Cohesive Adhesion Research Articles

Laparoscopy Compared With Laparotomy as a Risk Factor for Intra-abdominal Adhesion Formation [ID 2683454

INTRODUCTION: The objective of this study is to compare the incidence and severity of abdominal and pelvic adhesions after laparoscopy versus laparotomy. METHODS: All patients undergoing laparoscopic surgery with study staff were included in this IRB-approved study. Postoperatively, surgeons filled out data collection forms to capture pertinent details. Patients with a history of only laparoscopy or only laparotomy were included, whereas those with known past inflammatory events, no prior surgeries, or a combination of laparoscopic and open procedures were excluded. RESULTS: Seventy-six laparoscopy-only and 83 laparotomy-only patients were included in this cohort. Adhesions were noted in 31 laparoscopy patients (40.8%) versus 74 laparotomy patients (89.2%; P<.001). Filmy adhesions were noted in 22 laparoscopy patients (28.9%) versus 37 laparotomy patients (44.6%), without statistical significance (P=.06098). Higher-grade adhesions were significantly more prominent in the laparotomy group. Laparotomy group had significantly more dense adhesions (55.4% versus 11.8%; P<.001) and cohesive adhesions with attached surfaces (32.5% versus 10.5%; P=.001614). By location, the laparotomy group had significantly more periumbilical adhesions (34.9% versus 3.9%; P<.001). Adhesiolysis time was shorter in laparoscopy (3 versus 10 minutes; P=.008439). CONCLUSION: Our data demonstrate that not only does laparotomy present a greater risk for adhesion formation than laparoscopy, but they are more likely to be present in the periumbilical area and the quality of those adhesions are significantly more likely to be dense and/or cohesive in nature, subjecting patients to more risk and requiring more surgical time to address.

Cohesive failure modeling based on the phase‐field approach

AbstractRegarding resolving the crack‐induced strong discontinuity problems, e.g., crack faces separating, contact and friction, the recent established approach based on the Representative Crack Element (RCE) framework is developed to describe a robust crack kinematics or crack deformation. The work at hand presents cohesive fracture by elaborating phase‐field modeling within the RCE approach. It constitutes a classical traction‐separation exhibition at the crack faces of the RCE. As such, a phenomenological cohesive adhesion in the RCE can be modeled. In the sequel, the overall material status is interpolated by an intact material state (continuous description) and a fully broken state (RCE description) using the phase‐field degradation function. This allows not only to model a cohesive debonding failure for tensile and shearing deformation, but also to yield an expected contact algorithm when the crack is closing. Furthermore, the unknown crack deformations are solved according to virtual power principle, which provides a consistent framework for the comprehensive constitutive laws of this model.

7600 Identifying Risk Factors for Adhesion Formation in the Left Upper Quadrant - Preliminary Findings of a Prospective Study

<h3>Study Objective</h3> To identify risk factors for development of adhesions in the left upper quadrant (LUQ). <h3>Design</h3> Multi-site, prospective study approved by each institution's local institutional review board. <h3>Setting</h3> Two large academic tertiary referral centers. <h3>Patients or Participants</h3> All laparoscopic cases performed by study staff on adult patients were eligible. Cases were performed per standard protocol with entry approach and location per surgeon preference. Intraoperative photo documentation of four abdominal quadrants was obtained at the onset of each case, and additional areas as indicated. A data collection form was completed after each case to capture data on adhesiogenic events (such as prior surgeries, infections, endometriosis, radiation), time spent for adhesiolysis, route of entry, location and grade of adhesions, if present. <h3>Interventions</h3> No interventions were included in this study. The primary outcome of this study is the presence and severity of adhesions identified in the LUQ at the time of laparoscopy for benign gynecologic disease. <h3>Measurements and Main Results</h3> We present interval findings from study onset in 2019 until February 2022. A total of 520 laparoscopic cases have been collected, with an overall adhesion incidence of 59.4%. The overall incidence of adhesions present in the LUQ was 1.9%. Among patients with a history of gastric banding, sleeve gastrectomy, and Roux-en-Y bypass (n=24), there were 2 cases with adhesions in the LUQ (8.3%); one with filmy adhesions and one with dense cohesive adhesions between bowel and the anterior abdominal wall. These two patients had prior open gastric bypass and open gastric bypass revision with colectomy. No visceral or vascular injuries were noted when LUQ entry was performed. <h3>Conclusion</h3> Our early data suggests that the overall rate of adhesions in the LUQ is low, especially with prior laparoscopic gastric procedures. While a history of gastric surgery should not preclude abdominal entry in the LUQ, vigilance is important to avoid inadvertent injury to underlying structures.

