Cobb Test Research Articles

Eco‐Friendly Food Packaging Barrier Coatings Comprised of Ball‐Milled Polysaccharide Polyelectrolyte Complexes

ABSTRACTIncreasing demand for packaging has motivated research into sustainable materials to prevent continued plastic pollution. Materials based on polysaccharide polyelectrolyte complexes (PPCs) are emerging as a viable solution for packaging applications. We employed ball milling, a well‐established technology, for the preparation of PPC materials to create an innovative one‐step process capable of producing highly concentrated and homogeneous PPC particle precursor dispersions. We fabricated carboxymethyl cellulose (CMC) and chitosan (CS)–based PPC solutions exhibiting high‐solid loading and investigated the potential of PPC solutions made from ball milling as alternative barriers for packaging. PPC‐coated paperboard exhibited improved Cobb test performance and outstanding grease resistance as compared to pristine paper. The results certified that a single‐step process via ball milling can produce high‐solid content PPC solutions useful for creating bio‐based coatings with excellent barrier performance.

Effect of Commercial Cationic Starch on Paper Properties Made from Recycled Pulp

The production of packaging paper is growing steadily annually globally. Packaging paper such as liner paper and medium paper are mainly made from recycled pulp. The strength of pulp deteriorated over the cycle of recycling. To ensure the packaging paper strength produced from recycled paper is up to par, the additive is mandatory. Starch is one of the common and economical additives used in papermaking. In this research, the performance of commercial cationic starch as an additive in packaging papermaking is evaluated. 4 different percentages of starch, including 2%, 4%, 6%, and 8%, were studied. Five replicates of 60gsm hand sheets were produced for each level, and 0% was introduced as a control. The properties such as thickness, Canadian Standard Freeness Test, Cobb test, tensile index, folding endurance, and tear index were evaluated according to the TAPPI Standard. From the result, an 8% dosage of this commercial cationic starch exhibited the best performance in mechanical tests without compromising the drainage of water significantly.

Recycling kaolin from paper waste and assessment of its application for paper coating

In the cellulose industry, the paper coating process plays an essential role in reducing manufacturing costs while increasing the quality of the products. Given that cellulose products are being used increasingly, the ability to recycle and reuse these materials might be highly beneficial in this industry. Thus, kaolin—one of the most commonly utilized ingredients in the cellulose industry that has a major impact on the final quality—was recycled from paper waste for this study. Then, to confirm the successful recycling process, the particle distribution, morphology, and chemical composition of recycled kaolin were analyzed by DLS, SEM/EDS, FTIR, XRF, and XRD. The related results verified the recycled kaolin's high purity and crystallinity. Subsequently, coatings with thicknesses of 30, 60, 90, and 120 μm were applied to paper using a suspension of recycled kaolin. Their mechanical properties (burst strength and tensile strength), permeability (air passage, the amount of which indicates the porosity of the paper structure), wettability (the contact angle can reveal the wetting ability of the paper), and water absorbance (the Cobb test) were then assessed. The pertinent findings demonstrated that applying a coating considerably improves paper quality. So, a coating with a thickness of 30 µm is superior to uncoated paper. In addition, among all the coating thicknesses, the treatment with the best mechanical strength, permeability, contact angle, and Cob value values had a coating thickness of 120 µm. The corresponding values for the tensile index, burst index, air passage amount, and contact angle are 70 kNm/kgr, 3.61kPa m2/gr, 680 ml/min, and 46֯ ±2. Consequently, the 120 µm-thickness treatment was determined to be the most effective one in this investigation.

Effect of pressure and time on water absorption of coated paperboard based on a modified Cobb test method

This manuscript presents the study of water absorption by paperboard subjected to water at high hydrostatic pressure based on a modified Cobb tester. The new tester is based on TAPPI Standard Test Method T 441; however, the water column can reach up to 550 mm. The evaluation consisted of measurements of water absorption for coated and uncoated paperboard at different exposure times from 5 s to 45 s and water column heights from 10 mm to 500 mm (corresponding to hydrostatic pressures 98 Pa and 4.9 kPa, respectively). The coatings were formulated as a combination of styrene acrylate (SA; two binder levels) and two types of ground calcium carbonates (differing particle sizes) to form the two pre-coating structures: open and closed. The coating weight was 6 g/m2 applied on 210 g/m2 solid bleached board (SBB). In addition, 210 g/m2 uncoated boards were studied. Characterization of the coatings was performed with scanning electron microscopy (SEM), mercury intrusion, and roughness. It was found that the new device properly mimics the conditions of the current Cobb tester. The characterization of the coating also confirmed the presence of more open/larger pores of open coatings, confirming the desired coating structure. The absorption of boards was mainly driven by exposure pressure by comparing with exposure time. This was already evident after shorter periods of exposure time at 5 s and also 15 s exposure time. Paperboards with open coatings showed slightly higher absorption than other boards.

