The Effects of Processing Parameters on the Wedge Peel Strength of CF/PEEK Laminates Manufactured Using a Laser Tape Placement Process

Manufacturing thermoplastic composites (TPC) with excellent mechanical properties requires advanced methods with reduced costs and better overall efficiencies. In this study, fiber-reinforced thermoplastic polymer composite laminates were manufactured using an automated fiber placement (AFP) manufacturing technology. The effects of processing temperature (from 320 ℃ to 500 ℃), lay-up speed (from 20 mm/s to 260 mm/s), consolidation force (from 100 N to 600 N), and prepreg tape tension (from 0 N to 9 N) on the quality of the resulting laminates manufactured using the laser AFP system were investigated. The interlayer bond strength was characterized using wedge peel tests on samples prepared with different process parameters. The studies were complemented by measurements of the thermal properties of the composites using different scanning calorimetry. The optimized process parameter windows were determined to be 360 ℃ to 400 ℃ for the irradiation temperature, 140 mm/s to 160 mm/s for the lay-up speed, 100 N for the consolidation force, and 3 N to 5 N for the prepreg tape tension, respectively. The microscopic analysis of the cross-sections and peel-damaged surfaces revealed that the different distributions of the resin matrix resulting from the different processing parameters affected the interlayer strength. These results may provide an important reference for manufacturing TPC used in aerospace, defense, and automotive applications.

Influence of biobased polyol type on the properties of polyurethane hotmelt adhesives for footwear joints

Polyurethanes, one of the most used polymers worldwide, are strongly dependent of non-renewable fossil resources. Thus, boosting the production of new polyurethanes based on more sustainable raw materials is crucial to move towards the footwear industry decarbonisation. The aim of this study is to synthesise and characterise reactive hotmelt polyurethanes from biomass and CO2-based polyols as bioadhesives for the footwear industry. The influence of biobased polyols on the polyurethane structure, and therefore, on their final properties was analysed by different experimental techniques such us Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), Melting viscosity, Softening temperature and T-peel strength test, in order to assess their viability for the upper to sole bonding process. The results obtained indicated that the incorporation of different amounts of the biobased polyols produces changes in the structure and final performance of the polyurethanes. Therefore, adhesion test carried out by the T-peel test 72 h after the upper -to- sole bonding of the sustainable adhesives show high final adhesion values. These sustainable raw materials provide polyurethane adhesives with additional beneficial non-toxicity and sustainable characteristics, without harming their properties during their useful life.

P049 SAFETY AND EFFICACY OF ABSORBABLE AND NON-ABSORBABLE FIXATION SYSTEMS FOR INTRAPERITONEAL MESH FIXATION: AN EXPERIMENTAL STUDY IN SWINE

Aim Choice of the best fixation system in terms of safety and effectiveness for intraperitoneal mesh placement in hernia surgery remains controversial. The aim of this study was to compare the performance of four fixation systems in a swine model of intraperitoneal mesh fixation. Material and Methods Fourteen Landrace swine were utilized and the experiment included two stages. Initially, four pieces of polypropylene mesh with hydrogel barrier coating1 were fixed intraperitoneally to reinforce 4 small full thickness abdominal wall defects created with diathermy. Each mesh was anchored with a different tack device between titanium2, steel3 or absorbable (4,5) fasteners. The second stage took place after 60 days and included euthanasia, laparoscopy, and laparotomy. The primary endpoint was to compare the peel strength of the compound tack/mesh from the abdominal wall. Secondary parameters were the extent and quality of visceral adhesions to the mesh, the degree of mesh shrinkage and the histological response around the tacks. Results Thirteen out of 14 animals survived the experiment and 10 were included in the final analysis. Steel tacks had higher peel strength when compared to titanium and absorbable fasteners. No significant differences were noted regarding the secondary endpoints. Conclusions Steel fasteners provided higher peel strength that the other devices in this swine model of intraperitoneal mesh fixation. Our findings generate the hypothesis that this type of fixation may be superior in a clinical setting. Clinical trials with long-term follow-up are required to assess the safety and efficacy of mesh fixation systems in hernia surgery.

Interaction of Surface Preparation and Cure-Parameters on the Interface Reliability of Flexible Encapsulation in FHE Applications

Flexible devices, considered to be the next wave of electronics industry, require flexible encapsulation for protection while conforming to flexibility-needs in end applications. The characteristics of flexible electronics is not only reduced production cost but also thinner, lightweight and non-breakable which creates a new form application for the electronic devices. One such application is use to electronic devices in daily environment to monitor the vitals of one’s body. These devices are often expose to dust, sweat and moisture also they are generally subjected to flexing and folding motion which accrues stresses in those devices. These stresses and the harsh environment are often mitigated by using potting compounds, encapsulants to improve their survivability of the devices. In our study, we have chosen five different formulation of encapsulant subjected it various cure profiles to determine the adhesive strength of the various encapsulant. The benchmark peel strength was developed using a FE-model of the AU-biometric band and encapsulant peel strength at experimental conditions were compared to give us the best performing material. This paper includes the sample geometry which consists of five different encapsulants and two different substrate namely, polyimide and pet tested at four different cure schedule while the substrates were cleaned using two different cleaning methods. The encapulants are compared among each other to create a rank for possible future applications in FHE devices.