Phase-field fracture incorporating cohesive adhesion failure mechanisms within the Representative Crack Element framework

The recently developed phase-field evolution within the Representative Crack Element framework has been demonstrated to yield physically reasonable crack kinematics, including crack opening, closing, shearing as well as mixing aforementioned deformations. The work at hand presents cohesive fracture by elaborating phase-field modeling within the Representative Crack Element approach. A traction–separation law is postulated in the crack surfaces of the Representative Crack Element, which phenomenologically leads to cohesive adhesion in the RCE description. According to a continuous interpretation of an intact material and a fully broken material by the phase-field degradation function, a realistic material status is obtained with respect to different loading states, i.e. an opening or a shearing crack leads to cohesive adhesion failure but closing crack only shows a physical material contact behavior. This methodological constitutive relation is based on a straightforward variational approach and is derived out of the virtual power principles from both the RCE and the continuous descriptions. The unknown crack deformations are consistently resolved by a minimization algorithm of the RCE virtual power. Implemented into the context of the Finite Element Method framework, several demonstrative numerical examples are investigated. Some meaningful findings are pointed out and potential perspectives are proposed to consequently close this paper.

Relation Between Adhesion Properties and Microscopic Characterization of Polyphosphoric Acid Composite SBS Modified Asphalt Binder

The purpose of this study was to investigate the adhesive properties of polyphosphoric acid compounded SBS (PPA/SBS) modified asphalt. Three base asphalt binders, one SBS, one dibutyl phthalate (DBP), one furfural extraction oil, and two polyphosphoric acids (PPA), were used to produce the modified binders. The adhesive properties tested in this study included contact angle, cohesive work, adhesive work, and peak area ratio. Cohesive work and adhesive work indicators were calculated from the contact angle, the contact angle between PPA/SBS modified asphalt and three liquids (distilled water, glycerin, formamide) were tested by the contact angle tester, and the peak area ratio of the microscopic adhesion performance index by AFM. The relation between the microscopic adhesion performance characterization method (peak area ratio) and the macroscopic adhesion performance index (cohesive work, adhesion work) was established. The test results indicated that the PPA/SBS modified asphalt had the highest cohesive work and adhesion work under the conditions of 0.5% PPA, 1% DBP, 1.5% extracted oil, and 3.5% SBS, which was clearly greater than the original SBS modified asphalt, while the peak area ratio was consistent with the cohesive work and adhesive work, in which the correlation coefficient between the peak area ratio and cohesive work was 0.77788, and that between the peak area ratio and adhesion work was 0.87203. We recommend adopting the peak area ratio to characterize PPA/SBS modified asphalt’s microscopic adhesion properties.

\u201cBAX602\u201d in Preventing Surgical Adhesion after Extracorporeal Ventricular Assist Device Implantation for Refractory Congestive Heart Failure: Study Protocol for a Multicenter Randomized Clinical Trial

