CHEMICAL CHARACTERIZATION

OF PLASTIC USED IN MEDICAL

PRODUCTS

Dr. Andreas Nixdorf

China Medical Device Association, 2016 annual meeting

SGS - Life Sciences, Germany

Last changes: Jan. 19 2016

2

AGENDA

Introduction of SGS E&L German team in brief

Chemical characterization per ISO 10993, the normative framework

General analytical methods, ISO 10993 part 18

Extractables & Leachables: Sample preparation, ISO 10993 part 12, Solvents,

analytical techniques

What influences material chemical profiles?

Physical and morphological characterization, ISO 10993 part 19

Factors influencing biocompatibility

Examples of surface characterization

Failure analysis of materials

3

AGENDA

Introduction of SGS E&L German team in brief

Chemical characterization per ISO 10993, the normative framework

General analytical methods, ISO 10993 part 18

Extractables & Leachables: Sample preparation, ISO 10993 part 12, Solvents,

analytical techniques

What influences material chemical profiles?

Physical and morphological characterization, ISO 10993 part 19

Factors influencing biocompatibility

Examples of surface characterization

Failure analysis of materials

4

SGS EXTRACTABLES TEAM – TAUNUSSTEIN

(GERMANY)

We have long term experience

• Increasing regulatory requirements need knowledge about

guidelines and cross-disciplinary skills

• E&L reports are submitted for product registration

• Assessment to satisfy regulatory authorities:

US-FDA and EMA

by following PQRI, BPOG, BPSA, and ISO 10993 recommendations

We are Extractables Center of Excellence in Taunusstein

• International client network

• Testing performed in cGMP compliant laboratory or ISO accredited laboratories

• Solid basis of trust and high degree of market acceptance

We are global partner from Risk Assessment to Toxicological Evaluation

• Customized study design

• Expertise in regulatory questions

• Close communication and exchange with our clients

• Professional and efficient project management

5

EXTRACTABLES & LEACHABLES

OUR EXPERIENCE

Container testing

Stability studies

Method

development & validation Medical device testing

Biocompatibility

Toxicological

assessments

6

THE NORMATIVE FRAMEWORK OF ISO 10993

7

THE NORMATIVE SYSTEM OF ISO 10993

Evaluation Strategy

ISO 10993 Part 1: Evaluation and testing within a risk management process

Biological Testing

Part 3: Tests for genotoxicity, carcinogenicity and

reproductive toxicity

Part 4: Selection of tests for interactions with blood

Part 5: Tests for in vitro cytotoxicity

Part 6: Tests for local effects after implantation

Part 10: Tests for irritation and skin sensitization

Part 11: Tests for systemic toxicity

Part 20: Principles and methods for immunotoxicology

testing of medical devices

Others / Administrative

Part 7: Ethylene oxide sterilization residuals

Part 2: Evaluation and testing within a risk

management process

Part 8: Selection and qualification of reference

materials for biological tests (has been

withdrawn by ISO steering committees)

Part 12: Sample preparation and reference

material

Material Characterization

Part 18: Chemical characterization of materials

Part 19: Physico-chemical, morphological and

topographical characterization of

materials

Degradation Products / Toxicological Evaluation

Part 9: Framework for identification and

quantification of potential degradation

products

Part 13: Identification and quantification of

degradation products from polymeric medical

devices

Part 14: Identification and quantification of

degradation products from ceramics

Part 15: Identification and quantification of

degradation products from metals and alloys

Part 16: Toxicokinetic study design for degradation

products and leachables

Part 17: Establishment of allowable limits for

leachable substances

8

WHY CHEMICAL CHARCTERIZATION?

Chemical Characterization, ISO 10993-18 a useful and important

addition:

Regulatory bodies are increasingly asking for data on the material and

chemical components of devices

In Vitro and In Vivo biocompatibility studies are not so sensitive and often do

not allow the root cause of “irritation”

Complements in vivo biocompatibility studies for qualification of materials

selection

Analytical chemistry studies help to evaluate hazards that are associated with

the device or with the manufacturing process

Support process control in manufacturing

Demonstrate equivalency of proposed materials to a clinically established

material

9

WHY CHEMICAL CHARCTERIZATION?

