This presentation discusses thermal degradation products (TDPs) which are air contaminants that arise when materials are heated past a certain point. TDPs are typically more toxic than the original materials. The presentation covers definitions of pyrolysis and combustion, case studies on specific materials like plastics and fibers, methods for evaluating exposure to TDPs, and predictions of what TDPs may be produced from certain materials. It concludes with recommendations like developing lower-temperature processing methods and improving material safety data sheets to include more information on TDPs.
BTL are world-renowned freeze drying experts. Our experience covers small molecules, large complex biomolecules, cells, organisms, advanced materials and artefacts.
BTL are world-renowned freeze drying experts. Our experience covers small molecules, large complex biomolecules, cells, organisms, advanced materials and artefacts.
Sterilization: F0 - what it means - how to calculate it - how to use itFedegari Group
F0: A technical note
- What it means
- How to calculate it
- How to use it for adjustment, control and
validation of moist-heat sterilization processes
Bowie Dick Tests - Failure Modes and SpecificationChris Maughan
Bowie Dick Tests are used as a test of Air Removal in a Porous Load Autoclave.
This presentation looks at Bowie Dick failures and how to resolve them, ISO 11140 and Bowie Dick Test pack Specifications.
Batch and Continuous Sterilization of Media in Fermentation Industry Dr. Pavan Kundur
Continuous sterilization is the rapid transfer of heat to medium through steam condensate without the use of a heat exchanger. ... This is more efficient than batch sterilization because instead of expending energy to heat, hold, and cool the entire system, small portions of the inlet streams are heated at a time.
The all the content in this profile is completed by the teachers, students as well as other health care peoples.
thank you, all the respected peoples, for giving the information to complete this presentation.
this information is free to use by anyone.
Presentation made by Nikki Schopp at Interphex 2014. “USP 233: Sample Preparation" this covers the importance of sample preparation, and looking at each sample on a case by case basis, in applying the US Pharmacopeial Convention’s (USP) chapter on limits <232> and procedures for elemental impurities <233>. Read more http://bit.ly/RCkMpk
A powerpoint presentation on Environment Degradation in Trinidad. this scored a total of 9 out of the maximum 10 at the University of the West Indies... the explanation to accompany the slides are not available.
Sterilization: F0 - what it means - how to calculate it - how to use itFedegari Group
F0: A technical note
- What it means
- How to calculate it
- How to use it for adjustment, control and
validation of moist-heat sterilization processes
Bowie Dick Tests - Failure Modes and SpecificationChris Maughan
Bowie Dick Tests are used as a test of Air Removal in a Porous Load Autoclave.
This presentation looks at Bowie Dick failures and how to resolve them, ISO 11140 and Bowie Dick Test pack Specifications.
Batch and Continuous Sterilization of Media in Fermentation Industry Dr. Pavan Kundur
Continuous sterilization is the rapid transfer of heat to medium through steam condensate without the use of a heat exchanger. ... This is more efficient than batch sterilization because instead of expending energy to heat, hold, and cool the entire system, small portions of the inlet streams are heated at a time.
The all the content in this profile is completed by the teachers, students as well as other health care peoples.
thank you, all the respected peoples, for giving the information to complete this presentation.
this information is free to use by anyone.
Presentation made by Nikki Schopp at Interphex 2014. “USP 233: Sample Preparation" this covers the importance of sample preparation, and looking at each sample on a case by case basis, in applying the US Pharmacopeial Convention’s (USP) chapter on limits <232> and procedures for elemental impurities <233>. Read more http://bit.ly/RCkMpk
A powerpoint presentation on Environment Degradation in Trinidad. this scored a total of 9 out of the maximum 10 at the University of the West Indies... the explanation to accompany the slides are not available.
