The Damping And Shape Memoryp Roperties Of Acrylic Rubber/Polylactide Blends

In this work,for the first part,a damping material was successfully prepared by static vulcanization of acrylic rubber(ACM)and polylactide(PLA)blends with sulfur,soap salt as the vulcanizing agents and phenol-formaldehyde resin(PF)as a modifier.And the effects of PF on the mechanical properties,morphology,damping properties and shape memory properties of the blends were investigated.For the second part,the ACM/PLA blends were prepared by dynamic vulcanization with sulfur and soap salt as the vulcanizing agents.The effects of blending ratio and vulcanizing agents on the dynamic vulcanization performance,mechanical properties,dynamic mechanical properties,thermal properties and morphology of blends were investigated.For the third part,PLA/ACM blends were prepared by melting blending without vulcanizing agents.The difference of mechanical properties with different blending ratios under annealing and quenching condition was studied.And the effects on crystallization behavior and shape memory properties of different PLA/ACM ratios,annealing temperature and time were also investigated.The results revealed that for the static vulcanization ACM/PLA blends,effective damping temperature range at the ratio of 70/30 was wider than the other ratios.And for the 70/30 blends,the tensile strength of the blends was decreased and the toughness was increased with the increase of PF loadings.The introduction of PF improved the compatibility between PLA and ACM,which was deduced from the fact that the glass transition temperature of ACM was increased and the two loss factor peaks became closer.It was also found that the loss factor peak became higher and the effective damping temperature range became wider due to the formation of hydrogen bonding,implying that the damping properties of ACM/PLA blends were significantly improved.The ACM/PLA blends exhibited good dual-shape memory effect and its shape recovery ratio was increased by introduction of PF and raising the trigger temperature.The blends also exhibited good triple shape memory property,which was dramatically improved by the introduction of PF.The mechanisms for the enhanced shape memory effects were then analyzed.For dynamic vulcanization blends,the dynamic vulcanization speed,the tensile strength and the elongation at break were decreased when the ratio of PLA was increased.The effective damping temperature range at the ratio of 70/30 was wider than the other ratios for ACM/PLA.The PLA in each sample was almost amorphous.PLA dispersed like "island" in "sea" formed by ACM and the phase exhibited co-continuous structure when the ratio of PLA was increased to 50.Besides,the mechanical properties were decreased with the decrease of vulcanizing agents associated with lower cross-linking of ACM.For the dynamic mechanical properties,the peak value of damping factor was increased,while the compatibility and effective damping temperature range changed little.The samples exhibited higher shape recovery ratio due to reduction of vulcanizing agents and the increasing of PLA ratio.For PLA/ACM blends without vulcanizing agents,the blends were almost amorphous under quenching condition for each blending ratio.After annealing treating,the crystallinity of the PLA in the blend was greatly improved and ?' crystal in PLA was formed with the addition of ACM.The nucleation and growth of PLA crystals could be promoted by a certain amount of ACM.Regardless of the crystalline or amorphous state,the tensile strength of the blend was decreased and elongation at break was increased.It was proved that the toughness of PLA was greatly increased with the addition of ACM.ACM had a better toughening effect on PLA under the quenching condition.In PLA/ACM blends,the crystallinity of PLA was increased continuously with the annealing temperature increasing and the annealing time prolonged,which weakened toughening effect on PLA.The PLA/ACM blends exhibited certain shape memory properties.After annealing treating,samples exhibited high shape fixity ratio.When the driving temperature was 65°C,the sample annealed at 70°C exhibited the highest shape recovery ratio,reaching 96.1 %,which was related to the enhanced shape memory behavior by heat treatment.