Chemical characterization information can be used for:

As part of an assessment of the overall biological safety (10993-1, 14971)

Measurement of the level of leachable substances in a medical device in order to

allow the assessment of compliance – allowable limits for safety risk assessment

Judging equivalence of a proposed material to clinically established material

Judging equivalence of a final device to a prototype device to check the

relevance of data on the latter to be used to support the assessment of the former

Screening of potential new materials for suitability in a medical device for a

proposed clinical application

NOTE: Part 18 does not address identification or quantitation of degradation

products, which is covered in part -9, -13, -14 and -15.

10

CHEMICAL CHARCTERIZATION / ISO 10993-18

Materials characterization in 5+2 principal major steps (see also Dr. Stark in 2003)*:

1. Qualitative Information: Describe material and its intended purpose within the device. Data may be taken from

suppliers

2. Material equivalence: The new material is compared to an existing material that is used in a device with the

same clinical exposure

3. Quantitative data: Quantitative data will be needed, if a risk assessment cannot be made purely on

qualitative information

4. Quantitative risk assessment (see also ISO 14971): In The quantitative risk assessment of identified chemicals are compared to toxicological

information, rather than to another material

5. Estimate clinical exposure (see also ISO 14155): Finally the amount of potentially harmful chemicals, the dose, is compared to the clinical

dose a patient might receive in a lifetime, a procedure, or other unit of time

6. Exposure of Risk Assessment: As before, an evaluation for unacceptable toxicological risks shall be carried out

7. Biological evaluation Tests: Where the evaluation indicates that there are still unacceptable risks then appropriate

biological evaluation tests shall be considered in line with part 1

*Stark NJ, Biocompatibility Testing & Management, Fourth Edition, Clinical Device Group Inc, Chicago, IL (2003).

11

CHEMICAL CHARCTERIZATION (1/2) – FLOWCHART

OF RISK MANAGEMENT PROCESS ISO 10993-1*

~ *see FDA; Draft Guidance for Industry 2013, “Use of International Standard ISO 10993, Biological Evaluation of Medical Devices Part 1:

Evaluation and Testing”.

12

CHEMICAL CHARCTERIZATION (2/2) – FLOWCHART

OF RISK MANAGEMENT PROCESS ISO 10993-1*

*see FDA; Draft Guidance for Industry 2013, “Use of International Standard ISO 10993, Biological Evaluation of Medical Devices Part 1:

Evaluation and Testing”.

~

13

CHEMICAL CHARCTERIZATION / ISO 10993-18

Qualitative and Quantitative information:

Detailed description of the Material and it´s intended use.

Materials chemical composition:

Material constituents (Type of polymer, additives, processing aids, etc.)

Potential contaminants (unintentionally introduced via material handling)

The extent to which constituents are subjected to use conditions should be

assessed:

Perform extraction and migration experiments

Select analytical methods to give the required information for toxicological

evaluation

The scope of validation should correspond to the requirements and should become

part of the risk assessment

Starter materials should also be well characterized

Information should be provided by suppliers.

Used to identify toxic hazards arising from the chemical components of materials

Includes: technical data, specifications, certifications, literature data

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CHEMICAL CHARCTERIZATION (1/3) –ANALYTICAL

METHODS ISO 10993-18 AND OTHERS

General physico-chemical testing:

Analytical Technique Description Application

Dynamic mechanical thermal analysis

(DMTA)

Allows the material response to stress,

temperature, frequency and other values

to be studied

Changes in elastomers by dimension,

changes in stiffness and damping

Differential scanning calorimetry (DSC) Measures the heat capacity of a sample

by comparing the energy required to

change temperature compared wit

reference sample.

Characterization of polymers, change of

transitions and phase changes

Electron dispersal – X ray analysis-

Scanning electron microscopy (EDX-

SEM)

Electron microscopy combined with

elemental and compound analysis using

energetic electrons to liberate X rays for

analysis

Identification of materials in surfaces and

contaminants present. Useful for metals

and ceramics. Verification of deposition of

coatings

Three Dimensional Scanning Electron

Microscopy (3DSEM )

Combines the high resolution imaging of

SEM with quantitative surface metrology

information

Information about the sample's surface

topography and composition

X-ray photoelectron spectroscopy (XPS) Surface analysis by measuring energy of

electrons released by incident radiation.

Examination of surfaces for cleanness,

contaminants and coatings

X-ray fluorescence (XRF) Similar to XPS but delivered energy

results in secondary fluorescence.

