The influence of the industrial processing on the degradation of poly(hidroxybutyrate) - PHB

Abstract

PHB was characterized after different industrial processes by Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Melt Flow Index (MFI), Complex Dielectric Relaxation (CDR) and Size Exclusion Chromatography (SEC). Some properties of PHB were investigated before and after processing, in order to understand how temperature and other extrusion or injection conditions affect the polymer degradation. All the processed samples showed an increasing in the melt flow index, a decreasing of the dynamic crystallization temperature, and a reduction in the molar mass, suggesting some degradation. The molar mass reduction after processing, predicted when only thermal degradation is considered, was calculated in function of the kinetic parameters, such as constant thermal degradation and residence time during the industrial processing. It was found that the real molar mass reduction was higher than the theoretical value, indicating an important contribution of the shearing of polymeric chains during processing in the PHB degradation.

Environmental Stress Cracking of Poly(3-hydroxibutyrate) Under Contact with Sodium Hydroxide

“…PHB is obtained from renewable resources (mainly sugar cane) by biotechnological processes of low environmental impact. Ongoing research, intended on establishing its properties, extending its applications, and optimizing its processing conditions is reported in the literature [1][2][3][4][5][6] . During their lifetime, polymer products may be subjected to aggressive environments, like high temperature, ultraviolet radiation and certain chemicals, with consequences like the deterioration of mechanical properties and/or poor surface appearance.…”

From Obtaining to Degradation of PHB:Material Properties. Part I

“…Another method of obtaining is through natural plants and/or transgenic plants [11]. And the third, and more widespread, strategy for the synthesis of this polymer is by means of bacterial fermentation [1], [2], [29], [37], pure or mixed, commonly known as biosynthesis. In this process the substrate is used as a carbon source [28].…”

“…This material is nontoxic [9], optically active [26] and when pure, has a yellowish coloration [6], [27], presents barrier to permeability of water and gas [6] and stability to ultraviolet radiation [28], and can be processed by extrusion, injection, blowing and thermoforming [29].…”

Synergy Between Industry and Graduate Programs in Brazil: A Success Story on the Theme of Environmental Management

“…21 A fibra natural tem um papel de reforço mecânico, além da redução em massa de material não degradável. Os trabalhos desenvolvidos pelos alunos de pós-graduação focam no aperfeiçoamento de composições de fibras naturais e polímeros commodities que auxiliam nas propriedades mecânicas destes materiais plásticos, como, por exemplo, a produção de compósitos de polipropileno com fibras naturais de sisal ou pó de madeira [22][23] e, compósitos de poliamida com fibra de vidro reciclada.…”