Seal Strength Research Articles

Influence of processing conditions on heat sealing behavior and resultant heat seal strength for peelable heat sealing of multilayered polyethylene films

Abstract The effects of processing conditions for peelable heat sealing of multilayered polyethylene (PE) films on heat sealing behavior and heat seal strength were investigated. Two sets of seal bars, knurled shape and flat shape, were used for heat sealing. After the heat sealing, the sealed portion was cooled using a set of cooling bars. Heat sealing temperature was adjusted to yield the heat seal strength of 4.0 N/15 mm, 6.0 N/15 mm and 8.0 N/15 mm at the heat sealing pressure of 0.4 MPa for each set of heat sealing bars. The heat seal strength increased with the increase of heat sealing pressure for the knurled shape bars, while it was less affected by heat sealing pressure for the flat shape bars. In situ measurements of the sealing bar clearance and interface temperature revealed that the reduction speed of clearance was significantly affected by the pressure for knurled shape bars, while it was almost independent of pressure for flat shape bars. Even though the temperatures set for the similar heat seal strength were different between knurled and flat shape bars, the maximum temperatures at the interface were almost identical. The effect of the shape of seal bars on heat seal strength became less significant after the sterilization process.

Variation in electrosurgical vessel seal quality along the length of a porcine carotid artery.

Electrosurgical vessel sealing has been demonstrated to have benefits for both patients and practitioners, but significant variation in the strength of the seal continues to be a concern. This study aims to examine the variation in electrosurgical seal quality along the length of a porcine common carotid artery and explore the relationships between seal quality, vessel size and morphology. Additionally, the study aimed to investigate the minimum safety threshold for successful seals and the influence of vessel characteristics on meeting this requirement. A total of 35 porcine carotid arteries were sealed using the PlasmaKinetic Open Seal device (Gyrus). Each seal was burst pressure tested and a sample taken for staining with elastin van Gieson’s stain, with morphological quantification using image processing software ImageJ. With increasing distance from the bifurcation, there was an increase in seal strength and a reduction in both elastin content and vessel outer diameter. A significant correlation was found between burst pressure with both outer diameter (p < 0.0001) and elastin content (p = 0.001). When considering the safe limits of operation, vessels of less than 5 mm in outer diameter were shown to consistently produce a seal of a sufficient strength (burst pressure > 360 mmHg) irrespective of vessel morphology.

超音波パルスの瞬時振動数を用いたヒートシールの非破壊接着力評価

Heat sealing is a packaging technique for hermetic sealing of foods and medical supplies etc. Evaluation of seal strength is important to guarantee both airtightness and easiness to open which are conflicting requirements. There are few studies of nondestructive evaluation although conventional spot check with destructive evaluation costs a great deal. This study proposes a new nondestructive evaluation method for the seal strength with ultrasonic pulse. The proposed method focuses on instantaneous frequency of the ultrasonic pulse which is time varying frequency in waveform. This paper demonstrates that the instantaneous frequency is more effective to evaluate the seal strength than conventional indexes such as amplitude and arrival time of the pulse through experiments. The transmittance and reflectance on the welded boundary surface are supposed to vary depending on the seal strength because the welded condition does not affect only the seal strength but the characteristics on the welded boundary surface. We also analytically discuss the mechanism how the instantaneous frequency senses the change of the transmittance and reflectance on the welded boundary surface. Simulated instantaneous frequencies also vary according to the change of the transmittance and reflectance. This result indicates that our proposed method effectively senses the variation of the welded surface characteristics pertaining to heat strength.