Examination of surfaces for cleanness,

contaminants and coatings

Infra red spectroscopy (IR) Measures intra red transmission through

a thin film, or reflectance from a surface

Polymer identification and verification,

identification of particles

15

CHEMICAL CHARCTERIZATION (2/3) –ANALYTICAL

METHODS ISO 10993-18 AND OTHERS

General physico-chemical testing :

Analytical Technique Description Application

Secondary ion mass spectrometry

(SIMS-ToF, static and dynamic)

Used to analyze the composition of

solid surfaces by sputtering the surface

of the specimen with a focused primary

ion beam and collecting and analyzing

ejected secondary ions

Elemental composition of materials from the

surface to depths of 100 microns and

beyond. SIMS is generally considered to be

a qualitative, very sensitive technique

White Light Interferometry (WLI) Makes use of the wave superposition

principle to combine waves in a way

that will cause the result of their

combination to extract information from

those instantaneous wave fronts

Topographical information from the surface

including 2D, 3D images and profilometry as

well as roughness parameters including

surface roughness, peak height and valley

depth

Atomic Force Microscopy (AFM) Arguably the most versatile and

powerful microscopy technology for

studying samples where an extremely

sharp inert tip is scanned over a surface

Images in three-dimensional topography, it

also provides various types of surface

measurements. Can generate images at

atomic resolution with angstrom scale

Inductively charge plasma (ICP)

combined with MS or OES

Measures the masses of the element

ions (MS) or the light emitted at

element-specific characteristic

wavelengths (OES) from thermally

excited analyte ions generated by the

high temperature argon plasma

Detection of trace metals in extracts

16

CHEMICAL CHARCTERIZATION (3/3) –ANALYTICAL

METHODS ISO 10993-18 AND OTHERS

General physico-chemical testing :

Analytical Technique

(Chromatography)

Description Application

Mass spectrometry combined with

different ion sources

Identification of compounds by measuring

mass to charge ratios of ions

Elemental composition, identification of

chemical structure, quantitation of substances

Ultraviolet spectroscopy (UV) Absorption of light Analysis of extractions for organic substances

(Leachables) and others

Electrochemical detection (ECD) Amperometric electrochemical detection

the electrical current is measured

resulting from oxidation or reduction

reactions.

Electrochemically active substances

Gel permeation chromatography (GPC) Separation of polymers by transit time

through a gel by size.

Distribution of polymers of different chain

length. GPC is often used to determine the

relative molecular weight of polymer samples

as well as the distribution of molecular

weights

High performance liquid chromatography

(HPLC)

Liquid phase separation and quantitation

of chemical mixtures

Analysis of extractions for organic substances

(Leachables) or cation and anions

Gas chromatography (GC) Separation and quantitation of volatile

substances

Analysis of extractions for organic substances

(Leachables)

Nuclear magnetic resonance (NMR) Detailed analysis structure of complex

molecules by energy measurement of

nuclear environment

Structural analysis of molecules

17

CHEMEICAL CHARACTERIZAION – SAMPLE

PREPARATION ISO 10993 -12 (E&L)

Some important definitions:

Extractables: Soluble substances that are removed from a device using exaggerated conditions

Leachables: Soluble substances that are removed from a device using conditions of simulated use

Exaggerated extraction (e.g. by solvent): ..results in a greater amount of a chemical constituent being released (for identification) as compared to the amount generated under simulated use conditions

Accelerated extraction (e.g. by temperature): “…using conditions that shorten the time for leaching of the substances into the extraction vehicle…”

18

CHEMEICAL CHARACTERIZAION – SAMPLE

PREPARATION ISO 10993 -12 (E&L)

Extraction conditions (justify the selection):

(37 ±1)°C for (72 ±2)h

(50 ±2)°C for (72 ±2)h

(70 ±2)°C for (24 ±2)h

(121 ±2)°C for (1 ±0.1)h

Other conditions may be used but shall be described and justfied.

Complete dissolution of material may be appropriate (e.g. Oxidative digestion of polymer to determine total amount of metals by ICP-MS)

19

CHEMEICAL CHARACTERIZAION – SAMPLE

PREPARATION ISO 10993 -12 (E&L)

20

CHEMEICAL CHARACTERIZAION – SOLVENTS

ISO 10993 -12 (E&L)

Soft solvents:

Polar Water, Saline, Culture media (no serum)

Non-polar vegetable oil (may be replaced by pure solvents such as octane, hexane,…)

Additional extraction vehicles ethanol/water, ethanol/saline, PEG 400, DMSO and culture medium with serum

Harsh conditions could damage material, avoid it´s dissolution!

