Improvement of the Launderability of Polypropylene Multifilament Yarns

1969 ◽  
Vol 39 (12) ◽  
pp. 1150-1158 ◽  
Author(s):  
Robert P. Weimer ◽  
Willard P. Conner
Keyword(s):  
Molecular Weight ◽  
Experimental Evidence ◽  
Concentration Profile ◽  
Consumer Products ◽  
Epidermal Layer ◽  
Loss Mechanism ◽  
Antioxidant Concentration ◽  
Multifilament Yarns

Polypropylene multifilament yarns are being used in a variety of industrial and consumer products. Penetration into some textile markets, however, has been hampered by poor resistance to laundering. Cyclic wash-dry laundering causes heat-stabilized yarns to lose antioxidant and strength more rapidly than the sum of the effects of washing or drying alone. This phenomenon plus other experimental evidence indicate that the dominating loss mechanism is one of diffusion or “thermal pumping.” It is suggested that during washing the antioxidant is leached from the epidermal layer of the fiber. During drying, the antioxidant diffuses to the surface from within as the antioxidant concentration profile is leveled throughout the fiber. Increasing the molecular weight of an antioxidant species reduces its diffusivity with a concomitant loss in antioxidant capability. Very long lifetimes, however, under home laundering conditions have been achieved by a compromise between diffusivity and capability of the antioxidant.

Rate Coefficients and Mechanisms of Atmospheric Oxidation of the Esters

2011 ◽  
Author(s):  
Jack Calvert ◽  
Abdelwahid Mellouki ◽  
John Orlando ◽  
Michael Pilling ◽  
Timothy Wallington
Keyword(s):  
Vegetable Oils ◽  
Methyl Esters ◽  
Ambient Air ◽  
Consumer Products ◽  
Anthropogenic Sources ◽  
Atmospheric Oxidation ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Loss Mechanism ◽  
Animal Fats

Esters are emitted directly into the atmosphere from both natural and anthropogenic sources and are produced during the atmospheric oxidation of ethers. Methyl acetate and ethyl acetate have found widespread use as solvents. Vegetable oils and animal fats are esters. Transesterification of vegetable oils and animal fats with methanol gives fatty acid methyl esters (FAMEs) which are used in biodiesel. Many esters have pleasant odors and are present in essential oils, fruits, and pheromones, and are often added to fragrances and consumer products to provide a pleasant odor. Table VII-A-1 provides a list of common esters and their odors. It is surprising to note that despite their ubiquitous nature, volatility, and fragrance, it is only very recently that quantitative measurements of esters in ambient air have been reported (Niedojadlo et al., 2007; Legreid et al., 2007). The atmospheric oxidation of saturated esters is largely initiated by OH radical attack. Reaction with O3 and NO3 radicals contributes to the atmospheric oxidation of unsaturated esters. As discussed in chapter IX, UV absorption by esters is only important for wavelengths below approximately 240 nm and, hence, photolysis is not a significant tropospheric loss mechanism. When compared to the ethers from which they can be derived, the esters are substantially less reactive towards OH radicals. The ester functionality —C(O)O— in R1C(O)OR2 deactivates the alkyl groups to which it is attached with the deactivation being most pronounced for the R1 group attached to the carbonyl group. The atmospheric oxidation mechanisms of the esters are reviewed in the present chapter. The reaction of OH with methyl formate has been studied by Wallington et al. (1988b) and Le Calvé et al. (1997a) over the temperature range 233–372 K. Data are summarized in table VII-B-1 and are plotted in figure VII-B-1. The room temperature determination of k(OH + CH3OCHO) by Wallington et al. is in agreement with that by Le Calvé et al. (1997) within the experimental uncertainties. Significant curvature is evident in the Arrhenius plot in figure VII-B-1.

