Tiêu chuẩn iso 11357 1 2016

3.2 calbratio material mate ial for which one or mor of the the mal pro e ties ar suficiently homo eneous an w el es a l shed to be used for the cal bration of a DSC ins rument or for th

Plastics — Dif er ential scanning

Part 1:

Plastiques — An lyse calorimétrique diffr ntie lle (DSC) —

Partie 1: Principes g n ra x

T ir d edition

2 16-0 -1

Reference n mb r

ISO 1 3 7-1:2 16(E)

COPYRIGHT PROTECTED DOCUMENT

© ISO 2016, P blshed in Sw itz rlan

A ll rig hts r eserved Unles otherw ise spe ified, nopar of this p blc tion ma y be r epr od c d or utilz d otherw ise in an form

or b an me ns, ele tr onic or me hanic l, inclu in p oto opying , or postin on the internet or an intranet , w ithout prior

written permis ion Permis ion c n be req esed from either ISO at the ad r es below or ISO’s member bod y in the c u try of

F reword v

Introduction vi

1 Sc ope 1

2 Nor mati ve r eferenc es 1

3 Terms an definitions 1

4 Basic pr inciples 8

4.1 General 8

4.2 Heat-flux DSC 8

4.3 Powe -compensation DSC 8

5 A pparatus and mater ials 9

6 Specimen 10

7 Test c onditio s and specimen c onditio ing 11

7.1 Tes con itions 1

7.2 Conditioning of spe imens 1

8 Calbratio 11

8.1 General

1 8.2 Calbration mate ials 1

8.3 Temperatur e calbration 1

8.3.1 General 1

8.3.2 Pr oc d re 1

8.3.3 A ccuracy of calbr ation 1

8.4 Heat calbr ation 1

8.4.1 General 1

8.4.2 Pr oc d re 14

8.4.3 A ccuracy of calbr ation 14

8.5 Heat low rate calbr ation 1

8.5.1 General 1

8.5.2 Pr oc d re 1

9 Proc ed re .17

9.1 S tting upthe a p ratus .1

9.1.1 Switching on 1

9.1.2 P r g e gas 1

9.1.3 Ex pe imental con itions 1

9.1.4 Baselne dete mination 1

9.2 L ading thespe imen into the c ucible .1

9.2.1 General 1

9.2.2 S le tion of c ucibles 1

9.2.3 Weighing the spe imen c ucible .1

9.2.4 L ading the spe imen

1 9.2.5 Dete mination of the mas of the spe imen .1

9.3 Inse tion of c ucibles into the instrument 1

9.4 Pe forming measur ements 1

9.4.1 General 1

9.4.2 S anning mode 1

9.4.3 Isothe mal mode 1

9.5 Pos -ru che ks 2

9.5.1 Che k for los in mas 2

9.5.2 Inspe tion of spe imens 2

9.5.3 Che king of c ucibles an c ucible holde 2

10 Test rep r t 20

A nne x A (normative) Ex tended, high-precisio , temperatur e calbration 22

A nne x B (normative) Ex tended, high-precisio , he t cal bratio 24

A nne x C (informative) Rec ommended calbration mater ials

26

A nne x D (informative) Interaction of cal br atio mater ials w ith difer ent c ucible materials 29

A nne x E (informative) General r ec ommendatio s 31

Biblog raph y 33

ISO (he Int ernational Org nization for Stan ardization) is a worldwide fede ation of national s an ards

b dies (ISO membe b dies) The work of pr p ring Int ernational Standards is normaly car ied out

through ISO t ech ical committ ees Each membe b dy int er st ed in a subje t for w hich a t ech ical

committ ee has be n es a l shed has the right t o be r pr sent ed on that committ ee Int ernational

org nizations, g ove nmental an non-g ove nmental, in laison with ISO, also take part in the work

ISO cola orat es closely with the Int ernational Ele trot ech ical C mmis ion (IEC) on al matt ers of

ele trot ech ical s an ardization

The proc d r s used t o develo this document an those int en ed for it furthe maint enanc ar

desc ibed in the ISO/IEC Dir ctives, Part 1 In p rticular the dife ent a pro al c it eria ne ded for the

dife ent ty es of ISO document should be not ed This document was draft ed in ac ordanc with the

edit orial rules of the ISO/IEC Dir ctives, Part 2 ( e www.iso.org dir ctives)

