Resin-based composites can contain defects across multiple length scales. Conventional degassing techniques, including vacuum degassing and centrifugation, primarily target entrapped air and bubbles. Although these techniques can reduce physical porosity, they do not directly establish a particular molecular packing state within the polymer-forming material. [1, 2]

Even a resin that appears free of visible bubbles contains molecular-scale regions of relatively unoccupied space arising from its molecular arrangement. These regions constitute molecular free volume and are not necessarily gas-filled pores. [1, 2]

Molecular packing, free-volume distribution, and molecular mobility are interconnected aspects of polymer structure. They influence material properties and may contribute to how a resin responds to curing, deformation, stress, and fracture. [1–4]

NETFIL® is our proprietary resin-processing technology that extends the concept of degassing beyond conventional air removal. Its objective is to influence molecular dynamics and structural evolution to promote a more spatially uniform and mechanically consistent composite.

To understand this approach, we must first distinguish conventional physical porosity from molecular free volume and examine its relationship with molecular dynamics.

Unlike physical pores or air bubbles, molecular free-volume elements (FVVs) are not necessarily gas-filled cavities. They represent regions of relatively unoccupied space within the molecular arrangement of a material. [1, 2]

Polymer molecules and chains cannot pack perfectly. Their chemical structure, molecular size, temperature, intermolecular interactions, and mobility influence their local arrangements and packing density. Consequently, molecular packing can vary throughout a polymer or resin composite. [1–3]

Molecular free volume is not a collection of permanently fixed microscopic holes. Molecular vibrations, rotations, and rearrangements continuously influence local packing. Individual free-volume elements may expand, contract, disappear, or form elsewhere as molecular configurations evolve. [1–3]

Free-volume distribution may differ between polymers and between regions within the same polymer. Some regions may exhibit denser molecular packing, while others contain greater local free volume. [1, 2]

The amount and distribution of molecular free volume depend on chemical composition, thermodynamic conditions, molecular structure, and processing history. [1–3]

Molecular free volume and molecular dynamics are closely interconnected. Molecular rearrangements can alter free-volume distribution, while the availability and distribution of free volume influence molecular mobility. [1–3]

This relationship is particularly important before polymerization, when the resin precursor retains sufficient mobility for molecular arrangements to evolve.

Favorable molecular dynamics refer to molecular motions and rearrangements that promote a desired structural, thermodynamic, or mechanical outcome under specified conditions.

Unfavorable molecular dynamics refer to motions and rearrangements that produce or preserve configurations detrimental to those outcomes.

These are operational definitions used in the NETFIL® processing framework worthy to be further expounded. 

Molecules in a liquid resin precursor are constantly moving, rotating, and rearranging. These molecular dynamics continuously alter the separation distances between neighboring atoms and the attractive and repulsive forces acting between them.

The potential energy of an interatomic interaction depends on the distance separating the interacting atoms. At excessively short distances, repulsive forces dominate. At greater distances, attractive interactions may prevail. Between these regions lies an energetically favorable separation at which attractive and repulsive forces balance.

[Hansen, J.-P. & McDonald, I. R. (2013). Theory of Simple Liquids, 4th ed., Academic Press.]

Favorable molecular dynamics allow resin precursor molecules to progressively adopt orientations in which neighboring atoms achieve more energetically favorable separation distances.

These rearrangements can reduce unfavorable repulsive interactions, establish more favorable attractive interactions, and lower the collective intermolecular potential energy.

However, favorable molecular arrangements do not necessarily require every atom to move closer to its neighbors. Instead, the molecules collectively adopt configurations that provide a more favorable balance of interatomic forces.

[Allen, M. P. & Tildesley, D. J. (2017). Computer Simulation of Liquids, 2nd ed., Oxford University Press.]

Unfavorable molecular dynamics, in the context of the NETFIL® process, describe molecular motions and rearrangements that produce or preserve less energetically favorable molecular configurations.

Certain molecular orientations may prevent neighboring atoms from simultaneously achieving favorable separation distances. While some atoms may approach one another excessively, creating strong repulsive interactions, others may remain too far apart to establish stronger attractive interactions.

These competing interatomic interactions, together with steric constraints and restricted molecular mobility, can prevent the precursor from rapidly achieving a more favorable collective energy state or balance.

