High-density Polyethylene Surface Research Articles

Uranium accumulation in environmentally relevant microplastics and agricultural soil at acidic and circumneutral pH

The co-occurrence of microplastics (MPs) with potentially toxic metals in the environment stresses the need to address their physicochemical interactions and the potential ecological and human health implications. Here, we investigated the reaction of aqueous U with agricultural soil and high-density polyethylene (HDPE) through the integration of batch experiments, microscopy, and spectroscopy. The aqueous initial concentration of U (100 μM) decreased between 98.6 and 99.2 % at pH 5 and between 86.2 and 98.9 % at pH 7.5 following the first half hour of reaction with 10 g of soil. In similar experimental conditions but with added HDPE, aqueous U decreased between 98.6 and 99.7 % at pH 5 and between 76.1 and 95.2 % at pH 7.5, suggesting that HDPE modified the accumulation of U in soil as a function of pH. Uranium-bearing precipitates on the cracked surface of HDPE were identified by SEM/EDS after two weeks of agitation in water at both pH 5 and 7.5. Accumulation of U on the near-surface region of reacted HDPE was confirmed by XPS. Our findings suggest that the precipitation of U was facilitated by the weathering of the surface of HDPE. These results provide insights about surface-mediated reactions of aqueous metals with MPs, contributing relevant information about the mobility of metals and MPs at co-contaminated agricultural sites.

Effect of florfenicol on Piscirickettsia salmonis biofilm formed in materials used in salmonid nets, nylon and high-density polyethylene.

Piscirickettsiosis is the most prevalent bacterial disease affecting seawater salmon in Chilean salmon industry. Antibiotic therapy is the first alternative to counteract infections caused by Piscirickettsia salmonis. The presence of bacterial biofilms on materials commonly used in salmon farming may be critical for understanding the bacterial persistence in the environment. In the present study, the CDC Biofilm Reactor® was used to investigate the effect of sub- and over-MIC of florfenicol on both the pre-formed biofilm and the biofilm formation by P. salmonis under the antibiotic stimuli on Nylon and high-density polyethylene (HDPE) surfaces. This study demonstrated that FLO, at sub- and over-MIC doses, decreases biofilm-embedded live bacteria in the P. salmonis isolates evaluated. However, it was shown that in the P. salmonis Ps007 strain the presence of sub-MIC of FLO reduced its biofilm formation on HDPE surfaces; however, biofilm persists on Nylon surfaces. These results demonstrated that P. salmonis isolates behave differently against FLO and also, depending on the surface materials. Therefore, it remains a challenge to find an effective strategy to control the biofilm formation of P. salmonis, and certainly other marine pathogens that affect the sustainability of the Chilean salmon industry.

Listeria monocytogenes detection on food contact surfaces: suitability of different swab materials

The high binding capacity of Listeria monocytogenes to food contact surfaces increases the risk of cross-contamination in food. In addition to appropriate cleaning and disinfection procedures, a suitable sampling plan and technique for the earliest possible detection are necessary for prevention. This paper evaluates the sensitivity of 3 swab materials (cotton, viscose and nylon-flocked) for the qualitative and quantitative detection of L. monocytogenes on food contact surfaces (100 cm2). A L. monocytogenes cocktail of 3 serotypes (IIa, IIb and IVb) was applied to stainless steel, polyvinyl chloride, polytetrafluoroethylene and high-density polyethylene surfaces at a concentration of approx. 1.0 × 101-1.0 × 102 CFU/100 cm2 and approx. 4.0 × 104 CFU/100 cm2. The surfaces were sampled after 15 min of incubation by 3 different swabs using the double-swab technique, and then stored for 4 and 24 h until processing. The results of the qualitative and quantitative tests showed a few statistically significant differences in the detectability of L. monocytogenes by different swab materials, which implies that the detection rate of L. monocytogenes on a certain food contact surfaces can be increased by using the respective most suitable swab.

