Thermal Processing Properties Research Articles

Effects of different protein cross-linking degrees on physicochemical and subsequent thermal gelling properties of silver carp myofibrillar proteins sol subjected to freeze-thaw cycles

Knowledge regarding the denaturation process and control methods for depolymerized sol-state myofibrillar proteins (MPs) during freezing remains scant. This study investigated the effects of protein cross-linking treatment before freezing on physicochemical and subsequent gelation properties of MPs sol subjected to freeze-thaw (F-T) cycles. Results indicated that after five F-T cycles, cross-linked MPs sols showed increased high molecular weight polymers and bound water (T21a and T21b) mobility, suggesting enhanced protein-protein interactions at the expense of protein-water interactions. Upon heating after F-T cycles, gels formed from cross-linked sols exhibited significantly higher hardness, springiness, and cooking loss (P < 0.05), alongside more contracted gel networks. Correlation analysis revealed that the formation and properties of thermal gel after freezing closely relate to changes in molecular conformation and chemical bonds of cross-linked MPs sol during freezing. This study provides new insights into regulating the freezing stability and post-thawed thermal processing properties of sol-based surimi products.

High-performance thermoplastic starch/poly(butylene adipate-co-terephthalate) blends through synergistic plasticization of epoxidized soybean oil and glycerol

Utilizing starch, an abundant polysaccharide, as the renewable filler to blend with poly(butylene adipate-co-terephthalate) (PBAT) is a feasible tactic to construct cost-effective and high-performance biodegradable materials. It's worth noting that the thermal processing properties of starch can be manipulated by its plasticized behavior. Herein, epoxidized soybean oil (ESO) and glycerol were used as the plasticizer for native corn starch and the plasticized starch was integrated with PBAT to manufacture starch-based biodegradable blend films. ESO breaks the hydrogen bonds between starch chains through the fatty chains grafting reaction and increases the distance between starch molecular chains due to the large molecular weight of ESO. Meanwhile, glycerol molecules are incorporated into the starch molecular chains, and fatty chains grafted starch chains, effectively reducing the intermolecular forces of molecular chains. On account of the synergistic plasticization of ESO and glycerol which possess good compatibility with PBAT, the PSG20E10 blend film achieved a tensile strength, an elongation at break of 16.11 MPa and 612.09 %, and the balanced water and oxygen permeability properties.

Obtaining of a PET/SiC hybrid multifilament: Non-isothermal crystallization studies

Thermal processing properties are a key factor in the industrial processing industry. The obtaining of a PET-based hybrid composite multifilament with textile properties (yarns) is presented. The system is composed by ceramic silicon carbide (SiC) nanoparticles and a dispersing agent included in a PET matrix. With the objective to produce a suitable nanocomposite, the study is divided in three parts: (i) evaluation by non-isothermal crystallization of three different dispersing agents (two of them based on esters of montanic acids and, the other on an amide wax) to achieve an homogeneous nanocomposite; (ii) study of the influence of the concentrations of SiC and of the more suitable dispersing agent on the thermal properties of the PET-hybrid composite; and (iii) the obtaining of a PET-hybrid multifilament with textile properties together with its characterization by Gel Permeation Chromatography (GPC), Differential Scanning Calorimetry (DSC) and mechanical properties.

Preparation of poly (vinyl alcohol)/ionic liquid composites with improved processability and electrical conductivity for fused deposition modeling

This work aims to realize the fused deposition modeling (FDM) process of poly (vinyl alcohol) (PVA), which is a multi-hydroxyl polymer with good comprehensive properties. However, achieving the FDM process for PVA is quite challenging due to its narrow thermal processing window. To address this problem, an ionic liquid (IL) was introduced to improve the thermal processability of PVA. The materials, the FDM process and properties of the FDM products were systematically evaluated. The results indicated that the PVA/IL composites exhibited significantly improved thermal processing properties. The PVA/IL filament prepared with a suitable viscosity and modulus ratio showed good printability. The tensile strength of the FDM parts increased from 8.7 MPa to 13.6 MPa due to the difference in the interlayer bond strength when the nozzle temperatures ranged from 170 °C to 200 °C. The zero shear rate viscosity, the relaxation time and the surface tension at different printing temperatures were analyzed and provide theoretical insight into the diffusion of polymer chains at the interface during the FDM process. Interestingly, the 3D printed composites were flexible and exhibited tailored electrical conductivity with a strong dependence on the printing temperature, revealing the potential to be functional parts in the field of flexible electronics.

Precipitation and hot deformation behavior of austenitic heat-resistant steels: A review

The austenitic heat resistant-steels have been considered as important candidate materials for advanced supercritical boilers, nuclear reactors, super heaters and chemical reactors, due to their favorable combination of high strength, corrosion resistance, perfect mechanical properties, workability and low cost. Since the precipitation behavior of the steels during long-term service at elevated temperature would lead to the deterioration of mechanical properties, it is essential to clarify the evolution of secondary phases in the microstructure of the steels. Here, a summary of recent progress in the precipitation behavior and the coarsening mechanism of various precipitates during aging in austenitic steels is made. Various secondary phases are formed under service conditions, like MX carbonitrides, M23C6 carbides, Z phase, sigma phase and Laves phase. It is found that the coarsening rate of M23C6 carbides is much higher than that of MX carbonitrides. In order to understand the thermal deformation mechanism, a constitutive equation can be established, and thus obtained processing maps are beneficial to optimizing thermal processing parameters, leading to improved thermal processing properties of steels.

