Peel Rate Research Articles

VOLATILE ORGANIC COMPOUNDS FROM CITRUS FEED MILL EMISSIONS1

ABSTRACTAlthough citrus processors recover most of the essential oils in the peel, the amount remaining is released as air pollutants and volatile organic compounds (VOCs) during cattle feed manufacturing. Citrus processing plants are required to obtain permits allowing emission of 91 t/year (100 tons/year) of VOCs, an amount exceeded by most processors. The objective of this study was to develop an accurate, on‐site method to measure VOC emissions, accomplished by use of adsorbent traps subsequently analyzed by gas chromatography. Over 90 percent of the oil entering the feed mill was accounted for, with d‐limonene as the major VOC, including other terpenes, β‐pinene and myrcene. Of sampling locations in a typical feed mill, error analysis determined the least precision (16.9%) was associated with determining the input rates of peel to the dryer. The sampling technique developed is a viable method for monitoring VOCs with reproducible results.

Self-Adhesion of Polyethylene in the Melt. 1. Heterogeneous Copolymers

Development of self-adhesion above the melting temperature was studied in a group of linear low-density polyethylenes. An experimental procedure for consecutively sealing and peeling a polymeric film at the same temperature, above the melting point, was developed. This made it possible to measure melt adhesion over a wide range of temperatures, seal times, and peel rates. Taking advantage of the new experimental technique, the molecular mechanisms and kinetics of self-adhesion in heterogeneous ethylene copolymers with broad molecular weight distribution were investigated. It was found that the peel strength increased with the contact time in accordance with the conventional t1/2 dependence until saturation at the maximum strength. The time to achieve maximum strength was significantly shorter for the copolymer with more homogeneous copolymer composition; however, the maximum strength was the same for all the materials at each test temperature. The saturation time in all cases was 2 orders of magnitude lon...

Easy removal of pressure sensitive adhesives for skin applications

There are two essential requirements of medical pressure sensitive adhesives: that they should stick firmly to a difficult substrate (skin) and that they should be easily and cleanly removed from that substrate when desired. These requirements would seem to be in conflict: a high peel force usually signals the ability to stick firmly, while a low force is needed when removing dressings by peeling. A number of ways have been considered to resolve this conflict. These may be divided into two broad categories: those that make the best of existing pressure sensitive adhesives technology, broadly taking a physical approach, and those that introduce novel chemistry into the process. Physical approaches consider such details as the dependence of peel force on peel angle, peel rate, backing materials, the deformation of the skin during peeling and use of barrier films and solvents. As an alternative to simply making the best of the physics of the peeling process, various workers have devised chemical systems for making the adhesive less strongly adhering at the time of removal. These systems usually consist of introducing a ‘switch’ mechanism into a strongly adhering adhesive so that its adherence may be reduced significantly at the time of removal by operation of the ‘switch’. Means of activating the ‘switch’ include: heat (warming or cooling), application of water via an absorbent backing and exposure to visible light. These may produce physical or chemical changes in the adhesive. While these approaches bring benefits to patients, consideration of the science behind them is leading to an enhanced understanding of the peeling process.

Development of local patches containing melilot extract and ex vivo–in vivo evaluation of skin permeation

Melilot extract could be effective in treating localised varicose syndrome or capillary fragility. The monolayer patch was selected to obtain a prolonged release of coumarin contained in the phytocomplex. Two types of methacrylic patches (patch 1 based on a blend of Eudragit E100 and Eudragit NE; patch 2 based on Eudragit L100) were prepared. Both patches were equivalent in terms of coumarin release and ex vivo skin permeation profiles. The two patches differed significantly as regards respective adhesive properties. At low peel rate only patch 1 showed adhesive failure as confirmed by the in vivo performance. When comparing the behaviour of the patches containing melilot extract with analogous patches containing synthetic coumarin, no melilot phytocomplex enhancer effect was shown. The data of the ex vivo coumarin skin permeation and those obtained by the in vivo stripping technique showed a good correlation ( r 2=0.9727 for patch 1, r 2=0.9835 for patch 2).