A tt ention is drawn t o the p s ibi ity that some of the element of this document ma be the subje t of

p t ent right ISO shal not be held r sponsible for identifying any or al such p t ent right Detais of

any p t ent right identif ied d ring the develo ment of the document wi be in the Introd ction an / r

on the ISO ls of p t ent de larations r c ived ( e www.iso.org p t ent )

Any trade name used in this document is information given for the convenienc of use s an does not

cons itut e an en orsement

F or an ex lanation on the meaning of ISO spe if ic t erms an ex r s ions r lat ed t o conformity

as es ment, as wel as information a out ISO’ s adhe enc t o the WTO principles in the Te h ical

Bar ie s t o Trade (TBT) se the fol owing URL: F or word - Sup lementary information

The committ ee r sp nsible for this document is ISO/TC 6 1, Plas tic s , Subcommitt ee SC 5, Ph s ic al

chemic al pro erties

This third edition canc ls an r plac s the se on edition (ISO 1 3 7-1:2 09), 3.7.2 of w hich has be n

t ech icaly r vised

ISO 1 3 7 consis s of the folowing p rt , u de the g ene al title Plas tic s — Dife ential sc an in

c alorimetry (DSC):

— Part 1: G ene al princ iples

— Part 2 : Dete min tion o glas s tra s itio tempe atur a d glas s tra s itio s tep heig t

— Part 3: Dete min tio o tempe atur a d enth lp o meltin a d c rys tali s ation

— Part 4: Dete min tio o s pec ific heat c ap c it y

— Part 5: Dete min tio o charac te i s tic r ac tio -c urve tempe atur s a d times , enth lp o r ac tio

a d degr e o c on e s io

— Part 6 : Dete min tio o oxidatio induc tio time (i sothe mal O IT) a d ox idatio induc tio tempe atur

(dy namic O IT)

— Part 7: Dete min tion o c r ys tali zatio kinetic s

ISO 1 3 7 desc ibes the mo nalytical DSC t es methods w hich can be used for q alty as uranc

purp ses, for routine che ks of raw mat erials an f inished prod ct or for the det ermination of

comp ra le data ne ded for data she t or data ases Theproc d r sgiven in ISO 1 3 7 a ply as long

as prod ct s an ards or s an ards desc ibing spe ial atmosphe es for con itioning of spe imens do

not pe ify othe wise

Plastics — Dif erential scanning calorimetry (DSC) —

Part 1:

SAFETY STATEMENT — Per ons using this document sh uld be fami iar with normal laboratory

practice, if appl cable This d cument does n t p rport to addres al of the safety co cerns, if

any, as ociated with its use It is the responsibi ity of the use to establ sh appro riate safety

and he lth practices an to ensure complance with any re ulatory requirements

ISO 1 3 7 spe ifies seve al dife ential scan ing calorimetry (DSC) methods for the the mal analy sis of

p lyme s an p lyme blen s, such as

— the mo las ics (p lyme s, moulding compoun s an othe moulding mat erials, with or without

f ile s, fibr s or r infor ement ),

— the moset (u cur d or cur d mat erials, with or without f ile s, f ibr s or r infor ement ), an

— elast ome s (with or without fil e s, f ibr s or r infor ement )

ISO 1 3 7 is int en ed for the o se v tion an measur ment of v rious pro e ties of, an phenomena

as ociat ed with, the a o e-mentioned mat erials, such as

— phy sical transitions (glas transition, phase transitions such as melting an c y stal zation,

polymorphic transitions, et c ),

— chemical r actions (polyme ization, c os l n ing an curing of elast ome s an the moset , et c ),

— thes a i ty t o o idation, an

— theheat ca acity

This p rt of ISO 1 3 7 spe if ies a n mbe of g ene al aspe t ofdife ential scanning calorimetry, such

as the principle an the a p ratus, samplng, calbration and g ene al aspe t of the proc d r and t es

r p rt common t o al folowing p rt

Detaison pe forming spe if ic methods ar given in subseq ent p rt of ISO 1 3 7 ( e F or word)

