Study On The Crystallization Behavior Of P34HB And P34HB/Long Glass Fibre Composite

As a new kind of biomaterial, poly-3-hydroxybutyrate-co-4-hydroxybutyrate (P34HB)arouses great attention, because of its biosynthesis, and biodegradability.In the present work, the crystallization properties of P34HB was studied throughDifferential Scanning Calorimetry (DSC). It was found that P34HB had the bestcrystallization rate at70℃and the half crystallization time is95seconds, which is very lowcompared with1.25seconds of PP. Via Mo’s mathmatics model, we found that0.25phr ofsodium benzoate could remarkablely improve the crystallization rate. From Kissingerequation, we find the crystallization activation energy of P34HB reduced from-61.30kJ/molto-108.80kJ/mol when0.25phr of sodium benzoate was added, which meant sodiumbenzoate dramatically lowered the nucleation barriers of P34HB.In this paper, glass fiber enhanced P34HB composite was prepared. The mechanicalproperties peaked when the glass fiber loading was49.70phr, SiO2was5phr, andcompatibilizer P34HB-g-MAH gendered in the process of extrusion. For P34HB, the tensilestrength was29.70MPa, bending strength is56.43MPa, bending modulus is2085MPa,impact strength is4.05kJ/m~2. After the modification, the values improved to67.35Mpa,109.19Mpa,8643MPa and6.87kJ/m2, respectively. The infrared spectra(IR) indicated thatP34HB had strong ester group, which could form hydrogen bond with inorganic substance.Scanning Electronic Microscopy(SEM) photographs showed that the surface of glass fiberwas covered by a thick layer when P34HB-g-MAH was available. The shear flow rate ofP34HB was0.02cm3/s at153℃and soared to0.32cm3/s at170℃, whereas it remained0.04cm~3/s at170℃after modification, which meaned the composite has good processabilitythan P34HB. DSC showed that glass fiber is a good nucleation agent for P34HB, when theaddition content reached49.70phr, the Tpimproved by13.70℃. DerivativeThermogravimetric analysis(DTG) illustrated that the composite has better thermal stability.P34HB was found to be easily corroded by basic solution while stable in acid solution,and it degraded faster in soil than that in lake water. P34HB composite degraded faster thanpure P34HB. With the degradation going on, the crystallization capability of the samplesimproved, while with sarcrifice of thermal stability.