Properties Of Polymeric Materials Research Articles

Confocal Raman Microscopy for Measuring In Situ Temperature-Dependent Structural Changes in Poly(Ethylene Oxide) Thin Films.

Crystallization from the melt is a critical process governing the properties of semi-crystalline polymeric materials. While structural analyses of melting and crystallization transitions in bulk polymers have been widely reported, in contrast, those in thin polymer films on solid supports have been underexplored. Herein, in situ Raman microscopy and self-modeling curve resolution (SMCR) analysis are applied to investigate the temperature-dependent structural changes in poly(ethylene oxide) (PEO) films during melting and crystallization phase transitions. By resolving complex overlapping sets of spectra, SMCR analysis reveals that the thermal transitions of 50 µm thick PEO films comprise two structural phases: an ordered crystalline phase and a disordered amorphous phase. The ordered structure of the crystalline PEO film entirely disappears as the polymer is heated; conversely, the disordered structure of the amorphous PEO film reverts to the ordered structure as the polymer is cooled. Broadening of the Raman bands was observed in PEO films above the melting temperature (67 °C), while sharpening of bands was observed below the crystallization temperature (45 °C). The temperatures at which these spectral changes occurred were in good agreement with differential scanning calorimetry (DSC) measurements, especially during the melting transition. The results illustrate that in situ Raman microscopy coupled with SMCR analysis is a powerful approach for unraveling complex structural changes in thin polymer films during melting and crystallization processes. Furthermore, we show that confocal Raman microscopy opens opportunities to apply the methodology to interrogate the structural features of PEO or other surface-supported polymer films as thin as 2 µm, a thickness regime beyond the reach of conventional thermal analysis techniques.

One-Component polyurethane adhesive filled with milled carbon fibre and its effect on hydrothermal stability of beech-glued joints

ABSTRACT The effect of fibres of various lengths, thicknesses, origins, and quantities on mechanical and other properties of polymer matrices is well-known, including carbon fibres. These were used in the form of milled carbon fibres (MCF) to fill a one-component polyurethane (1C-PUR) commercial adhesive to determine hydrothermal resistance of beech-bonded joints tested in shear. The effect of MCF (1%, 3%, 5%, and 7%) was first tested on thin adhesive films before and after exposure to cold water (20°C) and boiling (wet state test and after drying). A good bond of 1C-PUR to MCF was demonstrated, with tensile mechanical properties significantly increased after the addition of 3% and 5% MCF in all tested environments. The aqueous environment, especially boiling water, led to a deterioration in mechanical properties, but after drying, there was a recovery and, in many composite films, an improvement. This was due to a change in adhesive’s domain structure, as demonstrated by differential scanning calorimetry. An increase in hydrothermal resistance of glued wood joints with MCF (1%, 3%, and 5%) was not demonstrated based on tensile shear strength. However, considering the achieved wood failure, it was proven that MCF has a positive effect on stress transfer into the wood adherend.

Amorphous conjugated polymer networks as an emerging class of polymer nanostructures

This Perspective focuses on the unique polymerization processes, structures, and properties of amorphous conjugated polymer networks (CPNs) derived from simultaneous and random copolymerization of multiple conjugated monomers.

Effect of Selective Surface Interaction on Polymer Phase Separation with Explicit Polydispersity During Polymerization

In polymerization-induced phase separation, the impact of polymer-substrate interaction on the dynamics of phase separation for polymer blends is important in determining the final morphology and properties of polymer materials...

Influence of 3D Printing Conditions on Physical-Mechanical Properties of Polymer Materials.

The popularity of 3D printing technology is rapidly increasing worldwide. It can be applied to metals, ceramics, composites, hybrids, and polymers. Three-dimensional printing has the potential to replace conventional manufacturing technologies because it is cost effective and environmentally friendly. This paper focuses on the influence of 3D printing conditions on the physical and mechanical properties of polylactic acid (PLA), poly(methyl methacrylate) (PMMA), and poly(ethylene terephthalate glycol-modified) (PETG) materials produced using Fused Deposition Modeling (FDM) technology. The impact of nozzle diameter, layer height, and printing temperature on the mechanical (i.e., bending stiffness and vibration damping) and physical (i.e., sound absorption and light transmission) properties of the studied polymer materials was investigated. It can be concluded that 3D printing conditions significantly influenced the structure and surface shape of the 3D-printed polymer samples and, consequently, their physical and mechanical properties. Therefore, it is essential to consider the type of filament used and the 3D printing conditions for specific 3D-printed material applications.

