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PKG2006 Introduction to Packaging Polymers

2nd Semester 2018

SEO JONGCHUL, PhD

CHAPTER 5. Evaluation, Characterization and Analysis of Polymers

Chem.hannam.ac.kr참고

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Properties Mechanical properties

Tensile strength,. tear strength, impact and bursting strength, folding endurance, pinhole/abrasion resistance etc.

Thermal propertiesTm, Tg, heat capacity, thermal conductivity, dimension changes etc.

Barrier propertiesDiffusion coefficient (D), solubility parameter (S), permeability(P)

Optical propertiesHaze, gloss, transparency, opacity

Electrical propertiesDielectric constant, electrical conductivity, dissipation factor etc.

Surfaces and adhesionSurface tension, wettability, adhesion bond strength, fraction, heat

sealing, etc.

Chemical resistances

MorphologyDegree of crystallinity

Crystal structureCrystal orientationMesomorphic order

Composition (Chemical)Molecular weight

Molecular weight distributionStereoreqularity

Copolymer composition

ProcessingThermal history

Stress/strain historyEnvironmental exposure

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5.3 Spectroscopic Methods of Analysis(광학적 분석법)

Table 5.1 Spectroscopic and scattering methods commonly used for studying polymers

VibrationalInfrared (IR)Raman

Spin resonanceNuclear magnetic resonance (NMR)Electron spin resonance (ESR)

ElectronicUltraviolet (UV)- visibleFluorescence

ScatteringX-rayElectronNeutron

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분광학의 원리

E: 빛 에너지: 진동수 (frequency)h: 플랑크 상수 (Planck’s constant, 6.62x10-34Jsec)c: 빛의 속도 ( = 3x108m/sec) :빛의 파장 (wave length)

E = h= hc/

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Radiation passes through the sample unchanged, except when its frequency (top) corresponds to the energy difference between two energy states of the molecule (bottom).

Bonds may stretch, bend, or rotate only with certain frequencies, and electron may only jump between orbitals with well-defined energy differences. we can measure various types of spectra

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Table 5. Types of spectroscopy and the electromagnetic spectrum

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NMR (Nuclear Magnetic Resonance)-a property that magnetic nuclei have in a magnetic field and applied electromagnetic

(EM) pulse or pulses, which cause the nuclei to absorb energy from the EM pulse

and radiate this energy back out.

-The energy radiated back out is at a specific resonance frequency which depends on

the strength of the magnetic field and other factors.

-This allows the observation of specific quantum mechanical magnetic properties of

an atomic nucleus.

관찰하고자 하는 화합물을 강한 자기장에 놓았을 때 시료 중의 핵이 자기장과 상호작용을 하게 되는데 상호작용의 정도는 핵의 자기적 성질(자기 쌍극자 모멘트)에 따라달라진다. 이와 같이 핵의 자기 쌍극자 모멘트와 외부 자기장 사이의 상호작용(핵자기 공명)을 관찰하여 화합물의 구조, 자기적 성질 또는 다른 화학적 성질을 규명하기 위해 이용되는 장비이다.

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Orientation of the nuclei in an applied field, and excitation of nuclei from the lower to the higher energy spin state

6~60x10-6 kcal/mol

Nuclei in a magnetic field exhibit nuclear magnetic resonance when they absorb a specific radio frequency of energy to go from a lower to a higher spin state

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1) 화합물의 구조 분석

- 천연물의 구조 분석

- 합성된 화합물의 구조 분석

2) 입체 화학적인 화합물의 구조 분석

- cis, trans 화합물

- 고분자의 3차원 구조의 개략적 분석

3) 개략적인 화합물의 정량 분석

4) 수소, 탄소, 인, 질소…… 등 포함한 유기물질의 구조 분석

5) 화합물의 온도 변화에 따른 동력학적 분석

NMR 사용 목적NMR 사용 목적

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Nuclear Magnetic Resonance (NMR) Spectrometry는 화합물이 강한 자기장 속에 놓여졌을

때 시료의 핵과 자기장간의 상호작용을 측정하여 분자의 구조를 밝히는데 쓰이는 장비이다.

