Fresh Latex Research Articles

Effect of Tomato Juice Volume on Coagulation Time and Latex Weight

Natural latex clumping takes longer than using chemicals. Another alternative is needed to coagulate the latex by adding acid from natural ingredients. Tomatoes (Lycopersicum esculentum Mill) have 29.32 mg of ascorbic acid and 0.54 g of citric acid every 100 grams, they have the potential to be used as a natural latex coagulator. The research method add tomato juice to fresh latex to break down the emulsion and form rubber lumps. After mixing, the weight of the latex is weighed. The constant variables are the latex volume of 10 ml, and the tomato juice volume of 5,10,20,30,40,50,60,70,80,90 and 100 ml respectively. The higher the volume of tomato juice, the faster it will clot. The best volume of tomato juice is 100 ml with a clumping time of 52 minutes. Increasing the volume of tomato juice increased the weight of latex to 13.1 grams and reduced the pH of latex to 4.9. Giving tomato juice every 5 ml accelerated clumping up to 360 minutes (6 hours) compared without tomato juice.

Green productivity and value chain analysis to enhance sustainability throughout the passenger car tire supply chain in Thailand

Although the tire industry is important for the economy of the country, focusing only on productivity will not lead to sustainable production and competitiveness in today's global market. This research aimed to enhance economic and environmental performance throughout Thailand's tire supply chain using green productivity (GP) and value chain analysis. The current performance of the tire supply chain was presented using GP level with value chain analysis for identifying the causes of extravagant resources, energy, or waste. The clean technology (CT) concept was used to develop options to improve GP and obtaining a sustainable tire supply chain. The results showed that the highest GP value of primary and intermediate rubber products was fresh latex and smoke sheet rubber. Cup lump and STR20 block rubber, in contrast, offered the lowest GP. Overuse of chemical fertilizer in the cup lump production, water consumption in the STR20 production and steam consumption in the tire manufacturing process were key issues selected for developing CT options from value chain analysis. The chosen options are to fertilize following the Rubber Research Institute recommendations, recycle used or treated water in the rubber industry and lower mold open time among tire manufacturers to reduce steam and coal consumption. These techniques were predicted to raise the GP value from 0.1495 to 0.1626 in cup lump production, 0.0320–0.0326 in the STR20 plant and 0.0098–0.0114 in a tire factory. It indicated a more sustainable business operation that could reduce environmental impacts and increase competitiveness simultaneously.

Insect-trapping glues made of natural rubber: Effects of nonrubber components and rubber molar mass on performance

An easy-to-prepare glue was produced from natural rubber (NR) latex and environmentally benign chemicals for use in control of insect pests in greenhouses. The effects of non-rubber components and the molar mass (MM) of NR in the latex and the glue on adhesion performance of the glues are reported. Glues were produced using five latex types: commercial high-ammonia concentrated latex (HA), fresh latex (FL), skim latex (SK), urea deproteinized latex (UD), and saponified latex (SP). The latexes’ characteristics (e.g., protein content, phospholipid content, gel content, and molar mass of NR chains) and the characteristics of the resulting glues (i.e., drying time, molar mass of NR chains, and adhesion performance) were evaluated by principal component analysis (PCA). The NR glues made of HA and SP latex types were found to have an adhesion performance comparable to commercial insect trapping glues. The HA latex was natural, more economical, and required less processing than the SP latex. PCA demonstrated that the adhesion performance of the glues correlated strongly to the gel content and the molar mass of the NR chains in the glue and the latex. Increased values of all these variables improved the cohesive strength of the glue. The HA glue was tested in a greenhouse to confirm its effectiveness: it showed an insect capturing efficacy of ∼68% of a commercial glue. The lower performance was caused by an absence of vulcanization, leading to creep behavior and degradation of the rubber chains in the hot environment of the greenhouse.

