Relationship of polymer structure to mechanical properties in crosslinked double-base binders

The polyvinyl chloride (PVC) polymer structure was studied using inverse gas chromatography (IGC). The specific retention volume (Vg°) of a vinyl chloride monomer (VCM) probe, as well as the thermodynamic parameters of the interaction between PVC and VCM were calculated.Changes in Vg°, free energy(ΔG°s), enthalpy (ΔH°s) and entropy (ΔS°s) observed as the temperature and the amount of VCM decreased, clearly indicate that the PVC—VCM interaction was both concentration and temperature dependent. The Vg° and thermodynamic parameters also varied with changes in polymer structure. Data were interpreted in terms of the active site hypothesis. Active sites in the PVC matrix strongly bind VCM at low enough concentrations and temperatures. Inferably, migration of VCM from PVC packaging materials containing very low concentrations of residual monomer should be for all practical purposes, essentially zero, particularly at low temperatures.

ABSTRACTA series of novel liquid crystalline monomers (M1−M8) and side chain polymers base polyacrylate backbone were synthesized. The chemical structures were characterized by FT-IR and 1H-NMR spectra. The mesomorphism and thermal behavior was investigated by polarizing optical microscopy, differential scanning calorimetry, and thermogravimetric analysis. The relationships of structure and mesomorphism are discussed in detail. The eight monomers and their corresponding polymers all show enantiotropic nematic phase. With increasing the spacer length or flexibility of the terminal group, the melting temperature (Tm) and isotropic temperature (Ti) of the corresponding monomers and polymers all decreased. However, with increasing the rigidity of the mesogenic core, Tm and Ti of the corresponding monomers and polymers all increased. TGA showed that all the polymers obtained in this study had excellent thermal stability.

Microstructural features affecting mechanical properties: Effect of processing on dispersion of carbon black (N220) nanoparticles reinforcement in poly (lactic acid)

Structure, degradation, drug release and mechanical properties relationships of iron-based drug eluting scaffolds: The effects of PLGA

The present study highlights the structure and property relationships of epoxidized castor oil (ECO) toughened Diglycidyl Ether of Bisphenol A (DGEBA) epoxy nanocomposites. Toughened epoxy systems have been prepared by an addition of 10–40 wt% ECO to the DGEBA epoxy resin. Nanocomposites were prepared by mixing small amounts of Cloisite 30B (C30B) clay and 3‐aminopropyltriethoxysilane to the DGEBA/ECO blends. The chemical structure of toughened systems was confirmed using proton nuclear magnetic resonance and fourier transform infrared spectroscopy. The triethylenetetraamine‐cured DGEBA/ECO/C30B (8:2:0.1) nanocomposites exhibited tensile strength (50 MPa), tensile modulus (1.7 GPa), flexural strength (120 MPa), flexural modulus (3.02 GPa), and elongation (19%). The fracture toughness (critical intensity factor,KIC) and fracture energy (critical energy release rate,GIC) of DGEBA/ECO/C30B (8:2:0.1) system found to be higher than the other systems (2.5 MPa.m1/2and 1.8 kJ/m2forKICandGIC, respectively). The thermal stability and heat of reaction of DGEBA/ECO blends increase with the addition of C30B clays that were analyzed using thermogravimetric analysis and differential scanning calorimetry. Rheological characterizations of uncured samples revealed a pronounced effect of the C30B clay on the DGEBA/ECO blend systems that exhibited a shear‐thickening behavior. On the other hand, the dynamic mechanical properties also revealed that the addition of C30B clays to the DGEBA/ECO blend a significant enhancements in viscoelastic and cross linking density behavior. Scanning electron microscope analysis was used to study the fractured morphology of DGEBA, DGEBA/ECO, and its nanocomposite systems. Copyright © 2015 John Wiley & Sons, Ltd.