Effect of Macromolecular Architecture on Adhesion.

The behavior of single linear chains on a substrate is a well-studied area of polymer science. Herein, one of the most essential issues is the interaction of the chains with the substrate, which determines both macromolecular conformations near the substrate and adhesive properties of polymer materials. However, very little is known about the effect of macromolecular architecture on adhesion. In particular, there was no assessment of the effect of chain branching on the adhesion force. On the other hand, an essential progress in macromolecular chemistry allows the synthesis of various macromolecular architectures, including star-, comb-like, etc., in a very precise way. They are widely used in numerous applications. In particular, synthetic peptides are currently an integral part of many systems for biomedical purposes including bioglues, for which the adhesion force is a fundamental property. In this study, we conducted force experiments on the desorption of star-like pentapeptide chains from a solid substrate using an atomistic model of computer simulations. The cases of a linear chain and four- and eight-armed stars were considered. We have shown that the presence of branching enhances the adsorption strength under a fixed mass of the macromolecules. The force needed for chain desorption was shown to be linearly dependent on the branching degree.

On the Properties of New Polyurethane Fast-Curing Polymer Materials.

A sequences of unconfined compressive strength tests and flexural tests were conducted in this study to evaluate the curing performance of a new type of polyurethane sand fast-curing polymer material. The mechanical properties of the material were investigated under different curing temperatures (-10 °C to 60 °C), particle sizes (10-15 mesh, 60-80 mesh, 100-120 mesh, and 325 mesh), and material proportions (20% to 60%). Additionally, SEM analysis was employed to further reveal the reinforcement mechanism. The results demonstrated that the developed polyurethane polymer material exhibited superior curing properties and applicability across a wide temperature range of -10 °C to 60 °C. Both the compressive strength and flexural strength of the solidified sand increased with the increase in solidification temperature, resulting in improved curing effects. This material exhibited the best curing properties when using sand within the 100-120 mesh range. As the particle size decreased under the remaining specifications, there was a reduction in specimen strain and an increase in strength, while still maintaining favorable ductility. The optimal proportion for polyurethane material was 40%. Moreover, the nonlinear mathematical relationships between the strength and multiple influencing factors were established through multivariate regression analysis. The sand consolidation specimens exhibited X-shaped conjugate shear failure, which tended to occur at the weak interface between the sand and material. Lastly, Pearson's correlation analysis revealed a strong positive correlation between temperature and material content with strength.

Examining the impact of anisotropic particle orientation in a polymer matrix on the electrical properties of composite materials

A number of works have experimentally shown the significant influence of mechanical stretching on the electrically conductive properties of composite polymer materials. Thus, stretching polymer composite films and filaments can lead to deterioration in electrical conductivity properties which can significantly affect the characteristics of products made from such materials. The research conducted in this study focuses on simulation the impact of anisotropic particle orientation within a polymer matrix and mechanical stretching on the electrical properties of composite materials. Based on the Boltzmann statistics, an expression was obtained that allows predicting the change in electrical conductivity during the stretching of polymer composite samples. The Monte Carlo method was used to simulate the destruction of a percolation chain of conductive particles during stretching.

Molecular dynamics simulation of aging properties in polymer materials: a review

Molecular dynamics simulation of aging properties in polymer materials: a review

Accessible preparation of a novel nitrogen‑phosphorus synergetic nanocellulose-based flame retardant with excellent char-forming ability for enhancing the anti-melting droplet property of PA66.

Developing eco-friendly and effective flame retardants is crucial for enhancing the fire resistance of polymeric materials. This study developed a novel nitrogen‑phosphorus (NP) synergistic nanocellulose-based flame retardant (CNC-PEI-PA) by grafting polyethyleneimine (PEI) and phytic acid (PA) onto the CNC. CNC-PEI-PA demonstrated remarkable thermal stability, char-forming ability, and antibacterial activity. Notably, the height of the intumescent char layer for CNC-PEI-PA increased by 700 %, and the char yield improved from 24.5 % to 45.0 % compared to CNC. Introducing CNC-PEI-PA into polyamide 66 (PA66) raised its maximum decomposition temperature to 470.0 °C and increased the char yield by nearly 330 %. More importantly, the quick formation of a dense intumescent char layer functioned as a robust protective barrier, enhancing the flame retardancy of PA66 while also greatly improving its anti-melting droplet property. The successful preparation of NP synergistic bio-based flame retardants through a facile and eco-friendly synthetic route shows their significant potential to enhance both the flame retardancy and anti-melting droplet properties of polymer materials.

