To expand the use of nitrocellulose, optimizing nitrocellulose production for fireworks, overcome shortages in raw materials for indoor fireworks, and improve emission agents towards a smokeless or slightly smoky environment, nitrocellulose is used as primary material with plasticizers, stabilizers, and auxiliary elements. Our research focuses on the effect of stabilizer, plasticizer, and moisture content on sample performance.
In addition to optimizing these parameters, other factors can further improve performance and safety:
- Paper properties affect the strength and weight of firecracker casings
- Identifying risks in the production process helps reduce safety issues
- Effective lightning protection prevents fires caused by static electricity
The best combustion results were achieved when the stabilizer content was 1.2%, plasticizer 3%, and moisture 2-3%. Samples met the requirements for:
- Ignition time
- Speed of combustion
- Flame height
- Environmental impact – meeting standards for indoor stage fireworks and toy fireworks.
Nitrocellulose, Indoor Fireworks, Preparation Process, Performance
|Color||White or Pale Yellow|
|Density||Approx. 0.2 g/cm³|
|Stability||Stabilizer-mixed & moisture-free storage|
- Nitrocellulose: The eco-friendly ingredient for indoor fireworks, boasting 96%+ content in repurposed single-base propellants
- Market demands: As live-fire exercises become the norm, there’s a growing need for alternative, eco-friendly energetic materials for indoor fireworks
- Challenges: Current nitrocellulose products require modifications to be compatible with indoor fireworks applications
This study aims to provide valuable insights into the production and application of nitrocellulose for indoor fireworks through the plasticization-kneading process, opening new doors for eco-friendly indoor fireworks solutions.
Quality indicators for indoor fireworks nitrocellulose:
|Quality Indicator||Control Range|
|Nitration Degree (mL·g⁻¹)||193.6 – 201.6|
|Finished Product Bulk Density (dry) (g·cm⁻³)||0.5 – 0.8|
|Stabilizer Content (dry) (%)||0.8 – 1.0|
|Abel Stability Test (min)||≥ 15|
|Particle Size Distribution (%)||60 – 100 mesh, > 80%|
|Ignition Temperature (℃)||≥ 170|
1.1 Reagents and instruments
Experimental instrument (equipment):
|Screw Extruder Kneader||NH-10L, Rugao Shengteng Kneading Machinery Co.|
|Small Rolling Press||JTC-752|
|Colloid Mill||JM-F65, Wenzhou Xiaojie Machinery Co.|
|Drying Oven||AH100, Taiyuan Xian Dao Automatic Control Tech|
|Particle Size Analyzer||NKT6100-C, Shandong NKT Analysis Co.|
Test raw materials:
|Nitrocellulose (193.6 – 201.6 mL/g N)||Northern Nitrocellulose Co., Ltd.|
|Plasticizer (Acetone)||Chengdu Kelong Chemical Co., Ltd.|
|Plasticizer (Epoxidized Soybean Oil, ESO)||Chengdu Kelong Chemical Co., Ltd.|
|Stabilizer (Diphenylamine)||Chengdu Kelong Chemical Co., Ltd.|
1.2 Experimental process
As depicted in Figure 1, the procedure for creating nitrocellulose plasticizing material is accomplished through kneading. Additionally, Fig. 1 outlines the process flow used to construct raw materials intended for indoor fireworks – a methodology studied and verified by laboratory experiments.
- First, mix 65 g of plasticizer, 1,800 g of acetone, and 21 g of stabilizer in a glass container and shake to form a uniform solution, preparing the plasticizing solution.
- Next, add 6,000 g of nitrocellulose containing 30% water to the kneader. Start the kneader and slowly add the plasticizing solution, mixing and stirring for 1 hour. At this point, the nitrocellulose will be completely plasticized and transformed into a gel-like solid.
- Add an appropriate amount of water to the gel-like solid. Under the kneading machine’s stirring, tearing, and kneading actions, the gel-like nitrocellulose solid gradually transforms into a sheet-like solid.
- Finally, grind the sheet-like solid using a colloid mill to obtain the final material.
Results and discussion
2.1 Determination of the amount of stabilizer added
Because of the slight solubility of the stabilizer in water, it can be dissolved and lost during processing – resulting in a lower content than initially designed. To prevent this from occurring, we tested to assess the amount that is being lost. Table 2 shows us that about 0.2% was dissipated into an aqueous solution when creating nitrocellulose for indoor fireworks. To obtain 1% stabilizer as planned, 1.2% Nitrocellulose should be added during plasticization instead!
