Лако-красочные материалы — производство

This is introduced using acrylamide or methacrylamide monomers. Once this was the most commonly encountered method of building a cross-linkable polymer system. However, with the advent of a wider range of commercially available functional monomers the use of acrylamide and methacrylamide is now not so prevalent in polymers for surface coating application. Acrylamide is now […]

Usually conferred by acrylic and methacrylic esters which have been substituted with an hydroxyl group. Examples of common hydroxyl substituted monomers are: 2 hydroxy propyl methacrylate Figure 1-24 (i) Carboxyl Functionality Acrylic and methacrylic acid are most commonly used to introduce carboxyl functionality into a polymer. О Methacrylic Acid Figure 1-25 (ii) Epoxy Functionality Glycidyl […]

  1. The Major Acrylic Monomers   TABLE 1-4: THE MAJOR ACRYLIC MONOMERS Monomer Chemical Formula Homopolymer Acrylonitrile CH2=CH—CN 97 Acrylic acid CH2=CH —COOH 106 Methyl acrylate CH^CH —COOCHj 10 Ethyl acrylate CH2=CH— COOC2H5 -24 Butyl acrylate CH2=CH —COOC4H9 -54 2 ethyl hexyl acrylate CH2=CH—COOC8H17 -70 Methoxyethyl acrylate CH^ CH — COOCH2CH2OCH3 -33 Dimethylamino acrylate […]

Since, as we have seen v = If the monomer concentration is kept constant then the kinetic chain length relationship is; As the rate of polymerisation increases with increase in temperature the molecular weight will decrease: v a [M] and Consider the case of termination by combination. The degree of polymerisation will be given by: […]

The degree of polymerisation, i, is defined as the number of monomer units in a polymer molecule. Assuming that little or no transfer occurs then the relationship between v and і will depend on the mode of termination. a) Termination by combination — two radicals of kinetic chain length v combine to form one molecule […]

Kinetic Chain Length v is defined as the number of molecules reacting with a reactive centre from its formation to its termination. V=R[> = Be = kp [M][M~] = kp [M][M‘] Rt Ri 2kt [M ]2 2fkd[l] thus; kp[M] _ kg[M]2 2kt [M*] 2kt Rp So that the Kinetic Chain Length is inversely proportional to […]

This proceeds in accordance with the equation Mx + My^MxMy (combination) or M x + M у Mx + My (disproportionation) Rate of termination Rt = 2k, [M ]2 which apphes to termination by combination or disproportionation. Thus an overall equation for acrylic polymerisation can be written as Rp = kp[M]( ^ )1/2 = кр[М]ф- […]

It has been shown experimentally that the propagating chain length has no effect on the reaction rate. Each propagation step proceeds at the same rate for a homopolymerisation. міс + мкрмхм’ Rate of propagation Rp = kp [M*] [M]

1. Initiation Initiation proceeds in two stages: a) decomposition of initiator into free radicals I kd 2R’ b) attack by the free radical on the monomer molecule forming a monomer radical R ‘ + M * RM ‘ If every radical from each initiator molecule reacts with a monomer molecule the rate of reaction will […]

Inhibitors act by removing free radicals from the system. Depending on the relative reactivities of the inhibitor and the radical concerned, the free radicals may be removed either as fragments of initiator decomposition or as very short chain radicals. Commonly encountered inhibitors include nitrobenzene NO, /WW СН,— CHX and Ferric chloride /WWCH2-CHX + FeCI3 ————— […]