AN INNOVATIVE MATERIAL AND MANUFACTURING TECHNIQUE TO REDUCE THE CARBON FOOTPRINT OF COMPOSITES

ABSTRACT

Composites are fabulous materials! Not only can you use it on all kinds of projects, but also you can design your composite material to achieve the best technical properties for the specific needs your project requires!

In the last 90 years, composite material imposed their versatility to be progressively most used in almost all industries and in so many other human applications.

Among all reinforcing materials, carbon fibers appear to be the most attractive, for its high mechanical strength and stiffness and for its lightness, but at a very high economic and ecological cost.

And so, the widespread use of carbon fibers on composites manufacturing, in the last decades, strongly increased the carbon footprint of composites industry.

The well-known need for reducing the use on carbon fibers and search for more sustainable alternative solutions, on structural and non-structural composites, inspired me to develop an innovative sandwich composite concept supported by an also innovative manufacturing technique.

The new concept is a sandwich composite, laminated in one only manufacturing process, with a reinforced core made of multiple cork layers with fiber laminates interposed.

The innovative manufacturing technique, on a hand lay-up technique, is a sequential manufacturing process to make the sandwich composite in one working session. This process starts with an external fiber laminate, continues with sequential layers of cork with fiber laminates interposed on the reinforced core and finishes with the second outer fiber laminate.

With this new composite material and its innovative one-session manufacturing sandwich technique, I wish to open the way to reducing the widespread use of carbon fibers and present an alternative use of more sustainable materials, as natural fibers and cork, as reinforcement materials on structural components, in all kinds of applications, from automotive or aeronautical and aerospace to naval or house construction industries.

INTRODUCTION

Composite materials are man-made structures that have been widely used by mankind, dating back to the use of straw in the manufacture of bricks in ancient Egypt.

For nearly a century, composite materials were developed using natural or synthetic fibers immersed in a polymer matrix.

Sandwich-structured composites were devised to obtain a moderate robust material with high strength and light weight, which is an ideal solution for most engineering applications. Such structure is obtained by combining high strength and stiffness materials, as external laminates, bonded to a light core material with low to moderate mechanical strength.

Although the use of a single core layer in traditional sandwich-structured composites reduces the overall weight of the composite material while relying on the external laminates to provide the desired mechanical strength and stiffness of the final material, when the composite is subjected to forces and moments with flexural, traction and compression efforts, with the consequent development of shear and axial stresses, the lower mechanical properties of the core material may result in its detachment from the external laminates, which ultimately leads to irreversible structural damage of the composite.

THE CLASSIC SANDWICH COMPOSITS PROBLEMS

The common use, on classic sandwich composites, of high mechanical strength and stiffness outer fiber laminates bonded to a core material with very low mechanical properties, in an also classic two stages manufacturing process, confers the final material a structural fragility.

In the most traditional manufacture process of sandwich composites the outer laminates are first made and cured, before being bonded to the lighter core materials.

When this classic sandwich composite is subjected to forces and moments with the induced shear and axial stress, the most feared result can be the breakdown of the (weak) core and/or of the core/outer laminates interface with the overall failure of all composite structure.

The sandwich composite and manufacturing process that I invented and propose to you innovatively provides a solution for such problems.

MY INNOVATIVE TECHNICAL SOLUTION

With my innovative material and manufacture technique I provide a solution to overcome these sandwich composite materials weaknesses and present an alternative to the intense and massive use of carbon fiber laminates on structural and non-structural components.

· The core additional reinforcement with multiple cork layers with fiber laminates layers interposed between them;

· The one working session manufacturing process, using in a preferable hand lay-up technique, with a simultaneous complete cure of this innovative sandwich composite, resulting in a final composite with better mechanical properties, more cohesive and unified, despite its heterogeneous composition.

With this new composite and manufacturing process we can expect not only to use the natural and glass fiber laminates as structural alternative to carbon fiber laminates, but also to reduce the use of carbon fiber on structural applications, always its use will be considered as unavoidable.

THE TECHNICAL SOLUTION DETAILS

One of the most unique features of composite materials is to be designed and made for the specific technical demands of the project to be used in.

And so, sure with the specific, mechanical and other, needs of a project, we calculate the properties of the composite material we must manufacture to be used on it.

To achieve those properties, we select the more adequate matrix polymer and fiber and cork reinforcement and calculate the number of fiber and cork layers and their relative orientation (for the fiber laminates) and relative position on the final sandwich composite.

In a preferred aspect of my invention, the distinct layered components of the laminate composite (1), namely the fiber laminates (2)(4)(6) and the cork layers (5) are bonded to each other by a matrix polymer, be it a thermoplastic one, such as polyamide resin, or a thermosetting polymer, such as polyester, epoxy resin or vinyl ester resin. In addition to promoting the permanent and stable adhesion of the different stacked layers comprised in the laminate composite (1), the matrix polymer also confers an increased mechanical and structural resistance to rupture and deformation of the laminate composite (1) after its full cure and hardening.