Influence of Recycling and UV Exposure on the Properties of 3D Printing Polymer Materials.

The use of polymer materials in various fields has increased significantly due to their ease of thermoforming and relatively low production costs. The production volume of these materials is extremely high, and according to forecasts from global statistical centers, it is expected to continue rising in the future. However, the extensive use and easy availability of polymeric materials have caused significant ecological problems. The world faces large amounts of polymer waste and environmental pollution. Plastic recycling remains challenging due to issues related to sorting polymer waste and separating it according to polymer types. Recycling certain plastics requires only a quarter of the energy needed to produce new plastic. To address this, circular economy principles should be applied to 3D printing products made from polymeric materials. A particularly wide application of these technologies is found when polymeric materials are used due to their low cost, low melting temperatures, and other advantageous properties. This paper investigates the impact of plastic recycling on the quality of 3D-printed products. During the research, samples were 3D printed and tested using both virgin and recycled PLA, ABS, and PET-G materials. The samples underwent static and dynamic tests to determine their mechanical properties, such as tensile strength, elongation, and impact resistance. The research results showed that the properties of recycled polymer materials deteriorate, with relative elongation of recycled and 3D-printed materials decreased by 16-45%. Despite this, recycled polymer materials can still be used, but it is necessary to account for the reduction in plasticity when creating products that will be exposed to dynamic loads. The impact strength is reduced by 6% for PLA, 54% for ABS, and 58% for PET-G. Additionally, the research included tests on samples printed with 3D printing technology that were exposed to UV irradiation. The results indicated similar dependences, as UV exposure also affects the reduction of material plasticity. After 66 Wh/m2 of UV radiation, the tensile strength of PET-G and PLA decreased by 17%, while ABS showed a reduction of about 5%.

Development and Investigation of Mucoadhesive Polymers Based on Chitosan for Intravesical Therapy

Intravesical drug delivery (IDD) refers to the administration of therapeutic agents directly into the urinary bladder through a catheter. Low permeability of the urinary bladder epithelium, poor retention of the therapeutic agents due to dilution and periodic urine voiding as well as frequent catheterizations (with potential risk of infections) are the major limitations of IDD used in the treatment of bladder-related disorders, such as bladder cancer. In this work, the mucoadhesive properties of polymeric materials based on chitosan, chitosan-gellan gum, and chitosan-Carbopol™ 940 containing sodium fluorescein (NaFI) were investigated for their potential application in intravesical drug delivery. The evaluation of mucoadhesive properties was carried out using an in vitro flow-through method with fluorescent detection that simulates the interaction conditions of polymers with the urinary bladder mucosa. Additionally, the release kinetics of NaFI from polymer compositions under conditions mimicking the physiological environment of the bladder was studied using a fluorescence spectrometry. The acquired data confirm the promise of using chitosan-based mucoadhesive polymers in developing systems for intravesical drug delivery, which could significantly enhance the efficacy of IDD therapy to treat urinary bladder-related disorders.

Creating Neoteric Inorganic-Organic Hybrid Functional Biocomposites By Fiber Welding

Natural fiber welding (NFW) is a process by which ionic liquids (ILs) are used to partially solvate and restructure biopolymer fibers. During NFW, the biopolymer fibers of adjacent cloth threads are intermingled, resulting in a highly nanoporous matrix surrounding a non-welded and structurally robust native thread core. Recent developments in this technique have led to the creation of all-biopolymer xerogel composites with pores of an ideal size regime (<20 nm) for growing and entrapping nanoscale materials, such as metal and semiconductor nanoparticles. However, larger nanoscale materials, such as traditional clay minerals, are too large (>100 nm in length and width) to include within the formed nanoporous matrix. These minerals are often used as fillers to enhance the properties of other polymeric materials, and their exclusion from NFW products is a significant limitation. Recent developments have shown that similar large additives can be entrapped in the welded matrix by first dispersing them in the welding solvent, though traditional clays (e.g., montmorillonite) are minimally soluble in typical welding IL. Fortunately, polyionic nanoclays (PINCs), an emergent class of synthetic and highly tailorable cationic clay minerals, are uniquely soluble in common NFW ILs. The present work aims to unite these two IL-based technologies by combining them into a suite of novel inorganic-organic hybrid functional composites. We will discuss the process for pre-treating NFW IL with PINCs to best aid their entrapment, then provide adequate characterization using microscopy, gas physisorption, and spectroscopic techniques to prove their inclusion within the NFW matrix. We will also demonstrate several basic applications of the hybrid cloth based on recent advances of PINC minerals, with a focus on selective dye sorption, fluorescence sensing, and catalysis.