Relationship between Cooling Conditions After Heat Sealing and Variation of Heat Seal Strength After Sterilization Treatment for Peelable Heat Sealing of Multilayered Polyethylene Films

Relationship between Cooling Conditions After Heat Sealing and Variation of Heat Seal Strength After Sterilization Treatment for Peelable Heat Sealing of Multilayered Polyethylene Films

Mechanical, thermal and heat sealing properties of fish skin gelatin film containing palm oil and basil essential oil with different surfactants

Fish skin gelatin films plasticized with glycerol and incorporated with basil essential oil, palm oil or a mixture of basil essential oil/palm oil (1:1), in the presence of different surfactants (soy lecithin and Tween-20) were characterized. Films incorporated with various oils had lower tensile strength (TS) and elastic modulus (EM) with the higher elongation at break (EAB) in comparison with the control film (without oil and surfactant incorporated) (p < 0.05). TS and EM of films varied with oils and surfactants used. Films prepared with Tween-20 as surfactant showed higher EAB than those added with soy lecithin, regardless of oil types (p < 0.05). DSC analysis revealed that the incorporation of oils resulted in gelatin-based films with the decreases in both glass transition temperature (Tg) and extent of ordered-phase. All films added with different oils and surfactants had lower seal strength than the control film (p < 0.05). Film containing palm oil exhibited the higher seal strength and seal efficiency than those with basil essential oil or the mixture (p < 0.05), regardless of surfactants. Tween-20 yielded the film with the higher heat sealability than soy lecithin (p < 0.05). Good quality seal (complete fusion) was observed via SEM in control film and films containing various oils using Tween-20 as surfactant. As evidenced by FTIR, partial degradation and covalent cross-link were observed in emulsified films upon heat sealing, contributing in part to varying strengths of the seals. Therefore, both oil and surfactants could affect the mechanical properties, thermal properties as well as heat sealability of resulting films.

Effect of intermediate nickel layer on seal strength and chemical compatibility of glass and ferritic stainless steel in oxidizing environment for solid oxide fuel cells

The effects of intermediate nickel layer on seal strength and chemical compatibility of seal glass and interconnect materials for solid oxide fuel cells (SOFCs) were investigated. Two types of samples (metal/glass/metal sandwiches and glass coated metals) were prepared with the sheet of AISI 430 (nickel plated and uncoated) and slurry of compliant silicate sealing glass (SCN-1). The joined and coated samples were heated at 850 °C for different time durations (0.5–100 h). Tensile and impact tests were performed and SEM micrographs were used to analyze the glass/metal interaction. The results indicate that nickel plated AISI 430 shows higher adhesion strength at short durations of heating due to dendrite development at the interface. For longer durations, intermediate nickel layer leads to rapid loss of adhesion strength due to extension of unstable austenite zones but prevents the accelerated weakening near the triple-phase boundaries metal/glass/air (TPB) by compensating for absence of protective oxide layer (Cr–Mn oxide).

The Effects of Nano-SiO2 on Mechanical, Barrier, and Moisture Sorption Isotherm Models of Novel Soluble Soybean Polysaccharide Films

In this research, a novel polysaccharide-based bionanocomposite film was prepared via dispersion casting method. Nano-silicon dioxide (SiO2-N) was incorporated into soluble soybean polysaccharide (SSPS) at different concentrations (i.e., 0%, 1%, 3%, and 5% w/w dried SSPS). Mechanical (tensile strength, elongation at break, and Young’s modulus), physical (moisture content, water solubility, and moisture uptake), and barrier properties of bionanocomposite films were evaluated. Incorporation of 5% SiO2-N to SSPS matrix decreased water vapor permeability (WVP) from 7.96×10−11 to 4.75×10−11 g m−1 s−1 Pa−1 and oxygen permeability from 215 to 96 cm3 µm m−2 day−1 atm−1. Heat seal strength and mechanical properties of SSPS films were improved. Moisture sorption isotherm of SSPS films supported by SiO2-N was shifted to lower moisture content, and monolayer moisture content of the films decreased significantly (p&lt;0.05). In summary, SiO2-N is a potential filler in SSPS-based films for packaging materials.

Functional, thermal, and antimicrobial properties of soluble soybean polysaccharide biocomposites reinforced by nano TiO2

This study describes a new polysaccharide-based bionanocomposite developed through solvent casting. Different concentrations (i.e., 0%, 1%, 3%, and 5% (w/w)) of nano titanium dioxide (TiO2-N) were incorporated into soluble soybean polysaccharide (SSPS), and the functional properties of the resultant SSPS films were estimated. Incorporation of TiO2-N into the SSPS matrix decreased water vapor permeability from 7.41 to 4.44×(10−11gm−1s−1Pa−1) and oxygen permeability from 202 to 98 (cm3μmm−2d−1atm−1). Moisture content also decreased, the glass transition temperature increased, and the mechanical properties and heat seal strength of the SSPS films improved. SSPS bionanocomposite films showed excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus. In summary, TiO2-N shows potential use as a filler in SSPS-based films for the food and non-food industries.