PSA Release Force Profiles from Silicone Liners: Probing Viscoelastic Contributions from Release System Components

Release force profiles of an acrylic- and rubber-based pressure sensitive adhesive (PSA) from silicone release coatings containing different levels of a high-release additive (HRA) were measured. The profiles of release force differed dramatically for the two different adhesive types. The general trends of either increasing or decreasing release force profiles with peel rate were predominantly attributed to the relative ability of the adhesive component to dissipate and store energy (i.e., tan δ) over the operating frequency range. The addition of HRA enhanced the dissipative character (G″ and tan δ increased) of the release coating which resulted in higher release forces. An empirical model based on the viscoelastic properties of the adhesive and release coating was proposed to describe release force profiles and initial estimates for the fitting parameters were determined. The release model was shown to predict successfully the impact of adhesive thickness on the release force profile using an acrylic PSA which was not used for the model development. Some evidence was also obtained for the validity in omitting the contributions of the elastic backing components from the model.

Influence of block molecular weight on the adhesion properties of segmented polyamides

The effects of molecular weight variations in the hard and soft segments on the adhesion strength of segmented polyamides against aluminium, copper, and steel were investigated using 180° peel strength measurements. It was found that the adhesion strength of the segmented polyamides was largely influenced by block molecular weight variations. The nature of the substrate, the rate of peeling, cooling in different environments, and thermal ageing, etc. had significant effects on the adhesion strength of the joints, whereas variation in the moulding conditions used in these experiments did not have much impact on the strength of the joints. The joint strength increased with a decrease in hard block molecular weight at a constant soft block molecular weight of 1000, or with an increase in soft block molecular weight at a constant hard block molecular weight of 1100.

ゴム系複合体の粘弾性と接着強さ

We studied the effects of temperature and rate on adhesive strength of the cord and rubber composite. The peel strength depended strongly on viscoelastic properties of rubber which relates deeply to temperature and the peeling rate. A master curve of the peel strength was also obtained by applying time-temperature superposition principle on the data obtained under several temperatures Observing fracture surface, some types of fracture were found corresponding to the change of viscoelastic properties of rubber compound.The pull-out strength was found to have a similar behavior to the temperature and rate dependencies of the peel strength. Viscoelastic functions could be also applied to the pull-out test.

Egusi Fruit Coring Machine

Based on relevant physical properties of the egusi fruit, a coring machine was designed to remove the seed-bearing core of the mesocarp and endocarp. The purpose of coring is to expose the seed-bearing core to microorganisms to achieve complete decomposition of the mesocarp and endocarp within a short period of time. The coring machine consists of reciprocating ring coring cutter which can be operated manually or by an electric motor. It produces a cylindrically shaped seed bearing mesocarp and endocarp core of the fruit. The prototype machine can core about 458 fruits/h when operated manually at 8–10 rev/min and about 2390 fruits/h when motorized at 50 rev/min, as against a hand peeling rate of 29 fruits/h. Decomposition of the mesocarp and endocarp of the seed-bearing core of the fruit took 2 d as against 7 d for the traditional method of processing.

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.

Muscle cell peeling from micropatterned collagen: direct probing of focal and molecular properties of matrix adhesion.

To quantitatively elucidate attributes of myocyte-matrix adhesion, muscle cells were controllably peeled from narrow strips of collagen-coated glass. Initial growth of primary quail myoblasts on collagen strips was followed by cell alignment, elongation and end-on fusion between neighbors. This geometric influence on differentiation minimized lateral cell contact and cell branching, enabling detailed study of myocyte-matrix adhesion. A micropipette was used to pull back one end of a quasi-cylindrical cell while observing in detail the non-equilibrium detachment process. Peeling velocities fluctuated as focal roughness, microm in scale, was encountered along the detachment front. Nonetheless, mean peeling velocity ( microm/second) generally increased with detachment force (nN), consistent with forced disruption of adhesion bonds. Immunofluorescence of beta1-integrins correlated with the focal roughness and appeared to be clustered in axially extended focal contacts. In addition, the peeling forces and rates were found to be moderately well described by a dynamical peeling model for receptor-based adhesion (Dembo, M., Torney, D. C., Saxman, K. and Hammer, D. (1988). Proc. R. Soc. Lond. B 234, 55-83). Estimates were thereby obtained for the spontaneous, molecular off-rate (kooff, (less than or equal to)10/seconds) and the receptor complex stiffness (kappa, approx. 10(-5)-10(-6) N/m) of adherent myocytes. Interestingly, the local stiffness is within the range of flexible proteins of the spectrin superfamily. The overall approach lends itself to elucidating the developing function of other structural and adhesive components of cells, particularly skeletal muscle cells with specialized components, such as the spectrin-homolog dystrophin and its membrane-linked receptor dystroglycan.