Pre-treatment with calcium hydroxide and accelerated carbonation for cellulosic pulp fibrillation

Abstract In this study, the effect of different concentrations of calcium hydroxide (Ca(OH)2) was evaluated as a pre-treatment for accelerated carbonation and its influence on the fibrillation of cellulosic pulps to obtain nanofibrils, and its application as a coating agent for papers. Eucalyptus (EUC) and Pine (PIN) unbleached cellulosic fibers were submitted to pre-treatment with Ca(OH)2 at concentrations of 5 and 10% and subjected to accelerated carbonation, being subsequently mechanically fibrillated to produce cellulose nanofibrils (CNF). Pretreatment with calcium hydroxide followed by accelerated carbonation provided a 35% reduction in energy consumption. Cellulosic pulps EUC and PIN pretreated with calcium hydroxide showed higher fibrillation efficiency. There was a reduction in the cobb test values for papers coated with CNF in PIN. The WVP was lower for papers coated with CNF of EUC and control PIN. The CNF coating of EUC and PIN provided an oil barrier for the kit 11 solution. The CNF coating improved the dispersion of PVA and PVOH. The papers coated in this work have the potential to be used as packaging for fatty and oily foods or as a spreading agent for other industrial coatings.

APPLICATION OF CHITOSAN-BASED PRODUCTS TO INCREASE HYDROPHOBIC PROPERTIES OF CRAFT PA-PER

We devoted our research to study and substantiate the possibility of using products based on commercial chitosan. As an animal polysaccharide, it was applied as an additive in manufacturing laboratory samples of kraft packaging paper with increased hydrophobic properties.
 The research aimed to optimize conditions to produce packaging kraft paper by means of mathematical planning method of the experiment in accordance with the three factor uniform-rotatable second-order model by Box and Hunter.
 It is shown that that the effective hydrophobization of a fairly thin cellulose fibrous material, weight of 1 m2 70 g, is possible. In the studied factor space, we have established mathematical dependences that fit well the influence of the main technological parameters – the consumption of chitosan (0.5–1.5%), the beating degree of paper pulp (25–35 °SR) and softwood content in fiber furnish (80–100%) on the hydrophobicity (increasing moisture resistance) of paper and its physical and mechanical properties.
 It is shown that the presence of chitosan in fiber furnish leads to the hydrophobicity of kraft paper in terms of surface water absorption during one-sided wetting (Cobb test) increases many times and reaches 24–25 g/m2 at the maximum product consumption (1.5%). At the same time, the values of beating degree of paper pulp and softwood content in fiber furnish can vary in a fairly wide technological range, in accordance with the studied factor spaces.
 Increasing the consumption of chitosan, the beating degree of pulp fibers and softwood content in fiber furnish simultaneously provides an increase in the values of almost all physical and mechanical properties of laboratory kraft packaging paper.

Tung oil-based coatings towards sustainable paper packaging materials

Nowadays, the dependence on synthetic plastic-based materials for the preservation and transport of different types of products is very high, leading to major environmental and human health concerns, which highlights the importance of investigating sustainable options. Paper is a widely used bio-based material for packaging however, the development of newer and straightforward approaches to produce paper-based materials with increased functionalities and performance is still highly desired. In this work, we report the use of a bio-based photopolymerizable coating formulation, composed of tung oil, and using Darocur 1173 as photoinitiator, to develop functional papers with hydrophobic and improved water barrier properties, without compromising other properties. Coated paper samples were prepared, using different irradiation times (0, 15, 30, 60, and 300 s), to study the effect of this parameter on the properties of the coated papers. The ensuing coated papers presented pick-up values between 6 and 7 g/m2. Their hydrophobicity was significantly improved as evidenced by the increase in the contact angle values from about 71° to 127° and the significant decrease in the water absorption, measured by the Cobb test, from 108 down to 17 g/m2, upon a curing time of only 15 s. Furthermore, with this time of curing, the optical (viz. whiteness, brightness, and opacity) and mechanical properties (viz. tensile and burst strength) of paper were not affected. These results highlight the great potential of tung oil photopolymerizable coating formulations as a simple and promising alternative for the fabrication of more sustainable and functional paper packaging materials.

