Side‐chain crystallinity. IV. Mechanical properties and transition temperatures of copolymers of methyl methacrylate with higher n‐alkyl acrylates and N‐n‐alkylacrylamides

Abstract

SynopsisMechanical properties were correlated with glass transition temperatures for a series of random copolymers of methyl methacrylate with comonomers selected from the higher n-alkyl acrylates and N-n-alkylacrylamides. The plasticizing comonomers were the n-butyl, Zethylhexyl, n-octadecyl, and oleyl acrylates, and the N-n-butyl-, N-noctyl-, N-n-octadecyl-, and N-oleylacrylamides. The complete range of compositions was investigated. However, the bulk of the data was obtained on compositions in the glassy region below the onset of the vitreous transition. In this region it was found that the decrease in tensile and flexural moduli and strengths with increase in internal plasticizer for all of the system was directly proportional to the decrease in T,,. It was concluded that the additive contribution to the free volume made by each side-chaii methylene group was alone responsible for the magnitude of the rate of change of properties. However, polar contributions of the amide group to stiffening the main chain exceeded those of the ester, so that the amides were less efficient plasticizers. An empirical equation was derived which described, with fair accuracy, the decrease in the mechanical parameters with composition for the amorphous copolymers. It was reasonably successful in predicting properties even into the composition range where the ambient testing temperature corresponded to or exceeded the transition temperature. In this transition region an accelerated decrease in the magnitude of the physical properties was observed. All samples exhibited brittle fracture except those tested in the transition region. Here the strain was largely irrecoverable flow. Side-chain crystallinity did not interfere significantly with the mechanical properties because moduli and strengths had already decayed to small values near the compositions where crystallinity commenced. Nonrandom copolymers of vinyl stearate and methyl methacrylate showed no internal plasticization, apparently because of macrophase aggregation.

Synthesis and characterization of functional polyethylene with regularly distributed thioester pendants via ring‐opening metathesis polymerization

“…In general, this type of crystallization appears in atactic vinyl homopolymers having linear side groups with of 10 or more carbon atoms . Studies involving first‐order melting transitions of different functional polymers with regular side groups have been systematically reported in the last decades . Notably, side chain crystallizable polymers have been developed to control the release of a variety of active molecules in response to temperature changes.…”

Disruptions in the crystallinity of poly(lauryl methacrylate) due to adsorption on silica

“…Hydrogen bonding was observed in Figure from the shift in the carbonyl resonance frequency as well as the disappearance of the isolated silanol peak. The effect of main chain mobility and structure on side chain crystallinity has also been extensively studied . It has been reported that chain stiffness retards the attainment of crystallinity .…”

“…The effect of main chain mobility and structure on side chain crystallinity has also been extensively studied . It has been reported that chain stiffness retards the attainment of crystallinity . The retardation of crystallization was evident in the smallest adsorbed amount sample (0.74 mg/m 2 ) which showed effectively no crystallinity.…”

“…This sample had the largest fraction of bound carbonyl groups directly on the surface, suggesting that it was in a configuration with less chain mobility and confinement in accord with the shape of the silica surface. Crystallinity requires the cooperative movement of the main chain and side chain units . When adsorbed, the polymer backbone of PLMA appears to be constrained as a result of hydrogen bonds between the carbonyl groups and the silica surface resulting in a reduction in the amount of crystallinity.…”

Comb-Like Copolymers Obtained by Copolymerization of 2-Amino-4-(N-alkylanilino)-6-isopropenyl-1,3,5-triazines

“…8 Furthermore, comb-like copolymers prepared by the copolymerization of long-chain monomers with common comonomers have been studied to improve solubility and to increase flexibility by internal plasticization. [9][10][11][12][13][14][15] and property of the copolymers. 1 7 -22 As a part of these studies, this paper deals with copolymerization parameters of isopropenyl-1,3,5-triazines containing long alkyl groups, and with the T 8 s and the side-chain crystallization of the resulting comb-like copolymers.…”