Presentation on Environmental Degradation
Its causes and effects on the environment
Awareness of environmental Degradation
Preventive Measures for environmental degradation
ANALYSIS OF THE COMBUSTION FUMES AND GASES RELEASED DURING THE BURNING OF SOM...Claudio Liciotti
Along with the strong growth of PV installations, also the
number of fires involving PV systems has grown. The fire
risk analysis due to PV systems has been taken into strong
consideration. About that, 3 were the most considered
issues:
1) PV modules and components fire behavior;
2) causes of fire ignition related to PV components;
3) risk of electrocution in firefighting activities in proximity
to photovoltaic generators.
To protect the firefighter and to respect the environment,
the type of fumes and gases that are released into the
environment during a fire of a PV system should also be
considered.
This paper shows the analysis of the fumes and gases
released during the burning and pyrolysis of some c-Si PV
modules.
Lyostat4 freeze drying microscope provides brighter, clearer images for easy analysis of formulations for freeze drying. Freeze drying microscopy is used to identify the collapse temperature of a product, which is necessary for product and process development.
This ppt includes all the key points of process of sterilization and its different techniques like physical,chemical,thermal,etc. sterilization is very important topic to go through during education as well as during practice to maintain a nice infection free environment of your health care office or clinic.
to overcome the problem of easily fire catching to fabrics
it will reduce the wealth loss and causing material saving as well as it will cause healthy environment without sudden damage due to fire
chemicals treated are chlorine bromine , and also the bad effects of flame retardants
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
CDSCO and Phamacovigilance {Regulatory body in India}NEHA GUPTA
The Central Drugs Standard Control Organization (CDSCO) is India's national regulatory body for pharmaceuticals and medical devices. Operating under the Directorate General of Health Services, Ministry of Health & Family Welfare, Government of India, the CDSCO is responsible for approving new drugs, conducting clinical trials, setting standards for drugs, controlling the quality of imported drugs, and coordinating the activities of State Drug Control Organizations by providing expert advice.
Pharmacovigilance, on the other hand, is the science and activities related to the detection, assessment, understanding, and prevention of adverse effects or any other drug-related problems. The primary aim of pharmacovigilance is to ensure the safety and efficacy of medicines, thereby protecting public health.
In India, pharmacovigilance activities are monitored by the Pharmacovigilance Programme of India (PvPI), which works closely with CDSCO to collect, analyze, and act upon data regarding adverse drug reactions (ADRs). Together, they play a critical role in ensuring that the benefits of drugs outweigh their risks, maintaining high standards of patient safety, and promoting the rational use of medicines.
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Local Advanced Lung Cancer: Artificial Intelligence, Synergetics, Complex Sys...Oleg Kshivets
Overall life span (LS) was 1671.7±1721.6 days and cumulative 5YS reached 62.4%, 10 years – 50.4%, 20 years – 44.6%. 94 LCP lived more than 5 years without cancer (LS=2958.6±1723.6 days), 22 – more than 10 years (LS=5571±1841.8 days). 67 LCP died because of LC (LS=471.9±344 days). AT significantly improved 5YS (68% vs. 53.7%) (P=0.028 by log-rank test). Cox modeling displayed that 5YS of LCP significantly depended on: N0-N12, T3-4, blood cell circuit, cell ratio factors (ratio between cancer cells-CC and blood cells subpopulations), LC cell dynamics, recalcification time, heparin tolerance, prothrombin index, protein, AT, procedure type (P=0.000-0.031). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and N0-12 (rank=1), thrombocytes/CC (rank=2), segmented neutrophils/CC (3), eosinophils/CC (4), erythrocytes/CC (5), healthy cells/CC (6), lymphocytes/CC (7), stick neutrophils/CC (8), leucocytes/CC (9), monocytes/CC (10). Correct prediction of 5YS was 100% by neural networks computing (error=0.000; area under ROC curve=1.0).
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
Thyroid Gland- Gross Anatomy by Dr. Rabia Inam Gandapore.pptx
Industrial Hygiene Aspects of Thermal Degradation Products
1. Industrial Hygiene Aspects of
Thermal Degradation Products
Presentation by:
Ron Pearson, M.S., CIH
Environmental Health & Safety, Inc.
