Review Reports - Evaluation of Fire Resistance of Polymer Composites with Natural Reinforcement as Safe Construction Materials for Small Vessels

Round 1

Reviewer 1 Report

The paper titled Evaluation of fire resistance of polymer composites with natural reinforcement as safe construction materials for small vessels compared compares selected characteristics of the reaction to fire of composite materials with glass fiber and hemp fiber reinforcement. The possibility of using polymer-hemp composites was assessed in terms of safety, i.e. fire resistance of these units. The article has some innovation, but there are still some problems that need to be explained or modified.

1. Are the plant fibers used in the manuscript treated with surface treatment? Such as silane treatment.

2. In abstract, we can not get any useful information, it is suggested that rewrite the abstract.

3. In introduction, it did not introduce clearly the questions to be studied and the innovation points of this paper.

4. There are articles that investigate the composite structures and natural fiber reinforced biocomposites, suggest citing: (http://dx.doi.org/10.1016/j.compstruct.2022.116313).(https://doi.org/10.1016/j.coco.2022.101448) (http://dx.doi.org/10.1016/j.compositesb.2022.110450)

5. In figure 2, name of every equipment should be added, these are easier to understand.

6. Please keep the style of the table consistent. For instance, the Table 3 is obviously different to other tables.

7. The discussion of the results should be deeper.

8. The writing should be improved, eg., the tense should be consistent, the sentences should be polished.

The writing should be improved, eg., the tense should be consistent, the sentences should be polished.

Author Response

Thank you for all your comments to improve the article and future works of the authors. We have responded to all comments below:

Are the plant fibers used in the manuscript treated with surface treatment? Such as silane treatment.

Modification of natural fibers with silanes can affect their flammability depending on the type of silane used. Silanes containing a methacryloyl group such as methacryloyloctyl(3-trimethoxysilane)propionate (MPS) or methacryloyloctyl(3-triethyloxysilane)propionate (TESP) are often used to modify the natural fiber to improve bonding to the polyester resin. Silanes such as methyltrialkoxysilanes can increase the flammability of natural fibers as they tend to react with moisture and release flammable gases. Unmodified fibers were used in the work. In addition, the preliminary research carried out by the authors shows that as a result of the use of fiber modifications in the form of fabrics, their mechanical properties deteriorate. However, a pro-adhesion agent was added to the resin.

In abstract, we can not get any useful information, it is suggested that rewrite the abstract.

Thank you for your attention. The abstract has been corrected.

In introduction, it did not introduce clearly the questions to be studied and the innovation points of this paper.

Thank you for your comment. We hope that the added excerpt improved our work.

There are articles that investigate the composite structures and natural fiber reinforced biocomposites, suggest citing: (http://dx.doi.org/10.1016/j.compstruct.2022.116313).(https://doi.org/10.1016/j.coco.2022.101448) (http://dx.doi.org/10.1016/j.compositesb.2022.110450)

Thank you for pointing out very interesting works. One of them we thought fit to be added.

In figure 2, name of every equipment should be added, these are easier to understand.

Thank you for pointing out the ambiguity of the message in Figure 2. This figure was supposed to show accidents on yachts broken down by type of accident. We have made a small correction to it, we hope it is now more readable.

Please keep the style of the table consistent. For instance, the Table 3 is obviously different to other tables.

Thank you for your attention. Table 3 was intended to be different from the other tables due to its content. It is a key element of summarizing the results.

The discussion of the results should be deeper.

Thank you for your comment. We hope that the changes introduced improve the discussion of the results.

The writing should be improved, eg., the tense should be consistent, the sentences should be polished.

Thank you for your attention. The final correction will be made after the article is accepted.

Thank you very much for your thorough substantive and editorial evaluation of our article.

Yours faithfully,

Katarzyna Bryll

Reviewer 2 Report

1, The abstract and conclusions are not specific enough and lacks data.

2, There is no information for the specification and properties of glass fiber and hemp fiber.

3, The authors must include the fabrication method and microstructures of GFRP and HFRP and more discussions about the results.

4, I suggests that measure the CTE value of both GFRP and HFRP, compare the CTE of the composites.