Preparation and characterization of novel bionanocomposite based on soluble soybean polysaccharide and halloysite nanoclay

In this research, casting method was used to prepare novel polysaccharide-based bio-nanocomposite films with halloysite nanoclay (HNC). HNC was incorporated into soluble soybean polysaccharide (SSPS) at different concentrations (e.g., 1, 3, and 5%, w/w). Functional properties of SSPS films were evaluated following by ASTM standards. Incorporating HNC to SSPS matrix decreased water vapor permeability from 7.41×10−11 to 3.27×10−11(gm−1s−1Pa−1) and oxygen permeability from 202 to 84cm3(μmm−2day−1atm−1). By addition of HNC to SSPS films, glass transition temperature, tensile strength, and heat seal strength was increased and elongation at break was decreased. Uniform and smooth surface morphology revealed by scanning electron microscopy and shows no sign of phase separation among the film constitutes. In summary, HNC has the potential to be a filler in SSPS-based films for use in food and non-food packaging industries.

Ferromagnetic Heating for Vessel Sealing and Division: Utility and Comparative Study to Ultrasonic and Bipolar Technologies.

Vessel sealing technologies have improved surgical efficiency and outcomes. Ferromagnetic technology has potential utility in this area. The aim of this study was to evaluate ferromagnetic heating in sealing and dividing vessels. A novel ferromagnetic (FM) sealer, FMsealer, was developed for sealing and dividing vessels. Using a swine in vivo model, the following endpoints were evaluated: (1) proof of concept, (2) 21-day survival surgery, and (3) comparison with ultrasonic (US) and/or bipolar (BP) devices for subjective outcomes. Seal burst strengths were measured in vitro. Mann-Whitney and Student's t test were used. After showing proof of concept, 5 swine underwent survival splenectomy, nephrectomy, hysterectomy, and mesenteric vessel division (arteries ranging from 1 to 7 mm in diameter) with necropsy after day 21 showing no evidence of surgical site bleeding. FM was equivalent to BP in tissue retention and superior to BP in spread/tissue desiccation, sticking, and charring (P ≤ .01). The FM was superior to US and BP in speed of 10 cm mesentery division (mean ± SD seconds): FM (12.9 ± 1.0 seconds), US (23.3 ± 4.4 seconds), BP (46.1 ± 5.2 seconds) (P ≤ .01 FM vs US or BP). Seal burst strength and success of sealing a 5-mm carotid artery were as follows (mean ± SD mmHg, % success burst strength >240 mm Hg): FM (710 ± 206 mm Hg, 94% success), US (848 ± 565 mm Hg, 79%), and BP (619 ± 373 mm Hg, 83%). Ferromagnetic heating is an effective and efficient technology for sealing and dividing of vessels. An initial prototype of the FMsealer compared favorably with commercially available products based on ultrasonic and bipolar technologies.

Preparation and Sealing Processing of Sodium Alginate Based Blending Film

Edible packaging has been successfully used for packaging of low moisture foods such as wrappers. One of the hurdles in the use of edible packaging for moisture rich foods is its ability to successfully seal the package, which is critical due to the lower strength and elastic characteristics of edible films compared to plastic based films. Three important sealing parameters, namely, adhesive concentration, pressure, and temperature during sealing, were investigated to assess sealing performance of the edible film. The edible film was prepared from blend of three polymers (sodium alginate, sodium carboxymethyl cellulose, and gelatin) based on previous research work. The seal was evaluated for seal strength and a quadric regression model to predict seal strength as a function of adhesive concentration, pressure, and temperature during sealing was established. The model was statistically significantP&lt;0.05and an optimum combination of sealing parameters was obtained to be 24.4% adhesive concentration, 0.28 MPa pressure, and 153°C temperature. A sealing time of 1 s was used for all samples. All three factors were significant taken individually and interactions of the three factors were also significant (P&lt;0.05or 0.10) except for the interaction between adhesive concentration and sealing temperature.