핵자기 공명(NMR) 장치핵자기 공명(NMR) 장치

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Superconduction magnet system

Data system

Host computer

Spectrometer

System box

NMR 구성NMR 구성

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1H NMR spectrum of p-xylene

tetramethyl silane: (CH3)4Si (reference compound)

The reasons for selecting TMS as a reference compound1) All 12 of its hydrogens are equivalent2) 1H signals appear at higher field than do most 1H signals in other organic compounds3) TMS is inert

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Typical 1H Chemical Shifts (Relative to Tetramethylsilane)

Chemical shift [ppm] = = (Distance of peak from TMS, in Hz) / (Spectrometer frequency in MHz)

iftChemicalsh

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1H NMR spectrum of diethyl ether, showing spin-spin splitting

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The 1H NMR spectrum of phenol

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FT-IR (Fourier Transform Infrared Spectroscopy)

-A technique which is used to obtain an infrared spectrum of absorption, emission

, photoconductivity or Raman scattering of a solid, liquid or gas.

-The term Fourier transform infrared spectroscopy originates from the fact that a

Fourier transform (a mathematical algorithm) is required to convert the raw data

into the actual spectrum.

To summarize, infrared spectra can be used to tell

1) what types of bonds might be present in a molecule

(by using the functional group region)

2) whether two substances are identical or different

(by using the fingerprint region)

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-Interaction between molecular dynamics and light

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- Infrared light and a molecule only interact when the dipole moment of the molecule changes due to vibration

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- Normal frequency of triatomic molecules (CO2)

Infrared spectroscopy is particular useful for determining the types of bonds that are present in a molecule.

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- Normal frequency of triatomic molecules (H2O)

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- Molecular Vibration of Polyatomic Molecules

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Infrared Stretching Frequencies of Some Typical Bonds

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-Process up to Obtaining a Spectrum

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The infrared spectra of two similar ketones

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The infrared spectra of two similar ketones

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NYLON의 투과도

투과도의 peak가700 부근에 위치: C-H기 포함

투과도의 peak가 1200, 2300 부근에 위치: C-N기 포함

투과도의 peak가3400부근: O-H기 포함

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UV-Visible spectroscopy–absorption spectroscopy in the ultra-violet-visible spectral region. This means it

uses light in the visible and adjacent (near-UV and near-infrared (NIR)) ranges.

-The absorption in the visible range directly affects the perceived color of the

chemicals. In this region of the electromagnetic spectrum, molecules undergo

electronic transitions.

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1. 기본 원리

: 원자 또는 분자가 외부에서 빛 에너지를 흡수

분자운동(전자 전이 및 진동, 회전, 병진)

바닥 상태에 있는 원자나 분자는 그 종류에 따라 특정 파장의자외선 및 가시선을 흡수하며 전자전이를 일으키면서 흡수 스펙트럼을 나타낸다.

흡수하는 파장: 원자 또는 분자의 전자구조, 조성

흡수하는 빛의 세기(흡광도) : 원자나 분자의 농도 결정

UV-Vis Spectrophotometer (자외-가시선 분광광도계)

어떤 시료 분자가 어느 파장의 빛을 흡수하며, 그 흡광도는 얼마나 되는지 측정하는 기기 장치.

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2. 빛의 흡수 및 분자 전이

Absorption: 물질이 복사에너지를 흡수하여 물질과 에너지

와 상호작용이 일어나는 것.