Gutta percha, natural rubber and balata-chemical characterization of polyisoprenes in the context of cultural heritage

Gutta percha, natural rubber, and balata are latexes produced by tropical trees that since the mid-nineteenth century have been extensively used commercially and in the creation of artworks and daily use objects. All three latexes are stereoisomers of polyisoprene that differ in their molecular structure. In gutta percha and balata, the molecular functional group is in the trans- position; in natural rubber, it is in the cis- position. This difference in their molecular structure affects the physical properties of these materials and their aging, turning natural rubber tacky and gutta percha brittle. Commercially focused analysis of natural polyisoprenes has typically used chemically modified materials. The present study characterizes natural, chemically unadulterated latex harvested from trees, aiming to differentiate the cis- and trans-forms. The analysed materials comprised fresh latexes harvested in Malaysia and Indonesia, naturally aged botanical samples, some over 100 years old, and minimally processed 10-year-old commercial stock; a total of 50 samples were examined, out of which 23 are discussed in detail. The harvesting practices of latexes were recorded during fieldwork in Southeast Asia in 2015–2019, in Cipetir (Tjipetir), on Lingga Island in Indonesia, and in Malay rubber plantations. The harvesting methods are the first indicators as to the type of latex harvested based on the pattern of incisions and time of coagulation upon exposure to air. The interviews of tappers, especially of gutta percha and balata, serve as a record of a disappearing craft. Therefore, this fieldwork report contributing to a general knowledge of working methods with natural latexes is of particular value considering the scarcity of published records. The laboratory analytical study of trans- and cis- forms relied on nuclear magnetic resonance (NMR) spectroscopy, which is the most accurate method to unambiguously determine the stereo chemistry of each polyisoprene. The characteristic spectroscopic features of cis- and trans-positions were clearly shown in all samples, in fresh latex, in over 100-year-old material, and in early twentieth century artifacts. This result indicated that the aging of the polyisoprenes does not prevent the identification of their stereochemistry. This analytical work is the first thorough examination of gutta percha, natural rubber and balata in the context of cultural heritage to guide preservation strategies for objects made of these materials.

A Review of the Parameters Related to the Rubber Sheets Production: Major Constituents of Rubber Latex, Rubber Particles, Particle Interaction of Rubber Latex, Rubber Porous Structure, Rubber Drying Kinetics and Energy Consumption

Natural rubber (NR) is obtained principally from Para-rubber trees of the species Hevea brasiliensis which grow in tropical regions. Using ultra-centrifugation method, fresh latex (FL) from Para-rubber trees can be mainly divided into four fractions; an upper white layer consists of rubber particles, Frey-Wyssling particles in a yellow or an orange layer, C-serum phase and lutiods particles in the bottom fraction [1-3]. The averages of rubber particles have diameters of 0.02 to 3.0 micron, and they are protected by a complex film containing lipids and proteins [4-8]. The main forces of attraction between neighboring rubber particles in latex system can be divided into five force types; Structural Forces (SF), Van der Waals Interaction (VWI), Electrostatic Force (EF), Exclusion Interaction (EI) and Polymer-Polymer Interaction (PPI) [9]. The porous model of rubber structure used to describe moisture transfer was based on the existence of two different regions referred to as non-hygroscopic region and hygroscopic region. The rubber products drying always produced a considerable shrinkage effect which considered in the physical of the product, such as the diffusion coefficient, mass and heat transfer. An initial moisture content of raw material, the experimental temperature and the drying equipment had affect to the EMC isotherms and the drying kinetics. Finally, discussions on the implications of the results for strategies to reduce the energy consumption in RSS and STR20 block rubber are also presented.

Laticifer Identification, Rubber Characterization, Phenolic Content, and Antioxidant Activity of Pergularia tomentosa Latex Extract.

