Increasing Processing Temperature Research Articles

Joncryl chain extender reactivity with polylactide: Effect of d-lactide content, Joncryl type, and processing temperature

In this study, a highly crystallizable and an amorphous polylactide (i.e., cPLA and aPLA) with, respectively, low (0.5 mol. %) and high (12 mol. %) d-lactic acid contents and similar molecular weights were melt compounded with two different multifunctional epoxy-based Joncryl chain extenders (CEs, i.e., ADR 4400 and 4468) at 190 °C. Reactivity of Joncryl grades with aPLA was also explored at melt processing temperatures of 150, 170, and 210 °C. Small amplitude oscillatory shear rheological analysis was conducted to understand the extent of the Joncryl reaction with PLA molecules, and the results were confirmed with molecular weight determination using gel permeation chromatography. Extensional viscosity of the processed samples was also compared to control their strain hardening behavior. Results showed that the Joncryl reaction with cPLA and aPLA differs in terms of preference for chain extension or branching, indicating that molecular regularity affected the interactions with both Joncryl grades during reactive melt processing. Moreover, although the increase in processing temperature accelerated PLA degradation, it noticeably increased the reactivity of both Joncryl grades with aPLA. In all cases, ADR 4468 was more reactive in molecular chain extension/branching due to its higher functionality than ADR 4400. Differential scanning calorimetry results also revealed that the crystallization of cPLA was differently affected by the change in the Joncryl content and type.

Methodology to establish a forming process window for thermoset aligned discontinuous fiber composites

Highly aligned discontinuous fiber composites have been pursued with the goal of achieving high performance properties with the formability of short fiber composites. The feedstock consists of a highly aligned discontinuous fiber preform which can be combined with thermoplastic or thermoset resins to create prepreg that can extend in the fiber direction. With this added benefit of lamina extensibility in the fiber direction, a methodology is needed to determine the degradation of material quality with applied forming strain. A framework is established to define a forming process window which sets the optimal process conditions—temperature and strain rate—for maintaining lamina uniformity after deformation. Digital image correlation was used to measure strain uniformity for samples stretched in uniaxial tension at constant temperature and strain rate. The experimental results show that forming strain rate should increase with increasing process temperature. The process window established in this work will be used to ensure that material uniformity can be optimized in manufacturing trials and other material characterization evaluations.

Formation and prediction of heterocyclic amines and N-nitrosamines in smoked sausages using back propagation artificial neural network.

Heterocyclic amines (HAs) and N-nitrosamines (NAs) are formed easily during the thermal processing of food, and epidemiological studies have demonstrated that consuming HAs and NAs increases the risk of cancer. However, there are few studies on the application of back propagation artificial neural network (BP-ANN) models to simultaneously predict the content of HAs and NAs in sausages. This study aimed to investigate the effects of cooking time and temperature, smoking time and temperature, and fat-to-lean ratio on the formation of HAs and NAs in smoked sausages, and to predict their total content based on the BP-ANN model. With an increase in processing time, processing temperature and fat ratio, the content of HAs and NAs in smoked sausages increased significantly, while the content of HA precursors and nitrite residues decreased significantly. The optimal network topology of the BP-ANN model was 5-11-2, the correlation coefficient values for training, validation, testing and all datasets were 0.99228, 0.99785, 0.99520 and 0.99369, respectively, and the mean squared error value of the best validation performance was 0.11326. The bias factor and the accuracy factor were within acceptable limits, and the predicted values approximated the true values, indicating that the model has good predictive performance. The contents of HAs and NAs in smoked sausages were significantly influenced by the cooking conditions, smoking conditions and fat ratio. The BP-ANN model has high application value in predicting the contents of HAs and NAs in sausages, which provides a theoretical basis for the suppression of carcinogen formation. © 2024 Society of Chemical Industry.

Bonding characteristics of aluminium laminates and aluminium–graphite composites processed by roll bonding