2. Presentation Overview
• Background information/emerging issues of
Thermal Degradation Products (TDPs)
• Information gaps
• Definitions
• Case studies/material examples
• Exposure assessment
• Looking ahead
3. This presentation is NOT...
• A review of Fire Science
• A treatise on engineering controls
• An outline of specific methodologies for
laboratory/ analytical testing methods
• An expression of opinions on behalf of any
manufacturers of materials cited as case
examples
4. Background/Emerging Issues
• When you heat most materials
past a certain point….
– new species of air contaminants arise,
typically orders of magnitude more toxic than
the “parent” material
– air contaminants may change phase (e.g.
particulates instead of vapors/gases)
5. Background/Emerging Issues
• New chemistries/new industrial processes
• Polymers heated past degradation points
• More emphasis among manufacturers on
“Life Cycle Management” and “Product
Responsibility/Stewardship”
6. Background/Emerging Issues
• Many legal cases have been brought based on
lack of information and/or consideration of
thermal degradation products
• Exposure issues around thermal
decomposition products have been studied
extensively in Scandinavia
7. Definitions (ASTM)
• Pyrolysis - irreversible chemical decomposition
caused by heat, usually without oxidation
• Combustion - a chemical process of oxidation
that occurs at a rate fast enough to produce
temperature rise, and usually light, either as a
glow or flame
• Fire - destructive burning as manifested by any
or all of the following: light, flame, heat, smoke
9. More on Pyrolysis...
• More in-depth definition: “...a process, by
which a solid (or a liquid) undergoes
degradation of its chemicals into smaller volatile
molecules under heat, without interaction with
oxygen or any other oxidants, that is necessary
for almost all solids (or liquids) to burn.”
10. Pyrolysis Basics
1. Decomposition of a material into simpler
compounds by the action of heat alone.
2. The pyrolysis process does not imply a
reaction between an oxidant and a reducing
agent. It is merely decomposition of a
material subjected to heating, without
involving any other substances.
11. Pyrolysis Basics
3. The more heat that is provided (energy
transferred), the faster the pyrolysis will
occur and eventually, if an oxidant (oxygen)
is present in the correct proportion, a
flaming fire will result.
4. The only solids that do not undergo
pyrolysis prior to burning are the solids that
undergo sublimation.
12. Information Gaps
• Thermal degradation products may be
synergists to other existing air contaminants in
the workplace atmosphere
• VERY few manufacturers conduct toxicity
testing on thermal degradation products of their
“parent” materials (or even identify them on
MSDSs)
• MSDSs authors routinely ignore or incorrectly
characterize thermal degradation products
13. Risk Evaluation
• Laboratory studies - headspace analyses,
thermogravimetric analyses (TGAs)
• Ideally, a manufacturer should test samples
as used by a customer or industrial user e.g. including all coatings, adhesives, etc.
• Evaluate both “normal” use scenario, and
abuse scenario
• Test at a wide range of temperatures to
determine variance in TDPs
14. Risk Evaluation Some industrial processes
•
•
•
•
•
•
•
Fabrication
Extrusion
Injection molding
Laser Cutting
Lamination
Waste disposal - e.g. incineration
Changes in manufacturing processes,
specifically those involving heat
16. Some basics of predicting TDPs
•
•
•
•
•
Organic materials - nearly always
CO, CO2
Nitrogen based materials
NH3, NOx, HCNChlorine based materials
HCl, Cl2, phosgene
Sulfur based materials
SO2
Fluorine based materials
HF
17. Some basics of predicting TDPs Plastics
•
•
•
•
Polypropylene (@270°C)
dimethylheptene
Polystyrene (@280°C)
styrene
Polyvinylchloride (@250°C)
HCl
(polyethylene will be described in more depth in
a later case study)
18. Some basics of predicting TDPs Miscellaneous materials
• Acrylic (polyacrylonitrile)/nylon fibers
HCN-,
acrylonitrile
• Polyester
benzene, benzoic acid
• Polyolefin
acrolein
• Cellulose
175 different organic compounds (demonstrates complexity of evaluation)
20. Historical Example - PCBs
• Under pyrolytic conditions, PCBs
(polychlorinated biphenyls) can be converted to
PCDFs (polychlorinated dibenzofurans)
• PCDFs are orders of magnitude more toxic
than PCBs
• Fires involving PCBs should always be
evaluated for PCDF contamination prior to
establishing necessary cleanup measures
21. Historical Example - PCBs
• If dichlorbenzenes are also present (was
common in AskarelTM products) can be
converted to even more toxic PCDDs
(polychlorinated dibenzodioxins)
22. Historical Example - PCBs
• 1981- State Office Building in NY - fire in
basement mechanical room
• 750 litres leaked from a transformer and caught
fire.