Characterization of Walnut (Juglans RegiaL.) Genotypes in Ladakh Region of India

Ladakh region includes Leh and Kargil districts of Jammu and Kashmir in India. The region is cold and arid limiting the growing of fruit crops. The study aims to characterize walnut diversity in the region which would be resourceful in the near future for various purposes and boost up walnut cultivation. Four genotypes are selected from various walnut growing areas of Ladakh viz. G1 from Skara, G2 from Nurla, G3 from Temisgam and G4 from Dhomkhar. It was evident that majority of the genotypes exhibited intermediate tree vigour with spreading nature of growth habit, glabrous shoot pubescence and leaf and rachis pubescence, strong shell seal and shell strength with good nut diameter and nut length, satisfactory kernel flavor, well filled kernel and easy removal of kernel halves. Leaflet shape observed was elliptic, leaflet margin was entire, green leaf and rachis colour, brown shoot colour, complete shell integrity and kernel plumpness was moderate in all the four genotypes. The branching habit was dense in genotypes G3 and G4, intermediate in G1 and intermediate to dense in G2. In general, the highest value of leaf length and kernel percentage was recorded in G2. G3 exhibited the maximum width of leaf, number of leaflets, inshell nut weight and kernel weight. The nut shape was broad to ovate in G2 and G3, while G1 was broad ovate and G4 was broad elliptic in shape. The shell texture of G2 and G4 was medium while G3 was medium to rough and G1 was rough. The shell colour of G1 was light, medium in G2, light to medium in G3 and medium to dark in G4. The shell thickness recorded the maximum in G4. The kernel colour was light in G2 and G4, while extra light and light to amber was observed in G1 and G3 respectively.

Molecular Orientation Effect of Heat-Sealed PP Film on Peel Strength and Structure

Heat sealing properties are optimized by controlling temperature, pressure and dwell time, while film strength depends on the drawn ratio and the molecular orientation of the film. However, heat seal strength of polymer films with high drawn ratio shows lower peel strength, because the adhesion of films needs a higher heat sealing energy for molecular orientation relaxation at heat sealing. In the present study, polypropylene films with a drawn ratio of 1.0×, 1.5×, and 2.5× are heat sealed by using the heat sealing technique. The heat sealing condition is set to heat sealing time 1.0 s, sealing pressure 0.2 MPa, and heat sealing temperature 145°C. The effect of drawn ratio and stabilization temperature of PP films for peel strength are investigated using T-Peel test, DSC, FT-IR, and Raman spectroscopy. As a result, it is found that the peel strength is decreased with increasing the drawn ratio and stabilization temperature of PP films. The difference of ?H and melting point from the result of DSC measurement are exhibited for 1.5× drawn ratio film as compared with 2.5× one. In addition, FT-IR imaging and Raman line mapping reveal the influence and variation of high order structure for heat sealed parts of the drawn PP films.

Extrusion of gelatin-based composite films: Effects of processing temperature and pH of film forming solution on mechanical and barrier properties of manufactured films

a b s t r a c t The composite films, gelatin incorporated with corn oil were manufactured using a twinscrew co-rotating extruder. The effect of extrusion temperature (90, 105, 120 and 130 8C) and film forming pH values (5.7‐8.7) on the mechanical and barrier properties of gelatin-based composite films were investigated. Increasing the temperature from 90 to 130 8C improved (P < 0.05) the tensile strength (TS) of films. Increasing temperature to 120 8C improved (P < 0.05) water vapour permeability (WVP) values of gelatin-based composite films; however, this was accompanied by a decrease (P < 0.05) in gas barrier properties. Additionally the use of film forming solutions possessing high pH values improved the mechanical properties of films and caused a decrease (P < 0.05) in oxygen permeability. Neither temperature nor pH had any significant effect on the seal strength for any of the gelatin-based composite films manufactured. Confocal laser scanning microscopy (CLSM) results showed a corresponding increase in the number of oil droplets when processing temperature increased.