Beauty in Efficiency

2016 ◽  
Vol 35 (1) ◽  
pp. 93-120 ◽  
Author(s):  
Odette da Silva ◽  
Nathan Crilly ◽  
Paul Hekkert
Keyword(s):  
Experimental Design ◽  
Experimental Evidence ◽  
Product Design ◽  
Consumer Products ◽  
Maximum Effect ◽  
Aesthetic Appreciation ◽  
Use Of Resources ◽  
Wide Range ◽  
The Aesthetic ◽  
Principle Of Maximum

Theory and discourse suggest that the aesthetic appreciation of a wide range of artifacts—including works of art and consumer products—is partially governed by the principle of maximum effect for minimum means. We conducted two studies to find experimental evidence of this principle in the context of product design. In Study 1, we tested the hypothesis that the aesthetic appreciation of a product would be positively affected by the perception of the product as the minimum means achieving the maximum effect. Encouraged by the results of this study, we conducted Study 2 to test again the principle of maximum effect for minimum means using a more controlled experimental design. Our findings provide support for our hypothesis, indicating that the aesthetic appreciation of a product depends, to some extent, on the perception that the product achieves more than other products from its category by making an efficient use of resources.

Surface Enrichment and Evaporation in a Polymer Mixture of Long and Short Chains

1989 ◽  
Vol 166 ◽  
Author(s):  
Russell J. Composto ◽  
Richard S. Stein ◽  
Gian P. Felcher ◽  
Abdelkader Mansour ◽  
Alamgir Karim
Keyword(s):  
Molecular Weight ◽  
Film Thickness ◽  
Concentration Profile ◽  
Scattering Length ◽  
Weight Fraction ◽  
Polymer Mixture ◽  
Light Chains ◽  
Neutron Reflectivity ◽  
Surface Enrichment ◽  
Polymer Interface

ABSTRACTNeutron reflectivity has been used to determine the concentration profile at the vacuum-polymer interface for a two polymer blend. To quantify surface enrichment and evaporation due to differences in chain length, we have measured the reflectivity of a mixture of short deuterated and long protonated polystyrene chains (DPS & PS), with a weight fraction of 0.5. When a mixture of DPS and PS chains of molecular weight 720 and 910k respectively were annealed, a small but measurable increase in asymptotic reflectivity occured, coupled with a decrease of film thickness and scattering length density. This is indicative of surface enrichment and evaporation of the light chains (DPS). Ellipsometry studies confirmed that the short chains evaporated and its rate was established as a function of the temperature. Upon increasing the DPS molecular weight to 9600, the enrichment becomes considerably greater whilst the evaporation becomes negligible.

Dynamic Mechanical Properties of Cross-Linked Rubbers. II. Effects of Crosslink Spacing and Initial Molecular Weight in Polybutadiene

1966 ◽  
Vol 39 (4) ◽  
pp. 905-914
Author(s):  
Etsuji Maekawa ◽  
Ralph G. Mancke ◽  
John D. Ferry
Keyword(s):  
Molecular Weight ◽  
Crosslink Density ◽  
Low Frequency ◽  
Dynamic Mechanical Properties ◽  
Cross Linking ◽  
Loss Mechanism ◽  
Low Frequencies ◽  
Molecular Weights ◽  
Monomeric Friction Coefficient ◽  
Lower Frequencies