Roll bonding is a solid-state welding process, employed to join similar and dissimilar metals. Roll bonding with secondary particles in-between and accumulating the roll bonded material multiple times is an alternative method for manufacturing high-strength composites. In the current work, commercially pure aluminium strips are roll bonded at room temperature to 400 °C. The percent reduction varied from 10% to 70%, with an increment of 10%. Moreover, the aluminium strips are roll bonded with graphite particles dispersed in between (Al–Gr–Al). The aim is to study the effect of graphite particles on bonding behaviour. The critical process parameters such as the effect of temperature and percentage reduction on the bond strength are determined. The lap shear test is used to evaluate the bond strength. It is observed that the dispersion of graphite particles in between aluminium significantly increased the threshold reduction required for bond establishment. The threshold reduction decreases for roll-bonding aluminium with increasing temperature. Furthermore, it is observed that the bond strength significantly increases with increasing processing temperature. However, roll bonding with the graphite particles dispersed in between reduced the bond strength, and the effect was significant with increasing temperature. The bond strength of both Al and the Al–Gr–Al composites increases by increasing the reduction percentage. The de-bonded sample surfaces are analyzed using a scanning electron microscope. It is worth mentioning that the experimental outcomes of the current study predict the roll bonding parameters for the successful fabrication of an Al/Gr composite by accumulative roll bonding.

Photocatalytic destruction of organic dyes by titanium dioxide particles doped with gold

Nanocomposites based on titanium dioxide doped with gold in concentrations of 0.2 and 0.8 wt.% were obtained by the sol-gel method using titanium tetraisopropoxide and chlorauric acid. Thermal treatment of precipitates at T = 600 °C led to the formation of highly dispersed anatase powders and increasing the temperature to 1000-1200 °C contributed to the formation of well-crystallized rutile particles. The gold in the structure of the powders is heterogeneously distributed. The size of the primary particles of anatase did not exceed 10 nm, and that of rutile reached 35-46 nm, gradually increasing with increasing processing temperature. The photocatalytic properties of TiO2&Au structures were studied during the decolorization of solutions of organic dyes (Methylene Blue, Rhodamine B, Methyl Orange, Orange G) with a concentration of 20 mg/dm3. The resulting structures did not show significant sorption activity, and visible light caused a slight desorption of the dyes. At the same time, under the influence of UV irradiation for 60 minutes, the decolorization process took place effectively and was subject to a pseudo-first-order reaction. The biggest photocatalytic activity was shown by the sample of anatase with a gold content of 0.8 wt.%. When it was added into the solution, the degree of decolorization of Rhodamine B reached up to 50%, Methyl Orange - up to 81.5%, Methylene Blue - up to 91%, and Orange G - up to 95.2%. Increasing the efficiency of the destruction of dyes can be achieved by supplementing the photo-catalytic process with a catalytic one.
 
 Аcknowledgements : Olena Lavrynenko is supported by the PAUSE program, a national emergency program for scientists and artists in exile, run by the Collège de France

A temperature-based synthesis and characterization study of aluminum-incorporated diamond-like carbon thin films

The present work deals with the study of various properties of aluminum (Al)-incorporated diamond-like carbon (DLC) thin films synthesized using the atmospheric pressure chemical vapor deposition (APCVD) technique by varying the deposition temperature (Td) and keeping the N2 flow rate constant. Surface morphology analysis, resistance to corrosion, nanohardness (H), and Young’s modulus (E) of the coatings were carried out using atomic force microscopy (AFM), corrosion test, scanning electron microscopy (SEM), and nanoindentation test, respectively. SEM results showed a smoother surface morphology of the coatings grown at different process temperatures. With an increase in process temperature, the coating roughness (Ra) lies in the range of 20–36 µm. The corrosion resistance of the coating was found to be reduced with a consecutive increase in the deposition temperature from 800℃ to 880℃. However, above 880℃, the resistance increases further, and it may be due to the presence of more Al weight percentage in the coating. The nanoindentation result revealed that H and E of the coating increase with an increase in the CVD process temperature. The elastic–plastic property indicated by H/E and H3/E2, which are also indicators of the wear properties of the coating, were studied using the nanoindentation technique. The residual stresses (σ) calculated using Stoney’s equation revealed a reduction in residual stress with an increase in the process temperature.

Effect of osmodehydration on the quality attributes of plum (Prunus domestica)

Plum (Prunus domestica) is a seasonal nutraceutical fruit rich in many functional food nutrients such as vitamin C, antioxidants, total phenolic content, and minerals. Recently, researchers have focused on improvised technologies for the retention of bioactive compounds during the processing of perishable fruits; plum is one of these fruits. This study looked at how the percentage of moisture content and percentage of acidity were affected by conventional drying and osmotic dehydration. Total phenolic content (mg GA/100 g of plum), total anthocyanin content (mg/100 g), and vitamin C (mg/100 g) Conventional drying of fruit was carried out at 80.0 ℃ for 5 h. At various temperatures (45.0 ℃, 50.0 ℃, and 55.0 ℃) and hypertonic solution concentrations (65.0 B, 70.0 B, and 75.0 B), the whole fruit was osmotically dehydrated. It was observed that the osmotically treated fruit retains more nutrients than conventionally dried fruit. The total phenolic content of fruit significantly increased with the increase in process temperature. However, vitamin C and total anthocyanin content of the fruit decreased significantly with process temperature, and hypertonic solution concentration was observed. Hence, it was concluded that osmodehydration could be employed for nutrient retention in plum fruit over conventional drying. This process needs to be further refined, improvised, and optimised for plum processing.