Comments for author File: Comments.docx

Minor editing of English language required

Author Response

Thank you for all your comments to improve the article and future works of the authors. We have responded to all comments below:

The abstract and conclusions are not specific enough and lacks data.

Thank you for your attention. The abstract has been corrected.

There is no information for the specification and properties of glass fiber and hemp fiber.

Thank you for your comment. Commercial fabrics were used in the work. Some information has been added to the text.

The authors must include the fabrication method and microstructures of GFRP and HFRP and more discussions about the results.

Thank you for your attention. Unmodified fibers currently available on the market were used in the work. In addition, the preliminary studies carried out by the authors shows that as a result of the use of fiber modifications in the form of fabrics, their mechanical properties deteriorate. However, a pro-adhesion agent was added to the resin. The analysis of the results has been extended.

I suggests that measure the CTE value of both GFRP and HFRP, compare the CTE of the composites.

Thanks for your suggestion. CTE was not measured for both composites during this study but will be determined in future work by the authors.

Yours faithfully,

Katarzyna Bryll

Reviewer 3 Report

Overall, the paper presents an interesting comparison between glass fiber reinforced polymer composites and hemp fiber reinforced polymer composites in terms of their reaction to fire.

As a reviewer, I would suggest that the authors consider improving the figures in the paper by using a scientific software such as OriginLab, which may help to improve the clarity and quality of the visual representations of the data. Additionally, I would recommend that the authors consider providing more information on the process of fabricating the vessel, as well as providing more context and background information to help the reader better understand the significance and implications of the study.

Furthermore, I would suggest that the authors work on improving the structure and organization of the paper to make it more reader-friendly and easier to follow. This may include reorganizing the sections of the paper and providing clearer and more concise headings and subheadings. Finally, I would encourage the authors to consider revising the writing style to make the paper more engaging and easier to read, while still maintaining a scientific tone and rigor.

However, there are a few areas that could be improved:

-The introduction should provide more context on the current state of the field and the importance of finding alternative, environmentally friendly construction materials. It could also benefit from a clearer statement of the research question and the objectives of the study.

-The methodology section could be more detailed to help readers understand the testing procedures and parameters used to evaluate the reaction to fire.

-The discussion section should provide a more in-depth analysis of the results and their implications. For example, the authors could explore why hemp fiber reinforced polymer composites have a higher heat release rate but a longer ignition time than glass fiber reinforced polymer composites. The authors could also discuss the potential limitations of using flame retardants to minimize the possibility of ignition in hemp fiber reinforced polymer composites.

-The paper could benefit from more comprehensive literature review and citation of relevant studies to support the authors' arguments and conclusions, like "An Overview of the Recent Advances in Composite Materials and Artificial Intelligence for Hydrogen Storage Vessels Design. Journal of Composites Science, 7(3), 119".

-It is important for the authors to clarify the practical implications of their findings for the construction and use of yachts or other recreational vessels. For example, how might the use of hemp fiber reinforced polymer composites impact the safety of people on board in the event of a fire?

-How might the use of other natural fibers, such as flax or bamboo, compare to hemp fiber in terms of their fire resistance and environmental impact?

-Have the authors considered the cost implications of using hemp fiber reinforced polymer composites compared to glass fiber reinforced polymer composites?

-Are there any potential drawbacks or challenges to using flame retardants in hemp fiber reinforced polymer composites, such as negative environmental impacts or reduced mechanical properties?

-How do the results of this study contribute to the broader discussion on sustainable materials and circular economy in the marine industry? What policy implications might these findings have?

-Are there any potential trade-offs or unintended consequences associated with replacing glass fiber reinforced polymer composites with hemp fiber reinforced polymer composites, such as changes in the overall performance or durability of the vessel?

-How might the results of this study be affected by different testing conditions or parameters? For example, how would the results differ if the tests were conducted on larger vessels or under different environmental conditions?

-How might the use of hemp fiber reinforced polymer composites impact the overall carbon footprint of the vessel, taking into account the entire lifecycle of the material, from production to disposal?

-Are there any ethical considerations that should be taken into account when using natural fibers for composite materials, such as concerns about labor practices or land use impacts?