[Hansen, J.-P. & McDonald, I. R. (2013). Theory of Simple Liquids, 4th ed., Academic Press.]

[Allen, M. P. & Tildesley, D. J. (2017). Computer Simulation of Liquids, 2nd ed., Oxford University Press.]

When a liquid resin precursor is displaced from equilibrium during processing, its molecular configuration may retain excess free energy.

Favorable molecular dynamics or interactions allows molecules to progressively rearrange toward more thermodynamically favorable configurations. These rearrangements alter interatomic separation distances, molecular orientations, and the collective balance of intermolecular forces.

The reduction of excess free energy is not necessarily instantaneous. Different molecular motions occur over different relaxation timescales, while energy barriers and restrictions on molecular mobility can delay access to more favorable configurations.

[Ferry, J. D. (1980). Viscoelastic Properties of Polymers, 3rd ed., John Wiley & Sons.]

[Doi, M. & Edwards, S. F. (1986). The Theory of Polymer Dynamics, Oxford University Press.]

At constant temperature and pressure, spontaneous relaxation toward equilibrium reduces Gibbs free energy. Changes in intermolecular potential energy may contribute to this reduction, although molecular entropy also influences the equilibrium configuration.

[Callen, H. B. (1985). Thermodynamics and an Introduction to Thermostatistics, 2nd ed., John Wiley & Sons.]

In a complex resin precursor, molecular rearrangements may not proceed at identical rates throughout the material.

Differences in local composition, molecular mobility, viscosity, and processing conditions can produce variations in relaxation behavior. Consequently, some molecular regions may approach their equilibrium configurations more rapidly than others.

[Doi, M. & Edwards, S. F. (1986). The Theory of Polymer Dynamics, Oxford University Press.]

If such differences persist until polymerization begins, the precursor may contain regions with different molecular configurations and relaxation histories.

The NETFIL® process seeks to influence these molecular dynamics and promote a more favorable and spatially uniform precursor state before hardening.

The resistance of an interatomic interaction to small changes in separation is related to the curvature of its potential-energy function near equilibrium.

A steep potential-energy curvature indicates greater local resistance to atomic displacement, while a flatter curvature indicates lower local stiffness.

[Born, M. & Huang, K. (1954). Dynamical Theory of Crystal Lattices, Oxford University Press.]

However, the macroscopic elastic modulus of a hardened polymer depends on the collective resistance of its molecular structure to deformation. This includes covalent network connectivity, intermolecular interactions, molecular orientation, and the ability of molecular segments to rearrange under load.

[Ward, I. M. & Sweeney, J. (2012). Mechanical Properties of Solid Polymers, 3rd ed., John Wiley & Sons.]

Therefore, effectively addressing the excess free energy in the liquid resin precursor, allows molecules to establish more energetically favorable intermolecular configurations before polymerization.

If these precursor arrangements influence the formation of a more effective and spatially uniform load-bearing network, they may contribute to increased resistance to elastic deformation and a higher flexural modulus.

This is an established relationship between polymer structure, molecular mobility, and flexural modulus.

[Ward, I. M. & Sweeney, J. (2012). Mechanical Properties of Solid Polymers, 3rd ed., John Wiley & Sons.]

[Ferracane, J. L. & Greener, E. H. (1986). The effect of resin formulation on the degree of conversion and mechanical properties of dental restorative resins. Journal of Biomedical Materials Research, 20(1), 121–131. DOI: 10.1002/jbm.820200111.]

NETFIL® PROCESS is based on influencing molecular dynamics in the liquid resin precursor before polymerization progressively restricts molecular mobility.

Its proposed objective is to promote favorable molecular rearrangements, reduce excess free energy, and establish a more spatially uniform molecular configuration before hardening.

By influencing the precursor's molecular dynamics, NETFIL® seeks to improve the structural and mechanical characteristics of the resulting composite, particularly its flexural modulus and mixed or dynamic strain- rate fracture behavior or toughness.

Molecular mobility  is not inherently favorable or unfavorable; its consequences depend on the material, its structural state, and the conditions under which molecular rearrangement occurs. [3, 4]

The molecular arrangements established within a resin composite precursor can influence its packing and free-volume distribution before curing begins. [1–3]

NETFIL® PROCESS focuses on reducing unfavorable molecular arrangements and promoting molecular dynamics that contribute to the desired mechanical response of the final composite.