Do extraction under circulation or agitation!

Maximize the amount of extractables

Do the extraction with treated (e.g. sterilization) material, if included in your material process.

21

CHOOSE APPROPRIATE TOOLS FOR

SEPARATION & DETECTION

Volatiles organics by GC Head-space technique, TDMS, FID and MS –detector

Semi-Volatiles organics by liquid injection GC FID and MS detector

Non-Volatiles organics by HPLC DAD, LC-MS/(MS) with accurate mass assignments

Metals / Elements ICP-MS, ICP-OES

Cations, Anions Ion chromatography

Special Techniques for critical compounds GC-TEA for Nitrosamines

Perfluorinated Carboxylic acids, -Amides, -Sulfonamides by LC-MS/MS

NMR- Technology, IR and others

22

Identification Categories

Establish a classification scheme that characterizes the significance of peak

identification data (tentative, confident, confirmed and unknown)

Best identification means the comparison of both the retention index and the

mass spectrum of an extracted component with its authentic reference

standard

Identification category

Identification Data

A Interpretation of mass spectrometric fragmentation behavior or component could be grouped to a series

B Confirmation of molecular weight

C Confirmation of elemental composition (not conducted in this study)

D Mass spectrum matches automated library or literature spectrum

E Chromatographic retention index match authentic specimen

F Mass spectrum and chromatographic retention index match authentic specimen

X No characterization possible

Attribute Description

Confirmed A Confirmed identification means that identification categories A, B (or C), and D (or E or F) have been fulfilled

Confident A Confident identification means that sufficient data to preclude all but the most closely related structures have been obtained, Library match factor ≥ 90

Tentative A Tentative identification means that data have been obtained that are consistent with a class of molecule only

unknown No sufficient information’s could be obtained

WHAT IS A TRUSTABLE IDENTIFICATION?

23

WHAT INFLUENCES A

MATERIAL’S CHEMICAL PROFILE?

Some major processing impacts (to be considered in assessment)

Defects and changes can be caused by incompatible resistance due to:

Short and long term exposure to:

Chemicals

Irradiation such as UV, e-Beam and Gamma

Ozone, Oxygen, Ethylene oxide (ISO 10993-7)

Moisture

Biological (see ISO 10993 framework)

Temperature

24

INFLUENCES ON MATERIAL CHEMICAL PROFILE –

EXAMPLE RADIATION RESISTANCE

Gamma Radiation

Sterility means that a product is free from microorganisms capable of

reproduction

EN ISO 11137 regulates the sterilization of health care products by

radiation: the manufacture and sterilization of a medical product labeled as

‘sterile’ has to take place under appropriate conditions

Both the manufacturing process and the subsequent sterilization process

have to be validated (biodurden)

No validation regarding changes in polymer structure and chemical profile is

considered by EN ISO 11137.

25

INFLUENCES ON MATERIAL CHEMICAL PROFILE –

EXAMPLE RADIATION RESISTANCE

Acrylonitrile butadiene styrene (ABS),

Literature: “Radiation Chemistry of Polymers”, V.S. Ivanov, VSP 1992; “Radiation resistance of polymer materials”, Atomic Energy, Vol. 76, No. 5, pp. 422–428, May, 1994; “A

review of radiation resistance for plastic and elastomeric materials”, Radiation Physics and Chemistry (1977), Volume 24, Issues 5-6, 1984, Pages 503-510

26

INFLUENCES ON MATERIAL CHEMICAL PROFILE –

EXAMPLE RADIATION RESISTANCE

Carbonic acids: C1, C2, C3 etc.

C2 – C5 -Aldehydes

Ketones

BHT derived from Irganox 1010, 1076

2,5-di-tert-butyl benzene and 2,5-di-tert- butyl phenol from Irgafos 168

Gamma 20-

25/45 kGy

BHT: 3,5-di-tert-butyl-4-hydroxytoluol

Oxidation of free radicals:

The energy-rich beta or gamma rays trigger chemical reactions in the plastics

which result in networking or ‘cross-linking’ of the polymer molecules.