2 Normati ve r eferences

The folowing document , in w hole or in p rt, ar normatively r fe enc d in this document an ar

in ispensa le for it a pl cation F or dat ed r fe enc s, only the edition cit ed a pl es F or u dat ed

r fe enc s, the lat es edition of the r fe enc d document ( inclu ing any amen ment )a pl es

ISO 47 , Plas tic s — Voc ab lar y

ISO 80 0 -5, Qu ntities a d u it — Part 5: The mody namic s

3 Terms and definitions

F or the purp ses of this document, the t erms an def initions given in ISO 47 an ISO 8 0 0-5 and the

folowing a ply

diferential s anning calorimetry

DSC

t ech iq e in w hich the dife enc between the rat e of flow of heat int o a spe imen c ucible containing

the spe imen an that int o a r fe enc e c ruc ible (3.3)is de ived as a fu ction of t empe atur an / r time

w hi e the spe imen an r fe enc ar subje t ed t o the same controled t empe atur pro ramme in a

spe ified atmosphe e using a symmetrical measur ment y st em

Not e 1 to entry: It is common practice t o record, for e ch me surement ru , a curve in which temperature or time

is plot ed as the a s is a an h at flow r te (3.4) diference as the ordinat e The en othermic an / r ex othermic

direction is in icated on the DSC curve

Not e 2 t o entry: A ccording t o the principles of thermod namic , energy a sorb d by a syst em is considered

positive while energy rele sed is ne ative This ap ro ch implies that the en othermic direction points u wards

in the ordinate an the ex othermic direction downwards (se Figures 1 an 2) It also has the ad anta e that he

direction of thermal efects in plots of h at flow r te (3.4) an specif ic he t is consist ent

3.2

calbratio material

mate ial for which one or mor of the the mal pro e ties ar suficiently homo eneous an

w el es a l shed to be used for the cal bration of a DSC ins rument or for the as es ment of a

measur ment method

3.3

reference c ucible

c ucibleused on the r fe enc side of the symmetrical c ucible holde as embly

Not e 1t o entry: Normal y, the reference c ucible is empty

Not e 2 to entry: In special cases, such as the me surement of highly f il ed or reinfor ed polymer or specimens

having a he t capacity compara le to that of the c ucible, a suita le material can b used inside the reference

c ucible This reference material should b thermaly inactive over the temperature an time rang of interest

an its he t capacity should b similar t o that of the specimen In the case of f iled or reinfor ed prod cts, the

p re f iler or reinfor ement can b used, for e ample

3.4

he t flow rate

q antity of heat trans e r d pe u it time (dQ /dt)

Not e 1t o entry: It is e pres ed in wat s (W) or mil iwat s (mW)

Not e 2t o entry: T e t otal q antity of he t ransfer ed, Q, cor espon s t o the time int egral of the he t low rat e:

q antity of heat a sorbed (en othe mic, ΔQ positive) or r leased (exothe mic, ΔQ neg tive) within a

spe ified time, t, or t empe atur , T, rang e b a spe imen un e g oing a chemical or phy sical chang e

an / r a t empe atur chang e:

∆ Q

Q

tt

TT

=

∫

6

12

β

d

dd

w he e

dQ is the q antity of heat, ex r s ed in joules (J), ne es ary t o raise the t empe atur of an amou t

of mat erial of mas m, ex r s ed in grams (g), b d T kelvins at cons ant pr s ur ;

β is theheating rat e, ex r s ed in kelvins pe min t e (K⋅min

Note 2 to entry: When analy sing polymer , ensure that he me sured specif ic he t capacity do s not inclu e an

he t chang d e t o a chemical re ction or a p y sical transition

3.7

baselne

p rt of the r corded curve in w hich no r actions or transitions take plac

Note 1 to entry: This can b an isothermal b seline when the t emperature is maintained constant or a d namic

b seline when the temperature is chang d in ac ordance with a controled temperature pro ramme

Note 2 t o entry: T e b selines def ined in 3.7.1 to 3.7.3 refer t o the q asistationary rang only, i.e when the

instrument is operating u der sta le con itions shortly afer starting an shortly b fore en ing the DSC ru (se

Figure 1)

3 specimen b selines

a

E dothermic dir ection

Figure 1 — Schematic drawing showing basel nes

DSCcurve o tained out ide any r action or transition zone() w hie the ins rument is lo ded with b th

the spe imen in the spe imen c ucible an the r fe enc e c ruc ible (3.3)