However, achieving favorable molecular arrangements in isolated regions is insufficient for the intended NETFIL® outcome. Their spatial distribution throughout the resin precursor is equally important.

To understand why these arrangements may differ from one region to another, we must examine how physical processing conditions influence molecular mobility.

The molecules of a liquid resin precursor are continually influenced by their physical environment. Temperature, pressure, and mechanical deformation can affect molecular mobility, relaxation behavior, and the ability of molecules to rearrange relative to their neighbors. [2–4]

When sufficient mobility exists, molecular positions and local packing can evolve over time. Depending on the processing conditions and molecular relaxation behavior, these rearrangements may produce structural states that differ in their subsequent response to curing and mechanical loading. [3, 4]

Changes in processing conditions do not necessarily restore an earlier molecular arrangement immediately. Structural recovery depends on molecular mobility, relaxation times, and the physical constraints imposed on the resin. [3, 4]

Consequently, a resin precursor may retain aspects of its processing history after the original physical conditions have changed. [3, 4]

This becomes particularly important during polymerization, when chemical network formation progressively restricts molecular rearrangement.

Polymerization of common thermosetting methacrylate-based composite resins is exothermic. Heat is released as reactive groups undergo chemical transformation and a polymer network develops. [5–7]

Depending on formulation, curing conditions, and reaction kinetics, the resulting temperature rise can influence molecular mobility and reaction behavior. Molecular rearrangements occurring during this period may affect local packing and the evolving structural state. [3, 5–7]

At the same time, polymerization progressively develops the molecular network. Gelation and, where applicable, vitrification restrict molecular rearrangement as conversion advances and the network becomes increasingly constrained. [5–7]

As mobility decreases, some nonequilibrium molecular configurations may become kinetically trapped within the hardened composite. This follows the established principles of restricted relaxation and glass formation. [3, 8]

The resulting structure therefore depends not only on resin composition but also on reaction kinetics, thermal history, molecular mobility, and the conditions under which structural relaxation becomes restricted. [3, 5–8]

This raises a central question for NETFIL® processing:

How uniformly are favorable molecular arrangements distributed throughout the resin precursor before polymerization restricts their mobility?

Favorable molecular arrangements may develop to different extents in different regions of the same resin precursor.

Therefore, the NETFIL® objective is not merely to promote favorable molecular dynamics, but to achieve their most beneficial and spatially consistent distribution throughout the material.

This introduces one of the central principles of NETFIL® processing: spatial uniformity of molecular arrangements.

For NETFIL®, the primary objective is to promote a spatially uniform distribution of favorable molecular arrangements throughout the resin composite precursor.

A resin precursor may contain regions with different molecular packing states and free-volume distributions. During polymerization, structural differences may persist as molecular mobility becomes restricted. [1–3, 8]

Consequently, the hardened composite may retain spatial variations in molecular structure and local mechanical behavior. The extent to which precursor free-volume variations survive curing depends on the material and curing history. [3, 5–8]

NETFIL® PROCESS is intended to reduce detrimental variations and promote a more consistent molecular and mechanical state throughout the composite.

This objective also accounts for filler distribution, polymerization kinetics, molecular mobility, thermal history, and local physical constraints, all of which can influence the resulting composite structure and properties. [5–7, 9]

The importance of spatial uniformity extends beyond molecular packing and free-volume distribution.

Differences in molecular structure, mobility, and curing history may also influence how polymerization stresses develop, accumulate, and relax throughout the composite. [5–7]

As the polymer network develops during curing, the resin undergoes polymerization shrinkage. This occurs because chemical reactions and network formation change the molecular structure and volume of the material. [5–7]

When shrinkage is mechanically constrained, internal stresses develop. These are commonly described as polymerization stresses, some of which may remain as residual stresses after curing. [5–7]

The magnitude and distribution of these stresses depend on volumetric shrinkage, polymerization kinetics, viscoelastic behavior, modulus development, temperature, and mechanical constraints. [5–7]

Molecular dynamics influence how the developing network accommodates deformation and redistributes stress. [4–7]

Stress does not necessarily remain constant after it develops. Viscoelastic composites can undergo stress relaxation, during which internal stress decreases over time under sustained deformation. [4, 10]

This relaxation depends on molecular mobility, relaxation times, temperature, network structure, and the material's state of cure. [4–7, 10]

Different regions of a composite may experience different curing histories and mechanical constraints. Consequently, their ability to accommodate shrinkage and relax stress may differ. [5–7]

Such differences can contribute to nonuniform residual-stress distributions within the hardened composite. [5–7]

NETFIL® seeks to influence these processes by promoting favorable molecular arrangements and a more uniform structural state during resin processing and curing.