Pergularia tomentosa is a perennial twining herb widely spread out arid and semiarid Tunisian regions. It is searched for its richness in enzymes, secondary metabolites, antifungal activity, and milk-clotting activity. Traditional use implies the fresh latex in wounding heals. The present study was aimed at identifying laticifer distribution in Pergularia tomentosa stems, leaves, and petioles. In the present study, the identification of latex extract's components and its valorisation by estimation of phenolic content, flavonoids, and antioxidant activity are conducted. Anatomical structures proved the presence of laticifers in the aerial parts of Pergularia tomentosa. They are particularly observed along the pith and cortical parenchyma in stem, in leaf mesophyll, and in petiole phloem. Identified laticifers were characterized as nonarticulated. FTIR spectroscopy proves the presence of several functional groups in the latex and mainly the cis-1-4-isoprene monomer. Results suggested that Pergularia tomentosa latex contributes significantly as a source of phenol content (62.3 mg Eq GAE/g) and flavonoids (24.8 mg Eq QE/g). Scavenging free radicals of DPPH exhibited IC50 value of 12 μg/ml. In conclusion, latex extracted from Pergularia tomentosa can be implied in industry as a natural rubber. It can be used, also, in medicine as a therapeutic agent.

Preliminary Qualitative Phytochemical Analysis and Acute Oral Toxicity Study of Latex of an Ethnomedicinal Plant Euphorbia fusiformis Buch.-Ham.Ex D.Don

Euphorbia fusiformis Buch.-Ham.Ex D.Don, (Synonym: Euphorbia acaulis Roxb) is an infrequent medicinal, geophytic herb belonging to family Euphorbiaceae. The latex obtained from tubers of Euphorbia fusiformis was traditionally used as an antidote in scorpion and snake bites. Fresh latex has been externally applied to heal chronic wounds and cracks and to cure skin diseases. Previous research on the Euphorbia fusifornis primarily focused on phytochemical investigation and pharmacological screening of various solvent extracts of dried root powder. Considering the therapeutic potential of the latex, there is a need to explore the studies on plant latex. The present work deals with the determination of physicochemical properties, preliminary phytochemical analysis and acute oral toxicity study of latex of Euphorbia fusiformis. Physicochemical characterization and preliminary phytochemical studies were carried out by using ethanolic solution of latex. The studies revealed the presence of alkaloids, glycosides, terpenoids, steroids and saponins. Acute oral toxicity study of latex were carried out by acute toxic class method of OECD 423 guideline. Euphorbia fusiformis latex was found to be safe at the dose of 2000 mg/kg and therefore characterized as Category 5 in the GHS system. It is concluded that further studies are essential for isolation and identification of chemical constituents from Euphorbia fusiformis and screening of pharmacological activities to support the traditional claims.

Study on rapid measurement technic of dry rubber content in latex cup lump by electrical properties

Dry rubber content meter is substantial tool for Impartial trade on rubber cup lump. Department of Agriculture researchers proposed rapid measurement technic of dry rubber content in latex cup lumps by their electrical properties. Two probe types needle and roller were designed, in the first phase, constructed, installed and tested. Needle type probe of 25 mm. in length and 5 mm. apart was selected in measuring electrical properties of cup lump samples as its penetration depth is half of the thickness. Two cylindrical rollers probe of 220 mm. in length and 101.6 mm. (4 inches) in diameter powered by 2 HP gear motor were designed, constructed, installed and tested. Rubber cup lump samples were each statistical divided into 9 regularly measuring parts in needle type probe. Rubber cup lump samples in rollers type probe were typically enforced to pass through 1-inch gap between two rollers. Irregular size sample of more than 76.2 mm. (3 inches) thickness of rubber cup were sliced before measuring into 2 equal thickness pieces. Electrical properties of samples were acquired by standard electrical measuring instruments and percentage of dry rubber content were determined by standard oven method for all sample segments. As the results of this study, rubber content percentage of cup lump was correlated with electrical capacitance than resistance. Electrical capacity value of the latex cup lump from needle-type and two roller-type probes were inversely correlated with the percentage of dry rubber content within the range of 0 – 75 nF and 0 – 380 nF and coefficient of determinations were 0.90 and 0.97, respectively. These initiate features will be utilized in designing of percentage of dry rubber content prototype meter by electrical property values in the future. Percentage of dry rubber content from DRC method of lump from fresh latex and conventional cup lump by oven method was significantly correlate. Electrical properties of latex cup lump produced in the laboratory and farmers are also significantly consistent.