Not e 1t o entry: In this part of the curve, the diference in h at flow r te (3.4)b tween the specimen c ucible an

the r fr nc e c ruc ible (3.3)depen s solely on the he t capacity of the specimen an the insrume t b s eln (3.7.1)

Not e 2 to entry: T e specimen b seline reflects the t emperature depen ence of the he t capacity of the specimen

Not e 3 to entry: For he t capacity det erminations, a d namic DSC curve is req ired an , in ad ition, the

ins r me t b s eln (3.7.1)an the isothermal start an en b selines (se Figure 1)

virtual baselne

ima inary l ne drawn through a r action an / r transition zone as uming the heat of r action an / r

transition t o be z ro

Note 1 t o entry: As uming the chang in he t capacity with temperature t o b line r, the virtual b seline is

drawn by int erpolating or e trapolating the specimen b seline in a straight line It is normal y in icated on the

DSC curve for convenience (se Figures 1an 2)

Note 2 t o entry: T e virtual b seline drawn from pe k onset, T

i, t o pe k en , T

f, ( he pe k b seline) alows the

determination of the pe k are from which the he t of transition can b o tained If there is no signif icant chang e

in he t capacity d ring the transition or re ction, the b seline can b drawn simply by con ecting the pe k onset

an pe k en by a straight line If signif icant he t capacity chang s oc ur, a sigmoidal b seline can b drawn

Note 3 to entry: Extrapolat ed an interpolat ed virtual b selines wil not neces arily coincide with e ch other

(se Figure 2)

3.8

step

a rupt p sitive or neg tive change in the height of a DSC curve, taking plac over a lmited

tempe atur range

Note 1t o entry: A step in the DSC curve can b caused by, for e ample, a glas transition (se Figure 2)

3.8.1

step height

dife enc betwe n the height of the extra olat ed b sel nes befor an aft er a st ep, measur d at the

time or t empe atur cor espon ing t o the p int on the DSCcurve w hich is eq idis ant betwe n the two

b selnes

3 9

pe k

p rt of the DSCcurve w hich depart from the s pec imen b s elne (3.7.2), r aches a ma imum or minimum,

an subseq ently r turns t o the s pec imen b s elne (3.7.2)

Note 1 t o entry: A pe k in the DSC curve may in icate a chemical re ction or a f ir t-order transition T e initial

departure of the pe k from the v ir tu l b seln (3.7.3)cor espon s t o the start of the re ction or transition

3 9.4

pe k height

gr at es dis anc in the ordinat e dir ction between the int erp lat ed v irtu l b s elne (3.7.3) an the DSC

curve d ring a peak

Not e 1 t o entry: The pe k height, which is e pres ed in wat s (W) or wat s per gram (W/ ), is not neces arily

proportional t o the mas of the specimen

3 9.5

pe k width

dis anc between the onset and en t empe atur s or times of a peak

3.10

characteristic temperatures, T, and times, t

v lues for t empe atur an time o tained from the DSCcurve

Not e 1t o entry: S e Figure 2

Not e 2to entry: For al ty es of DSC instrument, a distinction ne ds t o b made b tween two diferent categ ories

of t emperature:

— the temperature at the reference position;

— the temperature at the specimen position

The reference position temperature is the one prefer ed for plot ing thermo rams If the specimen position

t emperature is used, then this information wil ne d t o b inclu ed in the t est report

Not e 3 t o entry: C aracteristic t emperatures are e pres ed in de re s Celsius ( C), relative t emperatures an

t emperature diferences in kelvins (K)an characteristic times in secon s (s)or min t es (min) (se Figure 2)

Not e 4 t o entry: T e DSC curve can also b plot ed using time, t, as the a s is a inste d of t emperature, T

C aracter is ic temperatures

T e fir t subs rip or pair of subs ripts, denotes the position on the DSC curve w ith r espect o the step or pe k:

i

fir t detectable departur e of curve from

ex tr apolated start b seline;

— interpolated or ex tr apolated onset temperatur e T

ei

(or a pe k) point of inter ection of

interpolated virtual b seline an tang ent

draw n at point of inflection of ne r side of

pe k or (or a step) point of inter ection

of ex tr apolated start b seline an tang ent

draw n at point of inflection of step;

