MODULE FORENSIC CHEMISTRY AND TOXICOLOGY

CHAPTER 6: EXPLOSIVES AND EXPLOSIONS

Objectives:
a) Understand the legal use of explosives
b) Apply knowledge in classifying explosives
c) Determine the mechanism of explosions

❖ Explosives – any chemical compound or mixture

that undergo rapid burning or decomposition by
influenced of heat, pressure, friction, or shock producing
large amount of gas, heat and sudden pressure affects.

❖ WHY LAW ENFORCES SHOULD KNOW ABOUT

EXPLOSIVE?
o They often encounter them in stations brought by
citizen found at construction sites or have found buried
underground or explosive items kept as souvenirs.
o Law enforcers encounter these at crime scene as
booby traps.
o They should know the presence of any explosive items in closing of military bases
because of downsizing. Some of this land possibly contains toxic chemicals and
explosive ordnance.

DEVELOPMENT OF EXPLOSIVES

TROJAN The oldest known recorded explosives in history are the Greek fire
WAR

13th century gunpowder appears in writings of English monk Roger Bacon but
seems to have been discovered by the Chinese

14th century Sertold Schwartz may have been the first to employ gunpowder
to propelling projectile. Later Germany and England manufactured
gunpowder

1|Page
This study source was downloaded by 100000839999174 from CourseHero.com on 10-14-2022 20:20:16 GMT -05:00

https://www.coursehero.com/file/80848616/CHAPTER-6-converted-1pdf/
 MODULE FORENSIC CHEMISTRY AND TOXICOLOGY

17th century the modern era of explosives

1838 - Nitrocellulose was first synthesized by Pelouze

and discovered its explosive property by Schonbein and
Bottger in 1846.

1846 – Nitroglycerine was discovered by Ascanio

Sobrero and manufactured commercially by Alfred Nobel
in 1863.

1867 – Nobel accidentally discovered dynamite, patented

this mixture and invented mercury fulminate blasting cup.

Ohisson and Norbin discovered the use of ammonium

nitrate in dynamite.

1886 – Turpin patented the use of picric acid as bursting

charge for shell

18th century application and development of explosives

1902 – picric was replaced by TNT

1912 – TNT was officially adapted as bursting charge

bursting charge for HE shell for the mobile artillery of the
US Army.

World War I: saw the introduction of lead azide, amatol

and tetryl. During the next two decades, RDN, PETN,
lead styphnate, DEGN and lead azide were developed as
military explosives.

World War II: saw the development of rocket propellants.

US developed Haleite, tetrytol, picratol, and armor-

piercing bombs. Plastic explosives were also developed
in Great Britain and US.

The blast effect of explosives is developed and led to

the development of tritonal, torpex, and minol that
contains powdered blast effect.

2|Page
This study source was downloaded by 100000839999174 from CourseHero.com on 10-14-2022 20:20:16 GMT -05:00

https://www.coursehero.com/file/80848616/CHAPTER-6-converted-1pdf/
 MODULE FORENSIC CHEMISTRY AND TOXICOLOGY

CLASSIFICATION AND CATEGORIES

OF EXPLOSIVES

I. According to the Speed of Reaction

a. High Explosives (detonating charges) – the
speed of its detonation wave equal to 1000 m/s and
pressure equal to thousands of atmospheres. Such
intensity can break a material into fragments long before
its opportunity to move away.
• Two Classes of High Explosive
1. Primary – used to start explosion
2. Secondary – stable but can be detonated by primary
explosives

b. Low Explosives (deflagrating charge) – the rate of decomposition are

relatively slow process and the wave produced is less than the speed of sound.
They were applied for launching rockets, projectiles form guns and missile
systems.

• Classes of Low Explosives According to their Use

1. Primer – use to propel ammunitions
2. Igniter – use to initiate explosions (e.g. safety fuse)
3. Propellant – use to launch rockets and missile

II. According to their Application or Design

a. Military Explosives – use in military purposes

• Some Common Military Explosives
1. Grenades – derived from Greek word “Grabatus” as implied by the
Spanish in 16th century. Granada (Spanish word for Pomegranate)
o TYPES: MK2 fragmentation hand grenade and M26 fragmentation
hand grenade
o Three (3) Main Parts of Hand Grenade