• Pyrolysis of the liquid led to the formation of a
fine oily soot that spread throughout the building
via 2 ventilation shafts.
23. Historical Example - PCBs
• Several days after the fire:
• The average air concentration of PCBs in the
building = 1.5 µg/m3
• Soot samples were analysed:
• average levels of 3 mg TCDD/kg and 199 mg
2,3,7,8-TCDF/kg
24. Forensic Example - Auto Paints
Methyl
methacrylate
Butyl cyclohexyl phthalate
Dibutyl phthalate
Butyl benzyl
phthalate
Methacrylic acid
Chromatograph of Acrylic Lacquer (Mfr. 1)
25. Forensic Example - Auto Paints
Styrene
Butanol
Butyl methacrylate
2-ethyl acrylate
Chromatograph of Acrylic Enamel (Mfr. 2)
26. Forensic Example - Auto Paints
Isobutanol
Phthalic anhydride
Vinyl toluene
Phthalimide
Chromatograph of Alkyd Enamel (Mfr. 3)
27. Product Example - PTFE
• Polytetrafluoroethylene - Teflon R
• One of the earliest examples of thorough
evaluation of TDPs - 1975 (!)
• Mold filled with resin granules, compacted,
heated to 300°C for several minutes - forms a
rigid mass (sintering)
• Studies were undertaken to determine the
temperatures and types of toxicants evolved
from PTFE
28. Variables considered in TDP
exposure characterization
• Air flow rate and volume over the sample
while heating
• Relative humidity of the air
• Sample size
• Surface area
29. Laboratory Testing
• Off-gases analyzed by a gas
chromatographic procedure
– tetrafluoroethylene (TFE) at 450°C.
– hexafluoropropylene (HFP) at 460°C
– perfluoroisobutylene (PFIB) at 475°C
• Other gaseous products
– hydrogen fluoride
– carbonyl fluoride
– fluorinated hydrocarbons
30. Toxicity of off-gases
• Approximate lethal concentrations (ALC):
– TFE - 45,000 ppm
– HFP - 3000 ppm
– Perfluoroisobutylene (PFIB) - 0.5 ppm
• Polymer-fume fever
• Symptoms similar to metal fume fever
• Poorly understood mechanism of toxicity likely involves ultrafine particles
31. Study Conclusions
• Safe to sinter PTFE at 300°C
• Ventilation and respirators would provide
adequate protection in the event of any
overheating; at least at temperatures up to
approximately 500°C.
• > 500°C. would require closed, ventilated
system
33. Industrial Example
- Polyurethane Materials
•
•
•
•
Polyurethane foams (PUFs)
Polyurethane plastics (PURs)
Based on TDI or MDI chemistry
Studies found that thermal degradation @
300° - 350°C forms TDI and MDI monomer
• Particulate phase for TDI “parent” is only
3%, but MDI is 75% (!)
34. Polyurethane Materials - Examples
• Study of car repair shops
– grinding, cutting, welding of painted
metal sheets
– relatively low amounts of MDI vapor
released - 4 µg/m3
– BUT, high concentrations of ultrafine
MDI particles (0.05 µm to 0.2 µm)
35. Epidemiological Study Nylon Flocking
• Short fibers (flock) are cut from cables of
parallel synthetic monofilaments (tow) and
applied (flocked) to an adhesive-coated substrate
• Followed by heat curing
• The nylon manufacturer's MSDS stated: "As
shipped, Nylon Polyamide Fiber products do not
pose a hazard. Under normal conditions of use,
Nylon Polyamide Fiber does not generate
respirable fibers or dust."