Enhancement effect of carvacrol on yeast inactivation by mild pressure carbon dioxide.

Saccharomyces cerevisiae is one of the common spoilage microorganisms in fruit juices. This paper investigated the influences of carvacrol on S. cerevisiae inactivation by mild pressure carbon dioxide (MPCO2). The results demonstrated that carvacrol synergistically enhanced the antifungal activity against S. cerevisiae of MPCO2. With the increase of carvacrol concentration (20-160µg/mL), CO2 pressure (1.5-3.5MPa), process temperature (20-40°C), and treatment time (15-60min), the inactivation effect of carvacrol combined with MPCO2 on S. cerevisiae was gradually increased and significantly stronger than either single treatment. In the presence of carvacrol, MPCO2 severely disordered the plasma membrane of S. cerevisiae, including the increase of membrane permeability, and the loss of membrane potential and integrity. MPCO2 and carvacrol in combination also aggravated the mitochondrial depolarization of S. cerevisiae and reduced intracellular ATP and protein content. This study suggests the potential of carvacrol and pressurized CO2 as an alternative technology for food pasteurization.

Hot compressive deformation behavior of Ti-8Al-1Mo-1 V titanium alloy at elevated temperatures: Focus on flow behavior, constitutive modeling, and processing maps

The deformation behavior of the near-α Ti-8Al-1Mo-1 V titanium (Ti-811) alloy was studied by isothermal compression tests in the temperature range of 950–1075 °C and strain rates of 0.001–1 s−1. According to the physical properties of titanium alloys, the effects of adiabatic heat and friction during hot deformation process were modified on the stress-strain curves, especially at low temperatures and high strain rates. The results showed that the flow stress increases with increasing the strain rate and decreases with an increase in process temperature. Hyperbolic sine (sinh) and Cingara equations were used to model the flow behavior of Ti-811 alloy at elevated temperatures. Results showed a suitable fitting among the calculation and experimental results by the sinh equation at low strain rates (0.001 and 0.01 s−1) and by the Cingara equation at high strain rates (0.1 and 1 s−1). The activation energy values (Q) of Ti-811 alloy in two-phase and single-phase regions were calculated as 738 and 194 kJ/mol.K, respectively. The processing maps showed that in the single-phase region, the instability domain was located at 1025 °C and 1050 °C and high strain rates (0.1 and 1 s−1) and low strain rates (0.001 and 0.01 s−1) were considered as stability domain. For the α + β region, an instability domain was only observed at 1000 °C and 0.01 s−1. Microstructural observations showed occurring dynamic recrystallization, dynamic phase transformation, and globularization of alpha phase in stability domain.

Adsorption of Methyl Red and Methylene Blue on Carbon Bioadsorbents Obtained from Biogas Plant Waste Materials.

In this study, biocarbon was obtained from the waste material corn digest. Carbon adsorbents were obtained by physical activation of the precursor with CO2. Detailed physicochemical characterization of the biocarbon was carried out using low-temperature nitrogen adsorption/desorption, Boehm titration, zero-charge point (pHpzc) and iodine number. In addition, the sorption capacity of the biocarbon agents towards an aqueous solution of methylene blue and methyl red was determined, and the kinetics of the adsorption process were determined. The biocarbon adsorbents were characterized by an average developed specific surface area covering the range from 320 to 616 m2/g. The sorption capacity of the biocarbon adsorbents against methylene blue ranged from 40 mg/g to 146 mg/g, and for methyl red it covered the range from 31 mg/g to 113 mg/g. It was shown that the efficiency of organic dye removal by the obtained biocarbons depends on the initial concentration of the adsorbate solution, its mass, shaking rate, adsorbent-adsorbate contact time and temperature. The results obtained from the Langmuir and Freundlich kinetic models showed that the Langmuir model is the most suitable model for describing the adsorption of the studied pollutants on biocarbon. In turn, the adsorption kinetics of dyes is described according to the pseudo-second-order model. Adsorption studies also showed that as the process temperature increases, the removal efficiency of methylene blue and methyl red increases.

