Biodegradable polymer composites

Over the last two hundred years, the world has become dependent on synthetic plastics, from industrial applications to consumer use [1] plastics are among the prime products in many different applications, where huge masses are used. The most important feature of plastics can be the flexibility, abundance and durability of the raw materials; however, this feature comes with a side effect.

A series of biocomposites were developed by reinforcing
agar particles from red marine plant Gelidium robustum into poly(butylene adipate-co-terephatalate) (PBAT) using extrusion and injection molding technique.
The effect of different content of agar (0, 10, 20,
30, and 40 wt%) on the physico-mechanical properties
of the biocomposite was evaluated. The dynamic mechanical
behavior of the composites was studied to determine the storage and loss modulus. The incorporation of agar particles into PBAT enhanced the tensile strength and modulus with a reduced percentage of elongation at break. A reduction in the mechanical loss factor (tan d) was noticed with the addition of agar particles into PBAT. A reverse trend was noticed for storage and loss modulus. The thermogravimetric analysis
revealed that the degradation temperature of PBATagar
composites lies in between that of their individual components (agar and PBAT). An increase in melting (Tm) and crystallization (Tc) temperature of the biocomposites
were noticed as agar particle content increased. The rheological study carried out by dynamic frequency experiments demonstrated that viscosity is increased with the presence of agar particles. The morphology of the biocomposites was analyzed using scanning electron microscope.

Over the last two hundred years, the world has become dependent on synthetic plastics, from industrial applications to consumer use [1] plastics are among the prime products in many different applications, where huge masses are used. The most important feature of plastics can be the flexibility, abundance and durability of the raw materials; however, this feature comes with a side effect.

In this study, PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fiber mats were prepared via electrospinning.
Synthesized nanofibers were characterized by DSC, FT-IR and SEM. DSC results showed that the nanofibers were degraded at 400
C and 450
C. The addition of PVP-K30, PVP-I and chitosan to PVA/PAA structure increased the thermal stability
of the nanofibers. SEM micrographs showed that synthesized nanofibers are linear. Fiber diameter measurements showed that average diameters of the fibers are less than 0.5 micron. The average diameters of PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fibers were calculated as 458 nm, 237 nm, 139 nm, and 270 nm, respectively.

A plasticizer is an additive widely used to modify polymer materials in industry, because it can lower the glass transition temperature (Tg), reduce the melt viscosity, increase the workability, make the material softer and more flexible, and increase the toughness.1
Among these polymers, poly(vinyl chloride) (PVC) consumes the largest amount of plasticizers, and has wide application sectors such as food packaging, medical materials, children toys, and tubing systems.2,3
Esters of phthalic acid are the most commonly used plasticizers worldwide for their desirable properties of a plasticizer, such as minimal interaction with resins at room temperature, produce highly elastic compounds with reasonable cold strength, satisfactory insulation for cables, and low cost. With more than 30 different phthalates on the market, di(2-ethylhexyl) phthalate (DEHP) is by far the most widely used one.
In the last decade, adverse health effects of phthalates have been thoroughly investigated and discussed. These commercial plasticizers, like DEHP, can leach out from PVC into blood, certain drug solutions and fatty foods. Mankidy has discovered that DEHP at concentrations of 10 mg/L would affect the synthesis of sex steroid hormones.4
DEHP is moderately toxic to cells in vitro and in embryos of animals, and produces a spectrum of toxic effects in both developing and adult animals and in multiple organ systems, and US Food and Drug Administration (FDA) and some European Countries have forbidden its use from food packaging, medical materials, and children toys.5,6
The potential toxicity to human health has caused increasing attention of manufacturers and consumers,7 and many researches have been driven to find non-toxic and biodegradable plasticizers to replace traditional plasticizers in recent years.
In 2002, BASF made a market introduction of di(isononyl)- 1,2-cyclohexane dicarboxylate (DINCH) as an alternative plasticizer, and it has been applied to sensitive products such as medical devices, toys and food packaging.8,9
This plasticizer is obtained by the hydrogenation of the benzene ring that is present in o-phthalates, and it is biodegradable and shows no acute toxicity, no skin sensitization, no genotoxicity, and no toxicity to reproduction.
On the other hand, compared to phthalates, esters of cyclohexane-1,2-dicarboxylic acid exhibit a lower density and viscosity and lead to an improvement of the flexibility at low temperatures of plastisols, and the other mechanical properties, like tensile strength, elongation at break, and hardness, have no significant differences between the two kinds of plasticizers, so they are perfectly exchangeable.10–12
BASF’s DINCH is obtained by hydrogenating the diisononyl phthalate under high temperature and high pressure, and it is a little expensive.