Sulfur-Rich Norbornadiene-Derived Infrared Transparent Polymers by Inverse Vulcanization.

Infrared (IR) transparent polymer materials prepared by inverse vulcanization, as a promising candidate to replace inorganic materials, are new materials for constructing key devices in IR optics. However, it is difficult to achieve a balance between infrared optical and thermal properties in polymers due to the intrinsic infrared absorption of organic materials. Herein, our strategy is to construct a high boiling point symmetrical molecular norbornadiene derivative cross-linking agent (DMMD) which can be inverse vulcanized with molten sulfur, and obtain Poly (S-r-DMMD) with different sulfur content by controlling the feed ratio of sulfur. With the rigid core and low IR activity in DMMD, the prepared polymers exhibit tunable thermal properties (Tg: 98.3-119.8 °C) and high IR transmittance (medium-wave infrared region (MWIR): 42.9-52.6 %; long-wave infrared region (LWIR): 1.5-5.29 %). In addition, Poly (S-r-DMMD) can be used to prepare large-size free-standing Fresnel lenses for IR imaging by simple hot-pressing, which provides flexibility in the design and production of IR fine lenses. This study provides a novel strategy for balancing the thermal and optical properties of IR transparent polymer materials, while providing relevant references for balancing the IR optical and thermal properties of polymer materials.

Sulfur‐Rich Norbornadiene‐Derived Infrared Transparent Polymers by Inverse Vulcanization

AbstractInfrared (IR) transparent polymer materials prepared by inverse vulcanization, as a promising candidate to replace inorganic materials, are new materials for constructing key devices in IR optics. However, it is difficult to achieve a balance between infrared optical and thermal properties in polymers due to the intrinsic infrared absorption of organic materials. Herein, our strategy is to construct a high boiling point symmetrical molecular norbornadiene derivative cross‐linking agent (DMMD) which can be inverse vulcanized with molten sulfur, and obtain Poly (S‐r‐DMMD) with different sulfur content by controlling the feed ratio of sulfur. With the rigid core and low IR activity in DMMD, the prepared polymers exhibit tunable thermal properties (Tg: 98.3–119.8 °C) and high IR transmittance (medium‐wave infrared region (MWIR): 42.9–52.6 %; long‐wave infrared region (LWIR): 1.5–5.29 %). In addition, Poly (S‐r‐DMMD) can be used to prepare large‐size free‐standing Fresnel lenses for IR imaging by simple hot‐pressing, which provides flexibility in the design and production of IR fine lenses. This study provides a novel strategy for balancing the thermal and optical properties of IR transparent polymer materials, while providing relevant references for balancing the IR optical and thermal properties of polymer materials.

Physical and biological characteristics of electrospun poly (vinyl alcohol) and reduced graphene oxide nanofibrous structure

The fabrication of graphene-based nanocomposites has been a topic of increasing interest due to graphene’s exceptional physical properties and the ability to enhance the properties of various polymeric materials. Evaluating the biocompatibility of these nanocomposites is crucial to ensure their safe and effective use in biomedical applications. This study characterized and assessed the biocompatibility of previously fabricated electrospun polyvinyl alcohol (PVA)/reduced graphene oxide rGO fibrous structures by conducting a comprehensive assessment of their physical and biological characteristics. Contact angle measurements revealed that adding rGO to electrospun PVA fibers enhanced the surface wettability, improving the fibrous structure’s PBS absorption capacity and degradation behavior. Including the rGO content resulted in a higher water vapor transmission rate, reaching ∼48 g/m2·day for PVA + 0.5 wt.% rGO and ∼45 g/m2·day for PVA + 1.0 wt.% rGO, compared to ∼40 g/m2·day for electrospun PVA fibers. Cell culture studies, including MTT assay, alkaline phosphatase (ALP) activity analysis, alizarin red staining, fluorescence microscopy, and SEM analyses, demonstrated that electrospun PVA + 1.0 wt.% rGO nanocomposites exhibited superior cell viability, proliferation, and growth compared to other samples, due to the improved physical properties of the PVA + 1.0 wt.% rGO fibrous structure.

