Study On Modification Of PHBV And Preliminary Exploration In Preparation Of PHBV/PBAT Melt-Blown Nonwoven

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)copolyester is a thermoplastic bio-polymer synthesized by microbial fermentation, presenting the advantages of good biodegradability, histocompatibility and antithrombogenicity. It has a wide range of applications in industry, agriculture, packaging, biomedicine and other fields. It is a rich source in nature and no need of complex polymerization equipment. Besides, it is an alternative to general resins. For all these reasons, it has attracted many domestic and foreign researchers a great deal of attention in recent years.Due to the characters of PHBV, PHBV fiber shows many drawbacks in the processing of melt spinning, for example, the fiber intensity is much low, which was leaded by bad thermal stability of PHBV in the melt spinning process, and PHBV fiber is brittle. These have limited the application of PHBV in spinning field. Ecoflex, which is PBAT, is a new biodegradable polymer produced by BASF Corporation, which is often used to be blended with other biodegradable polymers to improve their process abilities. Therefore, this paper used the methods for blending PHBV and PBAT by Haake Torpue Rheometer to improve the defects of PHBV. Exploratory of PHBV/PBAT (50/50) blend in the melt-blown nonwoven application was also studied. PBAT can change the crystallization behavior and crystal morphology of PHBV. PHBV/PBAT(50/50) blend compared to pure PHBV have a wider processing window to broaden its melt spinnability.1. In this research, the basic properties of PHBV were characterized by ~1HNMR, GPC and ash testing. There were two different purification methods for PHBV before GPC experiment. One is chloroform as solvent, using Soxhlet extractor for purification; the other is chloroform as solvent, n-hexane as precipitant. The results indicated that different purified PHBV have different molecular weight.2. The crystallization behavior and crystal morphology of PHBV/PBAT blends were investigated by means of DSC, FTIR, WXRD and POM. The results demonstrate that the spherulite size and crystallization rate of PHBV in PHBV/PBAT blends are smaller. When PBAT content are less than 30%, PHBV/PBAT blends changes from one crystallization peak to two crystallization peaks. When PBAT content are more than 30%, PHBV/PBAT blends reverses to one crystallization peak. PHBV/PBAT blends have many smaller spherulites for PBAT as nucleating agents. Crystallinity of PHBV/PBAT blends decreases with the increase of PBAT.3. Rheological properties of PHBV, PBAT and PHBV/PBAT(50/50) were measured by rotary rheometer. The results indicated that the viscous flow activation energy of PHBV/PBAT(50/50) blends is less than that of PHBV and PBAT. PHBV/PBAT(50/50) has excellent thermal stability.4. Exploratory of PHBV/PBAT (50/50) blend in the melt-blown nonwoven application was studied. The properties of PHBV/PBAT(50/50) melt-blown non-woven are investigated by strength meter, aperture device, the contact angle instrument and antibacterial testing. The results showed that the mechanical strength of PHBV/PBAT(50/50) melt-blown nonwoven is not good. PHBV/PBAT(50/50) melt-blown nonwoven is water and oil repellent material. The bacteriostasis rate of PHBV/PBAT(50/50) melt-blown non-woven reached 49.55% for Staphylococcus aureus but it meet the GB bacteria standard.