Abstract The complex shear compliances of eight samples of polybutadiene crosslinked by cumyl peroxide and four samples crosslinked by sulfur have been measured over a frequency range from 0.2 to 2 cps at temperatures from − 6 to 45° C by a torsion pendulum. On four of the samples, measurements were extended by the Fitzgerald transducer from 45 to 600 cps at temperatures from − 71 to 55°. The vulcanizates had been prepared from polymers of two different molecular weights (180,000 and 510,000) with sharp molecular weight distribution; the physical crosslink density ranged from 0.57 to 2.68×10−4 mole/cm3, and the chemical crosslink density calculated following Kraus ranged from 0.22 to 1.49×10−4 mole/cm3. The mechanical data were all reduced to T0=298° K by shift factors calculated from the equation log aT=−3.64(T−T0)/(186.5+T−T0). In the transition zone of frequencies, the viscoelastic functions of the cumyl peroxide vulcanizates were closely similar, except for a shift toward lower frequencies with increasing crosslinking, corresponding to a small but unexpected increase in the monomeric friction coefficient. Cross-linking by sulfur caused a somewhat larger shift toward lower frequencies at a comparable crosslink density. In the rubbery zone, the sample with least cross-linking exhibited a substantial secondary loss mechanism at very low frequencies. The low-frequency losses are evident in all the samples, but their magnitude falls rapidly with increasing crosslink density as previously found for natural rubber. It also falls somewhat with increasing initial molecular weight, indicating a contribution from network strands with loose ends. The possible relation of the low-frequency losses to trapped entanglements is discussed.

scholarly journals Dietary intake and household exposures as predictors of urinary concentrations of high molecular weight phthalates and bisphenol A in a cohort of adolescents

2021 ◽  
Author(s):  
Anna R. Smith ◽  
Katherine R. Kogut ◽  
Kimberly Parra ◽  
Asa Bradman ◽  
Nina Holland ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Bisphenol A ◽  
High Molecular Weight ◽  
Fast Food ◽  
Building Materials ◽  
Endocrine Disrupting Chemicals ◽  
Consumer Products ◽  
Adverse Health Outcomes ◽  
Endocrine Disrupting ◽  
Ethylhexyl Phthalate

Abstract Background Phthalates and bisphenol A (BPA) are endocrine disrupting chemicals used in consumer products, building materials, and food processing and packaging materials. They are associated with adverse health outcomes, especially when exposure occurs during heightened windows of susceptibility. Objective We evaluated the relationship between housing and dietary characteristics and the concentration of several high-molecular-weight (HMW) phthalate metabolites and BPA in a cohort of Latina adolescents. Methods We collected information on recent food consumption and housing characteristics and quantified the concentration of HMW phthalate and BPA metabolites in urine collected at two different time points. We used generalized estimating equations (GEE) to assess predictors of each metabolite. Results No significant associations were observed between housing and dietary characteristics and metabolites of di(2-ethylhexyl) phthalate (DEHP) or BPA. In contrast, higher urinary monobenzyl phthalate (MBzP) concentration was associated with living in a home with vinyl or linoleum flooring (66.7% change, p-value <0.01), while higher urinary mono(3-carboxypropyl) phthalate (MCPP) concentration was associated with recent consumption of coffee (47.2% change, p-value <0.01), and fast food (30.3% change, p-value <0.05). Significance These findings may be useful in targeting interventions that reduce phthalate uptake in young adults.

Research of 3D weft-knitted fabrics designed to protect against mechanical risks and suitable for contact with skin

2020 ◽  
pp. 152808372092583
Author(s):  
Julija Krauledaitė ◽  
Kristina Ancutienė ◽  
Sigitas Krauledas ◽  
Virginijus Urbelis ◽  
Virginija Sacevičienė
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Outer Layer ◽  
Steel Wire ◽  
Strong Positive Correlation ◽  
Knitted Fabrics ◽  
Spun Yarns ◽  
Puncture Force ◽  
Multifilament Yarns ◽  
Knitted Structure

