Crystallization of semicrystalline block copolymers containing a glassy amorphous component

Shiomi, Tomoo; Tsukada, Harumichi; Takeshita, Hiroki; Takenaka, Katsuhiko; Tezuka, Yasuyuki

doi:10.1016/s0032-3861(00)00894-6

Cited by 66 publications

(62 citation statements)

References 28 publications

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“…The Avrami indices obtained here range from 2 to 3 and no systematic tendency can be observed. In our previous papers, it was found that the Avrami indices were reduced for block copolymers having a glassy amorphous component, because crystallization occurs within confined rigid microdomains 19,20) . On the other hand, for PEG-PBD, in which the amorphous component is rubbery in crystallization, we reported that the Avrami index is not reduced even when crystalline PEG is in cylindrical microdomains 26) .…”

Section: Crystallization Behavior Of Hei/pe and Hei/pip Blendsmentioning

confidence: 98%

“…In the block copolymers having a glassy component as an amorphous block, the dimension of the crystal growth is considerably confined and the activation energy of crystallization is high, because the crystallizable domain is surrounded or sandwiched by the rigid (i.e., glassy) amorphous domains 20) . On the other hand, the amorphous domain is soft for the block copolymers containing a rubbery amorphous component.…”

Section: Regular Articlementioning

confidence: 99%

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Structure Formation and Crystallization Behavior of Ethylene-Isoprene Block Copolymers and Their Blends with Corresponding Homopolymers

et al. 2008

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Time-resolved simultaneous synchrotron small-angle X-ray scattering and differential scanning calorimetry experiments have been performed on crystallization of polyethylene-polyisoprene diblock copolymers (HEI or LEI) and their blends with corresponding homopolymers, polyethylene (PE) and polyisoprene (PIp). For the neat block copolymer having a 50 wt% of the crystalline component, preexisting microphase separation structure in the melt was kept at high and low crystallization temperatures T c (T c Ն94°C and T c Ͻ60°C), while disrupted at intermediate T c (60°CՅT c Ͻ94°C). This complex behavior was interpreted by combination of two mechanisms. The behavior in the crystallization below 94°C was attributed to the competition between the crystallization and chain diffusion rates, that is, the fast crystallization rate at lower T c makes it difficult to rearrange the phase structure in the melt. On the other hand, at a higher T c (Ն94°C), the preservation of the microphase separation structure was explained by a small degree of crystallinity due to the ethyl branch of polyethylene (hydrogenated poly(butadiene)). For HEI/PE blends, crystallization behavior was the simple superposition of those for HEI and PE, while, for HEI/PIp with a small composition of PE, suppression of crystallinity was observed. Crystallization kinetics in the neat block copolymer and all the blends was not so different from that in the PE homopolymer.Keywords Microphase separation, Structure formation, Crystallization, Polyethylene-polyisoprene block copolymer. Regular Articlee-Journal of Soft Materials, Vol. 4, pp. 12-22 (2008) amorphous component T g A 19,20) . When crystallization temperature T c is lower than T g A , that is, the amorphous component is in glassy state at T c , microphase separation structure in the melt is usually maintained in crystallization, because the microphase separation structure is frozen by the glassy domains 19,21,22) . On the other hand, when T c is higher than T g A , it has been reported that structural change in crystallization depends on the segregation strength between components (cN t ). Quiram et al. explored the crystallization of a high molecular weight polyethylene-poly(3-methyl-1-butene) block copolymer (strongly segregated system) with a polyethylene weight fraction f E of 0.27, and found that polyethylene crystallized within preexisting cylindrical microdomains 23,24) . Nojima et al. 25) also investigated a crystallization process of crystalline-rubbery amorphous block copolymers for poly(e-caprolactone)-polybutadiene (weakly segregated system) through a time-resolved smallangle X-ray scattering (SAXS) technique using synchrotron radiation as a light source, and observed that a preexisting SAXS peak from the microphase separation disappeared with development of a new peak originating from the long period of crystal lamellae. Furthermore, we have reported that a high molecular weight poly(ethylene glycol)-poly(butadiene) block copolymer (PEG-PBD), which is relatively strongly segrega...

