Melting Definitions

فهرست عناوین اصلی در این پاورپوینت

فهرست عناوین اصلی در این پاورپوینت

● 2004 Training Seminars
DSC
● Heat Flow & Heat Capacity at the Glass Transition
● Measuring/Reporting Glass Transitions
● Glass Transition Analysis
● Effect of Aging on Amorphous Materials
● Suggestions for Finding Weak Glass Transitions
● Glass Transition Summary
● Melting Definitions
● Definitions (cont.)
● Melting of Indium
● Melting of PET
● Comparison of Melting
● Analyzing/Interpreting Results
● Baseline Due to Cp
● Baseline Type
● Is it a melt?
● Is it a Melt?
● Effect of Heating Rate on Melting
● Effect of Heating Rate on Polymorph
● Effect of Impurities on Melting
● Van’t Hoff Purity Calculation
● 2004 Training Seminars
DSC
● Crystallinity
● Change in Crystallinity While Heating
● Crystallization
● Effect of Nucleating Agents
● What is Isothermal Crystallization?
● Isothermal Crystallization
● Specific Heat Capacity (Cp)
● Why is Heat Capacity Important?
● Does DSC Measure Heat Capacity?
● Calculating Heat Capacity (Cp)
● Cp by Standard DSC
● Calculating Cp by Standard DSC
● Cp by Traditional DSC – 3 Runs
● Specific Heat Capacity
● Direct Cp from a Q1000
● Heat Flow w/ Different Heating Rates
● Benefit of Plotting Heat Capacity
● Heat Flow & Cp Signals
● Weak Tg Visible in Cp Signal
● Thermoset Curing & Residual Cure
● Curing of a Thermoset
● Photopolymer Cure by PCA
● Use PDSC to Study Phenolic Curing

نوع زبان: انگلیسی حجم: 2.09 مگا بایت
نوع فایل: اسلاید پاورپوینت تعداد اسلایدها: 57 صفحه
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گروه موضوعی: زمان استخراج مطلب: 2019/05/17 02:48:15

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عبارات مهم استفاده شده در این مطلب

عبارات مهم استفاده شده در این مطلب

melting, glass, transition, temperature, ., heat, amorphous, dsc, rate, baseline, crystal, c,

توجه: این مطلب در تاریخ 2019/05/17 02:48:15 به صورت خودکار از فضای وب آشکار توسط موتور جستجوی پاورپوینت جمع آوری شده است و در صورت اعلام عدم رضایت تهیه کننده ی آن، طبق قوانین سایت از روی وب گاه حذف خواهد شد. این مطلب از وب سایت زیر استخراج شده است و مسئولیت انتشار آن با منبع اصلی است.

https://research.cnr.ncsu.edu/wpsanalytical/documents/2004TrainingSeminarsInterpretingdata.ppt

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عبارات پرتکرار و مهم در این اسلاید عبارتند از: melting, glass, transition, temperature, ., heat, amorphous, dsc, rate, baseline, crystal, c,