Meta‐analysis of thermal contact resistance in injection molding: A comprehensive literature review and multivariate modeling

AbstractThis article provides the first multivariate analysis of reported thermal contact resistance (TCR) values from different characterization approaches (injection and compression molding) having missing data. The missing data are estimated by principal components analysis (PCA) with alternating least squares (ALS), and then the main effects are modeled using multiple regressions. Three models of increasing complexity are presented, each of which provides reasonable model fidelity relative to the TCR values reported in the literature. The primary cause of differences between reported TCR values as characterized by injection molding and compression molding can be explained by the melting of the polymer to make intimate contact with the metal mold during processing. Typical values of TCR are on the order of 0.0002 m2K/W, corresponding to heat transfer coefficients of 5000 W/(m2K). The analyses suggest that the TCR decreases significantly with increasing processing temperature and pressure but increases most significantly during cooling with the development of an air gap between the polymer and mold. Accordingly, it is strongly recommended that injection molding simulations incorporate modeling of the TCR as a function of the processing states for accurate prediction of the air gap, residual stresses, shrinkage, and warpage.Highlights Multivariate analysis of thermal contact resistance data from the literature. Sparse data handled by principal component analysis and alternating least square. Comparison of injection molding and compression molding measurements. Results suggest thermal contact resistance should be modeled as a function of the processing states.

Effects of Preparation Temperature and Liquid-Solid Lipid Composition to Curcumin-Nanostructured Lipid Carrier Characteristics Fabricated by Microfluidic Technique

Nanostructured Lipid Carriers (NLC) are lipid-based carrier that uses a combination of liquid and solid lipids which is believed to deliver a higher amount of active substance to the human body. This study aimed to obtain the best formulation and evaluate the stability of curcuminloaded NLC (C-NLC) using microfluidic technique at temperature of 40o C and 60o C with the ratios of liquid:solid lipids were 2 : 1 ; 3.5 : 1 ; 4 : 1 ; 6 : 1% w/w. Our results showed that the increase of process temperature and liquid lipid concentration reduced particle size. There was a non-linear relationship between lipid ratio and temperature to encapsulation percentage. At ratio of soybean oil:stearic acid 6 : 1 and, at 40°C, particles size (PS) obtained was 143.87 ± 3.36 nm, polydispersity index (PDI) obtained was 0.44 ± 0.01, zeta potential (ZP) obtained was -33.3 ± 6.53 mV with encapsulation percentage of 20.62%. At the same ratio at 60°C, the PS obtained was 60.21 ± 2.55 nm, PDI obtained was 0.72 ± 0.03, ZP obtained was -26.10 ± 1.83 mV and encapsulation percentage of 31.45%. Stability test showed that C-NLC produced at 60°C was more stable since the change of particle size and pH were lower than C-NLC produced at 40°C.

Effect of pack characteristics and process parameters on the properties of aluminide-coated Inconel 625 alloy

Abstract In this study, Inconel 625 alloy was initially aluminide coated by halide-activated pack cementation at 700 °C for 4 h using fine (40–45 µm) globular and coarse (10–75 µm) ligament aluminum particles. Microstructural features and hardness variation of the coatings along with their oxidation behavior at 1000 °C during 50 h were investigated to reveal the effect of pack characteristics on the properties. Investigations revealed that (i) a homogeneous and continuous coating layer was formed on the surface without internal oxidation, (ii) a thicker coating (∼60 µm) was formed due to the pack consisting of coarse particles, (iii) a higher hardness value (1369 HV0.5) was measured for the coated alloy using fine particles in the pack, and (iv) the coating with coarse powder exhibited higher oxidation resistance during the first 50 h of oxidation test period. Secondly, superalloy was coated at different temperatures (700 and 1000 °C) and times (2 and 4 h) using coarse particles. In this stage, the findings showed that by increasing process temperature and time, the accumulation of aluminum on the superalloy surface increased and the oxidation tendency remained at a lower level in coatings containing thicker layers.