Author Response

Thank you very much for all your comments to improve the article and future works of the authors. We have responded to all comments below:

Thank you for your attention. We hope that the changes introduced in the article will provide a better context for the researched materials.

-The methodology section could be more detailed to help readers understand the testing procedures and parameters used to evaluate the reaction to fire.

Thank you for your comment. We hope that the added excerpt will help readers understand the testing procedures and parameters used to evaluate the reaction to fire.

Hemp fiber reinforced composites tend to have a higher heat release rate than glass fiber reinforced composites for several reasons. First, hemp fibers have a lower thermal conductivity than glass fibers. It means that in the heat release process, heat is retained in the material for longer, leading to higher temperatures. On the other hand, glass fibers have a higher thermal conductivity, which allows for faster heat and thermal dissipation. Second, hemp fibers are typically less thermally stable than glass fibers. While glass fibers retain their structure at high temperatures, hemp fibers tend to thermally decompose at temperatures above 200°C. This means that in the case of hemp fiber reinforced composites, the release of heat can lead to faster fiber degradation and a reduction in the strength of the material.

Overall, hemp fiber reinforced composites tend to have a higher heat release rate than glass fiber reinforced composites due to differences in thermal conductivity, thermal stability of fibers. This is also associated with a longer ignition time.

Thank you for an interesting article. It was taken into account when expanding the literature analysis..

Polymer composites reinforced with hemp fiber can improve the safety of people on board in the event of fire, as they have better fire resistance properties compared to traditional materials used in shipbuilding. Hemp fibers used as reinforcement in polymer composites are natural materials with high strength and low weight, which allows you to reduce the weight of structural elements, and thus increase fuel efficiency and reduce CO2 emissions. In the event of a fire, polymer composites reinforced with hemp fiber retain their structure for a longer time, which delays the combustion process and gives time for evacuation of passengers. In addition, these composites give off less toxic gases when burned compared to traditional aerospace materials, which helps to increase the chances of surviving in the event of a fire. Additionally, hemp fiber reinforced polymer composites are more impact and fatigue resistant than traditional materials, which contributing to increased safety in the event of a collision. In conclusion, the use of polymer composites reinforced with hemp fiber can improve the safety of people on board in the event of a fire by increasing resistance to fire and reducing the emission of toxic gases, which allows for longer time for evacuation of passengers.

These considerations have been included in Tab. 3.

-How might the use of other natural fibers, such as flax or bamboo, compare to hemp fiber in terms of their fire resistance and environmental impact?

Natural fibers such as linen or bamboo can be used to reinforce composites, just like hemp fibers. However, the fire resistance and environmental impact of these different types of fibers depends on many factors. Flax is resistant to fire and emits little smoke, which makes it advantageous from a fire resistance point of view. Bamboo is lightweight but very strong and flexible, which makes it attractive from a mechanical strength point of view. It is also fire resistant and has a low environmental impact. If other reinforcement materials than hemp are used, it is also important to carry out appropriate tests to determine their fire performance and environmental impact. Flax tends to emit less smoke than hemp in the event of a fire, because it has a higher cellulose content, which is an organic material that burns slower than synthetic materials. Hemp fibers contain lignin, which is more prone to burning and producing smoke than cellulose. Hemp is also oilier than flax, which makes it easier to ignite and gives off more smoke in the event of a fire. However, it should be noted that the differences in smoke emission between flax and hemp are small and depend on many factors such as humidity, density and structure of the material.

However, hemp (Cannabis sativa L.) is a much faster plant compared to flax (Linum usitatissimum). Under favorable climatic and soil conditions, hemp can reach a height of up to 4 meters in one growing season, while flax usually reaches a height of 1.2-1.5 meters in the same period. In addition, hemp has a greater ability to regenerate and develop buds faster, which accelerates its growth. Both types of fibers - flax and hemp, have very good mechanical properties and show high tensile strength, wear and tear resistance. However, comparative studies have shown that hemp fibers have slightly better mechanical properties than flax fibers. The comparison of different types of natural fibers will be the subject of further work by the authors.

-Have the authors considered the cost implications of using hemp fiber reinforced polymer composites compared to glass fiber reinforced polymer composites?