Additive manufacturing (AM) offers advantages such as design flexibility and reduced production times, but defects like voids impact mechanical performance and limit its broader adoption. This study quantitatively examines the relationship between void characteristics (volume fraction, distribution, and size) and mechanical properties in both linear and non-linear geometries, represented by a dogbone model and an end-use component, respectively. Samples were produced using Fused Filament Fabrication (FFF) with varying overlap levels to control void content. As the overlap increased from 0% to 99%, voids transitioned from large linear gaps to smaller point-shaped voids. In non-linear geometry, void reduction from 12% to 2% led to a threefold improvement in mechanical response, while in dogbone samples, voids decreased from 12% to nearly 0%, improving the elastic modulus by only 1.5 times. This disparity is due to differences in void distribution, as voids in non-linear geometries affect both margins and internal layers, significantly influencing structural integrity. The findings highlight the importance of the void location in determining mechanical performance and emphasize the limitations of using linear dogbone models to assess void-property relationships in complex 3D-printed structures.

1D and 2D nanomaterials serve as foundational components for next-generation functional devices, owing to their exceptional and often unique mechanical, optical, and electronic properties. However, the precise characterization of their nanomechanical behaviors and underlying mechanisms remains a significant challenge due to their nanoscale dimensions. Atomic force microscopy (AFM) has emerged as a powerful platform that bridges this gap, offering powerful capabilities for in situ manipulation and quantitative measurement of physical properties with piconewton force sensitivity and sub-nanometer spatial resolution. This review comprehensively summarizes the progress of AFM-based techniques for probing the nanomechanics of 1D and 2D materials. We provide a critical analysis of the application of these techniques in assessing fundamental mechanical properties (elastic modulus, strength, and adhesion), dynamic behaviors (friction, superlubricity, and fatigue), and enabling precise nanomanipulation (picking, placing, folding, and rotating). These AFM-based methods enable versatile mechanical characterizations across diverse scenarios, ranging from point measurements to planar analyses. By integrating these diverse modes, AFM facilitates a multifaceted understanding of the intrinsic structure, atomic-scale mechanisms, and function relationships in low-dimensional systems. This thorough overview aims to inspire the broader application of AFM in materials science, providing technical support for the rational design and development of advanced functional materials.

This work focuses on the preparation and characterization of polystyrene/organoclay nanocomposites. The effects of the nature of the organoclays and the method of preparation were studied in order to evaluate their morphological, thermal and mechanical properties. X-ray diffraction (SAXS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM, TEM), atomic force microscope (AFM) were used to determine the characteristics of the resulting materials. Initially, cetyltrimethylammonium bromide was used as an organomodifier to modify the clay to form an organic clay. After that, polystyrene/organoclay nanocomposites were synthesized by an in situ mass polymerization process in which styrene was polymerized in the presence of different proportions of organoclay ranging from 1 to 15% by weight. The results obtained confirm the intercalation of cetyltrimethylammonium bromide (CTA) surfactant in the clay layers, while the nanocomposites obtained showed morphologies in which the exfoliated forms were obtained. Nanocomposites showed a significant improvement in thermal stability compared to unmodified polystyrene. The highlighting of the modification was examined by mechanical tests (shock, traction). The Charpy impact test showed an increase in impact resilience, and this is mainly due to a better interfacial adhesion of the matrix. The tensile test showed an improvement in stiffness.Graphic abstractThe preparation of polystyrene–clay nanocomposites containing various amounts of organoclays ranging from 1 to 15% using the mass polymerization technique has shown the positive effect of the introduction of a cetyltrimethylammonium bromide surfactant chain on the thermal stability of the nanocomposites. Exfoliated morphologies were obtained for the majority of the prepared nanocomposites. A structure, surface and thermal property relationship was established based on TGA, XRD and TEM/SEM analyses.

