Polyvinyl alcohol (PVOH),-(CH2-CHOH)n-, is a linear polymer, meaning it exhibits negligible amounts of branching. PVOH is soluble in water, which is unusual for synthetic polymers, but this allows PVOH to be used in many commercial applications as thickening and foaming agents. The purpose of this experiment is to calculate the viscosity of cleaved and uncleaved PVOH solutions and to calculate the fraction of head-to-head connections in the polymer. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay. This will be done using an Ostwald viscometer calibrated with water held at a constant temperature. Plots of e ) versus c were prepared for both the cleaved and uncleaved polymer, and the intrinsic viscosity, η, was obtained by linearly extrapolating when the concentration equaled zero via a least squares linear regression. Head-to-head chain linkage was determined as the difference between the molecular weights of the cleaved and uncleaved polymer multiplied by the molecular weight of polyvinyl alcohol. The average value of head-to-head links, Δ, was found to be -0. 00365%. It is a negative value because cleaved PVOH has a higher molecular weight than uncleaved PVOH. TheoryThe experiment performed derives from the Flory and Leutner experiment “Presence of head-to-head arrangements of structural units in polyvinyl alcohol. “They found that the degradation only comes from the 1,2-glycol structures, and the increase in the number of molecules is a result of the degradation and this therefore provides a measurement of the percentage of butt structures. It was also hypothesized that the structures 1,2 were randomly distributed throughout the polymer and that the molecular weight distribution for the degraded polymer represented the most likely distribution for linear polymers (Flory and Leutner, 1948) When a colligative property, such as pressure, is present osmotic, you would get a number average molecular weight. In our experiment we used viscosity measurements, so our molecular weight is called the viscosity average. Flory and Leutner used a common distribution where the probability of a chain termination reaction is constant over time and does not depend on the length of the polymer chain. The distribution used also serves for the distribution of the product after splitting. Using the following distribution:P(M) = (1/Mn) eM/MnThe relationship between the number average molecular weight (Mn) and the viscosity average molecular weight (Mv) was found to be:Calibration of the Ostwald ViscometerAn The Ostwald viscometer (U-tube viscometer or capillary viscometer) is an instrument used to measure the viscosity of a liquid with a known density. [image: ]The viscometer was calibrated using water. The viscometer was placed in a large beaker equipped with a thermometer and containing water at room temperature so that the viscometer could remain at a constant temperature. 10 ml of water was pipetted into the side labeled as C in the image above. Water was then drawn up to a point above the upper fiducial mark, labeled A above. The suction was released and the flow rate was measured with a stopwatch until the water dropped below the lower mark, labeled B. This process was repeated 5 times and the average flow rate was recorded. The viscometer used in this experiment had a range of 33.5 seconds for water. Experimental To prepare the polymer solutions, a stock solution containing 4.4263 g of polymer was first prepared.