聚（β－羟基丁酸酯）／聚双酚A羟基醚共混体系相容性及结构的研究

POLY(3-HYDROXYBURATE)/POLY(HYDRO ETHER OF BISPHENOL A) BLENDS:PHASE STRUCTURE AND MISCIBILITY

ＤＳＣ和ＦＴＩＲ测试表明，结晶／非晶共混体系聚（β－羟基丁酸酯）（ＰＨＢ）／聚双酚Ａ羟基醚（ＰＢＨＥ）是部分相容的．熔融结晶退火可以大大提高共混物的结晶度，增加其相容性，７５／２５组分ＰＨＢ相结晶度最大，５０／５０组分（０２０）、（１３０）晶面微晶尺寸最大．ＳＡＸＳ研究表明，纯ＰＨＢ的中间层约为１．５ｎｍ，片层厚约４．０ｎｍ；共混物的中间层在２．０ｎｍ左右，片层厚在５．０—７．２ｎｍ之间，５０／５０组分片层最厚．７５／２５组分晶相和非晶相的密度差最大．

oly(3-hydroxyburate)(PHB)and its copolymer with 3-hydroxyvalerate(P(HB-HV)) have attracted much attention because they are thermoplastic biopolyesters.It has been reported that Poly(3-hydroxyburate)(PHB)and Poly (ethylene oxide)(PEO),Poly(vinyl acetate)(PVAc)or Poly (vinylidene fluoride)(PVDF) are miscible in the melt,they all exhibit a single glass transition temperature.In this paper,we report the results of an investigation concerning the phase structure and miscibility of blends obtained by mixing PHB with uncrystallized component Poly (hydroxy ether of bisphenol A)(PBHE).It is found that PHB and PBHE are partially miscible by the results obtained from DSC and FTIR measurements.In comparison with the samples cast from solution,the annealled samples biodisplay higher degree of crystallinity and better miscibility(Fig.1).The results of FTIR measurements indicate that there are no hydrogen bonds between the carbonyl groups of PHB and hydroxy groups of PBHE in the,cast samples.But some interaction between the segments of two polymers are formed,because the wave numbers of some groups of PHB and PBHE change regularly with the increase in the content of PHB in the blends(Tab.1).The crystallite sizes of the annealled samples are listed in Table 2. Increasing the uncrystallized component in the blend from PHB/PBHE=100/0 to PHB/PBHE=50/50.It is observed that the crystallite sizes of(020)and(130)crystal faces become larger,and larger,which reach the largest sizes at the composition of PHB/PBHE=50/50. On the contrary,increasing the uncrystallized component from PHB/ PBHE=40/60 to PHB/PBHE=20/80,the crystallite sizes get smaller.Data from SAXS experiments indicate that the thickness of the interphase of pure PHB is 1.5nm and that of the blends are about 2.0nm; the period of C axis of a PHB orthorhombic cell is 5.96A, therefore the interphase consists of three lattice layers. This agrees with the results predicted theoretically by Paul J. Flory and Do Y. Yoon. Tee lamellae of PHB/PBHE=50/50 is the largest in thickness in all blends. With the increase in uncrystallized component,the lamellae of the blends change similarly as the crystallite sizes discussed above.In all blends,the density difference of PHB/PBHE=75/25 composition between crystalline and amorphous phases is the biggest.This agrees with that the degree of crystallinity for PHB/PBHE=75/25 composition, obtained by DSC measurements,(Tab.3).