BackgroundThe high surgical risk in redo cardiac surgery is largely attributed to adhesions around the epicardium and the great vessels. BAX602 is an adhesion prevention reagent composed of two synthetic polyethylene glycols. Spraying BAX602 over the epicardium and the great vessels reportedly contributes to adhesion prevention after pediatric cardiac surgery. The present study aims to evaluate the safety and effectiveness of BAX602 spray in patients undergoing extracorporeal ventricular assist device implantation surgery to treat refractory congestive heart failure.Methods and DesignThis investigator-initiated, multicenter, pivotal, two-arm, open-label, randomized trial will include a total of 30 patients. The primary outcome measure is the severity of adhesions, which will be evaluated during re-sternotomy surgery performed 2–12 weeks after the primary extracorporeal ventricular assist device implantation surgery. The adhesion severity will be evaluated at five predefined sites using a four-grade adhesion evaluation score (0 = no adhesion; 1 = filmy and avascular adhesion; 2 = dense/vascular adhesion; 3 = cohesive adhesion). This measure will be summarized in two ways to evaluate the effect of BAX602: (1) the total score of the severity of adhesions at all five sites (ranging from 0 to 15), and (2) the total number of sites with dense/vascular or cohesive adhesions (ranging from 0 to 5).Ethics and DisseminationThe study findings will be disseminated at regional, national, and international conferences and through peer-reviewed scientific journals.Trial RegistrationThe trial was registered in the UMIN Clinical Trials Registry (UMIN-CTR: UMIN000038998) on 6 January 2020.

Bonding repair of CFRP based on cold plasma treatment surface modification

The surface pretreatment before bonding repair determines the microscopic physical and chemical properties of the composites, and directly affects the bonding strength and maintenance effect. In this paper, the surface of the Carbon Fiber Reinforced Polymer (CFRP) was pretreated by Cold Plasma Treatment (CPT) under 2.5 times air atmosphere (0.25 MPa) to achieve the best interface micro-performance for bonding repair. Based on the surface microstructure and surface activity test, the single lap test was used to evaluate the bonding repair strength after surface modification. The results show that the optimized surface treatment parameters of the output power, the plasma flame-core distance, and the process time were 800 W, 7 mm, and 7 s, respectively. It is found that no damage to the fiber and the surface-free energy of the pretreated composites (800 W, 7 mm, 7 s) reaches 51.65 mN/m under the optimized process, which is higher than those of the untreated original value 43.83 mN/m and the manual-grinding treatment value 45.73 mN/m. The bonding strength of CFRP after CPT treatment was increased to 11.31 MPa, which was obviously better than the bonding strength of 7.11 MPa without pretreated specimen and the bonding strength of 8.14 MPa after manual-grinding treatment. The failure mode of samples after CPT treatment was cohesive failure, while those of manual-grinding treated and original untreated CFRP samples exhibited thin layer cohesive failure (TLC) and adhesion failure (ADH), respectively.

INVESTIGATING THE POSSIBILITY OF USING THE NATURAL BITUMEN OF GILSONITE TYPE FOR THE PRODUCTION OF ROAD BITUMEN

The heavy traffic combined with the adverse weather and climate factors which are characteristic for most of the year, makes high demands for asphalt concrete. The quality of asphalt concrete is largely determined by the properties of bitumen which plays the role of a binder which provides the formation of a monolithic composite road-building material from separate mineral grains. Compound bitumen obtained by mixing the peroxidized bitumen with tar have the best ratio of all physico-chemical indicators, it is also possible the option to compound residual bitumen with oxidized. Oxidized bitumen obtained by the oxidation of tar or a mixture of tar with other petroleum products is characterized by low cohesive strength, poor adhesion and considerable aging. The use of natural bitumen of gilsonite type is the most common method to improve the properties of bitumen. When introducing into the bitumen of this natural bitumen, its penetration at a temperature of 25° C is reduced, as well as the softening point is increased. In fact, the nature of the change in the properties of bitumen during introduction of natural bitumen is the same as during its oxidation. That is, natural bitumen can be used to produce road bitumen by compounding it with tar. This paper presents the results of bitumen research obtained by combining tar with natural bitumen of gilsonite type. The production of bitumen by combining tar with natural bitumen of gilsonite type allows obtaining different grades of road bitumen by changing the content of natural bitumen. Bitumen obtained by this technology is more heat- and crack-resistant, have high adhesion to the aggregates and are not subjected to the technological aging. This bitumen has a higher softening point and a lower Fraass breaking point and therefore a higher plasticity interval. Keywords: bitumen, production, equiviscous temperatures, natural bitumen, mixing.