Effect of Water-Resistant Properties of Kraft Paper (KP) Using Sulfur Hexafluoride (SF6) Plasma Coating.

Sulfur hexafluoride (SF6) plasma at different pressures, powers, and times was used to treat Kraft paper (KP) to enhance its water resistance. The KP was treated with SF6 plasma from 20–300 mTorr of pressure at powers from 25–75 Watts and treatment times from 1–30 min at 13.56 MHz. The prepared papers were characterized by contact angle measurement and water absorption. The selected optimum condition for the plasma-treated KP was 200 mTorr at 50 Watts for 5 min. Advancement with the change in treatment times (3, 5, and 7 min) on the physical and mechanical properties, water resistance, and morphology of KP with SF6 plasma at 200 mTorr and 50 Watts was evaluated. The changes in the chemical compositions of the plasma-treated papers were analyzed with an XPS analysis. The treatment times of 0, 3, 5, and 7 min revealed fluorine/carbon (F/C) atomic concentration percentages at 0.00/72.70, 40.48/40.97, 40.18/37.95, and 45.72/39.48, respectively. The XPS spectra showed three newly raised peaks at 289.7~289.8, 291.5~291.7, and 293.4~293.6 eV in the 3, 5, and 7 min plasma-treated KPs belonging to the CF, CF2, and CF3 moieties. The 5 min plasma-treated paper promoted a better interaction between the SF6 plasma and the paper yielded by the F atoms. As the treatment time for the treated KPs increased, the contact angle, water absorption time, and Cobb test values increased. However, the thickness and tensile strength did not show remarkable changes. The SEM images revealed that, as the treatment time increased, the surface roughness of the plasma-treated KPs also increased, leading to improved water resistance properties. Overall, the SF6 plasma treatment modified the surface at the nano-layer range, creating super-hydrophobicity surfaces.

Addition of wheat straw nanofibrils to improve the mechanical and barrier properties of cassava starch–based bionanocomposites

Cellulose nanofibrils (CNFs) were obtained from wheat straw, and different concentrations (0 %, 10 %, 20 %, 30 % and 50 %) of the CNFs were incorporated into cassava starch-based films. Thirty passages through a microfibrillator allowed us to obtain well-dispersed CNFs with reduced thickness (34.26 nm). The addition of CNFs promoted an average increase in tensile strength values on the order of 126.69 %. The treatments with higher CNF addition percentages (30 % and 50 %) presented higher Young's modulus values (566.68 and 585.72 MPa, respectively), which indicates an increase in stiffness. The elongation and puncture force decreased with the addition of CNFs, presenting average reductions of 83.72 % and 56.66 %, respectively. A significant decrease in water vapour permeability was observed for the treatments with higher percentages of CNFs added, with a drop from 2.15 × 10−6 in the control film to 1.39 × 10−6 g mm/KPa−1 day−1 m2 in the film with the maximum addition percentage. The contact angle values increased from 43.45° in the control film to 68.66° in the sample with the maximum CNF concentration. The lower hydrophilicity of the treatments with 30 % and 50 % CNF additions is evidenced by the lower values presented for the Cobb test (99.84 and 99.31 g m2), polar surface free energy (0.41 and 0.19 mN m-1) and polarity (0.01 and 0.007). In these treatments, there were stronger interactions between the CNF and starch molecules. Thus, the addition of 30–50 % wheat straw CNFs is recommended to strengthen the structure and improve the barrier properties of cassava starch-based films.

Whey protein concentrate-beeswax-sucrose suspension-coated paperboard with enhanced water vapor and oil-barrier efficiency

This study investigated the effect of whey protein concentrate (WPC):beeswax (BW): sucrose (Suc) coating on the moisture- and oil-barrier properties of paperboard. Six coating suspensions with different WPC:BW:Suc ratios (1:0:1, 1:0:2, 1:1:1, 1:1:2, 1:2:1, and 1:2:2) were prepared and coated on paperboards. Droplet size increased with higher BW and Suc concentration in the coating (p < 0.05). Higher concentrations of BW and/or Suc increased the coating suspension viscosity (p < 0.05). Scanning electron microscopy images indicated that the WPC:BW:Suc suspension-coating with higher BW concentration was thicker, more uniformly dispersed, and stable in the network structure formed. Further, Cobb test, water vapor permeability measurement, and oil penetration analysis indicated that WPC:BW:Suc coatings improved the water and oil-barrier properties of paperboards (p < 0.05). Therefore, paperboards with coatings containing WPC, BW, and Suc have the potential to replace pure paperboard in applications that require a moisture/oil-barrier.

