Engineering Polymers

Carbon nanotubes have long been recognized as the stiffest and strongest man-made material known to date. In addition, their high electrical conductivity has roused interest in the area of electrical appliances and communication related applications. However, due to their miniscule size, the excellent properties of these nanostructures can only be exploited if they are homogeneously embedded into light-weight matrices as

Natural abundance, much higher strength per unit weight than most inorganic fillers, lower density and their biodegradable nature make natural fillers attractive as reinforcements of engineering polymer systems. However, certain drawbacks such as incompatibility with the hydrophobic polymer matrix, the tendency to form aggregates during processing and poor resistance to moisture greatly reduce the potential of natural fibres to be used as reinforcements in polymers. In this review, the main results presented in literature are summarized, focusing on the processing behaviour and final properties of natural fibres with polymeric matrices (thermoplastics, thermosets and biodegradables) and paying attention to the use of physical and chemical treatments for the improvement of fibre-matrix interaction and composite mechanicaln properties. This work mainly focuses on the use of natural fibres for automotive applications.

Purpose: The aim of this study was to investigate the possibility of improving the tribological properties and thermal conductivity of composites with structural modification of polyamides by the additions of copper and graphite.
Design/methodology/approach: The study involved testing polyamide composites containing metallic powder. As the matrix was used polyamide 6 Tarnamid 27 Natural produced by Azoty Tarnów, which strengthened copper, graphite or molybdenum disulfide with varying participation in the composite. Taken tensile test, Brinell hardness, thermal conductivity and the tribological wear resistance. Analyzed the influence of the type of dopant and the participation of the studied property.
Findings: The study showed the desirability of the use of graphite and copper as fillers polyamide. The resulting composites are characterized by satisfactory mechanical properties and thermal conductivity. Applied fillers also showed a positive effect on the value of the coefficient of friction wear him down much.
Research limitations/implications: No synergistic effect of fillers on the properties of a ternary mixture polyamide-graphite-copper property in all test. Tribological wear for this material was significantly higher than for the binary mixtures of polyamide-graphite and polyamide-copper. According to the literature, composite reinforced with graphite and copper should have a best tribological properties, far in excess of other subjects. Low wear resistance of this material disqualify applications on the nodes friction.
Practical implications: The results obtained newly developed composites, combined with the relatively low price of graphite and copper as compared with the price of molybdenum sulfide II may be reasons to use them as analogues of commercial mixtures of PA with MoS2.
Originality/value: The results are original and valuable cognitive nature. They bring a new and expanded information about the effects of fillers on mechanical and physical properties. Unique data on tribological wear resistance depends on the type and amount of filler.

Tribological properties of polymer materials are traditionally tested on small-scale test rigs because of cost-efficiency and flexibility. For highly loaded applications (eg, sea lock doors, retaining walls, positioning systems) however, large-scale tests should be performed for estimating ...

Polyimides are used in friction and wear applications because of their high strength and thermal stability up to 310 (short term) or 450 °C (long term). After sintering, secondary transition temperatures do not occur up to the degradation point. The tribological characteristics of sintered ...

Purpose: The aim of this study was to investigate the possibility of improving the tribological properties and thermal conductivity of composites with structural modification of polyamides by the additions of copper and graphite. Design/methodology/approach: The study involved testing polyamide composites containing metallic powder. As the matrix was used polyamide 6 Tarnamid 27 Natural produced by Azoty Tarnow, which strengthened copper, graphite or molybdenum disulfide with varying participation in the composite. Taken tensile test, Brinell hardness, thermal conductivity and the tribological wear resistance. Analyzed the influence of the type of dopant and the participation of the studied property. Findings: The study showed the desirability of the use of graphite and copper as fillers polyamide. The resulting composites are characterized by satisfactory mechanical properties and thermal conductivity. Applied fillers also showed a positive effect on the value of the coefficient of...

Purpose The prognosis for glioma patients is poor, and development of new treatments is critical. Previously, we engineered polymer-based vaccines that control GM-CSF, CpG-oligonucleotide, and tumor-lysate presentation to regulate immune cell trafficking and activation, which promoted potent immune responses against peripheral tumors. Here, we extend the use of this system to glioma. Methods Rats were challenged with an intracranial injection of glioma cells followed (1 week) by administration of the polymeric vaccine (containing GM-CSF, CpG, and tumor-lysate) in the tumor bed. Control rats were treated with blank matrices, matrices with GM-CSF and CpG, or intra-tumoral bolus injections of GM-CSF, CpG, and tumor lysate. Rats were monitored for survival and tested for neurological function. Results Survival studies confirmed a benefit of the polymeric vaccine as 90% of vaccinated rats survived for >100 days. Control rats exhibited minimal benefit. Motor tests revealed that vaccination protected against the loss of forelimb use produced by glioma growth. Histological analysis quantitatively confirmed a robust and rapid reduction in tumor size. Long-term immunity was confirmed when 67% of survivors also survived a second glioma challenge. Conclusions These studies extend previous reports regarding this approach to tumor therapy and justify further development for glioma treatment.