The use of hemp fiber reinforced polymer composites can affect costs in various aspects compared to glass fiber reinforced polymer composites. Initially, the cost of the material itself may be higher for hemp-reinforced polymer composites due to the lower commercial availability and higher production cost of hemp fiber compared to glass fiber, which is common available. However, due to the lightweight of hemp fiber reinforced polymer composites, their use can help reduce fuel consumption and CO2 emissions, which can result in savings in operational costs. In addition, the use of hemp fiber reinforced polymer composites can lead to reduced maintenance and repair costs as they are more fatigue and impact resistant than traditional materials. In addition, thanks to the lightweight, the use of polymer composites reinforced with hemp fiber can reduce the costs associated with the transport and assembly of structural elements. Ultimately, the cost implications of using hemp fiber reinforced polymer composites versus glass fiber reinforced polymer composites depend on many factors such as raw material availability, manufacturing cost, as well as operational and maintenance costs. However, in the long term, the use of polymer composites reinforced with hemp fiber can bring economic benefits related to fuel savings, maintenance and repair costs, as well as costs associated with the transport and assembly of structural elements. However, this comparison is beyond the scope of this article.

-Are there any potential drawbacks or challenges to using flame retardants in hemp fiber reinforced polymer composites, such as negative environmental impacts or reduced mechanical properties?

Yes, there are potential downsides or challenges to using flame retardants in hemp fiber reinforced polymer composites. First, some flame retardants can have a negative impact on the environment. For example, some agents may contain bromine or chlorine compounds that are considered toxic to the environment. This can lead to environmental pollution during the production, use and disposal of the products. Second, some flame retardants can affect the mechanical properties of the composite, such as tensile strength, bending strength, and impact resistance. They can affect the performance of the material and increase production costs, which can negatively affect the competitiveness of the product. Halides can also affect the thermal stability of the material, which can affect durability and aging resistance. Similarly, some carbonate flame retardants may affect the mechanical properties such as impact resistance and tensile strength, particularly when exposed to high temperatures for long periods of time. Other flame retardants, such as some phosphorus compounds, may affect the thermal transmittance and mechanical properties of the composite which may lead to increased sensitivity to UV radiation and reduced resistance to fatigue. In any case, the choice of flame retardant must be selected taking into account the user's needs and fire safety requirements, while minimizing the impact on the mechanical properties of the material. The use of a properly selected flame retardant can increase fire resistance while maintaining good mechanical properties of the polymer composite. Third, some flame retardants can make composite recycling difficult, leading to more waste. Finally, some flame retardants may require more energy and resources to produce, which can lead to more CO2 emissions and increased use of natural resources. The conclusion is that the use of flame retardants in polymer composites reinforced with hemp fiber can lead to undesirable effects such as negative environmental impact, deterioration of mechanical properties and hindering recycling. However, this was not the subject of analysis in this article.

-How do the results of this study contribute to the broader discussion on sustainable materials and circular economy in the marine industry? What policy implications might these findings have?

The research results indicate the possibility of replacing glass fibers with natural fibres. The results indicate that this material can be safer (e.g. by extending the evacuation time of the crew) when used on small vessels. This may contribute to the marine industry's interest in this material for replacing existing materials. However, research is still needed to better understand this material before it is put into series production.

Replacing glass fiber reinforced polymer composites with hemp fiber reinforced polymer composites can lead to some potential trade-offs or unintended consequences, such as:

Mechanical strength: Glass fiber reinforced composites are known for their high mechanical strength and stiffness. Hemp fibers tend to be weaker than glass fibers and have less stiffness, which means hemp fiber reinforced composites can be less strong and less rigid. However, there are lighter materials. And they can be used in less responsible applications, e.g. partition walls.
Durability: Glass fiber reinforced composites are also known for their resistance to corrosion and degradation over time. Hemp fibers may be more susceptible to environmental influences and may degrade more quickly, which may affect the durability of composites.
Thermal properties: Hemp fiber reinforced composites can have different thermal properties compared to glass fiber reinforced composites. This can lead to problems with maintaining a constant temperature in the vessel.
Cost: Hemp fibers are usually less expensive than glass fibers, which means that hemp fiber reinforced composites can be less expensive than glass fiber reinforced composites. However, the change of materials may require additional costs related to the design and testing of new materials.
Environmental Impact: Hemp fibers are more environmentally friendly than glass fibers.

