Daniel Belchior Rocha

Bio: Daniel Belchior Rocha is an academic researcher from Universidade Federal do ABC. The author has contributed to research in topics: Cellulose & Coating. The author has an hindex of 6, co-authored 14 publications receiving 154 citations.

Valorization of industrial paper waste by isolating cellulose nanostructures with different pretreatment methods

Abstract: Industrial paper wastes are an underestimated source of lignocellulosic materials. In this work cellulose nanostructures (CNS) were produced from this residue by acid hydrolysis and two chemical pretreatments consisting of an alkaline (CNS-I) or an acid (CNS-II) treatment. These pretreatments and the obtained CNSs were characterized using compositional analysis, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), dynamic light scattering (DLS), zeta potential, atomic force microscopy (AFM), and X-ray diffraction (XRD). Results reveal a reduction in the non-cellulosic compounds in pre-treated samples, with different levels of components removal and lower lignin values for alkali treatment. TGA reveals that CNSs present lower thermal stability than the residue. The SEM images revealed that pretreatment led to fiber breakage. The XDR diffractions show the co-existence of cellulose I and cellulose II, with different crystallinity index for CNSs. The DLS and AFM revealed that the production of spherical nanoparticles was following the dimensions of ˜195 for CNS-I and ˜350 nm for CNS-II. All the analysis allowed a more comprehensive understanding of the CNS properties and their possible applications. Finally, it is possible to conclude that the conversion of paper wastes into CNS is an excellent opportunity to recovery this residue and aggregate value to them.

Coupling effect of starch coated fibers for recycled polymer/wood composites

Abstract: In this work is proposed the use of starch gum (SG) as a coupling agent for polymer matrix composites (virgin and recycled) reinforce with wood flour. The coupling agent is prepared using an aqueous starch solution containing 3 and 5 %wt. forming a coating over the reinforcement, and compared with maleic anhydride grafted (MAPP), a usual coupling agent. The starch gum coating characterization indicates that 5%wt. presents more cohesive coating on the reinforcement. The mechanical properties of the composites also indicate that 5 %wt. produces higher properties than 3 %wt. The starch coupling agent presents a lower performance compared to MAPP for the virgin polymer; however, for the recycled polymer, it increases the elastic modulus in 37%, overcoming MAPP. Computational tomography indicates that the starch gum promotes compatible interaction at the interface with a low formation of empty spaces in the recycled polymer, indicating that it can be an exciting alternative to produce low-cost composites with eco-friendly solutions.

The return of a forgotten polymer : Polycaprolactone in the 21st century

Abstract: During the resorbable-polymer-boom of the 1970s and 1980s, polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices. Its popularity was soon superseded by faster resorbable polymers which had fewer perceived disadvantages associated with long term degradation (up to 3-4 years) and intracellular resorption pathways; consequently, PCL was almost forgotten for most of two decades. Recently, a resurgence of interest has propelled PCL back into the biomaterials-arena. The superior rheological and viscoelastic properties over many of its aliphatic polyester counterparts renders PCL easy to manufacture and manipulate into a large range of implants and devices. Coupled with relatively inexpensive production routes and FDA approval, this provides a promising platform for the production of longer-term degradable implants which may be manipulated physically, chemically and biologically to possess tailorable degradation kinetics to suit a specific anatomical site. This review will discuss the application of PCL as a biomaterial over the last two decades focusing on the advantages which have propagated its return into the spotlight with a particular focus on medical devices, drug delivery and tissue engineering.

Biomedical applications of biodegradable polymers

Abstract: Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. To fit functional demand, materials with desired physical, chemical, biological, biomechanical, and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications.

Poly(lactic Acid): A Versatile Biobased Polymer for the Future with Multifunctional Properties-From Monomer Synthesis, Polymerization Techniques and Molecular Weight Increase to PLA Applications.

Abstract: Environmental problems, such as global warming and plastic pollution have forced researchers to investigate alternatives for conventional plastics. Poly(lactic acid) (PLA), one of the well-known eco-friendly biodegradables and biobased polyesters, has been studied extensively and is considered to be a promising substitute to petroleum-based polymers. This review gives an inclusive overview of the current research of lactic acid and lactide dimer techniques along with the production of PLA from its monomers. Melt polycondensation as well as ring opening polymerization techniques are discussed, and the effect of various catalysts and polymerization conditions is thoroughly presented. Reaction mechanisms are also reviewed. However, due to the competitive decomposition reactions, in the most cases low or medium molecular weight (MW) of PLA, not exceeding 20,000-50,000 g/mol, are prepared. For this reason, additional procedures such as solid state polycondensation (SSP) and chain extension (CE) reaching MW ranging from 80,000 up to 250,000 g/mol are extensively investigated here. Lastly, numerous practical applications of PLA in various fields of industry, technical challenges and limitations of PLA use as well as its future perspectives are also reported in this review.

Cellulose nanomaterials: new generation materials for solving global issues

Abstract: This review describes the recent advances in the production and application of cellulose nanomaterials. Cellulose nanomaterials (CNMs), especially cellulose nanocrystals and cellulose nanofibers, can be produced using different preparation processes resulting in materials with unique structures and physicochemical properties that are exploited in different fields such as, biomedical, sensors, in wastewater treatment, paper and board/packaging industry. These materials possess attractive properties such as large surface area, high tensile strength and stiffness, surface tailor-ability via hydroxyl groups and are renewable. This has been a driving force to produce these materials in industrial scale with several companies producing CNMs at tons-per-day scale. The recent developments in their production rate and their applications in various fields such as medical sector, environmental protection, energy harvesting/storage are comprehensively discussed in this review. We emphasize on the current trends and future remarks based on the production and applications of cellulose nanomaterials.