Manufacturing, Characterization, and Ballistic Testing of Natural Rubber Foam Based Bulletproof Vest’s Blunt Trauma Pad

• Main Author: Mayseptheny Hernawati, Resty
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/43769
• Institution: Institut Teknologi Bandung

Improving the quality of the body armor system in terms of light weight and high ballistic resistance is still being researched. The use of a body armor system consisting of hard body armor, soft body armor, and blunt trauma pad (BTP) for a variety of selected materials continues to be developed. In bullet proof vests, to determine body armor system depends on the type of threat the body armor will be faced. If the threat is a high-speed armor piercing (AP) rifle (around 900 m/s), the three components of the body armor system must be used. However, if the threat type is in the form of a handgun with full metal jacketed (FMJ) bullet with a lower speed than the AP bullet (around 300 m/s), the body armor system uses the soft body armor and BTP. Basically, even if the bullet is successfully stopped by the body armor system the remaining kinetic energy which is not absorbed by the system can be distributed to the body of armor user. Energy that affects the body can cause injuries such as bruising, internal organ damage, and potentially death. Injuries caused by defeated projectiles which not penetrate the body armor are known as blunt trauma or behind armor blunt trauma (BABT). To reduce potentially BABT injury a BTP is necessary to absorb residual kinetic energy. Material that must be selected as a blunt trauma pad is material with the main performance of absorbing energy. Commercial BTP which is generally used in body armor systems made from polyurentan foam and EVA foam. The similarities of the two types of commercial BTP are a cellular structure, have a low density, and tends to be flexible. Natural rubber has a unique characteristic that has high elasticity so that if the structure of the rubber is made into a cellular, it has the potential to replace the basic material for making BTP. Indonesia as the second largest natural rubber producer in the world has the potential to develop BTP. The initial step in making BTP based on natural rubber foam is compounding by adding chemical blowing agent (CBA). The selected CBAs are Sodium bicarbonate (NB) and Azodicarbonamide (AZ). After compounding, the compound is vulcanized using compression molding. There are 4 methods of producing BTP namely the free forming (FF) method, pressure and locking (K), and pressure without locking (NK) and fixed dimension with pressure and locking (DK). Then the BTP were morphologically characterized using Scanning Electron Microscopy (SEM) and its results were processed using ImageJ to determine the cellular structure of the produced BTP. Based on the results of characterization using SEM and cellular structure data processing, morphology of BTP NB was anisothropical open cell foam with an average cell size that is relatively larger. While for BTP AZ, the morphology was anisoptropical closed cell foam with relatively small cell size. Apart from that, the optimum manufacturing method was produced by using the K and NK methods, so that the four samples of BTP AZK, AZNK, NBK, NBNK are characterized by rebound resilience test. Based on its results, the largest energy absorption was obtained by BTP AZNK. Then BTP AZNK was ballistic tested in protection level IV while BTP NBK and BTP commercial EVA foam were ballistic tested in protection level IIIA. From the ballistic test resulted that BTP AZNK’s back face signature (BFS) was 5.952 mm, while BFS for BTP NBK was 13.94 mm and BFS for EVA foam was 17.56 mm. Both BTP filled required NIJ 0101.06 standard which is has BFS values below the allowable BFS value of 44 mm. Apart from that, using BTP NBK compared to EVA foam reduced the value of BFS by 20.62%. These results indicate the potentially alternative subtitution of commercial BTP that is generally used to natural rubber foam based BTP. In addition, the BTP performance of ballistic resistance was better than BTP’sexisting.