Laboratory Evaluation of Aging on Engineering Properties of Fine-Graded Porous-Asphalt Concrete

Abstract Porous-asphalt concrete (PAC), with its large portion of void content, would result in an increased potential for accelerating aging. Rapid oxidation of the asphalt binder films has an adverse impact on the structural durability of PAC pavements. In addition, the use of fine-graded PAC is more desirable; they have a potential to be more economical because they can be placed in thinner layers. The aim of this work is to characterize the influence of aging on the engineering properties of fine-graded PACs. Test results show that aged PAC mixtures are found to have the better performance in tensile strength and rutting resistance compared to unaged PACs, but the aging has a detrimental influence on the raveling resistance and moisture susceptibility. The 4-day long-term aging procedure led to a considerable reduction in the tensile-strength ratio for PAC mixtures irrespective of binder type and gradation. In addition, the values of resilient modulus and tensile strength for the fine-graded PACs appeared to be higher than those for the coarser-graded PAC mixture. Based on the results obtained from the wheel track testing, the use of premium asphalt enhanced the cohesive strength and adhesion, thereby reducing the proportional rut depth of PAC. In terms of the overall performance evaluation, the fine-graded PAC with the highly modified asphalt binder can be used without compromising engineering properties.

Attenuation of postoperative adhesions using a modeled manual therapy.

Postoperative adhesions are pathological attachments that develop between abdominopelvic structures following surgery. Considered unavoidable and ubiquitous, postoperative adhesions lead to bowel obstructions, infertility, pain, and reoperations. As such, they represent a substantial health care challenge. Despite over a century of research, no preventive treatment exists. We hypothesized that postoperative adhesions develop from a lack of movement of the abdominopelvic organs in the immediate postoperative period while rendered immobile by surgery and opiates, and tested whether manual therapy would prevent their development. In a modified rat cecal abrasion model, rats were allocated to receive treatment with manual therapy or not, and their resulting adhesions were quantified. We also characterized macrophage phenotype. In separate experiments we tested the safety of the treatment on a strictureplasty model, and also the efficacy of the treatment following adhesiolysis. We show that the treatment led to reduced frequency and size of cohesive adhesions, but not other types of adhesions, such as those involving intraperitoneal fatty structures. This effect was associated with a delay in the appearance of trophic macrophages. The treatment did not inhibit healing or induce undesirable complications following strictureplasty. Our results support that that maintained movements of damaged structures in the immediate postoperative period has potential to act as an effective preventive for attenuating cohesive postoperative adhesion development. Our findings lay the groundwork for further research, including mechanical and pharmacologic approaches to maintain movements during healing.

Structural characterization and adhesion appraisal of TiN and TiCN coatings deposited by CAE-PVD technique on a new carbide composite cutting tool

A new composite matrix was developed for a cutting tool based on tungsten carbide ligated with cobalt (WC-Co) using sintering technique. The admixtures of niobium carbide, tantalum carbide, and titanium carbide with the WC-Co matrix aim to inhibit the grain growth of WC and to promote covalent bonding at the interface. The modified WC-Co tools were coated with titanium nitride and titanium carbonitride layers by CAE-PVD technique. To substantiate the performances of the new coating-substrate systems, we have performed X-ray diffraction, atomic force microscopy, and scratch test measurements to estimate: phase content, average crystallite size, average texture coefficient, residual stress level, coating thickness, average roughness, square mean root, fractal dimension, cohesive adhesion, and adhesive adhesion. The results enable the in-depth understanding of the coating growth mechanisms and provide an objective evaluation of the coatings adhesion to the new cutting tools matrix. The results provide evidence to support the potential of TiN and TiCN coatings to enhance the working performances of the composite WC-Co cutting tools and to differentiate their properties. TiCN coating is shown to be superior to TiN coating in terms of adhesion and thus represents a better alternative for coating the modified WC-Co composite matrix.