Process variables and the performance of soybean-oil rosin-based polyester as an internal sizing agent

Soybean-oil rosin-based polyester (SRP) has many uses in papermaking, but its performance as an internal sizing agent differs depending on the circumstances. In this study, a comprehensive laboratory approach was used to investigate the process variables affecting SRP application. Five levels of SRP (0.5%, 1.0%, 1.5%, 2.0%, and 2.5%), five levels of aluminum sulfate (0.5%, 1.0%, 1.5%, 2.0%, and 2.5%), and five levels of cationic polyacrylamide (0.05%, 0.1%, 0.15%, 0.2%, and 0.25%) were considered to determine the best process variables within a pH range of 5.0 to 9.0. Aspects that were considered included the mechanical properties (tensile, burst, and tear indices), water resistance (Cobb test, dynamic c9197ontact angle test, and scanning electron microscopy), and chemical usage (economical and environmentally friendly procedures). The optimum conditions based on these factors were 1.0% SRP, 1.0% aluminum sulfate, and 0.15% cationic polyacrylamide levels at a pH of 7.0. The results showed that in the optimal sizing system, 15% calcium carbonate can be tolerated.

Enhancement of water resistance and antimicrobial properties of paper sheets by coating with shellac

The present study was focused on the effect of shellac as a natural polymer on the mechanical, physical, and antimicrobial properties of the paper sheets. The surface modification of paper sheets was carried out using different shellac solutions. The capability of the treated sheet to absorb water and to permit air follow was studied by Cobb test and air permeability, respectively. It was found that the treated sheet had little affinity for water and low air permeability. The change of sheet surface properties after modification was ascertained by scanning electron microscopy and Fourier Transform Infrared Spectrophotometer (FT-IR). The shellac treated paper sheet displayed improved mechanical properties when compared with untreated paper sheet. The shellac treated sheets exhibit efficient antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. Consequently, the prepared paper sheet can be used as novel materials for packaging applications.

Effect of heat treatment temperature on properties of electrosprayed paperboard

The purpose of this study was to investigate the effect of additional heat treatment on the properties of paperboard electrosprayed with poly(lactic acid) (PLA). For this study, paperboards electrosprayed with PLA at 1%, 2%, and 3% (w/v) were further heat‐treated at 170°C, 180°C, 190°C, and 200°C for 1 minute. Physical properties, such as basis weight, thickness, and colour of electrosprayed paperboards, were investigated. For mechanical properties, folding endurance and bursting strength of treated paperboard was tested. Water resistance property was observed through contact angle, and water absorption was monitored by Cobb test. In addition, water vapour transmission rate tests were also conducted. Surface characteristics were investigated using a scanning electron microscope and roughness tester. After heat treatment, PLA particles on the paperboard surface melted and formed a smoother continuous surface; this contributed to lower water contact angles and significantly lower water absorption. Furthermore, the higher the concentration of PLA, the better the water resistance. Moreover, heat treatment temperature between 180°C and 200°C could significantly improve the water vapour barrier and water resistance properties. Temperature and treatment time could not be further increased, as the electrosprayed paper substrate was damaged and became yellowish. In addition, for the mechanical properties, an increase in the heat treatment temperature improved the bursting strength; however, a reduction in folding endurance was observed, because the melted PLA particles were absorbed deeper into the paper structure and made the whole matrix more brittle.