Visual inspection of surface sanitation: Defining the conditions that enhance the human threshold for detection of food residues

Visual inspection is widely used in sanitation program monitoring. However, the degree of residual food soil on equipment surfaces that is below the limit of visual detection has not been determined. The overall goal of this study was to critically evaluate the limit of detection of visual inspections and establish evidence-based strategies to improve the implementation of this monitoring activity. Respondents (n = 101) completed a visual sensory test in which they viewed 15 stainless steel and 15 white high density polyethylene (HDPE) sheets, clean or soiled with dry wheat flour, in a randomly generated order. Respondents were asked if they could visually detect food residue on each surface and, if so, if the surface should be re-cleaned. Half of the respondents failed to visually detect up to 0.05 g and 0.02 g of flour per square foot (929 cm2) on HDPE and stainless steel surfaces, respectively. Tactile inspection improved respondent detection sensitivity to 0.001 g of flour per square foot (929 cm2) on both HDPE and stainless steel. Respondent height, visual acuity, and prior food safety experience had significant (p < 0.05) effects on visual detection sensitivity. Respondents were more likely (p < 0.001) to say that a food-soiled surface should be re-cleaned after an intervention training. The findings from this study support the use of surfaces that color-contrast food residue, tactile evaluation with a gloved hand, training, and the use of flashlights or positional changes (e.g., crouching) to improve pre-operational inspections. Nonetheless, the additional use of verification tests remains necessary given the limit of detection determined for visual evaluation. Further research is needed on other food residues with different visual properties such as oils.

Efficacy of Peracetic Acid and Sodium Hypochlorite against SARS-CoV-2 on Contaminated Surfaces.

SARS-CoV-2 is primarily a respiratory virus that can potentially be transmitted through fomites. Sodium hypochlorite (NaOCl) and peracetic acid (PAA) are widely used disinfectants on surfaces in diverse settings such as hospitals and food production facilities. The objectives of this study were to investigate the virucidal efficacy of NaOCl and PAA against SARS-CoV-2 using the ASTM standard methods. In the suspension assay, NaOCl and PAA (5, 50, and 200 ppm) were tested against SARS-CoV-2 in the presence/absence of soil load after 1 min of contact time. In the carrier assay, NaOCl and PAA were tested at 200, 400, 600, and 1,000 ppm for 1 min and 200 and 1,000 ppm for 5 and 10 min. Stainless steel (SS) and high-density polyethylene (HDPE) disks were used as carriers. The virus was suspended in soil load and the disinfectants were prepared in 300 ppm of hard water. Virus quantification was done by TCID50 assay using Vero-E6 cell line. NaOCl and PAA were effective (> 3 log reduction in infectious virus) at 50 ppm in the absence of soil load. However, in the presence of soil load, 200 ppm was required for > 3 log reduction in virus infectivity. In contrast, NaOCl and PAA at 200 ppm and with a 1-min contact time were not effective against SARS-CoV-2 on either SS or HDPE surfaces. PAA at 200 ppm for 10 min was effective against SARS-CoV-2 on SS and HDPE surfaces, whereas NaOCl required 1,000 ppm for 10 min to be effective against SARS-CoV-2 on both surfaces. IMPORTANCE In the context of the COVID-19 pandemic, the World Health Organization (WHO) recommended the use of chlorine-based products such as sodium hypochlorite (NaOCl) at 1,000 ppm for a minimum of 1 min to disinfect environmental surfaces. However, this recommendation was not based on validated studies on the actual SARS-CoV-2 itself. In fact, over half of the chemical disinfectants, including many peracetic acid products, listed in EPA List N were approved based on "kills a harder-to-kill pathogen" without further validation on SARS-CoV-2. Research on SARS-CoV-2 is restricted to BSL3 laboratories and the urgency of tackling the pandemic might explain the lack of studies on the actual virus. Our results show that the WHO recommendation of 1 min contact time with 1,000 ppm NaOCl is not effective against SARS-CoV-2 on surfaces. Also, our results indicate that PAA is effective against SARS-CoV-2 on surfaces and can be used as safer and more environmentally friendly alternative to NaOCl at a lower concentration.

Degradation of high density polyethylene (HDPE) through bacterial strain from Cow faeces