Its objective is to reduce detrimental stress development and residual-stress heterogeneity through controlled molecular and structural evolution.

However, residual stress is only one aspect of mechanical uniformity.

Even when residual stresses are relatively low, local variations in stiffness can cause neighboring regions to deform differently under applied loading. [9, 11]

This brings us to spatial modulus distribution.

The elastic modulus describes a material's resistance to elastic deformation. In simple terms, it indicates how stiff the material is under loading. [9, 11]

A composite may possess a particular average modulus while containing regions that are locally stiffer or more compliant. Spatial modulus distribution describes how stiffness varies from one location to another. [9, 11]

These variations can arise from differences in polymer network structure, degree of conversion, crosslinking, filler content and distribution, and local material history. [5, 9, 11]

The average modulus alone cannot fully describe how a heterogeneous composite responds to mechanical loading. [9, 11]

Regions with different stiffness can deform differently under the same applied conditions, influencing local stress transfer and redistribution. [9, 11]

A relatively stiff region may resist deformation more strongly than an adjacent compliant region. This mismatch can influence local stress distribution, particularly under bending or other nonuniform loading conditions. [11]

Near a sharp V-notch, where geometry already concentrates stress, local differences in stiffness and residual stress may further influence the mechanical response. [11, 12]

A composite may therefore exhibit favorable average mechanical properties while retaining local regions that respond differently to stress. [9, 11]

NETFIL® focuses on refining the spatial distribution of structural and mechanical properties to reduce detrimental modulus heterogeneity.

The objective is not simply to increase average modulus, but to promote a more consistent modulus distribution and mechanical response throughout the composite.

However, the structural and mechanical state established during curing may not remain unchanged indefinitely.

A hardened polymer can continue to evolve through physical aging.

The molecular structure of a polymer may continue to evolve after curing. [3, 8]

Physical aging refers to time-dependent structural relaxation of a nonequilibrium polymer glass, commonly observed below its glass-transition temperature. [3, 8]

Although large-scale molecular mobility is restricted, structural relaxation can continue as the material evolves toward a more equilibrated state. [3, 8]

These changes may involve molecular packing, specific volume, and free-volume distribution. They can also influence modulus, relaxation behavior, and other physical properties. [1–3, 8]

The rate and extent of physical aging depend on temperature, molecular mobility, material structure, and previous thermal and mechanical history. [3, 8]

The significance of aging becomes particularly important when the hardened composite contains spatially nonuniform structural states.

Regions with different molecular environments or histories may exhibit different relaxation behavior. This provides a physical basis for investigating whether local mechanical properties evolve unevenly during aging. [3, 8, 11]

Consequently, local stiffness and mechanical response may change over time, potentially influencing behavior near defects, interfaces, and notches. [8, 12]

Physical aging must also be distinguished from chemical aging.

Physical aging involves structural relaxation without necessarily changing chemical composition. Chemical aging involves chemical changes, including processes such as oxidation or hydrolysis. [3, 8]

Thus, the fracture behavior of a polymer composite may depend not only on its initial cured structure but also on how that structure evolves over time. [8, 12]

This establishes an important connection between molecular history, spatial mechanical uniformity, and fracture mechanics.

Fracture mechanics examines the conditions governing crack initiation, propagation, and resistance to fracture. [12]

A sharp notch or crack produces a concentrated stress field near its tip. Consequently, a material may become susceptible to fracture even when its average mechanical properties appear favorable. [12]

The local fracture response depends on material properties, loading conditions, crack or notch geometry, and the mechanisms through which the material deforms and dissipates energy. [12]

Molecular structure, physical aging, and local mechanical properties can influence the deformation and fracture behavior of glassy polymers. [8, 12]

In a heterogeneous composite, local differences in stiffness and structural properties may alter the stress and deformation fields encountered by a crack. [9, 11, 12]

The important distinction is between the average properties of the composite and the local mechanical response of the region where fracture begins.