Processing maps and microstructural evolution of the type 347H austenitic heat-resistant stainless steel

Abstract

Thermal effects of ionic liquid dissolution on the structures and properties of regenerated wool keratin

Keratins derived from wool and feathers are a source of raw materials for biomaterial use. Such biomaterials are essentially biodegradable polyamides, and offer many favourable features such as biocompatibility in contrast with petro-derived synthetic materials. In the present study, raw wool samples were dissolved in hot ionic liquid (1-butyl-3-methylimidazolium chloride) at temperatures ranging from 120 to 180 °C, resulting in regenerated keratins after coagulation with water. The physicochemical characteristics of the regenerated keratins were evaluated with respect to their protein profile, thermal stability, mechanical performance and SEM morphology, and contrasted with those of raw wool. Cysteine content reduced significantly on increasing temperature of ionic liquid and some disordering of protein secondary structures occurred in regenerated keratins. Keratin regenerated from a solution prepared with ionic liquid at 180 °C showed improved thermal processing properties, and it revealed dense fibrous network morphology of the film's cross-sectional surface produced under compression moulding. This in-depth study on regenerated keratins demonstrates a potential new route for the conversion of keratinous materials into bio-resin for industrial applications. However, further development is required to create keratinous materials that are melt-processable like classical synthetic polymers.

Effect of ageing heat treatment process on the microstructure and mechanical properties for high hardness 3J40 alloy

Alloy 3J40 is a nickel-based alloy with high hardness and high elasticity. Alloy 3J40 was widely used as bears and conical pivots in many fields, such as, navigation, aviation and antiaircraft gun due to its excellent properties of elasticity, strength, hardness, corrosion resistance, nonmagnetic characteristics and so on. However, after aging treatment, the hardness of 3J40 alloy was uneven, there were large differences in hardness between the air-cooled and the furnace-cooling alloys, and the properties were unstable. Previous researches basely focused on the distribution, size, shape and other aspects of inclusions, to improve the plasticity and thermal processing properties of the alloy. Studies about properties and microstructure of the alloy devoted to the studies of the traditional Ni3Al-γ-phase. Up to now no public research report had been found about the α-Cr phase strengthening mechanism of the 3J40 alloy. In this paper, the effect of α-Cr phase on the strengthen mechanism in 3J40 alloy was investigated. By thermodynamic phase equilibrium calculation, the possible phases, which may precipitate after heat treatment, have been predicted. Relationships between the mechanical properties and the ageing heat treatment parameters, such as, ageing temperature, ageing time and cooling rate, had been studied. Microstructure of the alloy under different heat-treatment process has been analyzed, especially cared about the morphology, particles size and quantity of the α-Cr phase. And the strengthening mechanism was also investigated. The results showed that the microstructure of the aged 3J40 alloy were composed of γ-based phase, precipitated γ’ phase, (Ni3Al) phase, and α-Cr phase in granular and laminar. And the main contribution for the strengthen mechanism may be associated with the α-Cr phase laminar.

Structure and Thermal Properties of Cellulose Diacetate-Graft-Poly(lactic Acid) Copolymer

To improve the thermal behavior of cellulose diacetate, cellulose diacetate-graft-poly(lactic acid) copolymers (CDA-g-PLAs) were synthesized by ring-opening polymerization of L-lactide using stannous octoate (Sn(Oct)2) as catalyst. The molecular structure of the copolymer was characterized by FT-IR and 1H-NMR and the thermal properties were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG-DTA). The results showed that the product was grafted copolymer of cellulose diacetate-graft-poly(lactic acid) with different side-chain structure. The thermal processing properties of CDA-g-PLAs are remarkably improved with melting temperature(Tm) about 140°C which lower than that of CDA and decomposition temperature (Td) higher than 260°C.

Catalyzed chain extension of poly(butylene adipate) and poly(butylene succinate) with 2,2′‐(1,4‐phenylene)‐bis(2‐oxazoline)

AbstractLow‐molecular‐weight HOOC‐terminated poly(butylene adipate) prepolymer (PrePBA) and poly(butylene succinate) prepolymer (PrePBS) were synthesized through melt‐condensation polymerization from adipic acid or succinic acid with butanediol. The catalyzed chain extension of these prepolymers was carried out at 180–220°C with 2,2′‐(1,4‐phenylene)‐bis(2‐oxazoline) as a chain extender and p‐toluenesulfonic acid (p‐TSA) as a catalyst. Higher molecular weight polyesters were obtained from the catalyzed chain extension than from the noncatalyzed one. However, an improperly high amount of p‐TSA and a high temperature caused branching or a crosslinking reaction. Under optimal conditions, chain‐extended poly(butylene adipate) (PBA) with a number‐average molecular weight up to 29,600 and poly(butylene succinate) (PBS) with an intrinsic viscosity of 0.82 dL/g were synthesized. The chain‐extended polyesters were characterized by IR spectroscopy, 1H‐NMR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, wide‐angle X‐ray scattering, and tensile testing. DSC, wide‐angle X‐ray scattering, and thermogravimetric analysis characterization showed that the chain‐extended PBA and PBS had lower melting temperatures and crystallinities and slower crystallization rates and were less thermally stable than PrePBA and PrePBS. This deterioration of their properties was not harmful enough to impair their thermal processing properties and should not prevent them from being used as biodegradable thermoplastics. The tensile strength of the chain‐extended PBS was about 31.05 MPa. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010