破坏和凝集破坏两种机理,在最大值及最大值之前的剥离破坏属于接着破坏,此时剥离强度随聚丙烯表面上COOH相对量的增加而增加;而最大值以后的剥离破坏属于凝集破坏,此时剥离强度随COOH相对量的增加而下降。     

环保型乳液型纸塑复膜胶研制

介绍了一种共聚改性醋酸乙烯-乙烯-丙烯酸异辛酯共聚乳液的合成过程及其性能和应用情况, 该乳液应用于聚丙烯(BOPP)或涤纶(PET)薄膜与纸张印刷品复合粘接,达到了良好的效果,粘接性能优良, 180°剥离强度达0．4 N/mm,即油墨层剥离的效果,且印刷品无气泡、变色现象。     

Influences of debonding rate and temperature on tack properties and peel behavior of polyacrylic block copolymer/tackifier system

The influences of debonding rate and temperature on the peel behavior of polyacrylic block copolymer/tackifier system were investigated. Poly(methyl methacrylate)-block-poly(n-butyl acrylate)-block-poly(methyl methacrylate) triblock copolymer (MAM) with hard block contents of 23 (MAM-23) and 16 wt.% (MAM-16) and a 1/1 blend with a diblock copolymer (MA) consisting of the same components (MAM-23/MA, total hard block content of 15 wt.%) were used as the base polymer. A special rosin ester was used as a tackifier at various contents in the block copolymer/tackifier system. The peeling process at the probe/adhesive interface during probe tack testing was observed using a high-speed microscope at 23 °C with debonding rate of 10 mm/s. Three different peeling mechanisms were observed. Type A, where peeling progressed linearly from the edge to the center of the probe without cavitation (MAM-23). Type B, where peeling progressed linearly from the edge to the center of the probe with cavitation (MAM-16). Type C, where cavitation occurred over the entire adhesive layer, and peeling initiation was delayed (MAM-23/MA). The peel behavior of MAM-23 changed from Type A to Type B with a decrease of the debonding rate (1 mm/s) or increase of the temperature (40 °C). In contrast, there was no change for MAM-16 and MAM-23/MA. Cavity formation in an adhesive layer restrains peeling; therefore, it is desirable for improvement of the adhesion strength. The tack properties increased with the tackifier content, and the formation of cavitation was less than that for the systems without the tackifier.     

提高RTV732硅酮胶剥离强度的试验研究

以RTV732单组分硅酮胶作为硅橡胶/铝合金粘接用胶粘剂,探讨了不同的固化条件对胶接件粘接性能的影响。结果表明:RTV732硅酮胶在不同固化条件下的剥离强度虽有所差异,但硅橡胶/铝合金胶接件经常温固化24 h、130℃固化2 h后的剥离强度明显优于常温固化24 h后的剥离强度。     

Quantifying the Relationship Between Peel and Rheology for Pressure Sensitive Adhesives

An attempt is made in this work to model quantitatively the peel force vs. rate behavior of a pressure sensitive adhesive (PSA) tape. The approach follows suggestions of previous authors in modeling the deformation of the PSA as uniaxial extension of individual strands. A debonding failure criterion based on stored elastic energy density is used. In this work, experimental measurements of dynamic mechanical master curves are used to provide the mechanical properties of the PSA in the model. The predictions are compared with experimental peel force vs. rate master curves on tapes made from those same adhesives. The only adjustable parameter for the fitting is the quantity related to the debonding criterion. In this set of natural-rubber-based PSAs, the general shape of the peel master curve and the changes in peel behavior associated with tackifier loading and rubber molecular weight are well explained by the model. The effect of changes in substrate chemistry are not well explained.     

SBS接枝胶的研究

以甲基丙烯酸甲酯和丙烯丁酯对ＳＢＳ进行接枝改性，研究了ＳＢＳ用量，引发剂浓度，单体配比，聚合温度，反应时间，增粘剂用量多种因素对胶液剥离强度的影响，所制得胶液用于粘接ＳＢＳ和皮类材料的９０°剥离强度最刘可达９１Ｎ／ｃｍ，可稳定在７０Ｎ／ｃｍ以上。     

Non-linear double-peeling: Experimental vs. theoretical predictions

The double peeling of detachment of non-linear adhesive tapes from a flat Poly(methyl methacrylate) (PMMA) surface has been investigated from both experimental and theoretical point of view. Double peeling tests show that, as the detachment process advances, the peeling angle stabilizes on a limiting value θ_lim corresponding to a critical pull-off force F_c above which the tape is completely detached from the substrate. This observed behavior is in good agreement with results obtained following the new theory of multiple peeling and taking into account the hardening-softening non-linear behavior of the experimentally tested adhesive tapes and clarifies some aspects of the experimental data. In particular, the theoretical model shows that the value of the limiting peeling angle depends on the geometry of the adhesive tape as well as on the stiffness properties and on the interfacial energy ?γ. Finally, theoretical predictions confirm that solutions with a peeling angle lower than θ_lim are unstable.     