3|Page
This study source was downloaded by 100000839999174 from CourseHero.com on 10-14-2022 20:20:16 GMT -05:00

https://www.coursehero.com/file/80848616/CHAPTER-6-converted-1pdf/
 MODULE FORENSIC CHEMISTRY AND TOXICOLOGY

a) Filler – the chemical or explosive substance

in the grenade body.
b) Body – this contains the filler and
provides fragmentation
c) Fuze Assembly – heart of then
grenade function to give chain reaction of
chemical, mechanical or electrical actions

2. Fuses – use to initiate explosive in

any war hood (part of missile)
o Two Types of Fuse:
1. Point-detonated (PD) – by impact, proximity or delay
2. Variable Time (VT) – detonates when the war head is at
certain distance from the target

3. Incendiaries – device that burns rather than explode

4. Chemical Ordnance – simple as riot grenade or smoke bomb or as

lethal as Sarin nerve gas. US type typically gray with color bonds.

5. Other Type: Ammunition, Rockets and Missiles, Mines,

Submunition, Air Drop, and Simulators

b. Industrial Explosives o Boosters

o Dynamites o Black or Smokeless Powder
o Ammonium nitrate explosives
o Water Explosives c. Improvised Explosive Device
o Slurries and water gels o Basic components include Power
o Explosive Emulsion Source Initiator Explosive and Switch
o Blasting caps (PIES)
o Safety Fuse d. Explosive with limited use
o Detonating Cord o Includes those which were used from
o Blasting Agents the past and become obsolete.

4|Page
This study source was downloaded by 100000839999174 from CourseHero.com on 10-14-2022 20:20:16 GMT -05:00

https://www.coursehero.com/file/80848616/CHAPTER-6-converted-1pdf/
 MODULE FORENSIC CHEMISTRY AND TOXICOLOGY

EXPLOSION

❖ Explosion is a violent bursting or expansion

caused by the release of the mechanical,
chemical, or nuclear energy from a confined area.
This is a phenomenon resulting from a sudden
release of energy and it happened so rapidly that
a local accumulation of energy occurs at the site
of explosion moving outward in various ways.

❖ An implosion is similar phenomenon except

that the energy released is initially directed inward.

QUESTION: Is there an explosion without explosives?

ANSWER: Yes, because even the tiniest drop of water can be considered as an explosion
compared to the strongest and loudest natural explosion – the volcanic eruption.

o Types of Explosion
1. Mechanical Explosion – it is a sudden breaking apart, shattering or
bursting into pieces by internal pressure as that of gas or steam boiler;
also known as pressure explosion.
2. Chemical Explosion – a source of explosion wherein the source of this
energy comes from an explosive such as gunpowder.
3. Nuclear explosion – an explosion due to nuclear fusion and fission of
particles.

❖ Effect of Explosion
o An explosion produces a very rapid growing shockwaves moving
outward as it transform into a more stable substance. It is accompanied
by a loud and sharp report as it liberates great amount of energy into
the form of heat, light, and other form of gasses.

5|Page
This study source was downloaded by 100000839999174 from CourseHero.com on 10-14-2022 20:20:16 GMT -05:00

https://www.coursehero.com/file/80848616/CHAPTER-6-converted-1pdf/
 MODULE FORENSIC CHEMISTRY AND TOXICOLOGY

MECHANISM OF EXPLOSION

o Chain reaction causes the decomposition and rearrangement of molecules with a

greater release of energy.

1. Damage Mechanism
a. Shockwave/ Pressure wave – if the detonation occurs above or just below
the surface of the ground, most of the damage will be given off by blast,
splinters or fragments from the explosive case that travels as fast as the speed
of sound. The damage produce depends on the location of explosion.
o Blast wave (positive pressure phase) – is generated when the atmosphere
surrounding the explosion is forcibly pushed back.
o Suction (negative pressure phase) – occurs when the compressed,
displaced atmosphere rushes back to fill the partial vacuum just created.
o Over pressure – is positive pressure which will cause the body to sustain
physical damage. Damage from over pressure reduces with distance from the
explosives.

6|Page
This study source was downloaded by 100000839999174 from CourseHero.com on 10-14-2022 20:20:16 GMT -05:00

https://www.coursehero.com/file/80848616/CHAPTER-6-converted-1pdf/
 MODULE FORENSIC CHEMISTRY AND TOXICOLOGY

▪ Property of shockwave – shockwave bounced to a border, funneling to a confined area

usually occurred and called the freak effect.