A composite may possess a favorable average modulus while containing localized regions with different mechanical characteristics. The interaction of a crack with such regions may influence its propagation behavior. [11, 12]

NETFIL® seeks to reduce detrimental structural and mechanical heterogeneity, promoting a more uniform response to applied loading and reducing conditions that favor localized stress accumulation.

In our experimental observations, NETFIL®-processed specimens have demonstrated substantially reduced V-notch sensitivity.

V-notch sensitivity describes how strongly a notch affects a material's measured mechanical response. Its interpretation depends on specimen geometry, loading conditions, material behavior, and the selected mechanical performance measure. [12]

Our proposed molecular explanation is that improved spatial structural and mechanical uniformity contributes to the observed reduction in notch sensitivity.

These observations demonstrate the importance of examining mechanical behavior beyond average material properties.

This leads to two complementary approaches within NETFIL® technology: NETFIL® PROCESS and NETFIL GLIMMER® FILM.

NETFIL® PROCESS and NETFIL GLIMMER® FILM address different aspects of composite structure and mechanical performance.

NETFIL® PROCESS focuses primarily on the internal molecular and mechanical state of the polymer matrix.

Its objective is to influence molecular arrangements, structural relaxation, and spatial modulus distribution to reduce detrimental heterogeneity within the hardened composite.

NETFIL GLIMMER® FILM, by contrast, focuses on the mechanical architecture of interfaces between adjacent composite layers.

GLIMMER® FILM introduces engineered macrotexture that creates distinct mechanical engagement features between layers.

These features are intended to increase interlayer mechanical interlocking and resistance to relative sliding.

Research on engineered interfaces demonstrates that interface geometry and mechanical interlocking can influence adhesion, stress transfer, and resistance to separation. [13–15]

Smooth interfaces may provide comparatively direct separation paths under certain loading conditions. Engineered interfacial geometries can modify crack paths and the mechanisms through which loads are transferred across an interface. [13–15]

Properly developed macrotexture may also contribute to crack deflection and energy dissipation. The effectiveness of these mechanisms depends on feature geometry, material properties, interface integrity, and loading conditions. [13–15]

The distinction between the two technologies is therefore clear:

• NETFIL® PROCESS addresses molecular arrangements, structural conditioning, and spatial mechanical uniformity within the composite.
• NETFIL GLIMMER® FILM addresses interlayer architecture, mechanical engagement, and interfacial stress transfer.

Together, these approaches are intended to improve notch tolerance, interlayer integrity, and fracture performance.

One addresses the internal structural state of the composite, while the other addresses how adjacent layers mechanically interact.

NETFIL® Nano Degassing extends the concept of degassing beyond the removal of conventional physical porosity.

It considers the relationships among molecular free volume, molecular dynamics, processing history, structural relaxation, polymerization, residual stress, modulus distribution, physical aging, and fracture mechanics. [1–12]

These are interconnected aspects of polymer structure, processing, and mechanical behavior. [3–12]

Molecular arrangements established during precursor manufacture and processing influence the structural state from which polymerization begins. [2–4]

During curing, chemical network formation, temperature, molecular mobility, reaction kinetics, and physical constraints influence how that structure evolves. [5–7]

As molecular mobility becomes restricted, nonequilibrium structural configurations may persist within the hardened composite. [3, 8]

Differences in curing history and local structure can contribute to variations in residual stress and mechanical properties. [5–9, 11]

After curing, physical aging may further modify molecular packing and mechanical response, potentially influencing fracture behavior over time. [3, 8, 12]

The central objective of NETFIL® is to promote favorable molecular arrangements and achieve a more spatially uniform structural and mechanical state throughout the polymer matrix.

Our underlying proposition is that composite performance depends not only on average mechanical properties but also on their spatial distribution and the local conditions governing deformation and fracture. This proposition is consistent with the principles of heterogeneous material mechanics and polymer fracture behavior. [9, 11, 12]

A composite's resistance to deformation and fracture may therefore depend on its molecular history, the conditions under which its structure develops, and the degree of structural uniformity achieved before molecular mobility becomes restricted. [3–12]

NETFIL® approaches composite processing from the molecular scale upward.