Demertzis, P.G.; Franz, R.; Welle, F.; „The Effects of Gamma-Irradiation on Compositional Changes in Plastic Packaging Films”, Packaging

Technology and Science 12 (1999), S.119-130.

27

INFLUENCES ON MATERIAL CHEMICAL PROFILE –

EXAMPLE RADIATION RESISTANCE Validation of radiation regarding impact on extraction level was missed!

Dose: approx. 32 kGy

Extraction of Pt cured silicone tube at 50 °C for 24 h with WFI

Analyte Blank µg/mL µg/cm2 Compared to Blank

(LOQ) an increase by

factor of

Formaldehyde < LOQ1 21 7 233

Formiate < LOQ2 106 34 25

Acetate < LOQ2 18 14 9

1 0.03 µg/cm2

2 1.6 µg/cm2

28

PHYSICOCHEMICAL, MECHANICAL, MORPHOLOGICAL AND

TOPOGRAPHICAL CHARACTERIZATION OF MATERIALS –

ISO 109993-19

Parameters to be Analyzed are depend on the clinical exposure/application

of the device:

Porosity

Morphology: crystallinity of polymer, amorphous, transition phases, hardness

Surface energy / charge: protein absorption/repulsion, cell attachment etc.

Abrasion resistance, stability of treated surface

Topography: surface chemical mapping, roughness

Particles and release of it: Size, shape, distribution

29

FACTORS INFLUENCING BIOCOMPATIBILITY –

WETTING OF SURFACES

Wetting is an important phenomenon in many industrial processes, it

has a strong influence on cell growth around implants

Wetting is dependent on both chemical composition and morphology of

the surface

Wetability can be studied by measuring the contact angle of the

substrate with the given liquid

Surface roughness measurements, see ISO 25178 and related normative frame work.

30

Grinding pattern Titanium implant

SURFACE CHARACTERIZATION

REM-EDX – Surface section

Implantat: Hip joint

31

Application: Surface characterization of medical stents

Problem: Determination of Surface Elemental composition ,100 nm layer depth

Method: AES (Auger Electron Spectroscopy)

Result: The stent is made from alloyed steel with a layer thickness of 22 nm

AES-Tiefenprofil, Stent D1

0

20

40

60

80

100

4 6 8 10 12 14

Sputterzeit [min]

Ato

mk

on

ze

ntr

ati

on

[%

]

C

O

Fe

Cr

Ni

Mo

Removal of surface

contamination by sputtering.

SURFACE CHARACTERIZATION OF MEDICAL

PRODUCT

32

Product failures are most costly at the pharmaceutical end-user side

Materials safety and robustness should be considered in any risk assessment

Product failures causes:

Recalls or delays in drug product registration

Warranty claims

Costs for independent failure analysis

Brand damage

The best strategy is to avoid failures:

Qualify your supplier and starter materials quality

Start to qualify your process at the early stage of product development

Generally problems do not solve themselves – usually the situation gets worse

Identify ways to improve or avoid failure in current and future parts

Advance the knowledge related to materials, design, production methods,

installation techniques, and testing methods

FAILURE ANALYSIS – WHY IS A FAILURE

ANALYSIS IMPORTANT?

33

MATERIAL ANALYSIS - DO YOU KNOW ALL OF

THESE TECHNIQUES?

Materialography, Light Microscopy

Electron Microscopy (REM, SEM)

Atomic-force microscopy (AFM)

X-ray diffraction (XRD; XRT)

Electron Probe Microanalyzer (ESMA)

Photoelectron Spectrometry (XPS)

Auger Electron Spectroscopy (AES)

Spreading Resistance Profiling (SRP)

Secondary Ion Mass spectrometry (SIMS)

Infrared Spectroscopy (IR),

Thermoanalysis (DTA, DSC)

Liquid Chromatography (HPLC, IC)

Gas Chromatography (GC-MS, HID, TEA, FID, ECD

Particle analysis D-SIMS Cameca ims 7f

XPS Quantum 2000

ICS 3000

34

STEPS FOR PERFORMING FAILURE ANALYSIS

(PLASTICS)

Obtain Part History

Macroscopic Examination

Microscopic Examination

• Stereomicroscopy

•Scanning Electron Microscopy

•Cross Section

Material Analysis

Composition

•FT-IR

•Energy Dispersive X-ray

•Thermo Gravimetric Analysis

Molecular Structure

•Differential Scanning Calorimetry

•Molecular Weight Evaluation

Physicochemical Analysis

•Dynamic Mechanical Analysis

•Mechanical testing

•Hardness Determine Failure Mode and

Cause

Determine Contribution

Factors

35

Embedded

Bubbles

The needle was inadequately glued in Luer-lock connector.