•Earth shock – wave produced when an explosive detonates

underground producing an earthquake.
• Water shock – wave produced when an ordnance was detonated
underwater.
b. Brisance – the direct measure of energy transmission from explosion to the
target. This is the most severe because of its shattering action. Brisance is
directly proportional to the speed of decomposition of explosives. Explosive
with high shattering power are termed high explosives. The brisance effect of
deflagrating materials is relatively small.

c. Sensitivity – the effort required to initiate explosive decomposition. The lesser

the effort require, the more sensitive the explosives.
▪ Arrhenius Activation Energy – energy required to activate the
decomposition process of a chemical substance like explosives.
▪ The energy is less than the released energy of decomposition, this will
furnish more than enough energy to activate neighboring material, thus the
explosion propagates spontaneously. Most of the sensitive material is
located in caps of explosives, thus more handling care is needed.

d. Mean detonation distance – measure of possibility that an explosion occurs

of one storage of explosive to another.

e. Oxygen Balance – measure of decomposition of explosives

2. Explosive Strength – the magnitude of an explosion can be established based on the

amount of energy that is released.

7|Page
This study source was downloaded by 100000839999174 from CourseHero.com on 10-14-2022 20:20:16 GMT -05:00

https://www.coursehero.com/file/80848616/CHAPTER-6-converted-1pdf/
 MODULE FORENSIC CHEMISTRY AND TOXICOLOGY

EXPLOSIVE LAWS IN THE PHILIPPINES

• Act #2255 (11 Feb 1913) – act prohibiting the manufacture, possession and sale of
dynamite and other explosives or components
without a special permit, from Chief, PC or Senior
Inspector in the province

• Executive order #9 (01 Feb 1954) – control and

supervise licensing sales, possession, use, storage
and manufacture of explosives.

• Executive order #60 (09 Feb 1967) – promulgating

rules and regulations on the control and supervision
of the importation, sale and possession of chemicals
used in manufacture of explosives.

• EO #52 (26 Nov 1966) – banning mfg, sales and

possession of firecrackers and pyrotechnics wares.

• Memorandum from SD (28 Dec 1947) – firecrackers

and pyrotechnic wares.

• Memorandum from president (18 Jan 1967) – license

to purchase explosives for mining and logging purposes.

• Comment 1 from C3 Division, PC (02 Sept 1968) – moving Phil Navy in the processing
of application for explosives

• PD 1058 (01 Dec 1976) – increasing the penalty for illegal fishing with the use of
explosives.

• PC SOP 9 (12 Apr 1973) – control and supervision of importation, sale, possession and
use of explosives

• PC SOP 4 (21 Sept 1974) – accounting of explosives issued to licensed blasters

• PC SOP 14 (26 June 1975) – renewal of explosive user license

8|Page
This study source was downloaded by 100000839999174 from CourseHero.com on 10-14-2022 20:20:16 GMT -05:00

https://www.coursehero.com/file/80848616/CHAPTER-6-converted-1pdf/
 MODULE FORENSIC CHEMISTRY AND TOXICOLOGY

• PC letter directive (29 Apr 1976) – security measures of explosives.

• PC letter directive (29 July 1977) – additional security measures.

• RA 7138 (30 Jan 1992) – An act regulating the sale, manufacture, distribution and use of
firecracker and other pyrotechnic device.

References:
Saferstein, Richard, Criminalistics: An Introduction to Forensic Science, 2nd edition, Prentice Hall New York,
2001.
Sunico, Lorenzo A, Forensic Chemistry, NBI, Manila.
Saferstein, Richard D, Criminalistics: An Introduction to Forensic Science, 2001. Prentice Hall, Upper Saddle
River New Jersey
Eckert,William, G, Introduction to Forensic Sciences, CRC Press, New York 1997
https://science.howstuffworks.com/blast-resistant-clothing1.htm

LINKS

TOPIC LINK FOR VIDEO

Weapons: Explore the world of

https://www.youtube.com/watch?v=VV71ZmCUJsE
explosives

How a Grenade (MK 2) Works! https://www.youtube.com/watch?v=ObJHpFCqoeE

9|Page
This study source was downloaded by 100000839999174 from CourseHero.com on 10-14-2022 20:20:16 GMT -05:00

https://www.coursehero.com/file/80848616/CHAPTER-6-converted-1pdf/
Powered by TCPDF (www.tcpdf.org)