Process Variables and the Performance of Cationic Rosin as an Internal Sizing Agent in Recycled Corrugated Container Pulp

Cationic rosin has many uses in papermaking; however, its performance as an internal sizing agent differs depending on the circumstance, especially in the recycling of pulps. In this study, a comprehensive laboratory approach was used to investigate the process variables affecting the cationic rosin application in the paper recycling process. In this respect, four levels of alum (0.5, 1.0, 1.5, and 2.0%) and four levels of cationic rosin (0.5, 1.0, 1.5, and 2.0%) were considered to find the best alum/cationic rosin combination in acidic conditions (pH 5). After considering all aspects of the paper, such as the mechanical properties (tensile, burst, and tear indices), wet resistance (Cobb test and dynamic contact angle test), and chemical usage (economically and environmentally-friendly procedures), the 1.0% alum and 0.5% cationic rosin levels were selected for optimum performance. This research also showed that the combined effect of alum with cationic rosin was favorable. Moreover, the sequence of alum and cationic rosin addition, which is a challenge in paper mills, also should be considered. The results indicated that the addition of cationic rosin after alum obtained the best mechanical and wet resistance results. In addition, the results showed that both acidic and neutral pH were acceptable in this sizing process.

Paper coating performance of hemicellulose-rich natural polymer from distiller's grains

• Hemicellulose-based gum from distiller's grains used binder for paper coatings. • Hemicellulose-based gum compared with polyvinyl alcohol as binder. • Paper coated with a formulation consisting of calcium carbonate and binder. • Demonstrated equivalent mechanical and optical properties for coated papers. • Demonstrated potential of gum to replace polyvinyl alcohol for paper coating binder. Coatings contribute to about 10% of the overall cost of paper production of which, the binder is the highest cost component in the formulation. In addition to costs, the binders that are currently being used are synthesized from fossil fuel feedstock raising concerns towards the sustainability of paper coatings. Furthermore, papers coated with waxes, polyolefins and other synthetic materials are difficult to recycle or compost. These challenges inherent with synthetic binders can be addressed by using renewable, plant based binders. This research focused on an abundant and underutilized source of hemicellulose based binders (DG gum) that can be extracted from distiller's dried grains. The extracted binder was compared with polyvinyl alcohol (PVA) in a coating formulation consisting of 10:1 CaCO 3 to binder formulation coated on light weight paper. Cobb test, dry and wet tensile tests, optical properties (brightness, color, opacity), water vapor transmission rate (WVTR) analysis were performed to compare the hemicellulose based binder with PVA. The results indicate water absorptivity reduction by 25% for both DG gum and PVA coatings from the base paper value. Dry tensile index was lower with higher coating weights for both coatings with similar performance. The performance on WVTR analysis for both coatings was also comparable. No significant differences in optical properties after coating were observed from that of the base paper. These results suggest that hemicellulose based binder extracted from distiller's grains has the potential to replace synthetic binders in paper coating formulations.

Construction technique of disposable bin from sludge cake and its environmental risk.

Now, a lot of researchers have tried to make recycled rigid materials from the sludge cake produced in paper mill industries for the purpose of decreasing its volume. In this study, the researchers tried to make economically a disposable bin and to examine whether it is toxic or not to the outside environment. To make a disposable bin, the researchers used the sludge cake, a plastic basket, as a fixed mold, white cloth or newspaper, as a removable supporter for wrapping around the mold, and latex or plaster, as a binder. The strength of the samples was measured by tensile-stress testing. The water absorption was evaluated by Cobb test. As toxicological tests, leaching test and seed germination test were selected. It was possible to form the disposal bin from the cleaned sludge cake. They seemed safe to carry garbage in the industry judging from the results of tensile-stress testing. Some of them showed less water absorptiveness (higher water resistance) in the results of Cobb test. The results of leaching test showed small values of three heavy metals, lead, nickel and copper, in the leachate. The seed germination test suggested no adverse effects of the bins in the clay and sand on the tomato growth. The results of these tests suggest that the bins have good strength, sufficient water resistance and no toxicological effect on the environment. This new recycled bin has the possibility to solve the environmental and health problems at disposing the sludge cake.

Water Absorbency and Mechanical Properties of Kenaf Paper Blended via a Disintegration Technique

In this study, blended paper was prepared by blending synthetic polyethylene (PE) via a disintegration technique. The produced paper was targeted to resist water or moisture. Unbleached kenaf whole stem pulp was used as the main source of fibre in making the paper. The pulp was blended with two types of PE: low-branched (LB) and high-branched (HB) polymers. To study the effect of PE addition to the paper, the water absorbency and mechanical properties were characterized. The pulp to PE mixtures were prepared at ratios of 9:1, 8:2, 7:3, 6:4, and 5:5. Scanning electron microscopy (SEM) showed that the PE was melted between the fibre linkages. The Cobb test determined that the blended paper absorbed less than 20 g/m2 of water within 60 s. The best water contact angle successfully achieved was at 84°, which is almost hydrophobic. The mechanical properties, such as tensile strength and tear strength, were in the range of accepted standard requirements. The obtained results indicated that blending via a disintegration technique can be applied in the process of making water-resistant paper. The produced paper is suitable for the manufacturing of water-resistant corrugated packaging materials.

