| This paper utilizes the Material Studio to simulate the change process of the microcosmic space structure of polyurethane,which is the main component of synthetic leather,and its comfort properties is studied.In the COMPASSII force field to take polyurethane synthetic leather(it is one kind primary polyurethane polymer that the degree of polymerization n is 20,it is called polyurethane for short)as the experimental object,and respectively simulating its microscopic dynamics process in 263 K,268K,273 K,278K,283 K,293K,303 K and 313 K eight different temperatures,obtaining its trajectory of motion and analysising related physical quantities(that is radius of gyration,radial distribution function,mean square displacement function)with the change trend of simulation temperature,and studying the mechanism of action that the temperature have influence on comfort properties of polyurethane.The reaearch contents are as follows:(1)The molecular shape and enengy of polyurethane with temperature change: With the increase of temperature,the polyurethane molecular chains from a straight line to a curved,the atoms of two ends of the molecular chain move to the middle part of the molecular chain atoms which has a trend of shrink into a regiment,the tightness degree of intramolecular atoms increased,and the whole molecular volume becomes smaller.The more intense the internal motion of polyurethane molecules,the more eneRgy they generate,indicating that as the temperature increases,the molecular volume decreases,and the distance between atoms in the whole molecule becomes smaller.(2)The radius of gyration(Rg)of polyurethane with temperature change:As temperature increases,the average value of the radius of gyration from 46.25? decrease to 40.75 ?,shows that with the rise of temperature,the internal gap is smaller of all atoms in molecular system,the atomic union is closer,and atoms interatomic distance is aslo smaller,the probabilities which air and water molecular pass through is more and more small.(3)The radial distribution function(RDF)of polyurethane with temperature change: As temperature rises,when the radial distance r is invariable,the average value of the function value g(r)of RDF increased from 2.46 to 2.63,indicates that with the increase of temperature,the atoms of polyurethane molecular system are more easily to accumulate,the force between molecules become laRger,it can reflect that the the position is smaller of molecular internal and the distance between atoms and atoms becomes closer.(4)The mean square displacement function(MSD)of polyurethane with temperature change:As temperature increases,the average value of MSD from 114.9(Angstrom^2)gradually decreased to 75.4(Angstrom^2),and then the average value of MSD from 75.4(Angstrom^2)up to 89.2(Angstrom^2).It is indicated that with the temperature rises,the value of MSD is decreasing.When the system reaches equilibrium,the average value of MSD increased slowly,it shows that temperature has a great influence on the polyurethane molecular system,all particles sport faster within polyurethane molecules system,all atom are active within molecular system,and the stability is poor,the nature is easy to change.In general,when combined with the results of analysis of polyurethane shape,energy and three physical quantities that it can be obtained: with the increase of environmental temperature,the spatial structure of polyurethane changes,the molecular interior has a trend of shrink into a regiment,the molecular volume decreases gradually;molecular internal gap become smaller,the interatomic distance becomes more closer;molecular is more easy to accumulate,poor stability,the plasticity of polyurethane decreased.It is confirmed that synthetic leather is easy to shrink and deform at high temperature,and its comfort properties is worse.So the macroscopic phenomenon features of synthetic leather is explained from microscopic spatial structure. |
PDF Full Text Request