Bipolar vessel sealing: instrument contamination and wear have little effect on seal quality and success in a porcine in vitro model.

The aim of this study is to systematically investigate under standardized experimental conditions the effects of instrument contamination and wear on the quality of bipolar vessel sealing (BVS) achieved using a reusable instrument. The study was designed as a prospective, randomized, and controlled in vitro study and conducted in an academic research environment. Reusable bipolar coagulation forceps (BiClamp® 200 C, ERBE Elektromedizin) were used to apply sealing pressures of 300-1,100 mN/mm(2) to 239 renal arteries from commercially slaughtered female pigs (Swabian-Hall Swine). Forceps jaws were coated with porcine blood, blood and collagen, or blood, collagen, and fat to simulate instrument contamination with biological material during surgery. Clinical wear was mimicked by sandpaper abrasion. The main outcome measures were seal success (resistance to 250 mmHg intraluminal pressure for 2 min) and seal stability (burst pressure). Sealing pressure had a significant impact, with 800 mN/mm(2) producing the best sealing results. Seal success increased with total energy applied to the tissue, a higher maximum temperature, and longer coagulation as indicated by desiccation time. Experimental contamination had no significant impact on seal success and only a limited effect on seal stability. Similarly, abrasive wear also had no significant effect on either seal quality or seal strength. The impact of bipolar forceps contamination and wear on seal success and quality was negligible in our in vitro model. To achieve high-quality seals, it is essential to use adequate sealing pressures. Our findings could have direct implications for the design and clinical handling of BVS instruments.

Preparation and characterization of bionanocomposite films based on potato starch/halloysite nanoclay

In this research casting method was used to prepare potato starch based bio-nanocomposite films with halloysite nanoclay as the reinforcing materials. The composition included potato starch with 40% (w/w) of a mixture of sorbitol/glycerol (weight ratio of 3 to 1as plasticizer) with nanoclay (0–5% w/w). The films were dried under controlled conditions. Physicochemical properties such as solubility in water, water absorption capacity (WAC), water vapour permeability (WVP), oxygen permeability, and mechanical properties of the films were measured. Results showed that by increasing the concentration of nanoclay, mechanical properties of films were improved. Tensile strength was increased from 7.33 to 9.82MPa, and elongation at break decreased from 68.0 to 44.0%. Solubility in water decreased from 35 to 23%, and heat seal strength increased from 375 to 580N/m. Also incorporation of clay nanoparticles in the structure of biopolymer decreased permeability of the gaseous molecules. In summary, addition of halloysite nanoclay, improve the barrier and mechanical properties of potato starch films and this bionanocomposites have high potential to be used for food packaging purposes.

A novel approach toward the effect of seal process parameters on final seal strength and microstructure of LLDPE

The optimization of heat-sealing process parameters, including time, temperature, and pressure, was performed on a monolayer linear low-density polyethylene (LLDPE) film. The seal properties examined for each process condition were: seal initiation temperature (Tsi), plateau initiation temperature (Tpi), final plateau temperature (Tpf), plateau seal strength (SSp), and failure mode. Increasing dwell time enhanced seal strength. However, it was found that the rate of this enhancement is different for each interval of dwell time. A narrow temperature plateau was observed for dwell times lower than 0.4 s and higher than 2 s, while in between a broad temperature window was observed. The pressure shows its influence up to the stage of wetting. And after providing the intimate contact between two film layers, additional increase in pressure does not enhance seal strength significantly. A 3D mapping of process safety zone was introduced for seal strength in the range of heat seal process variables for the very first time. The analysis of this 3D representation revealed that seal strength has a linear correlation with the square root of dwell time. In addition, the interfacial bond strength was shown to be proportional to the fraction of melted crystals. It was found that this fraction is determined by dwell time and temperature. Topography and morphology of surfaces after peeling revealed enlargement of fibrillar morphology to taller failure fracture complex shapes. Extensive roughness analysis on film surfaces after peeling found the much rougher surfaces after breakage of strong bonding.