There is a high risk for leakage and particle formation.

The glue does not fill the whole space between

connector and needle.

Cracking

FAILURE ANALYSIS – SYRINGE NEEDLE

36

Observation of Calcium phosphate crystals in finished drug:

Route cause: Ca2+ ions are leached out from Rubber stopper

forming Calcium phosphate precipitation due to incompatibility to

drug formula.

Calcium/Octa phosphate Ca3(PO4)2 / Ca4(PO4)3 3·H2O pKsp 28.9

/ 46.9**

Calcium phosphate are less soluble in neutral and alkaline

conditions and dissolve in acid.

*see: Institute of Validation Technology, published on IVT Network; Alan M. Mancini , Joanne Wong Paul L. Pluta, Ph.D., Compliance Case Study #11 ;

„Glass Fragments in a Parenteral Product , Aug 29, 2014.

** S. Kubo, T. Takahashi, H. Morinaga, and H. Ueki, “Inhibition of Calcium Phosphate Scale on Heat Exchanger: The Relation between Laboratory Test Results

and Tests on Heat Transfer Surfaces”, Corrosion’79, Paper No. 220, Atlanta (1979)

ROUTE CAUSE ANALYSIS – RUBBER

INCOMPATIBILITY TO DRUG FORMULA*

37

PRACTICAL INFORMATION DERIVED FROM

POLYMER ANALYSIS METHODS

38

LIFE INSPIRED (Medical Devices) THANK YOU FOR YOUR ATTENTION

Dr. Andreas Nixdorf Business Development/Senior Scientist QC

Life Science Services

SGS Germany

( phone: +49 6128 744-372 2 fax +49 6128 744-700 - e-mail : andreas.nixdorf@sgs.com

Cheney Lin 林春鑫 Agriculture, Food and Life (AFL)

SGS-CSTC Standards Technical Services Co., Ltd.

LSS Dept., 7/F, 3rd Bldg, No.889, Yishan Road, Xuhui District,

Shanghai China, 200233

上海市徐汇区宜山路889号3号楼7层

( phone: +86 (021) 6064 5136 2 fax +86 (021) 6495 1517 - e-mail : cheney.lin@sgs.com

39

LIFE INSPIRED (Failure Analysis) THANK YOU FOR YOUR ATTENTION

Gerald Dallmann Division Manager

Consumer and Retail Microelectronics

SGS Germany

( phone: + 49 351 8841 100 2 fax +49 351 8841 190

- e-mail : gerald.dallmann@sgs.com

40

APPENDIX 1 – POYMERS ABBREVIATIONS

ABC: Acrylnitrile butadiene styrene

COC: Cycloolefine Copolymers

FP: Fluorothermoplastic

LCP: Liquid crystal polymers

PA: Polyamide

PBT: Polybutylene therephthalate

PC: Polycarbonate

PE: Polyethylene

PEI: Polyethylenimine

PEEK: Polyetherketone

PES: Polysulfone

PET: Polyethylene therephthalate

PI: Polyimide

PMMA: Polymethylmethacrylate

PMP: Polymethylpentene

PP: Polypropylene

PS: Polystyrene

PPS: Polyphenylene sulfide

PVC: Polyvinychloride

SAN: Styrene acrylonitrile resin

FP: Fluoropolymer

LCP: Liquid Crystal Polymer (unique class of partially

crystalline aromatic polyesters based on p-

hydroxybenzoic acid and related monomers)

PMP: Polymethylpentene

PP: Polypropylene

TPU: Thermoplastic polyurethane

TPA: Poly(trimethylene terephthalate)

TPC: Thermoplastic Copolyester Elastomer

TPV/TPE-V: Elastomeric alloys, sometimes referred to as

thermoplastic rubbers, are a class of copolymers

or a physical mix of polymers (usually a plastic

and a rubber) which consist of materials with

both thermoplastic and elastomeric properties.

TPO: Thermoplastic polyolefin, refers to polymer/filler

blends

TPS: Thermoplastic starch polymer