Phytochemical Composition and Antioxidant Activities of Phosphate Buffered Saline and Aqueous Extracts of Aloe barbadensis Miller Leaf Latex and Gel from Three Counties of Kenya

Aims: Aloe barbadensis Miller (A. barbadensis) is one of the most treasured species from the Aloe genus that has been used in management of various ailments. However, there are few reports on the secondary metabolites, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities of its leaf latex and gel. This study aimed at comparing the phytochemicals and antioxidant activity of phosphate buffered saline (PBS) and distilled water extracts of latex and gel of A. barbadensis leaves from Kisumu, Elgeyo Marakwet and Baringo Counties of Kenya, East Africa.
 Study Design: The study employed quantitative and qualitative research designs.
 Place and Duration of Study: This study was conducted at the Department of Chemistry and Biochemistry, School of Sciences and Aerospace Studies, Moi University, Eldoret, Kenya between May 2021 and August 2021.
 Methodology: Leaf samples were extracted by maceration using distilled water and PBS. Phytochemical screening was performed following standard screening procures while TPC, TFC and antioxidant activity were determined using Folin-Ciocalteau method, Aluminum Chloride colorimetric assay and DPPH radical scavenging assay, respectively. One-way analysis of variance (ANOVA) was performed with Tukey post hoc test at P = .05. Correlations among TPC, TFC and antioxidant activity of the extracts were assessed using Pearson’s bivariate correlation. The analyses were performed using GraphPad Prism for windows (v9.0, GraphPad Software, California, USA).
 Results: Phytochemical screening results indicated the presence of alkaloids, phenols, saponins, flavonoids, cardiac glycosides, tannins, steroids, terpenes and quinones as the main secondary metabolites in the extracts. TPC and TFC were found to be highest for the aqueous extracts, with the highest contents (102.393 ± 0.121 mg GAE/ g DW and 47.228 ± 0.248 mg QE / g DW) being for dry latex of leaves from Baringo. The highest antioxidant activity (IC50 = 21.900 ± 0.0594 mg/mL) was for aqueous extract of fresh latex of leaves from Baringo, followed by those from Elgeyo Marakwet and then Kisumu.
 Conclusion: This study established that dry and fresh latex and gel extracts of A. barbadensis leaves possess therapeutic phytochemicals with antioxidant activities, which support their use in traditional phytomedicine in Kenya.

The effects of coagulant types on the quality and added value of raw rubber materials

Many processing problems still occur, causing the low quality of raw rubber materials and farmers low-income. This can be seen from the use of coagulants, storage methods and the level of cleanliness. This study was aimed at analyzing the quality and added value of raw rubber materials based on the use of coagulant types. This study was conducted in October - November 2021. Fresh latex was obtained from the rubber plantation in Mulyaguna Village, OKI Regency. Completely randomized design was used with 5 treatments and 4 replications. The coagulants used were the recommended ones (liquid smoke, formic acid), and the commonly used by the farmers (sulfuric acid, aluminum sulfate, and TSP fertilizer). The results of the study showed that liquid smoke and formic acid were better than the coagulants commonly used by farmers, which could be seen from the ash content, initial plasticity, and plasticity retention index. The dry rubber contents (DRCs) using liquid smoke, formic acid, sulfuric acid, aluminum sulfate, and TSP fertilizer were 66.081; 62.978; 59.067; 56.202 and 60.796 respectively. Liquid smoke and formic acid provided the added value for raw rubber materials of 1,203/kg IDR and 792/kg IDR compared to sulfuric acid commonly used by farmers.

Microstructure and Lamellae Phase of Raw Natural Rubber via Spontaneous Coagulation Assisted by Sugars.

Natural rubber (NR) as a renewable biopolymer is often produced by acid coagulation of fresh natural latex collected from Hevea brasiliensis. However, this traditional process is facing a huge economic and environmental challenge. Compared with the acid coagulation, spontaneous or microorganism coagulation is an ecofriendly way to obtain NR with excellent performance. To clarify the influence of different sugars on NR quality, several sugars were used to assist the coagulation process. Influence of different sugars on microstructure and cold crystallization were examined by 1H NMR, DSC, etc. The results indicated that sugars exhibit different biological activity on terminal components of fresh field latex and can influence the resultant molecular structure and basic properties. Brown sugar exhibits higher metabolic activity and is inclined to decompose the protein and phospholipids crosslinking compared with other sugars. The larger molecular weight of sugar molecule is beneficial for the formation of the stable α lamellae phase and higher overall degree of crystallization.