Rapid sealing and cutting of porcine blood vessels,ex vivo, using a high-power, 1470-nm diode laser

Suture ligation with subsequent cutting of blood vessels to maintain hemostasis during surgery is time consuming and skill intensive. Energy-based electrosurgical and ultrasonic devices are often used to replace sutures and mechanical clips to provide rapid hemostasis and decrease surgery time. Some of these devices may create undesirably large collateral zones of thermal damage and tissue necrosis, or require separate mechanical blades for cutting. Infrared lasers are currently being explored as alternative energy sources for vessel sealing applications. In a previous study, a 1470-nm laser was used to seal vessels 1 to 6 mm in diameter in 5 s, yielding burst pressures of ∼500 mmHg. The purpose of this study was to provide vessel sealing times comparable with current energy-based devices, incorporate transection of sealed vessels, and demonstrate high vessel burst pressures to provide a safety margin for future clinical use. A 110-W, 1470-nm laser beam was transmitted through a fiber and beam shaping optics, producing a 90-W linear beam 3.0 by 9.5 mm for sealing (400 W/cm2), and 1.1 by 9.6 mm for cutting (1080 W/cm2). A two-step process sealed and then transected ex vivo porcine renal vessels (1.5 to 8.5 mm diameter) in a bench top setup. Seal and cut times were 1.0 s each. A burst pressure system measured seal strength, and histologic measurements of lateral thermal spread were also recorded. All blood vessels tested (n=55 seal samples) were sealed and cut, with total irradiation times of 2.0 s and mean burst pressures of 1305±783 mmHg. Additional unburst vessels were processed for histological analysis, showing a lateral thermal spread of 0.94±0.48 mm (n=14 seal samples). This study demonstrated that an optical-based system is capable of precisely sealing and cutting a wide range of porcine renal vessel sizes and, with further development, may provide an alternative to radiofrequency- and ultrasonic-based vessel sealing devices.

Antibacterial, mechanical, and barrier properties of sago starch film incorporated with betel leaves extract

The antimicrobial, mechanical and barrier properties and light transmission of sago starch film incorporated with different percentage of Betel leaf extract (5%, 10%, 20%, and 30%) were evaluated. With regard to mechanical properties, tensile strength decreased when the percentage of extract increased. Elongation at break (%) and seal strength (N/m) increased with increasing percentage of extract from 5% to 20%, while decreased for films containing 30% extract due to heterogeneity of films in this percentage. With regard to barrier properties, water vapour and oxygen barrier properties decreased in all samples when percentage of the extract increased. Antimicrobial activity of all the films increased against both Gram positive and Gram negative bacteria as percentage of Betel leaf extract increased, except for Psuedomonas aeruginosa, which was not susceptible at any percentage of the extract.

Comparative Study of Flange-to-Seal Contact Couplings With Bolt Relaxation Under Creep Condition

Future coal-fired steam turbines promise increased efficiency and low emissions. However, this comes at the expense of increased thermal load from higher inlet steam temperatures and pressures leading to severe creep that significantly influences the sealing behavior and high temperature strength of bolted flange-seal couplings. Flanges with different thicknesses were employed for a comparative study. The important stress/creep values in the flanges and U-type seals had been obtained for variations in flange thickness and bolt relaxation while maintaining other leading parameters constant. The variation of contact stresses due to creep deformation plays an important role in achieving a leak proof sealing. In this paper, a two-dimensional finite element analysis of bolted flange-seal couplings has been carried out by taking the relaxation of bolt stress under full-loading turbine service. The creep strength of flanges and U-type seals are investigated by Cocks–Ashby (C–A) equivalent strain method. The multiaxial state of stresses is considered in this method by using C–A multiaxial coefficient. According to ASME allowable creep limit, the C–A equivalent strains of three flange-seal couplings are evaluated and compared. Furthermore, based on the results of contact stresses, the creep behavior of U-type seals is analyzed varying flange thickness. Finally, analysis shows that the thinner flange-seal coupling has larger long-term contact stress, while the U-type seal with the thicker flange has the least creep strength.