(or a pe k) point of inter ection of

interpolated virtual b seline an tang ent

draw n at point of inflection of far side of

pe k or (or a step) point of inter ection

of ex trapolated en b seline an tang ent

draw n at point of inflection of step;

f

last detectable deviation of curve fr om

ex tr apolated en b seline

T e secon subs ript in icates the type of tr ansition:

g g las tr ansition

c c ystal ization

a

E dothermic dir ection

Figure 2 — Typical DSC curve (s hematic)

4 Basic principles

The dife enc betwe n the rat e of heat flow int o a spe imen an that int o a r fe enc c ucible is

measur d as a fu ction of t empe atur an / r time w hie the spe imen an the r fe enc ar subje t ed

t o thesame t empe atur -control pro ramme un e a spe ified atmosphe e

Two ty es of DSC can be car ied out: heat-flux DSC an p wer-compensation DSC

4.2 He t-flux DSC

The spe imen an r fe enc p sitions ar subje t ed t o the same t empe atur -control pro ramme b a

single heat er A dife enc in t empe atur , Δ T, oc urs betwe n the spe imen p sition an the r fe enc

p sition be ause of the dife enc in heat ca acity betwe n the spe imen an the r fe enc From this

t empe atur dife enc , the dife enc in the rat es of heat flow int o the spe imen an r fe enc positions

is de ived an is normaly r corded a ains the t empe atur of the r fe enc , T

ref, or a ains time

A schematic drawing of a heat-flux DSC ins rument is shown in Figur 3

Key

1temperatur e at specimen position (T

spe imen)

2temperatur e at r efer ence position (T

f

r efer ence positions

5 me sur ement cir cuit for T

spe imen, T

f

an ΔT

Figure 3 — Schematic diagram i lustrating the basic principles of he t-flux DSC

4.3 Power-c ompensation DSC

In p wer-compensat ed DSC, in ivid al heat ers ar used for the spe imen an r fe enc positions

The dife enc in ele trical p wer r q ir d t o maintain both the spe imen position and the r fe enc

p sition at the same t empe atur is r corded a ains t empe atur or time, w hie each p sition is

subje t ed t o the same t empe atur -control pro ramme

F or p wer-compensat ed iso e ib lc calorimet ers, the sur oun ing t empe atur ( i.e the t empe atur

of the heat sin )has t o be kept cons ant

A schematic drawing of a p wer-compensation DSC ins rument is shown in Figur 4

1temperatur e at specimen position (T

spe imen)

2temperatur e at r efer ence position (T

6 he t-flux compensation cir cuit

7 surr ou ding he t sin

Figure 4 — Schematic dia ram i lustrating the basic principles of power-compensatio DSC

5 A pparatus and materials

5.1 Difer ential s anning calor imeter, with the folow ing featur es:

a) A symmetrical c ucible holde as embly w hich has holde s for the spe imen an r fe enc

c ucibles

b) The ca a i ty t o g ene at e cons ant heating and co lng rat es suita le for the int en ed

measur ment

c) The ca a i ty t o maintain the t es t empe atur cons ant t o within ±0,3K or les for at leas 6 min

d) The ca a i ity t o car y out st ep heating or st ep co lng

NOT Normaly, this is achieved by a suita le combination of line r he ting or co ling an

constant-temperature re imes

e) The ca a i ty t o maintain a cons ant purg e g s flow rat e control a le t o within ± 0% o e a rang e

of flow rat es (e.g 1 ml⋅min

−

t o 1 0 ml⋅min

−

)

NOT T e actual g s flow rate wil depen on the design of the instrument used

f) A t empe atur rang e in l ne with theex e imental r q ir ment

g) A heat flow rat e rang e of ± 0 mW or mor

h) A r cording devic ca a le of a ut omatical y r cording the measur d curve of heat flow rat e a ains

t empe atur an time

i) The ca a i ty t o measur t empe atur signals with a r solution of ± ,1K an an ac uracy of ± ,5 K

or bett er

j) The ca a i ity t o measur time with a r solution of ± ,5 s and an ac uracy of ± sor bett er

k) The ca a i ity to measur heat flow rates with a r solution of ± ,5 µW an an ac uracy of ± µW

or bett er

5.2 Cr ucibles, for the spe imen an r efer enc p sitions They shal be of the same type, made of the

same mate ial an ha ve simiar mas es They shal be physicaly an chemicaly ine t to the spe imen,

the calbration mate ials and the pur g e gas u de the measur ement con itions ( e A nnexes C and D)

