The fundamental rationale for adapting polyvinyl acetate (PVAC) resin to combustible cartridge designs is as follows: a key advantage of combustible cartridges (also known as combustible propellant cylinders) is that they can completely combust after firing without leaving any residue, while still possessing sufficient structural strength to support the propellant charge and withstand manufacturing processes, in addition to being compatible with existing injection molding or compression molding technologies.

Polyvinyl acetate (PVAC) is a typical flammable thermoplastic resin, with its elemental composition of carbon, hydrogen, and oxygen exceeding 98%; upon complete combustion, it produces only a minimal amount of gaseous oxides and virtually no solid residue, thereby fully meeting the combustion requirements for combustible components. Traditional propellant cylinders require substantial amounts of brass or high-grade steel; brass, being a strategic non-ferrous metal, entails high extraction and smelting costs, as well as the need for anti-corrosion treatments during storage and maintenance. In contrast, combustible cartridges primarily consist of cellulose-based combustible organic materials and binding resins, eliminating the need for metal resources. This approach results in lower production costs, simplified storage and maintenance procedures, and greater suitability for large-scale production and stockpiling. In conventional brass or steel propellant cylinders, the weight of the cartridge accounts for 30%–50% of the total projectile weight—for example, in large-caliber tank artillery projectiles, the weight of a single metal cartridge can reach 5–10 kg, which severely limits the projectile payload capacity. Combustible cartridges, however, combust completely after firing, eliminating the need for ejection mechanisms, empty cartridge storage, or handling of empty shells. Consequently, the total projectile weight is reduced by over 30%; for the same payload capacity, this design reduces the internal space occupied by the war vehicle, significantly increases the number of munitions a single soldier can carry, and directly enhances sustained combat capability. The combustible cartridge case itself participates in combustion within the barrel, effectively increasing the energy utilization efficiency of the propellant. This design allows for higher chamber pressure and increased projectile muzzle velocity without altering the chamber volume; furthermore, complete combustion leaves no solid residues, preventing the accumulation of impurities within the barrel. Consequently, this approach does not compromise the internal ballistic characteristics of subsequent projectiles, thereby enhancing ballistic consistency during continuous firing. For rifled guns, a fully combusted combustible cartridge case also avoids generating residues that could clog the rifling, leading to slower degradation of accuracy after prolonged continuous firing.

Simplifying the mechanism design of artillery guns reduces their failure rate. For guns using metal propellant cartridges, the mechanism must incorporate a ejection and discharge mechanism, which increases the complexity and weight of the mechanism; furthermore, the discharge process itself carries a risk of jamming. In contrast, guns using combustible propellant cartridges do not require ejection, eliminating the ejection and discharge steps. Consequently, their mechanism design is simpler, their weight is reduced, their failure rate is lower, and they are better suited for achieving high-rate automatic loading.

Polyvinyl acetate (PVAc) is a typical flammable thermoplastic resin, comprising over 98% carbon, hydrogen, and oxygen atoms. Upon complete combustion, it produces only a small amount of gaseous oxides and yields virtually no solid residue, thereby fully complying with the combustion requirements for combustible building components. PVAc can be dissolved in conventional organic solvents such as acetone and styrene, and can be uniformly blended with traditional combustible matrices—such as nitrocellulose and nitrocellulose derivatives—via solution mixing, thereby enhancing the processability of the matrix. PVAc itself exhibits excellent film-forming and bonding properties, which can improve the processing fluidity of combustible matrices, enhance the mechanical strength of the components, and reduce cracking defects during compression molding. Commercially available PVAc is non-toxic, odorless, readily available as a raw material, features well-established modification technologies, and presents low barriers to industrial-scale production.

Core Advantages of polyvinyl acetate (pvac) for : Combustion Characteristics: The decomposition temperature of polyvinyl acetate (PVAc) is approximately 200–250 °C, which is lower than the chamber temperature during shell ejection; this ensures complete combustion without compromising ballistic performance or generating residue that could clog the rifling. Process Compatibility: PVAc is inherently a shrinkage-resistant modifier commonly employed in SMC/BMC compression molding processes, exhibiting excellent compatibility with such molding techniques; thus, no significant modifications to existing combustible shell production equipment are required. Performance Tunability via Modification: The ester groups on the polymer chains of PVAc can be modified through hydrolysis or grafting with functional groups such as carboxyl or hydroxyl groups, thereby adjusting its polarity and further enhancing its compatibility with polar combustible matrices. Technical Challenges to Address: Moisture Absorption Control: Unmodified PVAc exhibits a certain degree of moisture absorption; excessive moisture can adversely affect propellant performance and the mechanical strength of the shell. This challenge can be mitigated through physical co-mixing with hydrophobic modifiers to reduce moisture uptake. Strength Balance: Pure PVAc possesses relatively low strength; therefore, it must be co-mixed with cellulose-based matrices in appropriate proportions to ensure the structural integrity of the shell during storage and loading. Storage Stability: It is essential to control the molecular weight and glass transition temperature of PVAc to prevent issues such as tackiness or deformation during prolonged storage.