Effect of Temperature on Surface Hardness of Different Acrylic Materials utilized for space maintainer

Aim of the study: surface hardness is essential to avoid the indentation or scratch of space maintainer. Efforts have been made to improve the flexible and cold-cured acrylic's strength, by raising the processing temperature, unless the temperature has a chemical impact on the acrylic's qualities. The aim of this study was to study the effect of elevated temperature on the surface hardness of flexible and cold cured acrylic utilized as space maintainer appliance.
 Methods: Sixty specimens were divided into three groups: flexible acrylic ( Lingchen dental) , cold-cured acrylic (vertex) and (Paladur). Each group was subdivided into two subgroups,10 control and10 experimental . The control group for flexible acrylic was injected at 270 °C ,while for the two types of cold -cure, control groups, the specimens were processed at 37°C . The experimental group for flexible acrylic was injected at 290°C and for the two cold -cure types were processed at 70°C. Hardness was tested by Shore A device for flexible acrylic while for cold -cure specimens, shore D device was used. 
 
 Results : results showed no significant increase in the hardness of flexible acrylic the mean value of control group is 66.44±0.47 while for experimental group is 66.50±0.48. For vertex and Paladur cold- cured acrylic the surface hardness was increased significantly with increasing processing temperature. The mean values of vertex and Paladur control groups are around 86.14±0.39 and 88.33±0.39 respectively, while for experimental groups are 88.39±0.40 and 88.70±0.25
 Conclusion : elevated processing temperature increased the surface hardness of both types of cold acrylic however; the hardness of flexible acrylic was not affected by temperature elevation.

CO2 uptake by activated hydrochar derived from orange peel (Citrus reticulata): Influence of carbonization temperature

In this study, activated hydrochar was prepared from orange peel (OP) waste using KOH for the first time for potential environmental applications. The influence of hydrothermal carbonization temperature (180 °C, 200 °C, and 220 °C) on the CO2 adsorption capacity of OP-derived activated hydrochar (OP-180, OP-200, and OP-220) was investigated. Scanning electron microscope (SEM) images revealed that the activated OP hydrochar has high microporosity, a desired attribute for effective adsorption. The yield and the oxygen content of the hydrochar decreased with the increasing process temperature whereas the carbon content showed an increase. Fourier-transform infrared spectroscopy showed the presence of various functional groups including ketone, aldehydes, esters, and carboxyl in the hydrochar. CO2 adsorption isotherm was determined for all hydrochar samples. At 25 °C and 1 bar, OP-220 showed the highest CO2 uptake at 3.045 mmol/g. The use of OP waste for CO2 adsorption applications contributes to carbon neutrality and a circular economy.

Study on the Deposition Characteristics of Molybdenum Thin Films Deposited by the Thermal Atomic Layer Deposition Method Using MoO2Cl2 as a Precursor

In this study, we conducted research on manufacturing molybdenum (Mo) thin films by a thermal atomic layer deposition method using solid MoO2Cl2 as a precursor. Mo thin films are widely used as gate electrodes and electrodes in metal-oxide semiconductor field-effect transistors. Tungsten (W) has primarily been used as a conventional gate electrode, but it suffers from reduced resistivity due to the residual fluorine component generated from the deposition process. Thus, herein, we developed a Mo thin film with low resistivity that can substitute W. The MoO2Cl2 precursor used to deposit the Mo thin film exists in a solid state. For solid precursors, the vapor pressure does not remain constant compared to that of liquid precursors, thereby making it difficult to set process conditions. Furthermore, the use of solid precursors at temperatures 600 °C and above has many limitations. Herein, H2 was used as the reactive gas for the deposition of Mo thin films, and the deposition temperature was increased to 650 °C, which was the maximum processing temperature of the aluminum nitride heater. Additionally, deposition rate, resistivity change, and surface morphology characteristics were compared. While resistivity decreased to 12.9 μΩ∙cm with the increase of deposition temperature from 600 °C to 650 °C, surface roughness (Rq) was increased to 0.560 nm with step coverage of 97%. X-ray diffraction analysis confirmed the crystallization change in the Mo thin film with increasing process temperature, and a certain thickness of the seed layer was required for nucleation on the initial wafer of the Mo thin film. Thus, the molybdenum nitride thin film was deposited after the 4 nm deposition of Mo thin film. This study confirmed that crystallinity of Mo thin films must be increased to reduce their resistivity and that a seed layer for initial nucleation is required.