흡수, 산란, 반사, 분자운동 (진동, 회전, 병진)

분자의 전체 에너지

EEEEE transrotvibeltot

hc

hE

*MhvM

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Name Chromophore Wavelength [nm] Molar extinction, e

acetylide -C=C 175-180 6,000

Aldehyde -CHO 210 1,500

amine -NH2 195 2,800

azo -N=N- 285-400 3-25

bromide -Br 208 300

carboxyl -COOH 200-210 50 - 70

disulphide -S-S- 194 5,500

ester -COOR 205 50

ether -O- 185 1,000

ketone >C=O 195 1,000

nitrate -ONO2 270 12

nitrile -C=N 160 -

nitrite -ONO 220 - 230 1000-2000

nitro -NO2 210 strong

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35Wavelength (nm)

200 300 400 500 600 700 800

Abs

orba

nce

(Arb

itar

y U

nit)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

PPC/ZnO 0%PPC/ZnO 1%PPC/ZnO 3%PPC/ZnO 5%PPC/ZnO 10%

- Effect of ZnO for UV absorbance

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Thermal Analysis☞ a branch of materials science where the properties of materials are studied as

they change with temperature. Several methods are commonly used - these are

distinguished from one another by the property which is measured:

Differential thermal analysis (DTA): temperature difference

Differential scanning calorimetry (DSC): heat difference

Thermogravimetric analysis (TGA): mass

Thermomechanical analysis (TMA): dimension

Dilatometry (DIL): volume

Dynamic mechanical analysis (DMA) : mechanical stiffness & damping

Dielectric thermal analysis (DEA): dielectric permittivity & loss factor

Evolved gas analysis (EGA) : gaseous decomposition products

Thermo-optical analysis(TOA) : optical properties

고분자과학과 기술2011 August Vol. 22, No. 4참조

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[열분석의 원리]

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[열분석 기기의 원리]

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[열분석의 종류]

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Differential Scanning Calorimetry (DSC) measures the temperatures and heat

flow associated with transition in materials as a function of time and

temperature in a controlled atmosphere

These measurements provide quantitative and qualitative information about

physical and chemical changes that involve endothermic or exothermic

processes, or changes in heat capacity.

What can DSC measure ?

- Glass transitions - Melting and boiling points

- Crystallization time and temperature - Percent crystallinity

- Heats of fusion and reactions - Specific heat capacity

- Oxidative/thermal stability - Rate and degree of cure

- Reaction kinetics - Purity

DSC (Differential Scanning Calorimetry)

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Metal 1

Metal 2

Metal 1

Metal 2

Sample Empty

Sample Temperature

Reference Temperature

Temperature Difference = Heat Flow

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Exo

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D S C (Differential Scanning Calorimeter)

Temperature

Hea

t F

low

Exo

ther

mic

GlassTransition

Crystallisation

Melting

Cross-Linking(Cure)

Oxidation

DSC Thermogram

En

dot

her

mic

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Heat Capacity (Cp)

-온도가 올라감에 따라 DSC와 연결되어 있는 컴퓨터에서는 heat flow의 차이, 즉 흡수하는

열의 차이에 따라 plot을 한다.

Heat Flow

- 시간에 따른 흡수되는 열과 온도 변화량에 따른 시간의 관계를 이용하여 Cp 구함

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Glass Transition Temperature (Tg)

- 온도가 올라감에 따라 pan은 흡열하며, heat flow가 변화하는 부분 Tg

-heat flow가 변화하기 시작하는 온도와 변화가 끝나는 온도의 중간값으로 결정

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Melting Temperature (Tm)

- 흡열 peak가 나타나는 온도

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Crystalline Temperature (Tc)

Crystalline Temperature at cooling

② 고온에서 고분자 시편을 급속 냉각시킨 후

온도를 일정한 속도로 올릴 때 측정할 수 있다.

Crystalline temperature at heating

① 고온에서 일정한 속도로 온도를 내

릴 때 특정 온도에서 발열이 된다.

△H: peak 부분의 넓이

△H(at100%): α−crystalline material (100%)

- crystallinity는 crystalline temperature가 나타나는 peak의 넓이

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일정한 속도로 온도를 올리면 Tg, Tc, Tm의 순서로 transition이 나타난다.

