Thermal Behaviour Of Blends Research Articles

Composition dependence of the synergistic effect of nucleating agent and plasticizer in poly(lactic acid): A Mixture Design study

Blends consisting of commercial poly(lactic acid) (PLA), poly(lactic acid) oligomer (OLA8) as plasticizer and a sulfonic salt of a phthalic ester and poly(D-lactic acid) as nucleating agents were prepared by melt extrusion, following a Mixture Design approach, in order to systematically study mechanical and thermal properties as a function of composition. The full investigation was carried out by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and tensile tests. The crystallization half-time was also studied at 105°C as a function of the blends composition. A range of compositions in which the plasticizer and the nucleation agent minimized the crystallization half-time in a synergistic way was clearly identified thanks to the application of the Mixture Design approach. The results allowed also the identification of a composition range to maximize the crystallinity developed during the rapid cooling below glass transition temperature in injection moulding, thus allowing an easier processing of PLA based materials. Moreover the mechanical properties were discussed by correlating them to the chemical structural features and thermal behaviour of blends.

Thermal behaviour of bisitaconimide and reactive diluent blends

Thermal behaviour of blends based on N,N'-bis(4-itaconimidophenyl) ether (IE) and 4,4'-bis(4-allyl-2-methoxyphenoxy) benzophenone (R1) or 4,4'-bis(2-allylphenoxy) benzophenone (R2) are described in this paper. The reactive diluent content was varied from 5-50% (mass/mass) in these blends. A decrease in the melting point and exothermic peak temperature was observed with increasing mass percent of reactive diluent. Thermal stability of blends was affected at high mass percentage of reactive diluents.

Thermal Behaviour of Bisitaconimide and Bisnadimide Blends

This paper describes the thermal behaviour of blends of bisitaconimide (I) and bisnadimide (N) resins of similar structures. Bisitaconimides/bisnadimides based on 4,4'-diaminodiphenyl ether (E);2,2'-bis[4-(4-aminophenoxy)phenyl]propane (B); 1,3-bis(4-aminophenyl)benzene(R) and 1,4-bis(4-aminophenyl)benzene (H) were prepared and were designated as E-I/E-N; B-I/B-N; R-I/R-N and H-I/H-N respectively. Itaconimides had lower melting points and curing temperatures than that of corresponding nadimides. The blends of bisitaconimides and bisnadimides were prepared in the ratios of1:3, 1:1, 3:1 by solution mixing (chloroform/acetone). A decrease in the melting point and characteristic curing temperatures was observed in the blends. Thermal stability of cured resin blends was only marginally affected by the blend composition.

Thermal behaviour of blends of HDPE with long-chain branched HBPE

The thermal behaviour of new blends on the base of high-density polyethylene (HDPE) and of long-chain branched polyethylenes (HBPE) made by means of new metallocene catalysts has been studied by DSC in relation to the melting and crystallisation characteristics and discussed in the phase behaviour of the mixtures. While HBPE's with 7.5 to 12 per cent by mass of octene as comonomer in the blends with HDPE are relevant for the formation of homogeneous composition regions. Especially, with higher HBPE contents, the phase separation and splitting of the melting and crystallisation peaks is observed. This behaviour has not been observed with 2 per cent by mass of octene in HBPE. The dependence of the melting and crystallisation temperatures of HDPE/HBPE blends on the octene content of the HBPE's for constant composition of mixtures have been shown for both the homogeneous and heterogeneous mixing. Blends of a high-molecular HDPE and a HBPE resulted in a reduction of the composition range not effected by phase separation.