مشاهده محتوای متنیِ این اسلاید ppt

مشاهده محتوای متنیِ این اسلاید ppt

۲ ۴ training seminars dsc ۳ interpreting dsc data glass transition melting glass transitions the glass transition is a step change in molecular mobility in the amorphous phase of a sample that results in a step change in heat capacity the material is rigid below the glass transition temperature and rubbery above it. amorphous materials flow they do not melt no dsc melt peak glass transitions the change in heat capacity at the glass transition is a measure of the amount of amorphous phase in the sample enthalpic recovery at the glass transition is a measure of order in the amorphous phase. annealing or storage at temperatures just below tg permit development of order as the sample moves towards equilibrium heat flow heat capacity at the glass transition polystyrene measuring reporting glass transitions the glass transition is always a temperature range the molecular motion associated with the glass transition is time dependent. therefore tg increases when heating rate increases or test frequency mdsc® dma dea etc. increases. when reporting tg it is necessary to state the test method dsc dma etc. experimental conditions heating rate sample size etc. and how tg was determined midpoint based on ½ cp or inflection peak in derivative glass transition analysis polystyrene ۹.۶۷mg ۱ °c min glass transition analysis polystyrene ۹.۶۷mg ۱ °c min step change in cp at the glass transition amorphous .۱۴۵ .۳۵۳ ۴۱ pet ۹.۴۳mg aged epoxy sample effect of annealing time on shape of tg importance of enthalpic relaxation is enthalpic recovery at the glass transition important …sometimes glass transition temperature shape and size provide useful information about the structure of the amorphous component of the sample. this structure and how it changes with time is often important to the processing storage and end use of a material. enthalpic recovery data can be used to measure and predict changes in structure and other physical properties with time. effect of aging on amorphous materials temperature max tg storage time h m s equilibrium liquid equilibrium glass kauzmann temp lowest tg entropy of crystal where h high relative cooling rate m medium relative cooling rate s slow relative cooling rate v suggestions for finding weak glass transitions know your empty pan baseline get as much material in the amorphous state cool slowly through the glass transition region heat rapidly through glass transition region use mdsc® or use quasi isothermal mdsc glass transition summary the glass transition is due to amorphous material the glass transition is the reversible change from a glassy to rubbery state vice versa dsc detects glass transitions by a step change in cp melting definitions melting – the process of converting crystalline structure to a liquid amorphous structure thermodynamic melting temperature – the temperature where a crystal would melt if it had a perfect structure large crystal with no defects metastable crystals – crystals that melt at lower temperature due to small size high surface area and poor quality large number of defects definitions cont. crystal perfection – the process of small less perfect crystals metastable melting at a temperature below their thermodynamic melting point and then re crystallizing into larger more perfect crystals that will melt again at a higher temperature true heat capacity baseline – often called the thermodynamic baseline it is the measured baseline usually in heat flow rate units of mw with all crystallization and melting removed…. assumes no interference from other latent heat such as polymerization cure evaporation etc. over the crystallization melting range melting of indium peak temperature extrapolated onset temperature heat of fusion for pure low molecular weight materials mw ۵ g mol use extrapolated onset as melting temperature melting of pet extrapolated onset temperature peak temperature heat of fusion for polymers use peak as melting temperature comparison of melting analyzing interpreting results it is often difficult to select limits for integrating melting peaks integration should occur between two points on the heat capacity baseline heat capacity baselines for difficult samples can usually be determined by mdsc® or by comparing experiments performed at different heating rates sharp melting peaks that have a large shift in the heat capacity baseline can be integrated with a sigmoidal baseline baseline due to cp baseline type dsc of polymer blend where is the cp baseline more on this sample in the mdsc® section is it a melt yes onset shifts by only .۳°c is it a melt no onset shifts by almost ۳ °c effect of heating rate on melting melt effect of heating rate on polymorph dsc at ۱c min dsc at ۱ c min dsc at ۵ c min dsc at ۱c min comparison of all ۳ heating rates effect of impurities on melting effect of p aminobenzoic acid impurity concentration on the melting shape temperature of phenacetin approx. ۱mg crimped al pans ۲°c min nbs ۱۵۱۴ thermal analysis purity set melting of eutectic mixture ۱ pure ۹۵. pure ۹۹.۳ pure ۹۶. pure as sample becomes less pure the melting peak broadens and shifts to a lower melting temperature. higher levels of impurities forms an eutectic – the lowest melting point of an alloy or soln that is obtainable by varying the proportions of the components van t hoff purity calculation ۲ ۴ training seminars dsc ۴ interpreting dsc data crystallization heat capacity and crosslinking crystallinity definitions crystallization – the process of converting either solid amorphous structure cold crystallization on heating or liquid amorphous structure cooling to a more organized solid crystalline structure crystal perfection – the process of small less perfect crystals metastable melting at a temperature below their thermodynamic melting point and then re crystallizing into larger more perfect crystals that will melt again at a higher temperature change in crystallinity while heating quenched pet ۹.۵۶mg ۱ °c min crystallization crystallization is a kinetic process which can be studied either while cooling or isothermally differences in crystallization temperature or time at a specific temperature between samples can affect end use properties as well as processing conditions isothermal crystallization is the most sensitive way to identify differences in crystallization rates …

کلمات کلیدی پرکاربرد در این اسلاید پاورپوینت: melting, glass, transition, temperature, ., heat, amorphous, dsc, rate, baseline, crystal, c,

این فایل پاورپوینت شامل 57 اسلاید و به زبان انگلیسی و حجم آن 2.09 مگا بایت است. نوع قالب فایل ppt بوده که با این لینک قابل دانلود است. این مطلب برگرفته از سایت زیر است و مسئولیت انتشار آن با منبع اصلی می باشد که در تاریخ 2019/05/17 02:48:15 استخراج شده است.

https://research.cnr.ncsu.edu/wpsanalytical/documents/2004TrainingSeminarsInterpretingdata.ppt

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