The prime objective of our research was to assess the efficiency of fecal bacteria Brevibacillus parabrevis CGK45 from cow in the degradation of HDPE plastic films without any physical or chemical pre-treatment. The biodegradation studies were conducted considering various parameters such as percent weight loss and half-life of HDPE film, biomass of surface adhered cells in terms of protein content as well as viability of bacterial biofilm (CFU/cm2) on plastic surface, and hydrophobicity of bacterial culture. The extent of biodegradation was assessed by implementation of various techniques i.e., Field Emission Scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDX) and Fourier Transform Infrared Spectroscopy (FTIR). The bacterial strain was identified as Brevibacillus parabrevis CGK45 (Accession number MW965577) by phylogenetic analysis using 16S rRNA gene sequence homology. A significant weight loss (4.03%) in the HDPE film treated with strain CGK45 was observed after 90 days. The SEM analysis visualized remarkable bacterial colonization as well as structural changes in the surface micromorphology on HDPE surface. Furthermore, SEM-EDX analysis showed excellent reduction in the atomic percentage of carbon content (2.2%) whereas FTIR analysis confirmed the conformational shifting of peak and formation of new functional groups [ester (1290 cm−1) and alcohol (1368 cm−1)] apparently due to bacterial biofilm biodegradation. The findings of our investigation provides an insight into the ability of cow dung strain B. parabrevis CGK45 in the colonization and utilization of high density polyethylene as a sole carbon source proving its suitability for future environment friendly degradation studies.

Tetracycline accumulation in biofilms enhances the selection pressure on Escherichia coli for expression of antibiotic resistance.

Microorganisms are present as either biofilm or planktonic species in natural and engineered environments. Little is known about the selection pressure emanating from exposure to sub-minimal inhibitory concentration of antibiotics on planktonic vs. biofilm bacteria. In this study, an E. coli bioreporter was used to develop biofilms on glass and high-density polyethylene (HDPE) surfaces, and compared with the corresponding planktonic bacteria in antibiotic resistance expression when exposed to a range of μg/L levels of tetracycline. The antibiotic resistance-associated fluorescence emissions from biofilm E. coli reached up to 1.6 times more than those from planktonic bacteria. The intensively developed biofilms on glass surfaces caused the embedded bacteria to experience higher selection pressure and express more antibiotic resistance than those on HDPE surfaces. The temporal pattern of fluorescence emissions from biofilm E. coli was consistent with the biofilm-developing processes during the experimental period. The increased expression of antibiotic resistance from biofilm bacteria could be attributed to the high affinity of tetracycline with extracellular polymeric substances (EPS). The enhanced accumulation of tetracycline in biofilms could exert higher selection pressure on the embedded bacteria. These results suggest that in many natural and engineered systems the higher antibiotic resistance in biofilm bacteria could be attributed partially to the retention antibiotics by the EPS in biofilms.

Restoration of mechanically obliterated credentials on high density polyethylene surfaces by combination of heat treatment and reagent polishing

Restoration of mechanically obliterated credentials on high density polyethylene surfaces by combination of heat treatment and reagent polishing

HYDROPHOBICITY IMPROVEMENTS OF POLYMERS USED IN BIOMEDICAL APPLICATIONS.

Improvement in hydrophobicity is important for polymers used in various applications such as biomedical applications, as it can delay their degradation due to long-term exposure to moisture environments. Although a number of surface modification techniques have been developed over the years to improve hydrophobicity, their specific influences on hydrophobicity enhancement as well as long-term mechanical and tribological performances are yet to be fully understood. In this study, surface textures, with variation in type and geometry, are introduced on Ultrahigh Molecular Weight Polyethylene (UHMWPE) and High Density Polyethylene (HDPE) surfaces to study the effect of surface modification on hydrophobicity and long-term mechanical and tribological performances. Based on the theoretical study using Wenzel and Cassie-Baxter models, surface textures of various types and dimension are introduced on UHMWPE and HDPE surfaces. The results show that introduction of surface textures significantly improves the hydrophobicity of polymers. Specific relationship between texture type and geometry, and improvement in hydrophobicity is explored. Based on the comparison between experimental results and theoretical models, transition state modeling seems to be more suitable in describing the change in hydrophobicity with the addition of surface texture. The study provides useful guidelines to improve hydrophobicity of polymers for biomedical applications.