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DSC panVolatile Sample Sealer Accessory

실험 방법

시료를 pan에 넣고 Volatile Sample Sealer

Accessory를 이용하여 DSC 실험에 필요한

sample을 만든다.

D S C (Differential Scanning Calorimeter)

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실험 결과의 예: Polypropylene (Crystalline Polymer)

PP에 대한 DSC 결과

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Thermogravimetric Analysis (TGA) measures the amount and rate of change in

the weight of a material as a function of temperature or time in a controlled

atmosphere.

Measurements are used primarily to determine the composition of materials and

to predict their thermal stability at temperatures up to 1000°C.

The technique can characterize materials that exhibit weight loss or gain due to

decomposition, oxidation, or dehydration.

TGA (ThermoGravimetric Analysis)

Thermal Stability of Materials Oxidative Stability of Materials Composition of Multi-component Systems Estimated Lifetime of a Product Decomposition Kinetics of Materials The Effect of Reactive or Corrosive Atmospheres on Materials Moisture and Volatiles Content of Materials

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Mechanisms of Weight Change in TGA

Weight Loss:- Decomposition: The breaking apart of chemical bonds.- Evaporation: The loss of volatiles with elevated temperature.- Reduction: Interaction of sample to a reducing atmosphere

(hydrogen, ammonia, etc).- Desorption.

Weight Gain:- Oxidation: Interaction of the sample with an oxidizing atmosphere.- Absorption.All of these are kinetic processes (i.e. there is a rate at which they

occur).

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Instrumentation

GAS-TIGHT

ENCLOSURE

SAMPLE

HEATER

(furnace)

TEMPERATURE PROGRAMMER

BALANCE

CONTROLLER

POWER FURNACE TEMP.

SAMPLE TEMP.

WEIGHTGAS IN

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Magnet

Sample

Tare

Furnace

%

temp

Offset

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What TGA Can Tell You

• Thermal Stability of Materials• Oxidative Stability of Materials• Composition of Multi-component Systems• Estimated Lifetime of a Product• Decomposition Kinetics of Materials• The Effect of Reactive or Corrosive Atmospheres on Materials• Moisture and Volatiles Content of Materials

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TGA의 실험결과의 예

① 폴리에틸렌의 조성분석☞ Carbon black을 함유하고 있는 폴리에틸렌의 시료를 조성분석하면 500℃이하에서폴리에틸렌에 완전히 분해가 일어나고(75%), 질소기체 기류 하에서는 Carbon black이그대로 남으나(25%), 산소기류 하에서는 산화되어 없어지는 것을 볼 수 있다.

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TGA의 실험결과의 예

② 고분자의 열 안정성 분석☞ 열 안정성이 가장 낮은 PMS의 분해가 먼저 일어나며 블록 공중합체인

경우에는 PMS가 먼저 열분해가 일어나고 다음 PS가 열 분해된다. 이를 이용하여 두 성분의 조성비를 알 수 있다. 불규칙 공중합체인경우 단일 물질처럼 열분해 되는데, 두 성분 중 조성비가 더 큰 성분의열분해 곡선과 비슷해진다.

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TGA의 실험결과의 예

③ 고분자들의 상대적인 열 안정성 비교

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Mechanical Properties

Mechanical properties that are important to a design engineer differ from those

that are of interest to the manufacturing engineer.

In design, mechanical properties such as elastic modulus and yield strength are

important in order to resist permanent deformation under applied stresses. Thus, the

focus is on the elastic properties.

In manufacturing, the goal is to apply stresses that exceed the yield strength of the

material so as to deform it to the required shape. Thus, the focus is on the plastic

properties.

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The yield behavior of a material is determined from the stress-strain relationship

under an applied state of stress (tensile, compressive or shear).