Effect of microwave and conventional heat treatment on trypsin inhibitor activity and in vitro digestibility of edamame milk protein

AbstractEdamame milk is a protein‐dense milk derived from green soybeans harvested before they mature. Being a legume of soy origin, it contains antinutritional factors for example, serine protease inhibitors, which hinder its in vitro digestibility. The objective of this study was to evaluate the effect of microwave processing techniques in improving the in vitro digestibility (IVPD %) of edamame milk protein by varying processing time and temperature. Conventional and microwave‐assisted processing was employed to investigate the effect on in vitro protein digestibility (IVPD %), using temperatures 70°Ϲ, 85°Ϲ, and 100°Ϲ for 5, 10, and 15 min, respectively. Fourier‐transform infrared (FTIR) data showed microwave and conventional treatments significantly modified the Amide I region of the edamame milk protein and the extent of modification varied with variation in the treatment temperature. In the FTIR analysis β‐sheet content was observed to change little with an increase in the temperature, suggesting similarity in the surface hydrophobicity of the protein leading to similar IVPD % values for all treatment temperatures. The experiment resulted in increased in vitro digestibility with increasing time and temperature during microwave processing conditions and conventional thermal conditions. It was also observed that the trypsin inhibitor activity decreased with an increase in processing time and temperature.

EFFECT OF PREPARATION TEMPERATURE ON ETHYLCELLULOSE MICROSPHERE PROPERTIES PREPARED BY OIL-IN-OIL EMULSION SOLVENT EVAPORATION PROCESS

The present study aims to formulate ethylcellulose microspheres using the oil-in-oil emulsion solvent evaporation method and judge the outcome of processing temperature on their features. The effects of the evaporation rate of the solvent on the particle properties and drug release characteristics of the microspheres were studied. Here, microspheres were prepared at different processing temperatues, viz., 10 0 C, 25 0 C, and 40 0 C, and their impact on the various characteristics of microspheres like surface topography, micrometrics, yield percent, encapsulation efficiency, in vitro dissolution, Fourier-transform infrared spectroscopy (FTIR) and release kinetics were elaborately studied. The FTIR study revealed that processing temperature did not affect drug-polymer compatibility. The study observed that the processing temperature had a great influence on the various characteristics of the prepared microsphere. It was observed from sieve analysis that the mean particle size of the microsphere increased with an increase in processing temperature, and the SEM study also corroborated the same result. SEM photographs showed processing at a higher temperature resulted in particles with a smooth surface, in contrast to a lower processing temperature that forms a bumpy surface. Furthermore, a higher temperature favoured formulation with a higher entrapment efficiency (94.42 ± 0.9 %) as compared to a lower temperature (85.2 ± 0.72 %). For a noteworthy timeframe, indinavir sulfate frames a solid solution in the ethylcellulose matrix and proceeds with the amorphous state. The results of an in vitro drug dissolution study showed that microspheres formulated at a higher temperature had a more sustaining effect as compared to those formulated at a lower temperature, which may have resulted due to their higher mean particle size. Using the Korsemeyer Peppas power law, it was found that the way drugs are released is controlled by diffusion.

Effects of temperature on the deformation of 6H–SiC during nanoscratching

With the aid of large-scale molecular dynamics simulations, this paper comprehensively investigated the effects of processing temperature on the deformation of single crystal 6H–SiC during nanoscratching. The effect was investigated across a wide range of temperature variations, from 1 K to 900 K. It was found that with increasing the processing temperature, the material removal mechanism of 6H–SiC experience a transition from intermittent cleavage to continuous plastic deformation. The deformation mechanism of 6H–SiC is achieved by the combination of surface amorphization and subsurface dislocations that reside mainly in the cubic diamond structural layer. The processing temperature significantly affects the dislocation distribution, groove morphology, scratching forces and coefficient of friction. The anisotropic effect on chip formation decreases with increasing the processing temperature. By evaluating surface roughness and the maximum subsurface damage depth, the investigation concludes that the scratched surface/subsurface quality of 6H–SiC deteriorates with increasing processing temperature.

Impact modification of PP with short PET fibers: Effect of heat setting on fiber characteristics and composite properties

Polypropylene (PP) composites containing poly(ethylene terephthalate) (PET) fibers were prepared by injection molding in the temperature range of 190–260 °C. Increasing processing temperature led to the shrinkage of the PET fibers caused by the relaxation of orientation and recrystallization. Structural changes in the fibers resulted in the deterioration of composite properties. Decreased fiber length and modified local stress distribution restricted the plastic deformation of the matrix resulting in the very poor impact resistance of about 1 kJ/m2 at 260 °C processing temperature. The heat setting of PET fibers resulted in more stable crystalline structure and thus decreased shrinkage and improved composite properties even at high processing temperatures. PP composites impact modified with PET fibers are suitable structural materials for the automotive sector with a sufficiently large stiffness of around 2 GPa and an impact resistance larger than 20 kJ/m2 if processing temperature is kept as low as possible.