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State of matter and properties of matter (Part-6)(Relative humidity, Liquid Complex, Liquid crystals, Glassy State.)

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State of matter and properties of matter (Part-6)(Relative humidity, Liquid Complex, Liquid crystals, Glassy State.)

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RELATIVE HUMIDITY, Humidity, Wet and Dry Hygrometer, LIQUID COMPLEX, LIQUID CRYSTALS, Types of liquid crystals, GLASSY STATES, Characteristics glassy state, Types of glassy state, What is the Glass Transition Temperature?

RELATIVE HUMIDITY, Humidity, Wet and Dry Hygrometer, LIQUID COMPLEX, LIQUID CRYSTALS, Types of liquid crystals, GLASSY STATES, Characteristics glassy state, Types of glassy state, What is the Glass Transition Temperature?

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State of matter and properties of matter (Part-6)(Relative humidity, Liquid Complex, Liquid crystals, Glassy State.)

  1. 1. IIIrd Semesester B. pharmacy Physical Pharmaceutics-I Unit-II State of matter and properties of matter (Part-6) (Relative humidity, Liquid Complex and Liquid crystals) Miss. Pooja D. Bhandare (Assistant professor) Kandhar college of pharmacy
  2. 2. RELATIVE HUMIDITY • Humidity: the amount of water vapor in air • A ratio between the actual amount of water vapour present in the air and the maximum amount of water the air can hold at a given temperature. • Expressed as a percentage (%)
  3. 3. • Formula: 𝑨𝒄𝒕𝒖𝒂𝒍 𝒂𝒎𝒐𝒖𝒏𝒕 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝒗𝒂𝒑𝒐𝒖𝒓 𝒊𝒏 𝒕𝒉𝒆 𝒂𝒊𝒓(𝒈/𝒎𝟑) 𝑴𝒂𝒙𝒊𝒎𝒖𝒎 𝒂𝒎𝒐𝒖𝒏𝒕 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝒗𝒂𝒑𝒐𝒖𝒓 𝒕𝒉𝒆 𝒂𝒊𝒓 𝒄𝒂𝒏 𝒉𝒐𝒍𝒅 (𝒈/𝒎𝟑) x 100 • Since the latter amount is dependant on temperature, relative humidity is a function of both moisture content and temperature.
  4. 4. Wet and Dry Hygrometer
  5. 5. LIQUID COMPLEX • Complex fluid are binary mixtures that have coexistence between two phase: Solid- liquid ( suspension or solution of macromolecules such as polymers), solid-gas ( granular), liquid-gas (Foams) or liquid-liquid (emulsion). • They exhibit unusual mechanical responses to applied stress or strain due to the geometrical constrains that the phase coexistence imposes.
  6. 6. • The mechanical responses includes transition between solid like and fluid like behaviour as well as fluctuations. • The mechanical properties can be attribute to characteristics such as higher disorder, caging and clustering on multiple length scales.
  7. 7. • Shaving cream is an example of a complex fluid. Without stress, the foam appears to be a solid: it does not flow and can support (very) light loads. • However, when adequate stress is applied, shaving cream flows easily like a fluid. • On the level of individual bubbles, the flows is due to rearrangement of small collections of bubbles. On this scale, the flow is not smooth, but instead consist of fluctuations due to rearrangements of bubbles and released of stress.
  8. 8. LIQUID CRYSTALS • A fourth state of matter is called as liquid crystal state or mesophase or (mesomorphic phase). • It is the state that occurs between a soild and a liquid. • It possesses characteristics both liquid and crystalline solids. • In crystalline solid state the molecule are held in a position by intermolecular forces • The particles in a solid move but cannot cross each other because the attraction of neighbouring atom or molecules are too strong to overcome.
  9. 9. • In the liquid state, the molecules move to random positions. • But in the liquid crystal state , the increased molecular motion overcomes molecule remains bound by stronger forces. This produces a molecular arrangement where the molecule is a layered but within each layer, the molecules are arranged a random position. The molecule can slide one around the other , and layers can slide over one another.
  10. 10. This molecular mobility generates fluidity in liquid crystal state.
  11. 11. Types of liquid crystals A. Thermotropic Liquid Crystals: Liquid crystals are said to be thermotropic if liquid crystalline properties depend on the temperature. a. Nematic Liquid Crystals: Here the molecules (mesogens) have no positional order, but they have long-range orientational order. b. Smectic Liquid Crystals: In this the mesogens have both positional order and orientational order. c. Cholestric Liquid Crystal: The cholesteric phases can be defined as a special type of nematic liquid crystal in which thin layers of the parallel mesogens have their longitudinal axes rotated in adjacent layer at certain angle.
  12. 12. B. Lytropic Liquid Crystals: Liquid crystals which are prepared by mixing two or more substances of which one is polar molecule, are know as lytropic liquid crystals. Example Soap in
  13. 13. GLASSY STATES • Glass is a nonequilibrium, non-crystalline state of matter that appears solid on a short time scale but continuously relaxes toward the liquid state. • Glass is a nonequilibrium, non-crystalline condensed state of matter that exhibit a glass transition. • The structure of glass is similar to that of their parent supercooled liquids (SCL), and they spontaneously relax toward the SCL state. Their ultimate fate, in the limit of infinite time, is to crystallize.”
  14. 14.  Characteristics Transparency Solid appearance Brittleness Molecule have no order structure Volume of the system is larger than that of crystalline system with the same composition
  15. 15. • These system are often referred to as: Amorphous ( i.e disorder) solid (e.g., glass) or Supercooled liquids(e.g., rubber, leather, syrup). • Glasses are generally formed by melting crystalline materials at very high temperatures. • When the melt cools, the atoms are enclosed in a random(disorder) state before they can form in a perfect crystalline arrangement.
  16. 16. Types: 1. The first type: It is characterized by the cessation of the vibratory movement of rotation of the molecules in a defined (critical) temperature region. This result in stabilization of the chain structures of rigidity associated polar molecule( by mean dipole) 2. The second type: It is consists of organic glassy polymerization products. These glass in the stabilized state have a fibrous structure of rigid valency bonded carbon atom with small lateral branches in the form of hydrogen atom or more complex radicals. 3. The third type: The third most extensive type of glass state consists of refractory inorganic compounds of multivalent elements. These glasses in the stabilized state have the most thermostable chemical structure in the form of three dimensional atomic valency-bonded spital network.
  17. 17.  What is the Glass Transition Temperature? • The temperature below which a polymer is hard, brittle and above which it is soft is called as Glass Transition Temperature. • The hard or brittle state is called glassy state • The soft flexible state is called rubbery state.
  18. 18. THANK YOU!

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