The Influence of Surfactants on the Peel Strength of Water-based Pressure Sensitive Adhesives

In order to study the effect of surfactants on the adhesive properties, peel measurements were performed with two series of model polymers of ethylhexylmethacrylate (PEHMA), the first prepared by emulsion polymerization with four anionic surfactants, and the second by post-adding the same surfactants to a surfactant-free latex. Cohesive fracture is observed at low peel rates; the peel strength depends on the bulk mechanical properties and is independent of the emulsifier. A transition to another type of separation occurs at higher peel rates, which seems to be an interfacial failure by visual inspection. Surface analytical studies, however, give evidence that this “interfacial” failure is, in fact, a mixed failure, leaving traces of the polymer on the substrate surface. The peel rate at this transition as well as the peel strength at mixed fracture are influenced by the surfactants. Large differences were observed between the four surfactants as well as between both series of polymers, leading to the conclusion that the surfactants have a different mobility within the film. This is also reflected by a different aging behaviour of the films.

Performance of laying pullets fed on cereal-free diets based on maize offal, cassava peel and reject cashew nut meal

1. A 70-d experiment was conducted to determine the response of 26-week-old laying pullets to cereal-free diets based on maize offal, cassava peel and full-fat cashew nut meal (CNM) in comparison with a standard 550 g maize/kg reference diet. The 4 test diets all contained 315 g CNM/kg 232.5, 155.0, 77.5 and 0.0 g/kg of maize offal in combination with 77.5, 155.0, 232.5 and 315.0 g/kg of cassava peel, respectively. 2. Pullets fed on the 4 CNM-based diets consumed (P <0.05) less food than those fed on the reference diet; they also had lower (P <0.05) rates of lay , produced less (P <0.05) egg mass, had lower (P <0.05) food conversion efficiencies and their eggs had a lighter (P <0.05) yolk colour. Pullets fed some of the CNM-based diets also gained more (P <0.05) weight, the heaviest (P <0.05) being birds reared on the diet containing 315 g/kg cassava peel. Egg weight, shell thickness and albumen height from all eggs were similar. Pullets fed on the CNM-based diets had inferior (P <0.05) retention of dry matter and protein. 4. It was concluded that feeding full-fat CNM allowed for high dietary inclusion rates of cassava peel and maize offal and the resultant diets, which contained no maize, supported satisactory performance of laying hens.

Effect of peel rate and temperature on delamination toughness of PC–SAN microlayers

The effect of peel rate and temperature on peel toughness and delamination failure mode of coextruded microlayer sheet consisting of alternating layers of polycarbonate (PC) and poly(styrene-co-acrylonitrile) (SAN) was studied with the T-peel test. Microlayers with thin (<1.5μm) SAN layers always failed by interfacial delamination and consequently the interfacial toughness was independent of rate and temperature. In microlayers with thicker SAN layers, the crack alternately propagated through crazes in the SAN and along a PC–SAN interface at intermediate peel rates. The length of the crack-tip zone, the number of crazes and the amount of craze fracture increased with increasing peel rate; the peel toughness increased accordingly. Extending the tests through eight decades in peel rate revealed a transition from craze-dominated cohesive fracture at intermediate rates to predominately interfacial fracture at either very high or very low peel rates. Transitional peel behaviour resulted from the rate sensitivity of yielding and crazing in SAN as determined from tensile tests of bulk polymer.