Equilibrium stress-strain properties and topological constraint release effects in end-linked model networks.- Determination of mechanical parameters related to the kinetics of swelling in an electrically activated contractile gel.- Dielectric and thermal relaxations in amorphous and semicrystalline poly(ethylene terephthalate).- The relaxation of additives in polymer matrix.- Relaxation properties of butadiene-styrene copolymers.- Dielectric relaxation processes in poly (epoxypropylcarbazole) layers.- Dielectric relaxation of polyurethane systems Part II: Shape parameters.- Dielectric study of aqueous solutions and solid samples of methylcellulose.- 1H-NMR transversal relaxation in crosslinked 1,4-cis-polybutadiene.- Flexoelectric effect in elastomers.- Description of the freezing-in process in poly(vinyl acetate) based on the meander model.- Modified epoxies as studied by ultrasonic methods.- Constraint release effects in polymer networks viscoelastic analysis.- Entanglement and reversible gelation for polymers of different architectures.- Dynamic light scattering measurements on semidilute solutions of polystyrene in ethyl acetate.- Quasielastic light scattering from solutions of branched epoxy resins below the gel point.- ESR on polymer semiconductors of poly(tetrathiafulvalene).- Migration of radicals in resist polymers - an example of microscopic transport processes.- Charging and charge-detection methods and their use in the characterization of polymer-electret materials.- Charge carrier photogeneration in polymers.- Self-trapping of charge carriers in polymers: A comparative study of poly(p-phenylene) and poly(N-vinylcarbazole).- Charge transport in polymers characterized by geometrical restrictions.- Charge carrier transport in polyethylene studied by surface potential kinetics.- Thermoluminescence and ESCA investigations in polymer resist layers.- Thermally stimulated depolarization currents in hydrated casein solid samples.- Thermally stimulated current studies on polyimide film.- Thermally stimulated currents in thin 1,4-cis polyisoprene filsm.- Electronic properties of polyaniline.- The fluorescence of the concentrated solutions of N-vinylcarbazole and the structure of the second excimer sites of poly-N-vinylcarbazole.- Low temperature spectroscopy of porphyrins in polymer hosts.- Electrical properties of 1,4-cis polybutadiene.- Physical processes during the long-time decay of the surface potential of thin films.- Carbonaceous thin films.- Semidilute polymer solution near the wall.- Phase diagram of polymer solution bounded by walls.- Calorimetric investigations of phase transitions in amyl-ethoxy-cyanstilbene (AECS).- Crystallization in oligomer and copolymer systems comprising lattice incompatible units.- Morphology and properties of blends of ethylene-propylene block copolymer with ethylene-vinylacetate copolymer.- On the morphology of high-modulus and high-strength polyethylene filaments.- Influence of filler on the polypropylene structure.- Water in some DNA model systems.- Note on the solution of the soliton problem in trans-polyacetylene.

The presented drug delivery polymeric systems (DDS), i.e., conjugates and self-assemblies, based on grafted and star-shaped polymethacrylates have been studied for the last few years in our group. This minireview is focused on the relationship of polymer structure to drug conjugation/entrapment efficiency and release capability. Both graft and linear polymers containing trimethylammonium groups showed the ability to release the pharmaceutical anions by ionic exchange, but in aqueous solution they were also self-assembled into nanoparticles with encapsulated nonionic drugs. Star-shaped polymers functionalized with ionizable amine/carboxylic groups were investigated for drug conjugation via ketimine/amide linkers. However, only the conjugates of polybases were water-soluble, giving opportunity for release studies, whereas the self-assembling polyacidic stars were encapsulated with the model drugs. Depending on the type of drug loading in the polymer matrix, their release rates were ordered as follows: Physical ≥ ionic > covalent. The studies indicated that the well-defined ionic polymethacrylates, including poly(ionic liquid)s, are advantageous for designing macromolecular carriers due to the variety of structural parameters, which are efficient for tuning of drug loading and release behavior in respect to the specific drug interactions.