NOTE 1 If req ired, smal variations in c ucible mas can b arithmetical y cor ect ed for, given the specif ic

he t capacity of the c ucible material

Crucibles should pr fe a ly be made of a mat erial with a high the mal con uctivity, e.g aluminium

Ventiat ed c ucibles should pr fe a ly be used t o a oid chang es in pr s ur d ring the measur ment

ru an t o alow the ex chang e of g s with the sur ou ding atmosphe e Howeve , for spe ial purp ses,

c ucibles closed with lds or he meticaly sealed c ucibles ma be r q ir d so that they wi l withs an

the o e pr s ur arising d ring the measur ment run

When using spe ial high-pr s ur or glas c ucibles, their r latively high mas an p or the mal

con uctivity shal be taken int o ac ou t R ecalbration of the ins rument ma be r q ir d

NOTE 2 When using high-pres ure or hermetical y closed c ucibles, me surements are not neces arily

performed at constant pres ure Hence, the constant-pres ure req irement for me suring enthalpies or c

pmay

not b fulf iled

5.3 Balanc e, ca a le of measuring the spe imen mas with a r esolution of ± ,0 mg an an ac uracy

of ± ,1 mg or bete

5.4 Calbration materials, co e ing the temperatur e rang e of inter es an pr eferably chosen from the

ls of r ecommen ed calbration mate ials in A nnex C

5.5 Pur g e gas, preferably a dry an ine t gas (e.g nitr og en of purity 9 ,9 % or bette ), used to a void

ox idative or hydr olytic deg radation d ring tes ing

F or the inves ig tion of chemical r actions, inclu ing o idation, spe ial r actant g ses ma be r q ir d

If a g s g ene at or is used t o sup ly g s for purging and environmental control d ring t es ing, rathe

than using a pr s uriz d g s b t le purg e, it isr commen ed that uita le drying an f ilt ering sy st ems

be ins aled

The spe imen shal be in the lq id or sold s at e Sold-s at e spe imens ma be in any form w hich f it

int o the c ucible (e.g p wde , pelet , gran les, fibr s) or ma be cut from bigg er pie es t o a suita le

siz The spe imen shal be r pr sentative of the sample being ex mined an shal be pr par d an

han led with car Particular car shal be taken t o avoid any contamination of the spe imen If the

spe imen is taken from larg er pie es b cut ing, car shal be taken t o pr vent heating, p lyme

orientation or any othe efe t hat ma alt er the spe imen pro e ties Ope ations such as grinding that

could cause heating or r orientation an could the efor chang e the the mal hist ory of the spe imen

shal be avoided The method of sampl ng an spe imen pr p ration shal be s at ed in the t es r port

If the spe imen c ucible is closed or sealed with a ld, this shal not cause any deformation of the b tt om

of the c ucible Go d the mal contact between the spe imen an c ucible an betwe n the c ucible an

holde shal be ensur d

Ty ical spe imen mas es ar between 2 mg and 40 mg

NOTE Incor ect specimen preparation can chang the thermal properties of the polymer e amined For

further information, refer t o An e E

7 Test conditions and specimen conditioning

7.1 Test c onditions

The ins rument shal be maintained an o e at ed in an atmosphe e suita le for the int en ed t es

Unles ex clu ed b spe ial r q ir ment for p rticular t es proc d r s, al calbration an t es

measur ment shal be pe formed using closed, venti at ed c ucibles, pr fe a ly made of aluminium, t o

impro e r prod cibi ity

It is r commen ed that he ins rument be prot ect ed from air draught , ex osur t o dir ct su lght an

a rupt chang esin t empe atur , pr s ur or mains v ltag e

7.2 Conditioning of specimens

Spe imens shal be con itioned prior t o the measur ment ru as spe ified in the r lev nt mat erial

s an ard or b a method a r ed betwe n the int er st ed p rties

Unles othe wise spe ified, spe imens shal be dried t o cons ant mas befor pe forming measur ment

