The glass transition process in humid biopolymers. DSC study

Grunina, N. A.; Belopolskaya, T. V.; Tsereteli, G. I.

doi:10.1088/1742-6596/40/1/013

Cited by 22 publications

(15 citation statements)

References 4 publications

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“…Absorption of 1% water has been shown to reduce the α‐peak ( T g ) by 30°C in Nylon 6,12 9. A pronounced reduction in glass transition temperature on water absorption has similarly been reported by Grunina et al for a range of biopolymers, such as DNA and elastin, using differential scanning calorimetric methods 1. It has been suggested that addition of water influences the molecular packing in amorphous polymers such as Nylon 9.…”

Section: Resultssupporting

confidence: 62%

“…Mechanical properties of biological and polymeric samples may vary considerably when in a fluid environment compared with the usual ambient (∼ 50% relative humidity, RH) testing conditions. While hydrophobic polymers do not absorb water significantly (so their mechanical properties are unchanged), polar materials in contrast such as biopolymers (for example DNA, elastin, starch, and cutin1, 2) absorb water and can swell significantly at saturation. Their mechanical properties are interlinked with their water content.…”

Section: Introductionmentioning

confidence: 99%

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Influence of water on the nanoindentation creep response of nylon 6

Bell

Bieliński

Beake

2007

J of Applied Polymer Sci

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A nanoindentation system fitted with a fluid cell has been used to probe the influence of water on the nanoindentation creep response of commercial Nylon-6 samples. Measurements on samples taken while immersed in deionized water were compared with measurements under usual ambient ($ 50% relative humidity) conditions. Water absorption reduces hardness by around 50% and elastic modulus by around 65%. The dimensionless creep parameter, A/d(0), where A is a constant and d(0) is the initial penetration at the start of the creep-hold period, is a measure of the proportion of time-dependent deformation compared with the total deformation. This parameter decreases significantly in water. We have suggested previously that A/d(0) correlates with tan d. The observed reduction in A/d(0) when wet is consistent with a decrease in the tan d peak due to a shift in the glass transition temperature when wet.

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Section: Resultssupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Influence of water on the nanoindentation creep response of nylon 6

Bell

Bieliński

Beake

2007

J of Applied Polymer Sci

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“…The effect of moisture content on the glass transition temperature has been extensively studied 9, 12, 17, 25, 46, 49–55. Water reduces the glass transition temperature and reduces the temperature at which secondary interactions between protein chains form.…”

Section: Structure/processing Relationshipsmentioning

confidence: 99%

Extrusion Processing and Properties of Protein‐Based Thermoplastics

Verbeek

Berg

2010

Macro Materials & Eng

289

204

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Increasing interest in competitive, sustainable, and biodegradable alternatives to petroleum‐based plastics has encouraged the developmentof protein‐based plastics. The formation of a homogeneous protein melt during extrusion occurs through: denaturation, dissociation, unraveling, and alignment of polymer chains. The presence of covalent cross‐links is unfavorable, decreasing chain mobility, increasing viscosity and preventing homogenization. Proteins have high softening temperatures, often above their decomposition temperatures. To avoid degradation, the required chain mobility is achieved by plasticizers. By understanding a protein's physiochemical nature, additives can be selected that lead to a bioplastic with good processability. The final structural and functional properties are highly dependent on the protein and processing conditions.

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“…[ 31 ] Steady decrease of glass transition temperature with increasing moisture content is a well recorded phenomenon reported in many synthetic and biological polymers. [32][33][34][35][36][37][38] Silk, for example, exhibits a dramatic decrease in glass transition temperature when comparing fully dry and wet fi bers, 197 °C and 30 °C, respectively. [ 39 ] Similarly, our results suggest that at relative humidity between 60% and 70%, the glass transition temperature of the interprismatic organic matrix drops close to room temperature.…”

Section: Water and Mechanical Properties Of Prismatic Layer Constituentsmentioning

confidence: 99%

Inherent Role of Water in Damage Tolerance of the Prismatic Mineral–Organic Biocomposite in the Shell of Pinna Nobilis

Bayerlein

Bertinetti

Bar‐On

et al. 2016

Adv Funct Materials

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The combination of high stiffness, strength, and toughness of many biological tissues is achieved through complex 3D arrangement of hard and soft components. While the hard building blocks are associated with the general stiffness of these biocomposite structures, the soft organic constituents provide the necessary flexibility and toughness and are susceptible to moisture uptake. Because many biological materials reside in humid environments, water is an inherent component of their microstructure. Hence, many studies have emphasized the effect of moisture content on mechanical performance of these materials. High toughness is indeed reported in materials, such as bone, teeth, mollusk shells, and glass sponges, when measured in high relative humidities, nevertheless, not much is known about the exact mechanisms that are responsible for this phenomenon. In the present work, newly developed environmentally controlled nanomechanical characterization techniques are employed to probe the prismatic layer in the shell of Pinna nobilis consisting of hard calcitic blocks surrounded by 1 μm thick organic matrix. Using spatially resolved mechanical data, it is demonstrated that water not only strongly affects the mechanical properties of the biocomposite tissue and its constituents but also is an integral part of explicit intrinsic and extrinsic toughening mechanisms revealed in this study.

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The glass transition process in humid biopolymers. DSC study

Cited by 22 publications

References 4 publications

Influence of water on the nanoindentation creep response of nylon 6

Influence of water on the nanoindentation creep response of nylon 6

Extrusion Processing and Properties of Protein‐Based Thermoplastics

Inherent Role of Water in Damage Tolerance of the Prismatic Mineral–Organic Biocomposite in the Shell of Pinna Nobilis

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