Application of chitosan emulsion as a coating on Kraft paper

AbstractKraft paper was coated with chitosan emulsion film. The novelty of this paper is the formation of a packaging bilayer system in only one drying step, which combines a biodegradable polymer emulsion (chitosan and palmitic acid) with Kraft paper. This system is described in detail and characterized for barrier properties (water vapor permeability rate (WVPR), air permeability and water absorption capacity (Cobb test)), mechanical properties (tensile properties, Taber stiffness and tear strength) and structural properties. The application of chitosan coating (3.5 g m−2, wet basis) on Kraft paper sheets provides a significantly lower WVPR (by ca 43%) and water absorption capacity (by ca 35%) as compared to uncoated Kraft paper. The incorporation of palmitic acid into the chitosan film solutions at 1.8 g m−2 improves the properties of Kraft paper even more by further reducing the WVPR and water absorption capacity by 51 and 41%, respectively. The air resistance of the coated Kraft systems is lower by 8‐ and 11‐fold compared to uncoated Kraft paper, which could be associated with the chitosan film acting as a gas barrier and as a coating agent that fills the pores between cellulose fibers. Copyright © 2011 Society of Chemical Industry

Sisal chemo‐thermomechanical pulp paper with a strongly hydrophobic surface coating produced by a pentafluorophenyldimethylsilane cold plasma

AbstractFluorinated thin layers were created on CTMP sisal and filter paper surfaces by using pentafluorophenyldimethylsilane (PFPDMS) under RF‐plasma conditions. Surface wettability and water absorption of unmodified and modified samples of both materials were evaluated through contact angle and Cobb test techniques, respectively. The mechanical strength and optical properties were also analyzed. The surface functional groups produced were evaluated using X‐ray photoelectron spectroscopy, Electron Spectroscopy for Chemical Analysis (ESCA) and Attenuated Total Reflectance Fourier Transform infrared (ATR FT‐IR) spectroscopy. Surface morphological changes after plasma treatment were evaluated using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). PFPDMS‐plasma treatment of sisal CTMP reduced water absorption from more than 400 g (H2O)/m2 to 18 g (H2O)/m2. The contact angle was increased from less than 15° to 119°–134°. Water absorption for untreated filter paper was 220 g (H2O)/m2 and after plasma treatment the value decreased to 13.6 g (H2O)/m2. Water drop contact angle for untreated filter paper was 24°, and after PFPDMS‐plasma treatment it was 134°. Strength properties were slightly reduced in some cases and brightness was reduced in most of the trials, turning to yellow. ATR FT‐IR and ESCA spectroscopy indicated a fluorinated aromatic surface, whereas AFM and SEM showed a smooth surface coating for both sisal and filter paper after PFPDMS‐plasma treatment. A fully coated surface with a very high hydrophobic character was observed. This new property can be attributed to the formation of a crosslinked polymer network of covalently bound PFPDMS‐based units on the paper surface as shown by the presence of CSi, COSi, CCFx, and CF bonds. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Effects of poly-aluminum chloride, starch, alum, and rosin on the rosin sizing, strength, and microscopic appearance of paper prepared from old corrugated container (OCC) pulp

The influence of rosin (0.1-0.3%), alum (0.4-0.6%), polyaluminum chloride (0.3-0.7%), and starch (0.5-1.5%) in the making of paper from old corrugated container (OCC) pulp on the freeness, breaking length, tear index, and burst index of pulp and paper sheets was studied. Using a full factorial design to identify the optimum operating conditions, equations relating the dependent variables to the operational variables of the chemical additives were derived that reproduced the former with errors lower than 5%. Using a high starch (1.5%), high PAC (0.7%), low alum (0.4%), and low rosin (0.1%) combination led to pulp that was sufficient to obtain paper with good strength properties (breaking length 5720m; burst index: 3.1 kPam2g-1; tear index: 6.2mNm2/g; Cobb test: 94; fold endurance: 1.52). SEM analysis showed increasing bonding between fibers together at this level of additives. The influence of starch on Cobb test values was not significant.