Table 2 Table of stabilizer content in samples
|Experiment No.||Theoretical Content (%)||Actual Content (%)||Deviation (%)|
We commenced by nitrating 195 mL/g of nitrocellulose to create samples with numerous plasticizers. After drying the combination, it was placed into a test burner tube (Table 3) and examined – to do so; its inner diameter had to be φ32 and its length 20 mm. Furthermore, other samples were extracted for further sensitization testing.
The ESO content must be kept under 4%, preferably 3%, for a prolonged burning time and lower burn height. When it surpasses this number, the sample will no longer continue to burn steadily nor reach its required standard.
Table 3 Effect of plasticizer content on the combustion performance of samples
2.3 The influence of the moisture content of the sample on its combustion performance
We created samples containing specific plasticizers and stabilizers by combining 194.5 mL/g of nitrocellulose, drying it to 0%, 1%, 2% or 3% weight, and loading them into the test burner tube. The results are documented in Table 4, depicting how each sample reacted during burning.
The moisture levels present heavily impact the combustion process of samples, as it acts as a flame retardant, slowing down heat conduction during burning, and absorbs some heat to evaporate. When there is 3.2% or less moisture in the sample, combustion can be smooth and efficient; yet if more than that amount exists, ignition time will elongate and possible extinguishment may occur.
Table 4 Effects of different factors on the combustion performance of samples
|Experiment No.||Sample||Burning Effect||Nitrocellulose Degree (mL·g-1)||Stabilizer Content (%)||Plasticizer Content (%)||Moisture Content (%)||Loading (g)||Burning Time (s)||Burning Height (mm)|
2.4 Effect of nitrocellulose nitration degree and plasticizer dosage on sample safety and application performance
The powder product was readied according to the instructions above and tested for impact, friction, and moisture absorption at the National Firework Quality Supervision and Inspection Center. Then it was compared with a retired single base powder sample.
It can be seen from Table 5 that:
1）Nitrocellulose nitrogenation levels exceeding 200 mL/g present an inherent hazard due to their high energy, low moisture absorption rate, and high friction and impact sense. On the other hand, a degree of less than 193 mL/g results in low friction and impact yet more excellent moisture absorption – making it more susceptible to fire yet unsafe for indoor use. For that reason, we’ve settled on controlling nitrocellulose between 197~198 mL/g which optimizes safety and keeps flammability at bay while providing sufficient protection against moisture damage.
2）The integration of the plasticizer ESO decreases our sample’s energy levels while positively influencing moisture absorption and safety performance – validating that including 3% plasticizer can improve both its practicality and protection.
3）The nitrocellulose agents employed in indoor fireworks were carefully chosen from samples using 197 to 198 mL/g, demonstrating lower impact and friction sensitivities than the previous monobasic powder. This ascertains that the powdered material produced in this experiment is safer for storage and usage when compared to its predecessor.
Table 5 Safety performance table of single-base powder and nitrocellulose for indoor fireworks
|No.||Nitrocellulose Degree (mL·g-1)||Stabilizer (%)||Plasticizer (%)||Impact Sensitivity (%)||Friction Sensitivity (%)||Humidity Absorption Rate (%)||Abel (min)||Ignition Temperature (℃)|
2.5 Sample particle size distribution
To analyze the particle size distribution of our prepared samples, we conducted a test and depicted its results in Figure 2. As seen from this figure, 45.59% of particles were below 150 µm (100 mesh), 78.32% had sizes that did not exceed 250 µm (60 mesh), with 32.7% located between these two ranges – namely 150-250 µm (60-100 mesh).
Utilizing only one crushing method presents a challenge in achieving the 150-250 mesh particle size distribution of greater than 80% for most requirements. To fully meet these industrialization processes, it is imperative to consider product sieving and crushing technology and equipment.
2.6 Performance test applied to indoor fireworks
Table 6 illustrates the quality indices of the ready-made specimens, except its particle size distribution of 60-100 purpose being lower than what indoor fireworks users typically demand (32.7%). Nonetheless, all other metrics meet nitrocellulose requirements for indoor fireworks.