Car shal be taken t o cho se suita le drying con itions t o pr vent phy sical chang es, such as ag eing or

chang es in c y stal nity of the spe imens

NOTE Depen ing on the material an its thermal hist ory, the methods of preparation an con itioning of the

sample an specimens may b c ucial t o the values o tained, the consistency of the results an their signif icance

8 Cal bration

Befor commis ioning a new ins rument or after r pla cing or modifying es ential comp nent or after

cleaning the measuring c l b heating to elev ated tempe atur s, the calorimet er shal be calbrat ed at

leas with r spe t t o tempe atur an heat In ad ition, heat flow rat e calbration ma be r q ir d for heat

ca a city measur ment Re albration of the ins rument shal be car ied out r gular ly at the r q ir d

calbration interv als, e.g when the ins rument is being used as p rt of a q alty as uranc sy stem

NOTE In man cases, the calibration proced res wil b built into the instrument control sof ware an th s

at le st partly automated

R ecalbration of the ins rument should pr fe a ly be pe formed each time the t es conditions ar

signif icantly chang ed Mor fr q ent che ks ma be car ied out as r q ir d

The calbration can be afe t ed b the folowing:

— ty e of calorimet er used an it s a i ty;

— heating an co lng rat es;

— ty e of co lng sy st em used;

— ty e of purg e g s used an it flow rat e;

— ty e of c ucible used, the c ucible siz an the p sitionsof the c ucibles in the c ucible holde ;

— location of the spe imen in the spe imen c ucible;

— mas an p rticle siz of the spe imen;

— the mal contact betwe n the spe imen c ucible an the c ucible holde

The con itions of the actual det ermination should the efor be def ined as pr cisely as p s ible an

the calbration car ied out u de these con itions as closely as p s ible Comput er-controled DSC

ins rument ma aut omaticaly cor e t for the efe t of some of these sour es of e ror

The calbration shal be car ied out using the same ty e of c ucible, made of the same mat erial, an

using the same purg e g sat the same flow rat e aswi be used for subseq ent measur ment

Calbration spe imens shal be heat ed only slghtly a o e their transition t empe atur s t o pr vent

r actions betwe n the calbration mat erials an the c ucibles

Immediat ely aft er the measur ment ru , the spe imens should pr fe a ly be co led u ti the transition

b ck t o the initial s at e has taken plac

F or mos practical measur ment , it wi l be suff icient t o use the calbration proc d r s spe ified in 8.2

t o 8.5 F or mor ac urat e cal brations, the proc d r s spe if ied in An ex es A and B ma be used

8.2 Cal bration materials

Pr fe a ly, c rtif ied r fe enc mat erials should be used The true t empe atur , T

calthe true heat of

transition, ΔQ

cal

an the true spe ific heat, c

p,cal

w hich ar used for the calbration shal be those

a pearing on the c rtif icat e ac ompanying the r fe enc mat erial

If c rtif ied v lues ar not a ai a le, the v lues given in Ta les C.1, C.2 an C.3 ma be used Ad itional

cal bration mat erials ma be used pro ided their the mal pro e ties ar sufficiently defined The

cal bration mat erials shal not int eract with the c ucibles or purg e g s used ( e An ex D)

F or each calbration, a fr sh calbration spe imen shal be used Any co ting ofo ide on the surfac

of the calbration spe imen shal be r mo ed, e.g b fr shly cut ing the spe imen The p sition of the

spe imen in the c ucible should pr fe a ly be kept the same t o improve the r peata i ty of the r sult

To a oid misleading r sult or damag e t o the c ucible holde , combinations of calbration an c ucible

mat erials w hich ar not ex e t ed t o ha e any influenc on the melting p int should pr fe a ly be used

( e Annex D) C mbinations in w hich the calbration mat erial is ex e t ed t o dis olve the c ucible

mat erial should be a oided

8.3 Temperatur e cal bration

8.3.1 General

This is the es a lshment of the r lationship betwe n the t empe atur , T

e s, in icat ed b the

ins rument an the true t empe atur , T

is a t empe atur cor e tion

When using calbration mat erials othe than those l st ed in Annex C, only f irs -orde transitions, e.g

the melting of pur subs anc s, shal be used for calbration purp ses

NOTE True transition temperatures can b o tained from calibration material certif icat es, other q alif ied

sour es or the lit erature

W ith the calbration mat erials l st ed in Annex C, t empe atur calbration shal be car ied out in the

heating mode only Howeve , cor e tly calbrat ed ins rument that give consist ent r sult in the heating

mode wi l not ne es ari y give consist ent r sult in the co l ng mode be ause of supe co l ng of the

subs anc d ring the transition in q es ion The symmetry of the t empe atur scale in the heating an

co l ng mode can be che ked with subs anc s that do not upe co l, e.g lq id c y stals