Abrasion of thin films deposited onto glass by the Taber test

The mechanism of abrasion of sputtered metal nitride thin films on glass by the Taber abrasion test and the effects of mechanical and tribological properties of thin films on Taber abrasion were investigated. The abrasion occurred in a peeling mode: the film was peeled off the substrate and the peeled area increased with increasing number of Taber abrading cycles. The peel rate per Taber cycle, a quantitative measure to represent the abrasion resistance of the thin films, was small in the film with greater adhesion strength, higher hardness and lower frictional resistance of the surface. The effect of these properties on the peel rate was represented with a mathematical equation of exponential form. The peel rate was found to vary most sensitively with the hardness.

Adhesion of latex films. Part III. Surfactant effects at various peel rates

In order to study the effect of surfactants on the adhesion of latex films, peel energy versus surfactant concentration curves were established at various peel rates. The main latex polymer was a methyl methacrylate (MMA)/ethyl acrylate (EA) copolymer synthesized in the presence of a hydrophilic polyester. Another polymer, less extensively studied, a styrene/butyl acrylate/methacrylic acid terpolymer, was also used for comparison purposes. The surfactants were either sodium dodecyl sulfate (SDS) or ethoxylated nonyl phenol containing 30 segments of ethylene oxide (NP30). The substrates were glass plates or poly(ethylene terephthalate) films. It was found that with SDS-containing films, whatever the substrate or the polymer, the curves went through a maximum, whereas with NP30 they went through a minimum, at medium or high peel rates. When the peel rate was decreased, the curves flattened out and at zero peel rate (extrapolated values), they became horizontal. The peel energies at zero peel rate were three to four times higher than the reversible works of adhesion. Qualitative interpretations are proposed for these results.

Adhesion of latex films. Part II. Loci of failure

In order to continue our work on surfactant effects on the adhesion properties of latex films, we investigated a new system based on an acrylic copolymer, synthesized in the presence of a hydrophilic polyester. The surfactants were either sodium dodecyl sulfate (SDS) or an ethoxylated nonyl phenol containing 30 ethoxy groups (NP30). As substrates, either glass plates or poly(ethylene terephthalate) (PET) films were used. This article describes the analysis of the loci of failure after peeling of the films. The analytical techniques used were X-ray photoelectron spectroscopy (XPS) (or ESCA), static secondary ion mass spectrometry (SSIMS), and contact angle measurements. It was shown that the loci of failure were independent of the peel rate and of the nature of the substrate. The failure occurs in a thick surfactant layer for SDS, and in a thin one for NP30. The thickness of the layer increases with the concentration of surfactant in the latex film. The surfactant is located near the surface of the substrate, on top of a layer of hydrophilic polyester. The consequences of the structure of the film-substrate interface on the adhesion properties is presented in Part III in this series.

Effect of the rheological properties of industrial hot-melt and pressure-sensitive adhesives on the peel behavior

Three factors govern the adhesion properties of hot-melt and pressure-sensitive adhesives: (1) thermodynamic interfacial properties (Dupré adhesion energy); (2) interfacial losses due to specific interactions; and (3) viscoelastic losses in the bulk related to the rheological properties of the adhesive. In the present paper, we focus on the main factor in the adhesion properties, which is the viscoelastic factor. We extend in this paper the results obtained on a series of model adhesives to the case of industrial formulations: one SIS triblock copolymer-based PSA formulation and one EVA copolymer-based hot-melt formulation. After studying the rheological properties of these adhesives over a wide frequency range using time-temperature equivalence, we present data obtained on peel tests at various temperatures. As with model adhesives, the peel rate-temperature equivalence leads to the same shift factors as rheology. The experiments demonstrate that there is a one-to-one relationship between the cohesive fracture domain and the terminal region of relaxation exhibited in rheological testing. The first interfacial fracture mode is related to the rubbery plateau, and the brittle interfacial fracture mode observed at high peel rates to the glassy behavior exhibited at very high frequencies in rheological measurements.