Regions in which the mechanical and dielectric properties of polymers change rapidly with temperature (transitions or relaxations) are supposed to be due to the onset of certain types of molecular motions. A precise description of these various molecular motions would be invaluable in the areas, of structure vs property relationships and the tailoring of polymers to end‐uses. However, our knowledge concerning these motions is quite limited and qualitative at best. The biggest stumbling block has been an inability to test the consequences of proposed mechanisms in terms of experimentally observed quantities. The problem in many cases has not been a lack of adequate theory but rather an insufficiency of knowledge, appropriate for input into the theory, concerning the energetics of chain motions. However, in the past few years there has been considerable progress in studying chain energetics by means of conformational energy calculations (molecular mechanics). In the present paper, this work on crystalline polymers will be reviewed and some recent calculations which illustrate the present state of the art are discussed.

In this work, two tri‐aryl and one bi‐aryl epoxy resin, bis[(glycidyloxy)phenyl)]‐m‐xylene (BGOPmX), bis[(glycidyloxy)phenyl)]‐p‐xylene (BGOPpX), and bis(glycidyloxy) biphenyl (BGOBP) are synthesized and cured with methylene dianiline and 4,4′‐diamino diphenyl sulfone. Structure, property, and processing relationships are investigated and compared against diglycidyl ether of bis‐phenol F epoxy resin to better understand the impact of rigid and flexible subunits within the network structure. The rigid BGOBP epoxy network has a higher yield strain, and displays the highest glass transition temperature and a higher coefficient of thermal expansion (CTE) regardless of amine. Conversely, the more flexible tri‐aryl epoxy resins, BGOPmX and BGOPpX, have higher moduli and lower CTE. Properties such as yield stress and thermal degradation are relatively unaffected by structure. Results where possible are discussed in terms of the likely equilibrium packing density of the network and short range and segmental motions of the polymer networks determined from sub‐ambient dynamic mechanical analysis. Differences between BGOPmX and BGOPpX highlight the effect of minor variations in structure on reactivity, glass transition temperature, and compressive properties. This work clearly illustrates how fine control of chemical structure can tune the mechanical and thermal properties and reaction kinetics of network polymers.

Secondary structure, microstructure, and mechanical properties of heat induced 11S globulin gel were studied to discover their relationships. Heat-induced 11S globulin gel at 80, 90, and 95°C were comprised of 7.2, 16.6, and 23.8% of α-helix; 19.4, 19.5, and 27.5% of β-sheet, and 73.5, 64.5, and 48.6%, of random coil, respectively. This indicated the gel formed at higher temperatures contained more α-helix and less random coil structures. Micrographs of gels heated at 90 and 95°C had a more extended and integral matrix. Gel strength of heat-induced gels at 90 and 95°C were significantly greater than that of 80°C. These data indicated that the increase in α-helix of heat-induced 11S globulin gel have facilitated the establishment of a good gel matrix.

The dynamic mechanical properties of the viscoelastic polymer materials are usually considered to be the key parameters for the vibration damping or acoustic materials. The relationship between the molecular structures of the random copolymer butadiene styrene rubber (SBR) obtained through the anionic polymerization method and their dynamic mechanical parameters under high pressure is studied to explore the energy loss mechanism of the polymer materials applied in the special conditions such as high pressure. The dynamic mechanical parameters were tested though experimental methods with pressure chambers, which can supply high pressure to the polymer samples. The results show that the most important effect factor of the molecular structure is the ratio of the content of the stiffer segments composed of styrene in the SSBR molecular chain to the softer ones composed of 1, 4-butadiene. This can be attributed to the stiffer segments supplying bigger free volumes for the molecular motion and higher modulus to resist to the high pressure, and the softer segments endue the effective energy loss ability to the polymer chains. However, the mass ratio of the stiffer and softer segments should be in an appropriate range, which the content of the styrene must be less than 40%.

Keys to enhancing mechanical properties of silica nanoparticle composites hydrogels: The role of network structure and interfacial interactions