Transforming hydrophobicity of high-density polyethylene surface to hydrophilicity and superoleophobicity by surface grafted with polyvinyl alcohols for oil contaminants cleanup

High-density Polyethylene (HDPE) is widely used in industrial processes due to its excellent mechanical properties, solvent resistance and chemical stability. However, its surface usually shows high hydrophobicity and lipophilicity, which makes it ineffective in resisting contamination by oil pollution. In this study, Polyvinyl alcohols (PVA) were grafted onto the surface of the glycidyl methacrylate (GMA) grafted HDPE to improve the surface hydrophilization, furthermore, the surface structure of the PVA@GMA-HDPE and the factors affecting its hydrophilic modification were investigated. The introduction of the GMA in HDPE surface results in a large number of reactive sites on the inert surface of HDPE, which allows for further grafting of PVA onto the HDPE surface. Most importantly, the addition of PVA improves the water wettability, which reduced the water contact angle from 87.82° to 23.33° in the air and increased the oil contact angle from 107.30° to 156.90° under water. With the help of the significant improvements in resistance to oil contamination, the grease on the surface of the modified HDPE can be easily removed by washing with water after many repetitions. The low cost, simple manufacture and versatility of the PVA@GMA-HDPE with superior hydrophilicity and submerged superoleophobicity have significant application value for sewerage pipes and membranes.

Short-term exposure to soils and sludge induce changes to plastic morphology and 13C stable isotopic composition

There is concern about the buildup of plastic waste in soil, their degradation into microplastics, and their potential to interfere with the natural processing of soil organic carbon and other nutrient cycling processes. Here we used scanning electron microscopy (SEM) and 13C isotope ratio mass spectrometry to determine if precut consumer plastics comprised of either high density polyethylene (HDPE), a blend of linear low density polyethylene and low density polyethylene (L/LDPE), or polyethylene terephthalate (PETE) would degrade or transform during a short-term, 32 day, exposure to soil or sludge in laboratory microcosms. SEM confirmed morphological changes occurred to all plastics, but the attachment of biofilm and presence of microorganisms mostly favored PETE and HDPE surfaces. These observations support the idea that abiotic and/or biotic processes may degrade plastics in soil; however distinguishable and significant changes in mean stable isotopic values (Δδ13C) of ~0.2–0.7‰ were only observed for exposed PETE and HDPE. This indicates that each plastic's degradation in soil may be dependent on their physical and chemical properties, with L/LDPE being more resistant and less prone to degradation compared to the others, and less dependent on the environmental conditions or properties of the soil or sludge. Our experiments were short-term and while the mechanisms of degradation are not clear, the results provide strong motivation for further studies of plastic fate and processing in soil systems. Direct mechanistic studies using stable isotopic approaches in combination with other characterizations and techniques are clearly warranted and may lead to a significant enhancement in our present understanding of the interactions and dynamics of plastics in the soil environment.

Improving Surface Functionality, Hydrophilicity, and Interfacial Adhesion Properties of High-Density Polyethylene with Activated Peroxides.

Polyolefins have had limited application in advanced technologies due to their low surface energy, hydrophobicity, and weak interfacial adhesion with polar coatings. Herein, we propose the use of transition metals at their lowest oxidation state and inorganic peroxides to improve the functionality, surface free energy, hydrophilicity, and adhesion properties of high-density polyethylene (HDPE). Among the nine combinations of transition metals and peroxides used in this study, the combination of Co(II) and peroxymonosulfate (PMS) peroxide was the most effective for surface modification of HDPE, followed closely by the combination of Ru(III) and PMS. After chemical treatment, HDPE's surface functionality, composition, and energy were analyzed via Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements. Hydroxyl, carbonyl, and carboxylic acid functional groups were detected on the surface, which explained the improved hydrophilicity of the modified HDPE surface; the contact angle of HDPE with DI water decreased from 94.31 to 51.95° after surface treatment. To investigate the effect of HDPE's surface functionality on its interfacial properties, its adhesion to a commercial epoxy coating was measured via pull-off strength test according to ASTM D54541. After only 20 min of surface treatment with Co(II)/PMS solution, the adhesion strength at the interface of HDPE and the epoxy coating increased by 193%, confirming the importance of polyolefins' surface functionality on their interfacial adhesion properties. The method outlined herein can improve HDPE's surface functionality by introducing sulfate radicals. It improves HDPE's hydrophilicity and adhesion properties without requiring strong acids or time-consuming pre- or post-treatment processes. This process has the potential to increase the use of polyolefins in various industries, such as for protective coatings, high performance lithium-ion battery separators, and acoustic sensors.