36. Nylon Flocking
• “Flock worker's lung”
– persistent respiratory symptoms
– previous work in the flocking industry, and;
– histologic evidence of interstitial lung disease
37. Nylon Flocking
• Nylon 6,6 melts at approximately 260°C
• At higher temperatures, can produce:
– ammonia
– various amines
– hydrogen cyanide
– nitrogen dioxide
38. Nylon Flocking
• Exposure confounders:
• Potato starch and tannic acid, two constituents
of the finish
• Airborne bacterial endotoxin
• Potato antigens
39. Industrial ExamplePolyethylene Processing
• Injection molding - PE is melted and injected into
a mold where it hardens.
• Blow molding - a tube is extruded vertically
downwards onto a spigot. The mold halves close on
to the extrudate (‘parison’) and air is blown through
the spigot so that the parison takes the shape of the
mold.
40. Polyethylene Processing
• Extrusion - granular PE is metered into a
heated barrel or cylinder, in which a rotating
screw moves up the granules, which are
compacted and plasticized. The melt is then
forced through an orifice to give a product of
constant cross section.
41. Polyethylene Processing
•
•
•
•
•
Typical processing temperatures
Extrusion (pipes): 140 – 170 ºC
Films and coatings: 200 – 340 ºC
Injection molding: 150 – 370 ºC
Welding or thermocutting - may be
significantly higher temperatures than above
mentioned processing applications.
42. Polyethylene Processing
• Laboratory simulations using degradation
temperatures close to those in industrial
processing identified following major
components:
• formaldehyde
• formic acid
• acetaldehyde
• acetic acid
43. Polyethylene Processing
• To show the complexity of TDPs - at processing
temps of 264 – 289 °C the following minor
components were identified (!):
Alkoxy radicals
Acrolein
Propionic acid
Heptane
Acrylic acid
Octene
Butyric acid
Octane
Isovaleric acid
Methanol
Hydroxyvaleric acid
Ethanol
Crotonic acid
Furan
Caproic acid
Tetrahydrofuran
Butyrolactone
Formaldehyde
Valerolactone
Acetaldehyde
Hydroperoxides
Propanol
Butene
2–Pentanone
Butane
2–Hexanone
Pentene
2–Heptanone
Hexene
Formic acid
Hexane
Acetic acid
Heptene
Butanal
Isobutanal
Ethene
Pentanal
Propene
Acetone
Propane
Methyl vinyl ketone
Cyclopropane
Methyl ethyl ketone
45. Newer Technologies Plasma Cutting
• Process that uses a high velocity jet of
ionized gas that is delivered from a
constricting orifice to cut through metals
• While cutting through mild steel, primary
contaminants:
– nitrogen dioxide
– formaldehyde
– ozone
46. Product Example - MSDSs and
Risk Evaluation
• Assume you’re going to initiate a new hot
process involving an acrylic copolymer
• You can buy the material from 4 different
manufacturers
• Let’s look at their MSDSs….
51. Product Example Circuit board overheating
• Environmental chamber, over
approximately 30 second period
• Metals:
– tin = 900 ug/m3
– lead = 750 ug/m3
• Acid gases
– 85 mg/m3
– 2 mg/m3
52. Conclusions and
Future Directions
• Developing processing methods that allow
lower temperatures, hence fewer TDPs e.g. “Squeeze”/pressure methods for
plastics molding
• MSDS quality initiatives may result in
more complete information on TDPs
53. Conclusions and
Future Directions
• More formal evaluation methods - e.g. TGA
(thermogravimetric analysis) can predict
when molecules will begin to “unzip”
• Inhalation toxicity testing of complex
mixtures, especially ultrafine particles
• GHS may incent more manufacturers to test
for and disclosed TDPs