The test will be conducted in accordance with the standards specified by the

American Society for Testing and Materials (ASTM; www.astm.org).

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Step 1: Original shape and size of

the specimen with no load.

Step 2: Specimen undergoing

uniform elongation.

Step 3: Point of maximum load and

ultimate tensile strength.

Step 4: The onset of necking

(plastic instability).

Step 5: Specimen fractures.

Step 6: Final length.

Basic Principles

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Concepts of Stress and Strain(Tension and compression)

To compare specimens of different sizes, the load is calculated per unit area.

Engineering stress: σ = F/A0

F is load applied perpendicular to specimen cross-section;A0 is cross-sectional area (perpendicular to the force) before application of the load.

Engineering strain: ε = ΔL/L0 (× 100 %)ΔL is change in length, L0 is the original length.These definitions of stress and strain allow one to compare test results for specimens of different cross-sectional area A0 and of different length L0.

Stress and strain are positive for tensile loads, negative for compressive loads

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Stress-Strain Behavior

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Elastic deformationReversible: when the stress is removed, the material returns to the dimension it had before the loading.Usually strains are small (except for the case of plastics).

Plastic deformationIrreversible: when the stress is removed, the material does not return to its previous dimension.

Stress-Strain Behavior

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Stress-Strain Behavior: Elastic deformation

In tensile tests, if the deformation is elastic, the stress-strain relationship is called Hooke's law:

σ = E ε

E is Young's modulus or modulus of elasticity, has the same units as σ, N/m2 or Pa

Higher E → higher “stiffness”

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o Electron microscopes are scientific instruments that use a beam of energetic

electrons to examine objects on a very fine scale.

o Electron microscopes were developed due to the limitations of Light

Microscopes which are limited by the physics of light.

o In the early 1930's this theoretical limit had been reached and there was a

scientific desire to see the fine details of the interior structures of organic cells

(nucleus, mitochondria...etc.).

o This required 10,000x plus magnification which was not possible using

current optical microscopes.

Electron Microscopy

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Comparison of OM,TEM and SEM

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Light Microscope Scanning Electron Microscope

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Characteristic Information from SEM

Topography (표면 형상)The surface features of an object or "how it looks", its texture; direct relation between these features and materials properties

Morphology (모폴로지, 형태학적 특성)The shape and size of the particles making up the object; direct relation between these structures and materials properties

Composition (화학적 조성)The elements and compounds that the object is composed of and the relative amounts of them; direct relationship between composition and materials properties

Crystallographic Information (배열)How the atoms are arranged in the object; direct relation between these arrangements and material properties

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Salmonella bacterium

microbe in soil

synthetic fibers

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고분자 분석법 실습 및 발표

11/20 (수) 11/25 (월) 11/27 (수)

일정 11:00 ~ 12:30 17:00 ~ 18:30 10:00 ~ 12:00

분석기기

FTIRUV/VIS

OTR/WVTR

TGADSC

SEMContact angle

Extruder

Sample LDPE vs Nylon LDPE vs Nylon

SEM: 무기Filler

(spherical ZnO, TZnO, composite)

Contact angle: LDPE vs Nylon

Extruder: 견학

장소 창371호 창371호SEM (창424호)

Contact angle (창356호) Extruder (창177호)

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[실습 내용]1. FTIR 분석: PE(or PP) vs Polyamide2. UV-Vis: PE(or PP), Polyamide3. TGA분석: PE(or PP) vs Polyamide4. DSC PE vs Polyamide5. SEM6. Contact Angle: PE vs Polyamide

7. OTR, WVTR (실습 또는 원리만 진행)8. Extruder (압출기)

실습 일시: 11/21(수), 11/25(월), 11/28(수)발표: 12월 2일(월) 14:00~발표시간: 조별 10분

발표 내용: (1) 분석 원리 및 응용, (2) 실험 방법, (3) 데이터 해석

고분자 분석법 실습 및 발표