Evaluation of Antifungal Activity of Various Plant Latex against Selected Fungal Strains

Abstract: Latex is a natural plant polymer and milky white fluid distributed throughout the plant body like leaves, stems, roots and fruits of all flowering plants and consists of proteins, alkaloids, starches, sugars, oils, tannins, resins and gums that coagulate on-air exposure. It is secreted by specialized plant cells called Laticifers. Plants exude latex in response to physical damage. The present study was carried out to assess the potential antifungal activity of latex of five different plants namely Plumeria rubra, Plumeria alba, Aloe vera, Calotropis procera and Calotropis gigantea against three different pathogenic strains of fungi. All five latexes were found to show good to moderated activity against all the three fungal strains, namely Trichoderma viride, Aspergillus flavus and Aspergillus niger. The latex of each plant was tested in two volumes (i.e. 10µl & 20µl), and it was found that the antifungal activity was volume-dependent, and a significant difference was also observed in the case of different fungal strains. The antifungal activity of plant latexes was evaluated by Agar well diffusion method; results revealed that among all the five latexes, the fresh latex of Plumeria rubra (Vol: 10µl &20µl) showed excellent antifungal activity against Aspergillus niger and Aspergillus flavus, whereas fresh latex of Aloe vera (Vol: 10µl & 20µl) showed excellent antifungal activity against Trichoderma viride. The results of the current research imply that the antifungal activity of latex varies with the species of plants and the fungal strains used. The results therefore demonstrated that, the used five latexes effectively inhibited the growth of three tested fungi. Hence, these plant latexes are natural, ecofriendly and can be used as good candidates for the treatment of various fungal diseases. In further words, they can be used for therapy of antifungal-resistant fungi. Keywords: Antifungal activity, Proteins, Alkaloids, Tannins, Resins, Laticifers, Plumeria rubra, Plumeria alba, Aloe vera, Calotropis procera, Calotropis gigantea, Aspergillus flavus, Aspergillus niger, Trichoderma viride, Latex, Agar well diffusion.

Rubber Degrading Strains: Microtetraspora and Dactylosporangium.

Rubber composed of highly unsaturated hydrocarbons, modified through addition of chemicals and vulcanization are widely used to date. However, the usage of rubber, faces many obstacles. These elastomeric materials are difficult to be re-used and recovered, leading to high post-consumer waste and vast environmental problems. Tyres, the major rubber waste source can take up to 80 years to naturally degrade. Experiments show that the latex clearing proteins (Lcp) found in Actinobacteria were reportedly critical for the initial oxidative cleavage of poly(cis-1,4-isoprene), the major polymeric unit of rubber. Although, more than 100 rubber degrading strains have been reported, only 8 Lcp proteins isolated from Nocardia (3), Gordonia (2), Streptomyces (1), Rhodococcus (1), and Solimonas (1) have been purified and biochemically characterized. Previous studies on rubber degrading strains and Lcp enzymes, implied that they are distinct. Following this, we aim to discover additional rubber degrading strains by randomly screening 940 Actinobacterial strains isolated from various locations in Sarawak on natural rubber (NR) latex agar. A total of 18 strains from 5 genera produced clearing zones on NR latex agar, and genes encoding Lcp were identified. We report here lcp genes from Microtetraspora sp. AC03309 (lcp1 and lcp2) and Dactylosporangium sp. AC04546 (lcp1, lcp2, lcp3), together with the predicted genes related to rubber degradation. In silico analysis suggested that Microtetraspora sp. AC03309 is a distinct species closely related to Microtetraspora glauca while Dactylosporangium sp. AC04546 is a species closely related to Dactylosporangium sucinum. Genome-based characterization allowed the establishment of the strains taxonomic position and provided insights into their metabolic potential especially in biodegradation of rubber. Morphological changes and the spectrophotometric detection of aldehyde and keto groups indicated the degradation of the original material in rubber samples incubated with the strains. This confirms the strains’ ability to utilize different rubber materials (fresh latex, NR product and vulcanized rubber) as the sole carbon source. Both strains exhibited different levels of biodegradation ability. Findings on tyre utilization capability by Dactylosporangium sp. AC04546 is of interest. The final aim is to find sustainable rubber treatment methods to treat rubber wastes.