Pengaruh Asam Itakonat terhadap Properti Polimer Perekat Akrilik Berbasis Air

Acrylic-based polymer adhesive is a type of adhesive that can be used for pressure sensitive adhesive (PSA). Itaconic acid (IA) is a type of acid with 2 (two) OH groups which can form hydrogen bonds. The acrylic base can be used purely from its class. In some cases, however, the acrylic base can be used together with another base. Therefore acrylic-based adhesive with variable addition of itaconic acid was introduced in this study. In this application, the holding power property is one of the important parameters of a PSA. Therefore, holding power is the main parameter in this study. This research includes the preparation of tools and materials, mixing the main raw materials of acrylic monomer and itaconic acid with the types of surfactants and water, and product characterization. The polymerization process is carried out at a pressure of 1 atm with a temperature of 75°C - 80°C accompanied by stirring with a rotation rate of ± 500 rpm. The characterization of this research resulted in a PSA product with a holding power of 2 kg for 30 seconds to 620 minutes. While the resulting peel strength is 1.12 kgf / inc to 0.76 kgf / inc. Keywords: itaconic acid, acrylic PSA, holding power

Influence of the Surface Chemistry of Graphene Oxide on the Structure–Property Relationship of Waterborne Poly(urethane urea) Adhesive

Small amounts—0.04 wt.%—graphene oxide derivatives with different surface chemistry (graphene oxide—GO-, amine-functionalized GO—A-GO-, reduced GO—r-GO) were added during prepolymer formation in the synthesis of waterborne poly(urethane urea) dispersions (PUDs). Covalent interactions between the surface groups on the graphene oxide derivatives and the end NCO groups of the prepolymer were created, these interactions differently altered the degree of micro-phase separation of the PUDs and their structure–properties relationships. The amine functional groups on the A-GO surface reacted preferentially with the prepolymer, producing new urea hard domains and higher percentage of soft segments than in the PUD without GO derivative. All GO derivatives were well dispersed into the PU matrix. The PUD without GO derivative showed the most noticeable shear thinning and the addition of the GO derivative reduced the extent of shear thinning differently depending on its functional chemistry. The free urethane groups were dominant in all PUs and the addition of the GO derivative increased the percentage of the associated by hydrogen bond urethane groups. As a consequence, the addition of GO derivative caused a lower degree of micro-phase separation. All PUs containing GO derivatives exhibited an additional thermal decomposition at 190–206 °C which was ascribed to the GO derivative-poly(urethane urea) interactions, the lowest temperature corresponded to PU+A-GO. The PUs exhibited two structural relaxations, their temperatures decreased by adding the GO derivative, and the values of the maximum of tan delta in PU+r-GO and PU+A-GO were significantly higher than in the rest. The addition of the GO derivative increased the elongation-at-break, imparted some toughening, and increased the adhesion of the PUD. The highest T-peel strength values corresponded to the joints made with PUD+GO and PUD+r-GO, and a rupture of the substrate was obtained.

An Assessment of Surface Treatments for Adhesion of Polyimide Thin Films

Polyimide films are currently of great interest for the development of flexible electronics and sensors. In order to ensure a proper integration with other materials and PI itself, some sort of surface modification is required. In this work, microwave oxygen plasma, reactive ion etching oxygen plasma, combination of KOH and HCl solutions, and polyethylenimine solution were used as surface treatments of PI films. Treatments were compared to find the best method to promote the adhesion between two polyimide films. The first selection of the treatment conditions for each method was based on changes in the contact angle with deionized water. Afterward, further qualitative (scratch test) and a quantitative adhesion assessment (peel test) were performed. Both scratch test and peel strength indicated that oxygen plasma treatment using reactive ion etching equipment is the most promising approach for promoting the adhesion between polyimide films.

Can UVA-light-activated riboflavin-induced collagen crosslinking be transferred from ophthalmology to spine surgery? A feasibility study on bovine intervertebral disc

Background Collagen cross-links contribute to the mechanical resilience of the intervertebral disc (IVD). UVA-light-activated riboflavin-induced collagen crosslinking (UVA-CXL) is a well-established and effective ophthalmological intervention that increases the mechanical rigidity of the collagen-rich corneal matrix in Keratoconus. This study explores the feasibility, safety and efficacy of translating this intervention in reinforcing the IVD. Methods Annulus fibrosus (AF) cells were isolated from bovine IVDs and treated with different combinations of riboflavin (RF) concentrations (0.05–8 mM) and UVA light intensities (0.3–4 mW/cm2). Metabolic activity (resazurin assay), cell viability (TUNEL assay), and gene expression of apoptosis regulators C-FOS and PT5 were assessed immediately and 24 hours after treatment. Biomechanical effects of UVA-CXL on IVDs were measured by indentation analysis of changes in the instantaneous modulus and by peel-force delamination strength analysis of the AF prior and after treatment. Results Different intensities of UVA did not impair the metabolic activity of AF cells. However, RF affected metabolic activity (p < 0.001). PT53 expression was similar in all RF conditions tested while C-FOS expression decreased 24 hours after treatment. Twenty-four hours after treatment, no apoptotic cells were observed in any condition tested. Biomechanical characterizations showed a significant increase in the annular peel strength of the UVA-CXL group, when compared to controls of UVA and RF alone (p < 0.05). UVA-CXL treated IVDs showed up to 152% higher (p < 0.001) instantaneous modulus values compared to the untreated control. Conclusion This is the first study on UVA-CXL treatment of IVD. It induced significantly increased delamination strength and instantaneous modulus indentation values in intact IVD samples in a structure–function relationship. RF concentrations and UVA intensities utilized in ophthalmological clinical protocols were well tolerated by the AF cells. Our findings suggest that UVA-CXL may be a promising tool to reinforce the IVD matrix.