Quantitative Equivalence and Performance Comparison of Particle and Field-Theoretic Simulations.

Particle and field-theoretic simulations are both commonly used methods to study the equilibrium properties of polymeric materials. Yet despite the formal equivalence of the two methods, no comprehensive comparisons of particle and field-theoretic simulations exist in the literature. In this work, we seek to fill this gap by performing a systematic and quantitative comparison of particle and field-theoretic simulations. In our comparison, we consider four representative polymeric systems: a homopolymer melt/solution, a diblock copolymer melt, a polyampholyte solution, and a polyelectrolyte gel. For each of these systems, we first demonstrate that particle and field-theoretic simulations are equivalent and yield exactly the same results for the pressure and the chemical potential. We next quantify the performance of each method across a range of different conditions including variations in chain length, system density, interaction strength, system size, and polymer volume fraction. The outcome of these calculations is a comprehensive look into the performance of each method and the systems and conditions when either particle or field-theoretic simulations are preferred. We find that field-theoretic simulations are equal to or faster than particle simulations for nearly all of the systems and conditions examined. In many situations, field-theoretic simulations are several orders of magnitude faster than particle simulations, especially if the polymer chains are long, the system density is high, and long-range Coulombic interactions are present. We also demonstrate that field-theoretic simulations are considerably faster at calculating the chemical potential and bypass the challenges associated with particle-based Widom insertion techniques. Taken together, our results provide quantitative evidence that field-theoretic simulations can reach and sample equilibrium considerably faster than particle simulations while simultaneously producing equivalent results.

Combining Injection Molding and 3D Printing for Tailoring Polymer Material Properties

Combining Injection Molding and 3D Printing for Tailoring Polymer Material Properties

Deformation Behavior of Microparticle-Based Polymer Films Visualized by AFM Equipped with a Stretching Device.

Understanding the structural changes and property alterations at the nanoscale and microscopic levels is critical to clarifying the deformation behavior and mechanical properties of polymer materials. Especially, in latex films composed of polymer nanoparticles, it is widely accepted that the remaining interfaces between microparticles in the film affect their brittleness. However, detailed information on nanoscale changes of latex films during deformation remains unclear due to technical difficulties in analyzing the microstructures under mechanical stress. In this study, we employed atomic force microscopy equipped with a uniaxial stretching device to visualize the surface structures of films composed of slightly cross-linked microparticles under elongation strain. The observations revealed that the latex film deforms in a nonaffine manner, which is attributed to the concurrent deformation of individual microparticles and the pull-out of interpenetration between them. Furthermore, by introducing a load-strain measurement mechanism to the stretching device, we compared the relationships between nanostructural changes, local property changes, and macroscopic deformation of microparticle-based films. The results suggest that loads are dominated by the deformation of microparticles and dissipate as the interpenetration of surface polymer chains between microparticles is pulled out.

Effects of electron beam and atomic oxygen irradiation on hypervelocity - Impact tested / polyimide coated carbon fiber-reinforced plates

In a low-Earth orbit, space debris orbit at approximately the first cosmic velocity. When space debris strike a spacecraft, ejecta (fragments) from the spacecraft are widely scattered. The reduction in the number of ejecta (fragments caused by impact) must also be considered when selecting spacecraft materials. The authors’ group has previously examined the size of ejecta (fragments) and reduction in the number of ejecta. In general, the mechanical properties of polymer materials and CFRP plates may be damaged by space environments, such as radiation (gamma rays and electron beams (EBs)), atomic oxygen (AO), ultraviolet rays, temperature, and thermal cycling. The authors suggested an anti-AO coating/polyimide CFRP as a material resistant to space environments. The effects of EB and AO irradiation on the fracture behavior and ejecta of anti-AO coating/polyimide CFRP were examined for hypervelocity impacts. The results of static three-point flexural tests were compared with the fracture behavior and ejecta. A two-stage light-gas gun was used for the impact tests. Spherical projectiles formed of aluminum alloy 2017-T4 with a diameter of 1.6 mm were used. Photographs of the ejecta scattered in front of each polyimide CFRP plate were captured from the side using a high-speed video camera. The number and weight of the ejecta on the front side and perforation holes were examined.