Quantifying the Forces Driving Cell–Cell Adhesion in a Fungal Pathogen

Owing to its ability to form biofilms on implanted medical devices, the fungal pathogen Candida albicans causes frequent infections in humans. A hallmark of C. albicans biofilms is the presence of two types of cells, budding yeast cells and growing hyphae, which are bound together and embedded in extracellular matrix material. Although cell-cell adhesion is critical to biofilm formation, architecture, and cohesion, we know little about the fundamental forces behind this interaction. Here, we use single-cell force spectroscopy to quantify the forces engaged in yeast-hyphae adhesion, focusing on the role of Als (agglutinin-like sequence) proteins as prototypes of cell adhesion molecules. We show that adhesion between individual yeast and hyphal cells involves strong, short-range cohesive interactions (1.1 ± 0.2 nN; 86 ± 33 nm) and weak, long-range tether interactions (0.4 ± 0.2 nN; 234 ± 81 nm). Control experiments demonstrate that these interactions originate from cell surface proteins that are specific to C. albicans. Using mutant strains deficient for Als expression, we find that Als3 proteins, primarily expressed on the germ tube, play a key role in establishing strong cohesive adhesion. We suggest a model in which cohesive adhesion during biofilm formation originates from tight hydrophobic interactions between Als tandem repeat domains on adjacent cells. When subjected to force, the two interacting cell surfaces detach, but the cell bodies remain tethered through macromolecular extensions. Our results represent the first direct, noninvasive measurement of adhesion forces between interacting fungal cells and provide novel insights into the molecular origin of the cohesive strength of fungal biofilms.

Adhesion formation after intracapsular myomectomy with or without adhesion barrier

To show the prevention of adhesion formation by placing an absorbable adhesion barrier after intracapsular myomectomy. Prospective blinded observational study. University-affiliated Hospitals. Patients ≥ 18 years old with single or multiple uterine fibroids removed by laparoscopic or abdominal intracapsular myomectomy. A total of 694 women undergoing laparoscopic or abdominal myomectomy were randomized for placement of oxidized regenerated cellulose absorbable adhesion barrier to the uterine incision or for control subjects without barriers. The presence of adhesions was assessed in 546 patients who underwent subsequent surgery. The primary and secondary outcomes of the analysis were the presence and severity of adhesions for four groups: laparotomy with barrier, laparotomy without barrier, laparoscopy with barrier, and laparoscopy without barrier. There was a higher rate of adhesions in laparotomy without barrier (28.1%) compared with laparoscopy with no barrier (22.6%), followed by laparotomy with barrier (22%) and laparoscopy with barrier (15.9%). Additionally, the type of adhesions were different, filmy and organized were predominant with an adhesion barrier, and cohesive adhesions were more common without an adhesion barrier. Oxidized regenerated cellulose reduces postsurgical adhesions. Cohesive adhesions reduction was noted in laparoscopy.

Laparoscopy in Children With Acute Intestinal Obstruction by Aberrant Congenital Bands

Aberrant congenital bands are a rare cause of acute intestinal obstruction and usually present a diagnostic challenge. In 2008, the authors encountered 2 children with acute terminal ileal herniation. In the first case, it was caused by a mesodiverticular band, and numerous freely hanging filmy membranes attached to the antimesenteric side of the small intestine were found concurrently; whereas, an anomalous band from the distal ileum to the cecum was the leading cause in the second case. The vascularity of both herniated intestines was not compromised, and laparoscopy was successfully carried out 84 and 93 hours after the onset of the symptoms, respectively. Instead of cohesive adhesions, both of the causes related to a single vascular band, and laparoscopy was an effective and safe tool in diagnosis and subsequent treatment. The case with a mesodiverticular band and filmy membranes is the first case report with incomplete regression of both the vitelline circulation and the ventral mesentery.