Comparison of FANT results using the ENDF/B-VII.1, JEFF-3.3 and TENDL2017 nuclear data libraries

FANT (Fuente Ampliada de Neutrones Térmicos; in Spanish) is a thermal neutron irradiation facility with an extended and very uniform irradiation area, that has been developed by the Neutron Measurements Laboratory of the Energy Engineering Department at Universidad Politecnica de Madrid (LMN-UPM). This device is a parallelepiped box made of high-density polyethylene (HDPE), moderator material, that uses an A95241m/B49e neutron source of 111 GBq nominal activity for irradiating materials. The facility design was previously optimized, and the neutron spectra were estimated by extensive calculations with the MCNP6.1 code and carrying out experimental measurements (Bedogni et al., 2017). The facility takes advantage of the scattering reactions of neutrons with the HDPE surfaces of the chamber, where the moderation process is effective, achieving relevant thermal neutron fluence rates. The main goal of this work has been to simulate and analyse the FANT system by Monte Carlo methods using the MCNP6.1 code, employing 3 different nuclear data libraries: ENDF/B-VII.1, JEFF-3.3 and TENDL 2017. The transport of thermal neutrons in HDPE, E < 1eV, has been calculated in all the cases taking into account the thermal S (α,β) treatment. The results achieved in this work have been compared with those previously obtained in the former development of FANT, using the MCNP6.1 code with the ENDF/B-VII.1 nuclear data, and experimental measurements. These results have shown that the JEFF-3.3 nuclear data library is the nuclear data library that provides of the best matching between the MCNP computational results, and the experimental data collected at FANT. Hence, the JEFF-3.3 nuclear data library seems to be the most correct library to design and benchmark thermal neutron activation devices.

Adhesion of water-based paint on plasma-treated high-density polyethylene sheets

In this study, high-density polyethylene (HDPE) surfaces were treated with plasma to enhance the adhesion of a water-based paint. A custom-built cold atmospheric pressure plasma jet (CAPPJ) device using a neon transformer as its power source was developed and used in the surface treatment. The jet nozzle of the device was made from polytetrafluoroethylene with two bare stainless-steel electrodes positioned laterally through the nozzle and opposite each other with a 1 mm gap. Gas was allowed to pass through the nozzle, exiting through a 1 mm diameter hole where a plasma jet is ejected through the arc from the electrodes. The effect of plasma treatment on HDPE surfaces was determined. Air and nitrogen were used as the process gases and exposure times were also varied. Hydrophilicity of the surface increased with longer plasma exposure with a corresponding 50% increase in surface free energy compared to the untreated surface. From Fourier transform infrared and x-ray photoelectron spectroscopy analysis, it was seen that plasma treatment introduced oxygen containing functionalities onto the surface. Increase in adhesion of a water-based paint was observed for plasma-treated HDPE sheets.

Simultaneous sorption behaviors of UV filters on the virgin and aged micro-high-density polyethylene under environmental conditions

The simultaneous sorption behaviors of four analytes from the UV filters group, benzophenone (BPh), 4-methylbenzylidene camphor (4MBC), benzophenone 3 (BPh3), and benzophenone 2 (BPh2) on virgin and aged high-density polyethylene (HDPE) with a particle size of 125 μm in milliQ and river water were examined in this study. The aging processes of HDPE particles were carried out with the use of simulated sunlight. Conducted research revealed that the sorption of UV filters on HDPE particles follows pseudo-second-order kinetics. A Temkin isothermal model best described the adsorption process for 4BMC, BPh, BPh3, BPh2 on aged HDPE in river water, and 4MBC, BPh, BPh3 on virgin HDPE in milliQ water. The adsorption of BPh2 onto virgin MPs in milliQ water was consistent with the Langmuir isothermal model. Environmental conditions and physicochemical properties of analytes influenced the sorption mechanism between UV filters and MPs particles. It was observed that the main mechanisms responsible for the sorption of BPh, 4MBC, BPh3, and BPh2 on the surface of HDPE are hydrophobic interactions, that may change through the involvement of electrostatic interactions.

Catalytic C–H Oxidation Enhances Polyethylene Bonding

Selectively adding functionality to commodity plastics is an abiding challenge in polymer science. In this issue of Chem, Hartwig and co-workers describe a selective, catalytic oxidation of polyethylene C–H bonds by using high-valent ruthenium-oxo species. The transformation increases polyethylene’s adhesive properties without significantly modifying its thermal stability or mechanical strength.