Eight different 3D weft-knitted fabrics, consisting of outer, binding, and inner layers, were designed and produced on E20 and E28 circular weft-knitting machines. First, in the outer layer, high molecular weight polyethylene multifilament yarns and steel wire (0.05 mm diameter), twisted with high molecular weight polyethylene multifilament yarns, were used because of their exceptional properties to resist the mechanical risks. Second, in the inner layer, hydrophobic polyester spun yarns were chosen for their suitability to be used in contact with skin. Finally, in the binding layer, synthetic elastic textured polyamide yarns were used to connect the outer and inner layers. Following the standard EN 388, diverse tests were conducted to determine the resistance of the developed 3D weft-knitted fabrics to mechanical risks, i.e., circular blade cut, puncture, abrasion, and tear. The analysis showed that the quantity of steel wire in knitted structure highly influences circular blade cut and abrasion resistance, and moderately influences tear resistance for all the investigated knitted fabrics. While a strong positive correlation between the quantity of steel wire and the puncture force was defined only for 3D fabrics knitted on an E20 circular weft-knitting machine. The findings of the research lead to the conclusion that the designed 3D weft-knitted fabric structures, where the outer layer ensures protection against mechanical risks, while the inner layer is designed for contact with skin, provide complex protection against diverse mechanical risks.

Gel Permeation Chromatography/Fourier Transform Infrared Interface for Polymer Analysis

1993 ◽  
Vol 47 (8) ◽  
pp. 1128-1130 ◽  
Author(s):  
L. M. Wheeler ◽  
J. N. Willis
Keyword(s):  
Molecular Weight ◽  
Concentration Profile ◽  
Elevated Temperatures ◽  
Polymer Concentration ◽  
Gel Permeation Chromatography ◽  
Direct Access ◽  
Copolymer Composition ◽  
Ir Detector ◽  
Gel Permeation ◽  
Small Change

A new solvent elimination interface capable of operating at elevated temperatures, here 145°C, has been used to collect polymer molecular weight fractions eluting from a gel permeation chromatogram and to prepare them for IR analysis. The sample is deposited continuously onto a rotating germanium disk which can subsequently be scanned with the use of GC/FT-IR software, allowing direct access to the polymer or copolymer composition as a function of molecular weight. Data are presented here for an ethylene-propylene copolymer which has a distinct bimodal molecular weight distribution. Both the concentration profile and the “composition distribution” are examined. For the polymer concentration profile, comparison is made between the chromatogram obtained with a differential refractive index (DRI) detector and the IR detector (plotting the absorbance as a function of time using Gram-Schmidt vector orthogonalization). The copolymer composition is determined from the relative absorbance of methyl and methylene groups in the CH stretching region. The results show a small change in propylene content as a function of molecular weight, and there is good agreement between composition calculated with the use of the Gram-Schmidt and point-to-point methods.

Viscosity Variation of Polymer Solution through Low Permeability Cores

2010 ◽  
Vol 34-35 ◽  
pp. 732-736
Author(s):  
Li Juan Zhang ◽  
Xiang An Yue ◽  
Hua Wei Chen ◽  
Jie Zhang ◽  
Tang Suo Chen
Keyword(s):  
Molecular Weight ◽  
Polymer Solution ◽  
Loss Rate ◽  
Injection Velocity ◽  
High Permeability ◽  
Long Distance ◽  
Loss Mechanism ◽  
Viscosity Variation ◽  
Polymer Migration ◽  
Flow Experiments

Viscosity loss occurs in polymer flooding in middle and high permeability reservoir. For larger specific surface and more clay in low permeable rock, the actual viscosity of polymer solution is more important. Polymer cores’ flow experiments are reported which were performed using long natural geological outcrop sands cores. These cores were in good simulation of natural cores and the length of cores allows viscosity variation mechanisms that occur when polymer solution flows through long distance. These mechanisms can not be assessed by silica cores of conventional length. Results of polymer cores’ flow experiments gives viscosity of polymer solution after it through different permeability cores, and the effects of molecular weight, concentration of polymer, migration distance, permeability, and injection velocity on viscosity loss rate. Results show the molecular weight and concentration of polymer is higher, or the core’s permeability is lower, and the viscosity loss of polymer solution through cores is greater. Injection velocity is found to be insignificant within 15m/d for polymer with middle or low molecular weight. This simulation work confirms the viscosity loss mechanism for one polymer in low permeable cores.

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