Switching to hemp fiber reinforced composites can therefore bring environmental benefits.

However, the environmental benefits and ease of recycling favor the implementation of these materials.

Environmental conditions as well as the size of the vessel will affect the burning process of the vessel, e.g.:

Air humidity: If the air is moist, the material is less likely to ignite because moisture can inhibit the combustion process. On the other hand, in dry air, the material is more prone to ignition, because the lack of moisture makes it easier to ignite.
Temperature: High temperature can increase the susceptibility of a material to ignite as it speeds up chemical reactions and produces combustible gases more quickly. On the other hand, very low temperatures can make the combustion process more difficult because the fuel may tend to condense instead of burning.
Atmospheric Pressure: High atmospheric pressure can affect the rate of combustion and chemical processes and therefore can affect the ignitability of the material.
Presence of Oxygen: The presence of oxygen in the atmosphere is crucial to the combustion process. A high oxygen content in the air favors easier ignition and faster combustion of the material, while a low oxygen content can hinder the combustion process.
Presence of other chemicals: The presence of other chemicals in the air or on the surface of the material may affect its susceptibility to ignition. For example, the presence of chemicals such as oils or solvents can make a material more susceptible to ignition.

Therefore, the article uses a standardized and recognized research method. The purpose of which was to initially determine the properties of the material.

The use of hemp fiber reinforced polymer composites can benefit the overall carbon footprint of a ship compared to polymer composites reinforced with glass fiber or other construction materials. Here are some factors that can affect a ship's overall carbon footprint:

Production: Hemp fibers are more environmentally friendly than glass fibers because they require less energy to produce and process. The hemp fiber manufacturing process is less energy intensive than glass, leading to lower greenhouse gas emissions during the manufacturing process.
Transportation: Hemp fibers are usually produced close to growing areas, which means they can be transported shorter distances compared to glass, which often has to be transported far away. Shorter transport distance means less fuel consumption and less greenhouse gas emissions.
Weight: Hemp fiber reinforced polymer composites are typically lighter than glass fiber reinforced polymer composites, which means they can be more fuel efficient and greenhouse gas emitted during vessel operation.
Disposal: Hemp fibers are biodegradable and can be disposed of in many ways, which means that hemp fiber reinforced polymer composites are more environmentally friendly when disposed of.

In summary, the use of hemp fiber reinforced polymer composites can help reduce the overall carbon footprint of a vessel as it requires less energy to produce, less fuel to transport and can be more efficient over the life of the vessel. Additionally, hemp fibers are environmentally friendly when disposed of, which can also help to reduce your overall carbon footprint.

However, determining the carbon footprint was not the topic of this article.

-Are there any ethical considerations that should be taken into account when using natural fibers for composite materials, such as concerns about labor practices or land use impacts?

Yes, there are ethical considerations to consider when using natural fibers in composite materials. First, labor practices in the production of natural fibers must be taken into account, especially if they come from developing countries. Sometimes these practices can lead to the exploitation of workers, the exploitation of child labor and the use of forced labor. It is therefore important that manufacturers of composite materials ensure that all labor practices comply with international labor standards. Secondly, the use of natural fibers can affect land use, in particular afforestation and agricultural crops. For the cultivation of hemp, a popular source of natural fibers, there are concerns about the impact on land use and the environment. Therefore, it is important that manufacturers of composite materials use natural fibers from sustainable cultivation, which does not negatively affect ecosystems and land use. Ultimately, it is important that manufacturers of composite materials are aware of and consider ethical considerations, such as labor practices and land use, when using natural fibers in their products. Taking care of these aspects is important not only from the point of view of ethics and social responsibility, but also from the point of view of the company's reputation and image and its long-term success.

However, this issue was not the subject of this work.

Thank you again for the thorough analysis of our article and all your comments and questions. We hope that our answers are sufficient to dispel all doubts.

Yours faithfully,

Katarzyna Bryll

Round 2

Reviewer 2 Report

Would be nice to include microstrures of composites, and validate CTE value of both GFRP and HFRP.

Reviewer 3 Report

The paper can be accepted in the present form.