It considers not only what a composite is made of, but also how its molecular structure evolves, how uniformly that evolution occurs, and how the resulting structure responds to mechanical loading and aging.

The following 15 sources form the numbered bibliography for this edition. They include peer-reviewed reviews, experimental studies, and foundational polymer-science literature.

[1] Consolati, G., Nichetti, D., & Quasso, F. (2023). Probing the Free Volume in Polymers by Means of Positron Annihilation Lifetime Spectroscopy. Polymers, 15(14), 3128.

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[2] Takahashi, K. Z. (2023). Mapping Positron Annihilation Lifetime Spectroscopy Data of a Polymer to Classical Molecular Dynamics Simulations Without Shifting the Glass Transition Temperature. The Journal of Chemical Physics, 159, 084903.

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[3] Hodge, I. M. (1995). Physical Aging in Polymer Glasses. Science, 267(5206), 1945–1947.

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[4] Sperling, L. H. (2005). Polymer Viscoelasticity and Rheology. In Introduction to Physical Polymer Science, Chapter 10. Wiley.

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[5] Braga, R. R., Ballester, R. Y., & Ferracane, J. L. (2005). Factors Involved in the Development of Polymerization Shrinkage Stress in Resin-Composites: A Systematic Review. Dental Materials, 21(10), 962–970.

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[6] Ferracane, J. L. (2005). Developing a More Complete Understanding of Stresses Produced in Dental Composites During Polymerization. Dental Materials, 21(1), 36–42.

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[7] Kleverlaan, C. J., & Feilzer, A. J. (2005). Polymerization Shrinkage and Contraction Stress of Dental Resin Composites. Dental Materials, 21(12), 1150–1157.

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[8] Struik, L. C. E. (1978). Physical Aging in Amorphous Polymers and Other Materials. Elsevier Scientific Publishing Company.

ISBN: 9780444416557.

[9] Masouras, K., Silikas, N., & Watts, D. C. (2008). Correlation of Filler Content and Elastic Properties of Resin-Composites. Dental Materials, 24(7), 932–939.

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[10] Winter, H. H. (2026). Viscoelastic Stress Relaxation, Fast and Slow. Soft Matter, 22, 884–891.

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[11] Elfakhri, F., Alkahtani, R., Li, C., & Khaliq, J. (2022). Influence of Filler Characteristics on the Performance of Dental Composites: A Comprehensive Review. Ceramics International.

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[12] Rottler, J. (2009). Fracture in Glassy Polymers: A Molecular Modeling Perspective. Journal of Physics: Condensed Matter, 21(46), 463101.

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[13] Aliheidari, N., Christ, J., Tripuraneni, R., Nadimpalli, S., & Ameli, A. (2018). Interlayer Adhesion and Fracture Resistance of Polymers Printed Through Melt Extrusion Additive Manufacturing Process. Materials & Design, 156, 351–361.

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[14] Printing Orientation and Interfacial Mechanical Design Enable Superior Bonding in Multimaterial Additive Manufacturing. (2026). npj Advanced Manufacturing.

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[15] Overcuring-Assisted Mechanical Interlocking of Metal–Polymer Composites Fabricated by Vat Photopolymerization. (2026). Defence Technology.

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The most immediate benefit of NETFIL processing is a clear improvement in elastic modulus and fracture toughness of the resin composite. This increase arises from the highly uniform reduction of nanoscale porosity within the resin composite, which raises the realized density of the resin toward its theoretical density. By eliminating nanoporosity and free volume voids uniformly, NETFIL processing reduces structural defects that would otherwise cause stress concentrations and compromise the composite resin's mechanical response, while allowing the material to behave much closer to its inherent mechanical potential. Through improved density at the submicroscopic level, NETFIL processing helps the resin composite deliver its fullest potential when it comes to its flexural strength or fracture toughness. But it should  be clearly noted at this point that the post-processing technique of cleaning the 3D printed part using powerful solvents such as IPA, is damaging to the surface integrity of the Netfil processed resin 3D printed component.