Effect of water absorption in polymers at low and high temperatures

Baschek, G; Hartwig, G.; Zahradnik, F.

doi:10.1016/s0032-3861(98)00560-6

Cited by 150 publications

(94 citation statements)

References 11 publications

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“…The first weight loss of the extracted tannins and resins is attributed to the loss of moisture in a single step around 303-328 K and 380-384 K, with the highest loss being observed in GT (7%) and GTR (11%), respectively. According to Sepe [38], almost every resin contains some degree of absorbed atmospheric moisture which may influence the mechanical performance [39], and also the rate of absorption of the material [40].…”

Section: Thermal and Functional Group Properties Of The Tannins And Rmentioning

confidence: 99%

Removal of Pb2+ from Water by Synthesized Tannin Resins from Invasive South African Trees

Okoli

Shilowa

Anyanwu

et al. 2018

Water

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Contamination of water by Pb2+ and the threat of invasive vegetation affects the quality and quantity of water accessible to all life forms and has become a primary concern to South Africa and the world at large. This paper synthesized, characterized, and evaluated the resins from tannin-rich invasive Acacia species as an environmentally benign Pb 2+ adsorbent. The analysis of the pore volume and surface area of the resins reveals a small pore dimension of 9 × 10 −3 cc/g and large surface area (2.31-8.65 m 2 /g), presenting suitable physical parameters for adsorption of Pb 2+ . Langmuir model offers the best correlation data at pH 6 with maximum monolayer coverage capacity of 189.30, 105.70 and 98.82 mg/g for silver, black and green wattle tannin resins in aqueous solutions, respectively. The kinetic data suitably fits into a pseudo-second-order model, with the Dubinin-Radushkevich adsorption energy (E) ≤ 7.07 KJ/mol and intra-particle diffusion model confirming an associated physisorption process within the bio-sorption system. The thermogravimetric analysis (TGA) and Fourier-transform infrared (FT-IR) data of the resins were informative of the high thermal stability and chelating functionality such as -OH and -NH 2 responsible for the removal of Pb 2+ . All the resins showed good adsorption characteristics while silver wattle tannin resin has the best adsorption capacity compared to black and green wattle tannin resins. This study provides a prototype adsorbent from invasive plants for the removal of Pb 2+ in water.

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Section: Thermal and Functional Group Properties Of The Tannins And Rmentioning

confidence: 99%

Removal of Pb2+ from Water by Synthesized Tannin Resins from Invasive South African Trees

Okoli

Shilowa

Anyanwu

et al. 2018

Water

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“…As several other studies have concluded, this can be attributed to a higher water affinity, which attracts water molecules during absorption [10,[21][22][23][24]. This attraction can cause swelling within the cavities of the polymer network, which further increases M ∞ (%) and D. The diffusion coefficients of individual layers were also compared with those of multi-layer coatings as shown in Table 3.…”

Section: Water Uptake Processmentioning

confidence: 96%

“…9. Water is commonly considered to act as a plasticizing agent in polymers [9,21,[26][27][28] such as hydrogen and dipole-dipole bonding, cause some degree of reduction in chain mobility [29]. This has the effect of "averaging" or decreasing the distribution of the relaxation times for the individual components of the system.…”

Section: Stretched Exponential Relaxation Behaviormentioning

confidence: 99%

Water Absorption and Degraded Stress Relaxation Behavior in Water-Borne Anticorrosive Urethane/Epoxy Coatings

Takeshita¹,

Becker²,

Sakata³

et al. 2015

JCCE

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Abstract:The kinetics of water absorption in water-borne anticorrosive urethane/epoxy coatings, which were actually introduced in the industrial field, are studied. It is found that the high water affinity of a water-borne coating supports a higher saturated water content, M ∞ , and helps to facilitate absorption D. The three parameters of stretched exponential function called the William-Watt equation, E o , τ, and β, are determined to fit the degraded stress relaxation behavior in the water absorption process because this function quantitatively describes the relaxing ability and has been successfully used by a number of researchers. An increasing in the water content is shown to correlate strongly with a decrease in E o and β early in the absorption process between M t /M ∞ = 0 and M t /M ∞ ≈ 0.5. The adhesive characteristics of the coatings are correlated with water content, and shown to exhibit higher cohesive failure in coating epoxies under saturated conditions. This suggests that water interferes with the intermolecular bonding between polymer chains which degrades the bulk materials ability to diffuse stress concentrations and reduces its overall strength.

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“…Once absorbed, the water is considered to be present in the free volume, inducing property changes through the connection of molecular chains to form hydrogen bonds and hydrogen bridges. 1 In commercially available and thermoplastic polyamides, moisture has been reported to act as a plasticizer in the polymer matrix, lowering the glass-transition temperature (T g ). 2 The scission of hydrogen bonds by water is expected to cause undesirable changes or decrease of mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

“…2 The scission of hydrogen bonds by water is expected to cause undesirable changes or decrease of mechanical properties. As such, the changes in structure and properties of various polyamides due to moisture absorption have been investigated over a wide range of temperature, including polymeric materials such as nylon 12 1,3 , nylon 66 4,5,6 , nylon 1010 5 , nylon 6 7 , nylon 610 5,8 , nylon 612 9 , recycled nylon 66 10 , and semiaromatic polyamide synthesized using aliphatic diamine and metha-or para-oriented phthalic acids 11 .…”

Section: Introductionmentioning

confidence: 99%

Hydration in a new semiaromatic polyamide observed by humidity‐controlled dynamic viscoelastometry and X‐ray diffraction

Uddin

Gotoh

Ohkoshi

et al. 2005

J Polym Sci B Polym Phys

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Hydration in a new semiaromatic polyamide, named polyamide 9-T (PA9-T), a copolymer of terephthalic acid with n-and iso-nonanediamine, is studied by dynamic viscoelastic analysis under controlled humidity conditions and wide-angle x-ray diffraction analysis in comparison with common polyamide nylon 6. The storage modulus of PA9-T is retained at up to 60 ºC with increasing humidity, then dropping with further increases in temperature past 70 ºC. The decrease in mechanical properties at 70 ºC due to moisture uptake is found to be substantially improved by annealing to develop molecular packing and/or crystallization. In contrast, the storage modulus of very highly crystallized (50% crystallinity) nylon 6 decreases markedly with humidity at low temperatures such as 20 ºC. Thus, PA9-T retains its mechanical properties in humid atmospheres at much higher temperatures than nylon 6. The crystalline x-ray diffraction peaks for nylon 6 corresponding to (002) + (202) of α form shift upon absorption of moisture, speculated to be due to the weakening of hydrogen bonds and the subsequent conformational disordering of the chains. Unlike nylon 6, the crystalline peaks of PA9-T do not shift due to moisture uptake. This is considered to be attributable to that the long aliphatic chain in PA9-T forms the large hydrophobic domain, rendering PA9-T less hygroscopic than nylon 6. Additionally, strong hydrogen bonds formed by terephthalamide residues together with a strong stacking force of phenylene groups may also repel water, preventing moisture bind with the amide groups of PA9-T crystals.

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Effect of water absorption in polymers at low and high temperatures

Cited by 150 publications

References 11 publications

Removal of Pb2+ from Water by Synthesized Tannin Resins from Invasive South African Trees

Removal of Pb2+ from Water by Synthesized Tannin Resins from Invasive South African Trees

Water Absorption and Degraded Stress Relaxation Behavior in Water-Borne Anticorrosive Urethane/Epoxy Coatings

Hydration in a new semiaromatic polyamide observed by humidity‐controlled dynamic viscoelastometry and X‐ray diffraction

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