Each cork layer (5) comprised in the sandwich composite core (3) may be selected from the group consisting of: natural cork, agglomerated cork, and expanded cork. The type of cork material used in the sandwich composite core (3) affects the overall mechanical properties of the laminate composite, such as density, flexibility and resistance to traction and to compression, which allows further tuning of the mechanical properties of the laminate composite, depending on the desired application of the composite. The porosity of the cork material used (3) improves the impregnation of the bonding matrix polymer during the manufacture of the laminate composite (1), which also impacts the overall mechanical properties of the final product.

Each fiber layer (7) of the first fiber laminate (2), the second fiber laminate (4) or in the intermediate fiber laminate (6) comprises least one fiber material selected from the group consisting of: natural fibers, synthetic fibers, fiberglass, aramid fibers, boron fibers and carbon fibers. The preferred fiber materials comprised in each fiber layer (7) can be chosen between natural fibers, such as linen, bamboo or other fibers of biological source, to minimize the ecological footprint and to promote a more sustainable product development.

The hand lay-up technique suits better than any other to the manufacture of this innovative material.

We start with the successive application of a first absorbable film layer, such as felt, on a working surface or mold and of a peel-ply layer over it. Then we start to laminate one of the outer fiber laminates with the manual application of the fiber laminae, one by one, bonded with the appropriate matrix polymer interposed to assure the best mechanical and other desired properties.

After laminating the first outer fiber laminate, we continue the manufacturing process with the core by applying the first cork layer, bonded with the same matrix polymer. Then, and over this cork layer, we laminate the first internal fiber laminate, with the apposition of the fiber laminae, one by one, bonded with the same matrix polymer interposed.

Over this first internal fiber laminate we then apply the second cork layer of the core, and over it we laminate another fiber laminate, again with the same matrix polymer. This fiber laminate can be a second internal fiber laminate, if we intend to apply a third cork lamina on the core, or the second outer fiber laminate, depending on the use of two or more cork layers on the core of the composite.

By the above-described manufacturing process, it is obvious that the number of cork layers on the core will always be one more than the internal fiber laminates.

We will finish the manufacturing process by applying a second peel-ply layer over the second outer fiber laminate, a second absorbable film layer, such as felt, over it, and the outer working surface or mold over it.

The cure of the matrix polymer will bond the whole sandwich composite simultaneously, and can be made, ideally on an autoclave and inside a vacuum bag, so that any inner pockets of air are removed from the stratified body.

In the end of this one session manufacturing process, we can expect that the final sandwich composite will have all the mechanical and other properties to best fit on the solicitations of the project he was made for.

In this innovative manufacturing process, additional layers of cork material (5) may be added to the core (3), being intercalated with additional intermediate fiber laminates (6), so that the total number of layers of cork material (5) is superior to the number of intermediate fiber laminates (6) by one layer. The addition of more layers of cork material (5) and intermediate fiber laminates (6) in the core (3) allows the tuning of the overall mechanical performance of the laminate composite (1), while minimizing the increase of the overall density of the laminate composite (1) resulting from the addition of intermediate fiber laminates (6) to the core (3).

The manufacturing process of the laminate composite may be adapted to be applicable in the automobile and aerospace industries, and naval engineering, to produce molded components comprising reinforced laminate composites as described above. The use of the laminate composite (1) may be also applicable in building construction and in the manufacturing of refrigerating equipment comprising laminate composites.

BUSINESS BENEFITS

The main advantages for the industry that uses this innovative sandwich composite and manufacturing process solution:

· The carbon footprint reduction.

· Additional economic advantage.

· Thermal and acoustic insulation.

There can be several prestigious marketing and image advantages to any company that consider using this innovative solution:

· The planet friendly image for the carbon footprint reduction.

SUMMARY

My sandwich composite with reinforced core and one session manufacturing process can be applied to several industries, such as the automobile, aerospace and naval industries, construction and refrigeration industry.

My innovative composite will result from assembling a laminated composite (1) that will comprise a first outer fiber laminate (2), a sandwich-like core (3) and a second outer fiber laminate (4).

The sandwich-like core (3) is stacked between the first outer fiber laminate (2) and the second outer fiber laminate (4) and is reinforced by comprising at least two layers of cork material (5) and at least one intermediate and inner fiber laminate interposed between the two layers of cork material.

My innovative reinforced sandwich-structured core composite and it’s also innovative one session manufacturing process will have an increased mechanical strength and stiffness and improved resistance to compression, traction and bending efforts, while maintaining an overall and also desired light weight.

CALL ME!

If you want your company to be in the first line of a more sustainable development, and your projects to be considered state-of-the-art in modern materials and more sustainable technology, contact us.

And do it fast…

Our beloved planet needs all our efforts to make it healthier!