Study on transvaginal hydrolaparoscopic pelvic adhesiolysis in the infertile women

To investigate the safety and efficacy of transvaginal hydrolaparoscopic pelvic adhesiolysis (THLPA) treatment in the infertile women. From May 2007 to Sep. 2008, 30 infertile patients underwent THLPA. The dye-test, hysteroscopy, and dye-test using catheterization of tubal ostium by hysteroscopy were performed at the same time. Pelvic adhesions were scored according to the revised American Fertility Society classification of endometriosis (1985). The adhesions were graded as mild (score 1-9), moderate (10-19), and severe (>/= 20). Twenty-four cases were in mild adhesions, 5 moderate adhesions, and 1 severe adhesion. The duration of the operation and discharge, pelvic adhesions score, tubal patency, complications, and pregnancy rate were investigated. (1) THPLA: the majority of pelvic adhesions in all patients were successfully performed adhesiolysis. Only a little filmy adhesions of proximal peritube of 7 tubes and proper ligament of 5 ovaries and cohesive adhesions of 4 ovaries did not underwent surgical lysis. (2) Tubal patency: 35 tubes were of proximal occlusion by dye-test, of which 21 (60%, 21/35) were unobstructed and 4 (11%, 4/35) were partly unobstructed after the dye-test using catheterization of the tubal ostium by hysteroscopy. (3) The duration of operation: the overall operative time were (32 +/- 6) minutes in mild adhesion, (52 +/- 6) minutes in moderate adhesion, and 83 minutes in severe adhesion. Of which the time of THLPA were (11 +/- 5) minutes in mild adhesion, (35 +/- 7) minutes in moderate adhesion, and 62 minutes in severe adhesion, respectively. (4) The duration of discharge: the postoperative discharge time was 120 - 175 minutes. No complications occurred. (5) The rate of pregnancy: in the (15.8 +/- 4.3) months' follow-up, the rate of pregnancy was 45% (13/29), which one patient lost follow-up. THLPA is safe, efficacious and not being hospitalized management. When compared with laparoscopy, it is simpler, more economic, and less minimally invasive approach. The appropriate indication of THLPA is to treat filmy, especially mild pelvic adhesions. It could partly avoid transabdominal operative laparoscopy for the infertile women.

Septums and Synechiae: Approaches to Surgical Correction

If the Müllerian ducts fail to fuse, or, if the wall which is the result of fusion is not adequately resorbed, the result is a spectrum of uterine abnormalities called Müllerian fusion and absorption defects. The impact of these abnormalities on fertility is a subject for debate, but at least a subset seems to have a negative impact on reproductive performance manifesting in recurrent abortion and/or premature labor. Previous surgical interventions required laparotomy, but, with careful application of imaging techniques, a group of patients can be identified with a uterine septum amenable to removal under hysteroscopic direction with little morbidity. Intrauterine adhesions or synechiae are usually secondary to curettage in the context of missed abortion or pregnancy-related hemorrhage. These lesions cover a spectrum that ranges from minor and insignificant to severe cohesive adhesions that affect menstrual function and fertility. Surgical repair of the endometrial cavity affected with such adhesions presents a challenge to the hysteroscopic surgeon. Appropriate management is controversial but may include second loop hysteroscopy and the use of postoperative adjuvants such as systemic estrogens and intrauterine devices or systems designed to impede the development of adhesions.

Analysis of Tantalum Coatings Produced by the Kinetic Spray Process

Tantalum (Ta) coatings have been produced using a relatively new process, kinetic spray. Ta starting powders having particle diameters greater than 65 µm are injected into a de Laval-type nozzle, entrained in a supersonic gas stream, and accelerated to high velocities due to drag effects. The particles’ kinetic energy is transformed via plastic deformation into strain and heat on impact with the substrate surface. Particles are not thermally softened or melted, producing relatively low oxide, reduced residual stress, high adhesion and low porosity coatings. Analysis of the mechanical and physical properties of these Ta coatings demonstrated increasing hardness, cohesive adhesion, and decreasing porosity as a function of particle velocity. Comparison between kinetically sprayed coatings and coatings produced using conventional coating methods will be discussed.

