A polyethylene (PE)/starch copolymer was prepared by a grafting technique in the presence of benzoyl peroxide as a catalyst and xylene as a solvent. The ratio of PE grafted onto starch was in ratio 1:5, respectively. The obtained grafted copolymer was characterized by Fourier transform infrared (FTIR) spectroscopy. The obtained grafted copolymer was mixed with rice and wheat straw as well as calcium carbonate (CaCO3) as a filler to form biodegradable films. Various analyses such as viscosity, tensile strength, elongation at break, water contact angle, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and solubility tests have been used to study the properties of biodegradable films in water and soil. CaCO3 and rice and wheat straws improved the biodegradability of the grafted copolymer. The presence of CaCO3 in the presence of rice and wheat straws increased the viscosity, tensile strength, thermal stability, and weight loss of the film in the soil. While elongation at break, the water contact angle and solubility in water decreased. According to the study, samples that were between 380°C and 400°C showed the highest polymer breakdown values and adding CaCO3 resulted in the lowest water contact angle.
We present efficiency and lifetime results for solar cells composed of blends of poly(3‐hexylthiophene‐2,5‐diyl) and N,N′‐bis(3‐pentyl)perylene‐3,4,9,10‐bis(dicarboximide) or P3HT:PDI. This combination represents a baseline system for future studies of PDIs as electron acceptors. Poor performance in the fabricated devices was correlated with unusual sample morphologies. Large aggregates in the form of rods and crossbones were observed using both optical and electron microscopy. Energy dispersive X‐ray elemental analysis was used to identify the composition of the structures. These results illustrate the critical connection between polymer organization and solar cell efficiency, providing insights into the structure‐function interaction between PDI and P3HT.
In this chapter, the fundamental science of polymer crystallization has been discussed. The chemical composition and thermal histories, such as cooling conditions during the fabrication process and post-thermal treatment, the size of the structural units, or the molecular orientation, in addition to the degree of crystallinity of the starting melt, paths of nucleation, organization of lamellar crystals, and evolution of the final crystalline structures, affect the mechanical, thermal, and optical final performance of semi-crystalline polymer materials. An understanding of the complex processing of polymers from their amorphous states to their crystalline states for a variety of applications is provided by addressing the fundamentals of polymer crystallization via a combination of unique thoughts, concepts, and sophisticated methodologies.
Molecular simulation is an effective and powerful method to study the microscopic mechanisms of polymer crystallization. Firstly, based on molecular simulation, some new theories about polymer crystallization were proposed, such as the intramolecular crystal nucleation mode. Secondly, some specific polymer crystallization processes can be detected at the molecular scale. For instance, the molecular mechanism for the nanohybrid shish-kebab structure can be revealed. The influences of some factors on stereocomplex crystallization can also investigated. Besides, the simulation results can provide strong microscopic evidence for the multi-scale and multi-step process of polymer crystallization induced by flow field.
Polypropylene has developed into one of the most relevant thermoplastic polymers, both technically and commercially, since its development in the 1950s. Both the far more relevant isotactic variety and the syndiotactic polymer are crystalline with an interesting polymorphism, and they can be modified by copolymerization and blending to cover a wide range of mechanical and optical properties. The different crystal polymorphs can be controlled by chain structure and nucleation, allowing either higher stiffness or toughness and facilitated processing. In multiphase systems with amorphous and crystalline inclusions, especially polyethylene shows relevant epitactic interaction. Processing effects related to cooling rate and flow further determine crystalline morphology and performance. A wide variety of characterization methods are available today to study the related phenomena.