Supercritical CO 2 extraction of essential oil from orange peel. Effect of operation conditions on the extract composition

The supercritical fluid extraction (SFE) of orange essential oil was studied using dehydrated orange peel (0.0538 kg H 2O/kg dm) from naveline cultivars as raw material and CO 2 as solvent. The effect of operation conditions was analyzed in a series of experiments at temperatures between 293 and 323 K and pressures between 8 and 28 MPa. The collected extracts were analyzed and the relative composition of the essential oil was determined. Limonene was the principal component extracted, the optimum conditions for limonene extraction were 12.5 MPa and 308 K, in these conditions limonene represents more than 99.5% of the essential oil. Within the operating range conditions, the optimum for extracting linalool was found at 80 bar and 35°C, conditions which coincide, in quite an approximate way, with those in the bibliography (F. Temelli et al., Food Technol. 42 (1988) 1451). Furthermore, the effect of CO 2 flow rate and particle size of orange peel was studied in the range of 0.5 to 3.5 kg h −1 and 0.1 to 10 mm, respectively. For a rapid extraction, particle sizes lower than 2 mm are adequate. For particle size of 0.3 mm and any CO 2 mass flow, approximately 75% of the total content of essential oil was extracted using a solvent ratio of 6 kg of CO 2 per kg of orange peel. A model based on the assumption of plug flow of a solvent through a fixed bed of milled material was applied to analyze the experimental results. The model successfully fitted the kinetic extraction of the essential oil.

Complete epiretinal membrane separation in highly myopic eyes with retinal detachment resulting from a macular hole

PURPOSE: Epiretinal membranes (ERMs) in highly myopic eyes may result in macular holes and subsequent retinal detachment. However, removing friable, thin ERMs from detached retinas is often difficult. We report the efficacy of a diamond-dusted silicone cannula in the removal of ERMs from detached retinas. METHODS: Seventeen consecutive highly myopic eyes (16 patients) with retinal detachment underwent pars plana vitrectomy with gas tamponade. Peeling of the ERM adjacent to the macular hole was performed using either conventional tools (n = 11) or a diamond-dusted silicone cannula (n = 6). The rate of complete membrane peeling and the effect of membrane removal on the anatomic success rate were compared between groups. RESULTS: Retinal reattachment occurred in 13 (92.9%) of the 14 eyes in which the ERM was removed completely; redetachment occurred in the other three eyes, with further surgical interventions in two eyes. The reattachment rate was significantly higher ( P = .005) when ERM removal was complete than when there was residual ERM. In the initial surgery, the ERM was successfully removed in all 6 eyes (100%) in the diamond-dusted silicone cannula group and in 5 of 11 eyes (45.5%) in the conventional group ( P = .041); the reattachment rate was 100% in the diamond-dusted silicone cannula group and 45.5% in the conventional group ( P = .005). When a second surgery was performed, the use of the diamond-dusted silicone cannula was also better than conventional tools for removing the residual ERMs, resulting in retinal reattachment. CONCLUSION: In highly myopic eyes with a macular hole and subsequent retinal detachment, complete ERM removal is closely related to successful retinal reattachment. The diamond-dusted silicone cannula appears to be more effective than conventional tools for removing ERM and may increase the anatomic success rate. Because of the limitations of a small series, a prospective, randomized trial is required to confirm the current beneficial results of using a diamond-dusted silicone cannula.

Rheological modelling of the peeling of pressure-sensitive adhesives and other elastomers

The transient extensional viscosity of a polyisobutylene (PIB)-based pressure-sensitive adhesive (PSA) is measured in a filament stretching instrument at three stretch rates, and compared with theoretical predictions based on the linear viscoelastic (LVE) properties of the PSA and the use of linear and non-linear constitutive equations. Based on previously reported adhesive stretch rate profiles across the peel front, a model predicting peel force from peel rate is proposed and evaluated for each constitutive equation. A new expression for the relative contributions of the individual relaxation modes of the polymeric material to the total measured peel force is derived and the result is discussed with regard to correlation of LVE data to peel performance. Comparison of predicted and measured peel force values reveals that peeling of this PSA is only qualitatively described by linear viscoelasticity; quantitative agreement is obtained when the strain-hardening behaviour of the adhesive is properly modelled.