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Section: Crystallization Behavior Of Hei/pe and Hei/pip Blendsmentioning

confidence: 98%

Section: Regular Articlementioning

confidence: 99%

Structure Formation and Crystallization Behavior of Ethylene-Isoprene Block Copolymers and Their Blends with Corresponding Homopolymers

et al. 2008

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“…When a polyester and retinol showed a good miscibility, the existence of retinol would affect the crystalline structure of the polyester nanoparticles, thereby influencing T m and ΔH. 49 Conversely, the bad miscibility between the two molecules will less influence the structure of the polyester in the nanoparticles due to their phase separation. Thermodynamically, the miscibility between the polyesters and retinol is predictable by calculating the solubility parameters (δ) of the polyesters and retinol and their differences.…”

Section: 34mentioning

confidence: 99%

Effect of Polymer Characteristics on the Thermal Stability of Retinol Encapsulated in Aliphatic Polyester Nanoparticles

Cho¹

2012

Bulletin of the Korean Chemical Society

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The present study investigates how the thermal stability of retinol (vitamin A) encapsulated in polyester nanoparticles is influenced by the types of polyester used for the nanoparticles. A variety of polyester-retinol nanoparticles were prepared with various polyesters like: poly(ethylene adipate), PEA; poly(butylene adipate), PBA; poly(hexamethylene adipate), PHMA; and three polycaprolactones, PCL, of different molecular weights (M n ~10, 40, and 80K). C. More importantly, this study has also found that the thermal stability of the retinol in the nanoparticles was closely connected with the melting temperatures of polyesters and polyester nanoparticles. The results were further discussed with possible factors -such as sample preparation condition (or history) and miscibility between the polyesters and retinol -affecting T m of the polyesters and the nanoparticles.

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“…[4] On the other hand, extremely small values of the Avrami exponents were found when the crystallization of one component occurs from a domain surrounded by the glassy matrix of the second component and is much more restricted. [6] In order to compare the crystallization rate, the crystallization half-time, t 1/2 , defined as the time at which the polymer reaches a crystalline fraction equal to 0.5, was used as kinetic parameter. This value is obtained by subtracting the induction time (t), i.e.…”

Section: Isothermal Crystallizationsmentioning

confidence: 99%

“…These analyses are mainly carried out on dior triblock copolymers with a narrow block length distribution and a well defined structure. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] The role of the block length in influencing the crystallization behavior is considered fundamental: it was found that the extent of folding increases with length of both crystalline and amorphous blocks, influencing melting temperature and enthalpy. [13,[15][16][17][18][19] The transesterification reactions performed in the molten state generally give copolymers with a broad block length distribution due to the poor control on the macromolecular structure.…”

Section: Introductionmentioning

confidence: 99%

Crystallization of Poly(ethylene terephthalate) in Poly(ethylene terephthalate)/Bisphenol A Polycarbonate Block Copolymers: Influence of Block Length and Role of the Rubbery Amorphous Component

Celli

Marchese

2004

Macro Chemistry & Physics

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Summary: Analysis was made of the crystallization of the PET blocks in PET/PC copolymers as a function of the block length, varying from $\overline M _{\rm n}$ = 5300 to 17100 g · mol−1 (Xn PET = 28–89, PET monomeric sequences). Analysis was also made of a series of PET homopolymers with the same $\overline M _{\rm n}$ values. The copolymers were found to crystallize at a slower rate, with lower crystallinity and lower crystal perfection, than the homopolymers and secondary crystallization does not take place, unlike with PET homopolymers. However the crystallization mechanism is the same. The plot of the crystallization rate versus Xn PET shows that the homopolymers have a maximum crystallization rate at Xn PET ≅ 50 ($\overline M _{\rm n}$ ≅ 10000 g · mol−1), whereas the crystallization rate for copolymers continuously increases with the increment of Xn PET (see Figure). The decrement of the crystallization rate for homopolymers with $\overline M _{\rm n}$ higher than 10000 g · mol−1 has been interpreted as due to the effect of the high melt viscosity. For copolymers with long PET blocks, instead, a phase separation is likely and improves the PET reptation and fold, causing an increment in crystallization rate. Block size and miscibility between the components are therefore the key parameters in understanding the crystallization process in PET/PC block copolymers.

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Crystallization of semicrystalline block copolymers containing a glassy amorphous component

Cited by 66 publications

References 28 publications

Structure Formation and Crystallization Behavior of Ethylene-Isoprene Block Copolymers and Their Blends with Corresponding Homopolymers

Structure Formation and Crystallization Behavior of Ethylene-Isoprene Block Copolymers and Their Blends with Corresponding Homopolymers

Effect of Polymer Characteristics on the Thermal Stability of Retinol Encapsulated in Aliphatic Polyester Nanoparticles

Crystallization of Poly(ethylene terephthalate) in Poly(ethylene terephthalate)/Bisphenol A Polycarbonate Block Copolymers: Influence of Block Length and Role of the Rubbery Amorphous Component

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