Preparation and Properties of Papain Precipitated from Fresh Latex of Papaya Fruits (Carica papaya)

Papain was precipitated from cysteine hydrochloride extract of fresh latex of papaya fruits planted in AlexandriaGovernorate, Egypt. Three precipitants; namely, ethyl alcohol, acetone and sodium chloride resulted in proteolyticactivity recovery 84.8 (of three fractions), 85.2 and 76.7 %, respectively. Acetone was found to be the most promisingrapid and simple conditions for preparing acetone dry powder of partially purified crude papain. Papain propertiesindicated that the maximum activity was attained at pH 7.5–8.0, and temperature of 75 -85°C. The activity was notaffected by Na+ or Ca++ ions. Various degrees of inhibition were exerted by Ni+,+, Co++, Pb ++,and Hg++., while Cu++,caused complete inhibition .On the other hand, the proteolytic activity increased to various levels, in the presenceof Sn++, cyanide, thioglycolic acid, and cysteine hydrochloride. The catalytic activation (49%) of Sn++ was found todepend to some extent on the concentration. A mixed stored papain-oryzae protease preparation ,was found to retain71, 63, and 54 % of its proteolytic activity upon storage at 25°C for 1, 2 ,and 3 months ,respectively. The retainedactivity was more pronounced, being 92, 80,and 69 %, respectively upon storage at –5°C for the aformentioned durations,accordingly, storage at –5°C for up to 2 months, was recommended. The storage stability of papain powder andsolutions were studied. A papain-oryzae protease preparation was formulated for further use in meat tenderization.

Sustainability indicators for rubber plantations in Thailand: Environmental integrity dimension

The natural rubber industry has played a vital role in Thailand’s economic, environmental, and social contexts. Therefore, sustainable rubber production is a significant concern. At present, a wide variety of international tools has been developed to assess the agricultural sector’s sustainability performance. The Food and Agriculture Organization of the United Nations developed the Sustainability Assessment of Food and Agriculture systems ( SAFA) in 2013. Environmental integrity is one of the dimensions of sustainability in SAFA. SAFA is applied to assess the impact of agriculture operations on the environment. This research aims to assess suitable environmental integrity indicators in compliance with SAFA for rubber plantations in Thailand. The system boundary is set to cover rubber plantations, harvesting of fresh latex, and rubber tree felling. This work conducted focus group discussions, using the SAFA, guidelines, indicators, and tools for rubber plantations, the review process by rubber plantation experts, representatives of rubber associations, SAFA researchers, and environmental scholars, and site visits to interview rubber farmers in the south, northeast, and north of Thailand. Environmental themes, including the atmosphere, water, land, biodiversity, and material and energy were included in assessing the environmental integrity of a rubber plantation. Animal welfare was not included.

The investigation of optimum condition of natural rubber epoxidation reaction in latex phase

Natural rubber (NR) latex epoxidation is a chemical modifcation of natural rubber to produce natural rubber with higher polarity (oil resistant) which is commonly called epoxidized natural rubber (ENR). ENR is produced from the reaction of natural rubber latex with performic acid. Performic acid is formed from in situ reaction between formic acid and hydrogen peroxide. During epoxidation process, the carboxyl group of natural rubber is converted into epoxy group and various side reaction products such as carbonyl, hydroxyl, and hydro furan. These side products must be minimalized to optimize the epoxy level. The epoxidation reaction was carried out at 70 ° C for 6 hours using 2 types of latex: fresh latex (FL) and concentrated latex (CL). The addition of reactant was varied in two ways: dropwise (coded “1”) and poured all at once (coded “2”). The epoxy product and rate constant (k) were analyzed to obtain optimum reaction condition. The epoxy and side reaction content were determined by Attenuated Resonance Fourier Transform Infrared (ATR-FTIR). The slope of epoxy-time plotting curve was determined as ENR rate constant (k). The optimum NR epoxidation reaction was achieved in CL2, which exhibited lowest value of side reaction and highest value of k (2.8082x10 -5 L mol -1 sec -1 ).