Adhesion of poly(4,4′-oxydiphenylene pyromellitimide) to copper metal using a polymeric primer: Effects of miscibility and polyimide precursor origin

Poly(amic acid) (PAA) and poly(amic diethyl ester) (PAE) precursors of poly(4,4′-oxydiphenylene pyromellitimide) (PMDA-ODA PI) were synthesized. Miscibility of these precursors with poly(arylene ether benzimidazole) (PAEBI), which is known to exhibit a strong cohesive adhesion to copper metal, was investigated in N-methyl-2-pyrrolidone (NMP) as well as in the condensed and the imidized state. PAEBI is completely miscible with the PAA precursor in NMP and also in the condensed state. This miscibility might result from complex formation of imidazole groups of PAEBI and carboxylic acid groups of the precursor. Furthermore, the imidized blend films are optically transparent. However, aggregation of polyimide chains in the films is evident from X-ray diffraction patterns. In contrast, the miscibility of PAEBI and PAE precursor in NMP is limited up to a concentration of 11.06–15.9 wt.-%. They were almost fully immiscible in the condensed state so that phase separation took place during soft-baking. This suggests that there are relatively weak interactions of the imidazole groups of PAEBI with both ester and amide linkages in the precursor, leading to phase separation in the blend. The phase separation occurred further during thermal imidization. The phase-separated domains were in a size of ≥ 2.3 μm, depending on the blend composition. Only the 10/90 and the 90/10 blend films were observed to be optically transparent. The difference in the miscibility of PAEBI with the polyimide precursors is correlated with the adhesion strength of PI/PAEBI/copper joints: higher miscibility results in higher peel strength.

Miscibility behavior of polyimide (PI)/poly(arylene ether benzimidazole) (PAEBI) blends and its effects on the adhesion of PI/PAEBI/copper joints

Poly(amic acid) (PAA) and poly(amic diethyl ester) (PAE) precursors of poly(p-phenylene biphenyltetracarboximide) (BPDA–PDA), which is a representative polyimide (PI) being used widely in the microelectronic industry as an interdielectric material, were synthesized. The miscibility behavior of these precursors with poly(arylene ether benzimidazole) (PAEBI), which is known to exhibit strong cohesive adhesion to copper metal conductor, were studied in N-methyl-2-pyrrolidone (NMP) as well as the condensed state and the imidized state using light scattering technique. And, the miscibility effect on the adhesion strength of PI/PAEBI/copper joint, in which the locus of failure is known to be within the PI layer, was investigated by 90° peel test. The PAA precursor was miscible completely with PAEBI in the NMP solution as well as in the condensed state via the strong interaction between carboxylic acid groups of the precursor and imidazole groups of PAEBI. However, imidization-induced phase-separation took place during thermal imidization of the PAA precursor, leading to domains of 0.7–1.4μm for the imidized blends containing 30–70wt% PI. The other blend compositions still were optically transparent. In contrast, the PAE precursor was miscible with PAEBI in the NMP solution with a limited concentration of <11.3–14.5wt%, but immiscible almost completely in the condensed state, causing phase-separation. The phase-separation occurred further during thermal imidization, producing domains of 0.8–3.0μm. In particular, the 50/50 (=PAEBI/PAE, wt/wt) blend had domains of >3.6μm. Only the 90/10 blend film was optically transparent. The difference in the miscibilities of PAEBI with the polyimide precursors was reflected on the adhesion strength of PI/PAEBI/copper joint. The PAA precursor gave a relatively high peel strength, compared to the PAE precursor. In addition, the PAEBI having a relatively low intrinsic viscosity provided a high peel strength in the adhesion joint.

On the evaluation of adhesion of coatings by automatic scratch testing

Automatic scratch testing is an expedient technique for comparatively evaluating the cohesive failure load and adhesion failure load of thin coatings on various substrates. In combination with SEM examination of the scratch track, this technique has been used herein to detect and evaluate various effects on coating strength and adhesion. For soft Triballoy T-800 and Stellite SF-6 cobalt-base coatings on 4340 low alloy steel, adhesion was found to be strong and failure was found to be cohesive in the coating. In the presence of a plated chromium interlayer, pre-existing cracks lowered substantially the cohesive failure load, which was also lowered by an increase in the coating deposition pressure. The spacing of transverse cracks within the coating was found in all cases to decrease with increasing applied normal load. In soft aluminum coatings on depleted uranium (DU)-0.75% Ti alloy specimens, alloying aluminum with magnesium or zinc enhanced the coating strength and adhesion. In (Al-Mg) coatings on this ...