Improving the bonding of polyethylene to E-glass/epoxy composites using ultraviolet irradiation

One of the problems in type-IV pressure vessels (composite pressure vessels with a thermoplastic inner liner) is the quality of bonding between the liner to the outer reinforcement layer. In the present research, the effect of the ultraviolet (UV) irradiation on the surface of the high-density polyethylene (HDPE) for the co-bonding process of E-glass/epoxy composites to HDPE liner was investigated experimentally. To recognize the effect of the UV irradiation on the surface properties, the contact angle measurement, and the atomic force microscopy (AFM) were performed. Asymmetric double cantilever beams (ADCB) tests were conducted to determine the strain energy release rate (SERR) as a factor indicating the crack resistance of the joint. According to the results, it was found that 20 min of UV irradiation exposure time presented the lowest contact angle on the surface of HDPE, and the highest strain energy release rate in ADCB specimens. The result of the tensile test for HDPE under the UV radiation demonstrated less than 8% degradation in the mechanical properties. Therefore, it can be concluded that 20 min of UV irradiation exposure time could be used as a surface treatment of the HDPE liner of type-IV pressure vessels.

Hydrophilicity Improvement of Polymer Surfaces Induced by Simultaneous Nuclear Transmutation and Oxidation Effects Using High-Energy and Low-Fluence Helium Ion Beam Irradiation.

Two commodity polymers, polystyrene (PS) and high-density polyethylene (HDPE), were irradiated by high-energy He ion beams at low fluence to examine the wettability changes at different fluences. The water contact angles of the PS and HDPE surfaces were reduced from 78.3° to 46.7° and 81.5° to 58.5°, respectively, upon increasing the fluence from 0 to 1 × 1013 He2+/cm2 for irradiation durations ≤4 min. Surface analyses were performed to investigate these wettability changes. Surface texture evaluations via scanning electron and atomic force microscopies indicated non-remarkable changes by irradiation. However, the chemical structures of the irradiated polymer surfaces were notable. The high-energy He ions induced nuclear transmutation of C to N, leading to C–N bond formation in the polymer chains. Further, C–O and C=O bonds were formed during irradiation in air because of polymer oxidation. Finally, amide and ester groups were generated by irradiation. These polar groups improved hydrophilicity by increasing surface energies. Experiments with other polymers can further elucidate the correlation between polymer structure and surface wettability changes due to high-energy low-fluence He ion irradiation. This method can realize simple and effective utilization of commercial cyclotrons to tailor polymer surfaces without compromising surface texture and mechanical integrity.

Biofilm growth on PVC and HDPE pipes impacts chlorine stability in the recycled water

This study investigated the effects of pipe materials on biofilm growth in full-scale recycled water (RW) distribution system. A biofilm reactor containing high-density polyethylene (HDPE) and polyvinyl chloride (PVC) pipe coupons was fed directly with chlorinated water from the storage reservoir of a full-scale RW distribution system. The reactor was operated at a variable water flow rate of 0.08−0.30 L/min and free chlorine residuals of 0.05−0.7 mg/L. Total carbohydrate, biofilm thickness, biofilm mass, and extracellular polymeric substance (EPS) measurements showed that both HDPE and PVC pipe surface materials are susceptible to biofilm formation and there was no significant difference in biofilm formation between the two pipe materials used in this study. The difference between total chlorine and free chlorine was significant even in the presence of minimal ammonia-nitrogen (<0.066 mg/L) demonstrating chlorine is largely in the form of organic chloramines. Additionally, a significant role of biofilm in decaying chlorine demonstrates the need for biofilm management strategies to maintain water quality in the RW distribution systems.

Mold replication in injection molding of high density polyethylene

AbstractIn order to deepen the mechanisms at the basis of mold surface replication onto the molded plastic surface, a novel experimental approach is proposed. Up to 20 different mold surface textures were made by machining with repetitive patterns of peaks and valleys. Mold replication tests were performed by over‐molding of high density polyethylene (HDPE) on steel inserts. The surface morphology of inserts and injection molded parts was acquired by surface analyzer, and all the main roughness parameters were extracted and compared as well as the geometrical profiles. Surface morphology was also measured on molded samples after thermal relaxation at 100°C. As expected, a strong correlation was found between the roughness of mold insert and molded part over the full experimented range. Profiles on the molded surface have the same repetitive pattern of the corresponding insert surface but with lower peaks, higher valleys, and a horizontal shrinkage. Comparing molded HDPE surface profiles before and after thermal relaxation, it was observed a similar change to the one highlighted between mold insert and molded part. This occurrence suggests that the final surface appearance of the molded part is also a function of the relaxation mechanism during or immediately after injection molding.