Adhesion at Poly(Butylacrylate)–Poly(Dimethylsiloxane) Interfaces

We present an investigation of the adhesion modulation mechanisms of silica-like nanoparticles (MQ resins) incorporated in polydimethylsiloxane (PDMS) elastomers and acrylic adhesives. The Johnson-Kendall-Roberts (JKR) test has been used to gain information on the both zero velocity and the velocity dependence of the adhesive strength, avoiding as much as possible contributions to the adhesive strength of bulk dissipation in the adhesive (which is not the case with peel tests). As the incorporation of the MQ resins into the elastomers deeply affects their own mechanical properties, the loading and unloading curves of small poly(butylacrylate) (PBA) lenses on either PDMS elastomers, adsorbed PDMS and pure MQ resin layers are compared in a systematic manner. The PBA chains are observed to have a neat affinity for the MQ resin nanoparticles. When MQ resins are present at the interface, they tend to prevent facture propagation, thus producing a larger deformation of the PBA lens. The modulation of adhesion is then dominated by the corresponding dissipation inside the acrylic adhesive.     

一种预涂膜(纸塑)复膜粘接乳液的研制

介绍了一种共聚改性型醋酸乙烯酯-叔碳酸乙烯酯(veova10)-丙烯酸酯共聚乳液的合成过程及其性能和应用情况,该乳液应用于聚丙烯(简称BOPP)或涤纶(PET)薄膜的背涂,该预涂膜与纸张印刷品复合粘接,达到了良好的效果,粘接性能优良,剥离强度(180°)达0．6N／mm,即油墨层剥离的效果,且印刷品无气泡、变色现象。     

Adhesion at Poly(Butylacrylate)-Poly(Dimethylsiloxane) Interfaces

We present an investigation of the adhesion modulation mechanisms of silica-like nanoparticles (MQ resins) incorporated in polydimethylsiloxane (PDMS) elastomers and acrylic adhesives. The Johnson-Kendall-Roberts (JKR) test has been used to gain information on the both zero velocity and the velocity dependence of the adhesive strength, avoiding as much as possible contributions to the adhesive strength of bulk dissipation in the adhesive (which is not the case with peel tests). As the incorporation of the MQ resins into the elastomers deeply affects their own mechanical properties, the loading and unloading curves of small poly(butylacrylate) (PBA) lenses on either PDMS elastomers, adsorbed PDMS and pure MQ resin layers are compared in a systematic manner. The PBA chains are observed to have a neat affinity for the MQ resin nanoparticles. When MQ resins are present at the interface, they tend to prevent facture propagation, thus producing a larger deformation of the PBA lens. The modulation of adhesion is then dominated by the corresponding dissipation inside the acrylic adhesive.     

丁腈酚醛橡胶胶粘剂的研究

通过对一种高温固化的单组分丁腈一酚醛型胶粘剂的研究，讨论了酚醛树脂用量、硫化压力对胶粘剂粘接性能的影响；考核了胶粘剂的综合性能。结果表明，丁腈橡胶和酚醛树脂的用量比例在一定范围内有最佳值；剥离强度随硫化压力的增大而提高，但当硫化压力大于40MPa时，再增大压力剥离强度增加趋势不显著。     

Possibilities of strength prediction of adhesive joints of polymers by master curve method

In the present work it is shown that the strength, depending on temperature and strain, and durability, depending on temperature and static load, of adhesive joints of polymers with adhesive of elastomer type can be predicted from master curves, drawn according to the principle of temperature–time analogy. Shift factors, determined by the Williams-Landel-Ferry (WLF) equation with universal values of constants, have been used to draw the master curves. It allowed to find relations between reference temperature and glass transition temperature of the adhesive. Their existence can be explained on the basis of free volume theory. Referring to the analogous influence of temperature and the part of the plasticizer inserted into the adhesive, on the strength of adhesive joints the existence of temperature–concentration analogy has been determined on the phenomenological level. Nomograms have been suggested for the calculation of strength and durability values from the master curves. Their application is convenient for repeated usage of master curves.