The preparation of the esters of dicarboxylic and polycarboxylic acids with plasticizer alcohols, i.e. unbranched or branched primary alcohols having from about 6 to 12 carbon atoms, occuring in a liquid phase can been carried out by the classical process by reacting the acids or acid anhydrides with an alcohol or a mixture of different alcohols in the presence of an acid, preferably sul furic acid, as catalyst. The alcohol component is usually used in excess. 0007. A further development in the preparation of esters Suitable as plasticizers constitutes the use metal-containing esterfication catalysts. Suitable catalysts are, for example, tin, titanium and Zirconium which are used as finely divided metal or advantageously in the form of their salts, oxides or soluble organic compounds. These catalysts are high-temperature catalysts which reach their full activity only at esterification temperature above 180° C. Examples are tin powder, tin(II) oxide, titanate esters such as tetraisopropyl orthotitanate or tetrabutyl orthotitanate and also Zirconium esters such as tetrabutyl Zirconate. Alkyl titanates and titanium chelates, i.e. titanates of polyalcohol, have achieved particular importance in industrial production process.

This manuscript reviews various aspects of fi ber/resin interface in fi ber reinforced composites, with special emphasis on green composites that use plant based fi bers and sustainable resins. In this chapter we describe the importance of fi ber/resin interface, factors affecting it, various modifi cations of fi ber and resin that can be employed to improve the interfacial property and the experimental techniques to characterize the interface. The nature of the bonding between the fi ber and resin and the mechanism of fi ber/resin interaction are also discussed. Improving the fi ber/resin interface is critical in the case of green composites since the hydrophilic plant fi bers and some of the hydrophobic resins have very poor bonding. Strong adhesion at the fi ber/resin interface is desirable for effective transfer of stress from broken fi bers to intact fi bers and, thus, to obtain good mechanical properties of the composites. However, weak bonding can provide energy absorbing modes through interface failure, making the composites tough. Thus, from the same set of fi bers and resin it is possible to obtain composites with different properties simply through the control of fi ber/resin interface.

This research work is concerned with the development of unsaturated polyester composites reinforced with betelnut fibers. Moreover, the fibers were chemically modified by sodium hydroxide and its effects on the fiber/matrix interaction were also evaluated. Raw and chemically modified fibers have been used in different proportions for the preparation of these composites. The optimization of fiber proportions has been done in term of their tensile strength. The sodium hydroxide treatment effect of fibers was verified by FTIR analysis and the fibers morphological aspects of fibers by SEM. Likewise, the sound absorption coefficient of composites were studied using impedance tube method. The thermal analyses of composites were made using Thermogravimetric analysis. Compared with untreated fiber composites, there was an improvement in the tensile strength of the treated fiber composites. SEM micrographs of betelnut fiber surface revealed the rough and perforated surface of fibers. Whereas, the cross sectional of the betelnut fibers showed the bigger lumen structures. The sound absorption coefficients of composites increased as the frequency increased and thicker composites appeared to perform better than those of thinner ones. The thermal stability of the treated fiber composites was found to be higher than that of untreated fiber composites.

The natural fiber-reinforced polymer composite is swiftly growing both in phrases of their industrial applications and fundamental research. They are renewable, cheap, absolutely or in part recyclable and biodegradable. The incorporation of herbal fibers consisting of sisal with glass fiber hybrid composites has additionally received growing industrial packages. Herbal and synthetic fibers are mixed in the same matrix (unsaturated polyester) to make sisal/glass fiber hybrid composites and the mechanical residences of those hybrid composites had been studied. A giant development in mechanical homes of sisal/glass fiber hybrid composites has been observed. the chalk powder (additive) is likewise introduced to the resin (unsaturated polyester) in proportions of 1%, 2%, 3% by way of weight of resin respectively and sisal/glass fiber hybrid composites were organized through the usage of this resin to take a look at the effect of chalk powder on mechanical homes of those hybrid composites. It is also found that because the chalk powder quantity increases tensile and flexural residences are decreases.