Table 6 Main quality indicators of nitrocellulose for indoor fireworks
|Sample Quality Indicator||Test Result|
|Nitrocellulose Degree (%)||197.6|
|Finished Product Bulk Density (dry) (g·cm-3)||0.56|
|Stabilizer Content (dry) (%)||0.98|
|Sample Abel (Stability) (min≥)||16|
|Sample Particle Size Distribution 60-100 mesh (%)||32.7|
|Flash Point (℃≥)||189.1|
To evaluate the quality of the powdered materials as ignition chemicals for indoor fireworks and toy fireworks, these substances were tested to measure smoke emission, ignition time per unit mass, and height. The combustion phenomena are presented in Figures 3a & 3b; assessments demonstrate that powder materials created during this experiment produce reliable results.
The prepared samples were sent to the users for stage and toy fireworks performance testing. The test results are shown in Table 7. The results show that:
- For firework compositions, the nitrocellulose content is 78%, the loading amount is 2.5 g, the burning time is 30-42 s, and the average burning time is 13.8 s/g.
- For toy firework compositions, the nitrocellulose content is 85%, the loading amount is 4.5 g, the burning time is 57-61 s, and the average burning time is 13.1 s/g.
Both met the expected burning time of 12-15 s for indoor fireworks. The flame height was stable at around 15 cm, reaching the expected value of 10-15 cm. At the same time, both had minimal smoke generation.
This indicates that the materials prepared in this experiment fully meet the environmental requirements for indoor fireworks and can be used for raw material production. However, the particle size of the prepared material is not uniform, with a 60-100 mesh distribution of 32.7%. The application requirement is a 60-100 mesh particle size distribution of >80%. During industrialization, it is necessary to focus on sieving and grinding equipment to meet the particle size requirements of nitrocellulose for indoor fireworks.
Table 7: Test Results of Prepared Indoor Firework Compositions
|Firework Type||No.||Nitrocellulose Content / %||Launch Tube Diameter / mm||Loading Amount / g||Burning Time / s||Flame Height / cm||Smoke Generation||Conclusion|
|Stage Fireworks||1||78||20||2.5||30||15||Very little||Satisfactory|
|Toy Fireworks||1||85||10||4.5||57||15||Very little||Satisfactory|
1）Compared to other ways of preparation, the plasticization-kneading approach is straightforward and practical, with only a few steps involved. Additionally, its energy consumption levels are low, plus it has ample room for adjustments. Nitrocellulose, stabilizers, and plasticizers must be blended in precise ratios and then pre-granulated before they become suitable nitrocellulose agents made explicitly for indoor fireworks use.
2）The nitrogen levels in the nitrocellulose used for making indoor fireworks measured 197-198 mL/g. For optimal burning performance, 1.2% of a stabilizer and 3% ESO plasticizer were added to the dry amount of nitrocellulose and 30% plasticizer in total. Furthermore, this determined quantity impacted moisture absorption and ignition capability. Compared to single base powder samples, these modified samples have lower sensitivities (frictional and impact), making them more secure during application.
3）Our laboratory samples of nitrocellulose showed remarkable results: ignition times ranged from 12 to 16.8 seconds per gram, and the flame height reached 15 cm with no smoke produced – all within industry standards for indoor stage fireworks, toy fireworks, and other cold light products. Although our sample size wasn’t quite up to par regarding the particle distribution quality required by consumers, we must shift focus onto developing more efficient sieving and crushing processes when it comes to industrialization going forward.
In conclusion, producing high-quality fireworks requires careful consideration of various parameters. Our experiments have shown that optimizing nitrocellulose production using the plasticization-kneading method is an effective way to prepare reliable materials with low energy consumption for indoor fireworks such as sparklers, Roman candles, aerial shells, and fountains.
However, it’s important to also consider other factors, such as paper properties in scarlet ground firecracker manufacturing, to achieve the desired performance and safety.
Fireworks production involves handling and processing hazardous materials, which poses safety risks to workers, equipment, and the environment. To identify and mitigate these risks, manufacturers can conduct risk assessments, implement safety policies and procedures, and provide training to employees.
In addition to traditional safety risks, fireworks production facilities are also vulnerable to natural disasters such as lightning strikes. Effective lightning protection strategies, such as installing lightning rods, surge protectors, and grounding systems, should be implemented to minimize the risk of damage.
At PyroEquip, we arecommitted to providing the necessary hardware and expertise to help our clients optimize their fireworks production and safety. Whether you need guidance on nitrocellulose production, paper properties, safety protocols, or lightning protection, our team of experts is here to help. Contact us today to learn more about how we can assist you in creating a better, safer, and more enjoyable experience for your customers. Together, we can push the boundaries of fireworks technology while prioritizing safety, sustainability, and innovation