Effect of Preservative HB on Preservation Effect of Fresh Latex and Property of Raw Rubber

Effect of Preservative HB on Preservation Effect of Fresh Latex and Property of Raw Rubber

Evaluation of the potential environmental impacts of condom production in Thailand

ABSTRACT This study aims to analyse the potential environmental impact of natural rubber (NR) condoms over its entire life cycle. The environmental performance of the production process of NR condoms is also compared to that of synthetic polyisoprene (PI) condoms. Options to reduce the environmental impact of condom production are proposed and evaluated. The potential environmental impacts are quantified by life cycle assessment (LCA). The study takes a cradle-to-grave approach, and considers six phases: 1) fresh latex production, 2) concentrated latex production, 3) condom production, 4) condom use, 5) condom transportation, and 6) condom disposal. The comparative analysis of NR and PI condom production takes a gate-to-gate scope. The functional unit is one gross condom. The results indicate that the condom production phase has the largest share (34–73%) in the environmental impact during the life cycle of NR condoms, followed by the disposal phase (20–60%). Comparing the production of NR and PI condoms reveals that the production of PI condoms results in a 1.5–2.5 times higher environmental impacts than the NR condom production, due to higher electricity consumption, especially for the compounding, dipping, and leaching processes. Reduction of electricity use is a key measure to reduce the environmental impact. Combining natural gas with electricity for the dipping process is a promising option to reduce the electricity use; it results in ~10–17% reduction in environmental impacts.

Lipid Composition of Latex and Rubber Particles in Hevea brasiliensis and Taraxacum kok-saghyz.

Natural rubber is usually synthesized in the rubber particles present in the latex of rubber-producing plants such as the Pará rubber tree (Hevea brasiliensis) and rubber dandelion (Taraxacum kok-saghyz). Since the detailed lipid compositions of fresh latex and rubber particles of the plants are poorly known, the present study reports detailed compound lipid composition, focusing on phospholipids and galactolipids in the latex and rubber particles of the plants. In the fresh latex and rubber particles of both plants, phospholipids were much more dominant (85–99%) compared to galactolipids. Among the nine classes of phospholipids, phosphatidylcholines (PCs) were most abundant, at ~80%, in both plants. Among PCs, PC (36:4) and PC (34:2) were most abundant in the rubber tree and rubber dandelion, respectively. Two classes of galactolipids, monogalactosyl diacylglycerol and digalactosyl diacylglycerol, were detected as 12% and 1%, respectively, of total compound lipids in rubber tree, whereas their percentages in the rubber dandelion were negligible (< 1%). Overall, the compound lipid composition differed only slightly between the fresh latex and the rubber particles of both rubber plants. These results provide fundamental data on the lipid composition of rubber particles in two rubber-producing plants, which can serve as a basis for artificial rubber particle production in the future.

Rheological behavior of fresh latex polymeric mortar by squeeze-flow technique

This work reports the first experimental effort using the squeeze-flow technique for evaluating the rheological behavior of latex polymeric mortar. Polymeric mortar (PM) is a new class of building material used for laying bricks on non-structural walls replacing Portland cement mortar. The rheological behavior of using fresh PM as a function of the latex resin content was assessed by squeeze-flow technique. Samples were tested at two displacement rates (0.01 mm/s and 3 mm/s), up to a maximum displacement of 9 mm. The results indicated that the squeeze-flow technique is a viable method for the rheological characterization of fresh polymeric mortar. Rheological parameters such as viscosity and yield stress were determined successfully. Mortars with a higher resin content were more difficult to deform, resulting in higher loads. Furthermore, the viscosity as well as the yield stress showed a strong positive linear correlation with the resin content of the PM. The test results suggest that the rheological parameters are sensitive to displacement rates. The lowest displacement rate (0.1 mm/s) resulted in lower deviations, higher viscosity and lower yield stress.