8.3.2 Proc edure

The folowing proc d r desc ibes the minimum r q ir ment for car ying out t empe atur

calbration

Weigh at leas two calbration mat erials, co e ing the t empe atur rang e r q ir d, int o c ucibles,

pr fe a ly made of aluminium with an o idiz d surfac

Aft er ha ing melt ed and r c y stal z d each calbration spe imen, car y out a heating run d ring w hich

the melting peak is r corded Pe form co lng an heating ru s at the same rat e as wi be used for

subseq ent measur ment

F or each melting peak measur d, det ermine the extra olat ed peak onset t empe atur , T

ei,m( e

Figur 2), using the int erp lat ed virtual baselnebetwe n peak onset an peak en

F or each calbration mat erial, i, o tain the t empe atur cor e tion, ΔT

i

c al:

c or r cal ei,m

Then cor e t the t empe atur scale of the ins rument, b l near int erpolation of the t empe atur

cor e tion within the t empe atur rang e co e ed b the calbration mat erials used, in ac ordanc with

ar the t empe atur cor e tions for the two cal bration mat erials;

ar the true transition t empe atur s of the two calbration mat erials

In orde t o keep e rors caused b deviation from lnearity of the t empe atur cor e tion ve sus

t empe atur r lationship smal, it is r commen ed that the t empe atur rang e co e ed b the two

cal bration mat erials be kept as smal as p s ible If bigg er t empe atur rang es ar r q ir d, mor than

two calbration mat erials should be used

NOTE 1 If more than two calibration materials are used, it is pos ible to use a poly omialinterpolation

NOTE 2 T e t emperature cor ection may b performed automatical y by some instruments

This calbration proc d r is depen ent on the heating rate an has to be pe formed for ea ch heating rate

8.3.3 Ac curacy of calbratio

The ac uracy of this t empe atur cal bration proc d r is ex e t ed t o be bett er than ± ,8 K pro ided

the t empe atur dife enc betwe n the calbration mat erials does not ex ce d 5 K an the e is no

deviation from l nearity of Δ T

cor

ve sus T Bigg er t empe atur dife enc s an signif icant deviations

from lnearity wi l r sult in lower ac uracy

∆ Q

Q

tt

an the true heat, ΔQ

t, a sorbed or r leased b the spe imen as a r sult ofa transition The r lationship

F r calbration mat erials, ΔQ

t

iseq al t o ΔQ

cal

8.4.2 Proc edure

Thefolowing proc d r desc ibes the minimum r q ir ment for car ying out heat calbration

F or heat cal bration, the same measur ment can be made as those made for t empe atur calbration

Car y out a heating ru with one mat erial, pr fe a ly indium

Draw the lnear virtual b sel ne ( e Figur 1) and o tain the spe ific heat of melting from the ar a

betwe n the DSCcurve an the virtual b sel ne, using F ormula (3):

TT

m

dd

i,mf,m

m is the mas of the calbration spe imen;

β is the heating rat e;

d

d

(DQ)

t

is the dife enc in heat flow rat e betwe n the DSCcurve an the virtual b sel ne;

T is the t empe atur of the cal bration spe imen

The heat cal bration fact or, K

Q, is o tained b dividing the true spe ific heat of the transition of the

cal bration mat erial, Δq

cal

b the measur d spe ific transition heat, Δq

m:

8.4.3 Ac curac y of calbratio

Theac uracy of this method isnot ex e t ed t o be bett er than ± ,5 % for in ium Due t o the depen enc

of the calbration fact or on the mas an the mal con uctivity of the spe imen an on heating rat e,

peak sha e an t empe atur , thisma det eriorat e t o ± 0% an even beyon

[1 ][1 ]

F or an ext ended, mor pr cise, method of heat calbration, r fe t o An ex B